University of Southampton

Faculty of Engineering and Applied Science

Department of Civil and Environmental Engineering

Institute of Irrigation Studies

Potential of Sewage Effluent Reuse

for Irrigation in Jordan

By

Suzan Taha

A dissertation submitted in Partial fulfilment of

the degree of MSc (Irrigation Engineering) by

instructional course

September 1993

1. INTRODUCTION

The Demand for water in Jordan is increasing due to high

population growth, urbanization and increased industrial

and agricultural activities. In order to meet the

country's increasing needs, Jordan's limited water

resources have been stretched by overabstraction from

renewable groundwater and pumping out of non-renewable

resources. The limited availability of water is further

worsened by increased costs to develop and transport

additional sources. Since water is a limiting factor for

industrial and agricultural development, a rational plan

to manage the country's water resources should be

undertaken. Minimizing wastage is only one step in this

regard. It has already been decided in Jordan that

wastewater reuse has an effective role in minimizing

wastage.

Unlike fresh water, sewage effluent is increasing in

supply and is usually unsuitable for anything but

irrigation. Because wastewater in Jordan is being

treated for environmental protection, treated effluent

reuse becomes relatively cheap. Hence, the only costs

involved are the marginal cost of additional treatment

and distribution system.

When used near the wastewater treatment plant, treated

effluent recycling through irrigation provides a means of

disposal without polluting receiving waters. An example

of the latter is provided by the eutrophication and

deteriorating water quality of King Talal Reservoir,

downstream of As Samra Treatment plant. Other advantages

include:-

1. The use of available fertilizing constituents and

the organic matter as a soil conditioner.

2. Protection of the effluent from further

contamination.

3. Protection against transmission of disease from one

area to another.

On the other hand, if sewage effluents are to be used

for irrigation, one has to consider the following

potential problems:-

1. Salinity, sodicity and toxicity hazards resulting in

lower crops yield and produce quality.

2. Public health risks.

3. Environmental degradation.

The aim of this dissertation is to identify the potential

of treated effluent reuse for irrigation in Jordan. The

latest available information on the treated effluents

quality is presented. The sewage effluents suitability

for irrigation is assessed using WHO health regulations

and FAO guidelines on water quality for irrigation. Of

all the treated effluents presently discharged, detailed

analysis is made of As Samra treatment plant effluent,

being the most significant in terms of quantity and reuse

potential. The potential hazards in relation to public

health and irrigation use are assessed, and the necessary

management practices are prescribed.

2. THE NEED IN JORDAN FOR WASTEWATER REUSE

2.1 Background

Jordan is an arid to semi-arid country with a land area

of about 90,000 Km2, east of the Jordan River. A

mountainous range runs from north to south. To the East,

the land slopes gently to form the desert. To the west,

the land falls steeply towards the Jordan Rift Valley,

which extends from Lake Tiberias (at an altitude of -220

m) to the Red Sea at Aqaba, (Map 2.1). About 120 Km

South of Lake Tiberias lies the Dead Sea, at -405m. The

Southern Ghors and Wadi Araba, south of the Dead Sea,

form the southern part of the Rift Valley (13)

. Jordan's

population estimated at 3.888 Million (1991) is growing

rapidly, at 3.6% a year. Almost 78% of the population is

urban, with 1.231 Million concentrated in Greater Amman,

the capital, and 0.585 Million in Zarqa, the second

largest city (20)

.

Jordan's average rainfall amounts to about 8.4 Million

Cubic Meter (MCM)/year. The average annual precipitation

ranges between 50 and 600 mm. Rainfall exceeding the

limit necessary for cultivated agriculture (300 mm)

covers about 4% of the land area in the north, north

western highlands and Jordan Valley (35)

, (Map 2.2). About

85% of rainfall evaporates, 5-10% drains into the

Groundwater and the rest flows in rivers and wadis

leading to the Jordan River and its tributary, the

Yarmouk, along the northern frontier with Syria. The

rainy season is normally between late October and April,

with the heaviest rains between January and March (34)

.

2.2 Water Resources in Jordan

At present, surface water resources average about 692 MCM

distributed unevenly in 15 basins (34)

, (Map 2.1). The

Yarmuk River accounts for about 35% of Jordan's total

Insert Map 2.1

Insert Map 2.2

surface water resources, and is of good quality with

total dissolved solids (TDS) in the 400-800 ppm range (40)

.

Other surface resources include the Zarqa River and

several wadis that run west from the highland to the Rift

area. The Zarqa river flow is augmented by sewage

effluent from As-Samra and smaller treatment plants

serving Amman and Zarqa area. The river is controlled by

the King Talal Reservoir which has a storage capacity of

86 MCM. Because of the large quantity of sewage effluent

entering Zarqa River and King Talal Reservoir, water

quality becomes a concern. The quality of the water in

the wadis is generally good, except for a few saline

springs in some. To date about 500 MCM/year of surface

water resources have been developed for irrigation,

municipal, and industrial use. Full development is

impeded by regional political considerations and related

riparian rights of the Yarmuk River, and the high cost to

develop and transport the remaining sources of water

estimated at US$ 6-7 per m3 (21)

.

The long-term safe yield of renewable groundwater

resources is 275 MCM/year. The main nonrenewable

groundwater resource in Jordan exists in the Disi aquifer

in the South, with a safe yield of 125 MCM/year for 50

years. Its water quality is generally less than 500 ppm

TDS. Other nonrenewable groundwater resources are

estimated at an annual safe yield of 18 MCM, table 2.1 (34)

.

Table 2.1 Available Water Resources in Jordan

Source Quantity (MCM/Year)

A. Groundwater

- Renewable

- Nonrenewable

418

275

143

B. Surface Water

- Base flow

- Flood flow

692

358

334

Total 1110

Source: MWI (1993)

2.3 Water Resources Use in Jordan

The semi-arid climate of Jordan characterized with low

precipitation, the high population growth rates and the

annual growth in municipal, industrial and irrigation

demand contribute to water scarcity and overstress the

existing water supplies. In 1991 the total annual use of

water has been estimated at 833 MCM. Of this total, 512

MCM were abstracted from groundwater, and surface water

consumption amounted to 321 MCM, table 2.2 (34)

.

Table 2.2 Water Use in Jordan (1991)

Resource

Quantity (MCM/Year)

Municipal Industry Irrigation Total

Groundwater 155 31 326 512

Surface Water 23 11 287 321

Total 178 42 613 833

Source: MWI (1993)

The total use of 833 MCM compared to an estimated annual

supply of surface and replenished groundwater of 596 MCM

for the same year. The overdraft of 237 MCM was covered

by overabstraction from renewable groundwater, and

pumping out of nonrenewable resources.

2.3.1 Agricultural Water Use

About 613 MCM, 74% of the total water supplied, is used

for irrigation, of which 53% is abstracted from wells

developed mainly in the highlands by the private sector

under drilling permits, with the remaining 47% being

provided by surface water. About 64% of the groundwater

supplied and 89% of the surface water consumption is used

for irrigation, with nearly 80% of the latter diverted

for the irrigated agriculture in the Jordan Valley and

Southern Ghors through the Jordan Valley Authority (JVA).

Drip irrigation is mostly used in areas irrigated from

privately owned wells and presently covers about 90% of

those areas. About 66% of the irrigated lands in the

uplands utilize drip irrigation, 16% sprinklers and 18%

surface (33)

. In the Jordan Valley, where developed

surface waters are used mainly for irrigation, the

percentages are 40% drip, 52% surface and 8% sprinklers (29)

. The share of each of these methods, however, differ

from one region of the valley to another, depending on

water scarcity and cropping pattern. Surface methods are

most common in the northern region where surface

irrigation system still exists, and become less favoured

in the south valley where water is usually more scarce.

2.3.2 Municipal and Industrial Use

About 220 MCM were used for municipal and industrial

purposes, of which 178 MCM were provided for municipal

use, about 21% of the country's water use in 1991. More

than 87% of municipal water and about 74% of the

industrial water is provided by groundwater. The average

offer of municipal water of 46 m3/capita/year constituted

only 46% of the minimum accepted internationally (34)

.

This average share does not reveal, however, the per

capita demand variations between the urban and rural

population. Included within the per capita municipal

supply are losses due to leakages in the networks,

estimated at 30-35%.

2.3.3 Reuse of Treated Wastewater

The present amount of reused treated wastewater is

37 MCM/year, which constitutes about 6% of the water used

for irrigation in 1991. It is expected that this amount

will increase to 69 MCM in the year 2000 and 110 MCM in

2010, constituting more than 10% of the total available

resources and about 40% of the renewable groundwater

resources.

2.4 Water Demand and Supply

Despite overabstractions from aquifers in the uplands,

water used for irrigation in 1991 constituted only 77% of

the total irrigation requirements estimated at 800 MCM.

Of the 475 MCM required for irrigation in the Jordan

Valley and Southern Ghors (at 118% cropping intensity)

only about 53% was actually diverted. Part of the

deficit was met by leaving irrigated lands fallow, and by

reduced cropping intensity.

In 1991, the average per capita share of all water uses

amounted to 215 m3/year, way below the water poverty line

defined at 2000 m3 of fresh water per capita per year

(4).

According to this definition, Jordan is considered to be

chronically short of water. The water deficit based on

demand requirements, estimated in 1991 at 321 MCM, is

expected to increase to about 654 MCM by the year 2010.

Table 2.3 shows the widening gap between annual water

demand and supply assuming no further development of

water resources.

It is evident that with the severe limitations on the

availability of water in Jordan and the growing

competition on potable water, decreasing amounts will be

allocated for agriculture in the future. Hence, tapping

of unconventional sources of water should be a major

consideration in supplementing the entirely committed

conventional resources. Since agriculture can accept low

quality water, wastewater reuse in Jordan should allow

the release of higher quality water for drinking and

hence has to be considered as part of the water balance

table. Furthermore, the increasing supply of sewage

effluent should provide a relatively cheap source of

water for agricultural purposes in spite of the increased

demands from the domestic and industrial sectors. Other

benefits include environmental pollution control of the

receiving waters such as King Talal Reservoir. In

addition, the nutrients and organic matter can be

considered as fertilizers and soil conditioners, respect-

ively, and are capable of improving crop yield. While it

is realized that the wastewater quantities generated are

not sufficient to solve the water balance deficit, the

potential of wastewater reuse as one of several measures

to enhance water supply and manage demand in the country

should not be overlooked.

Table 2.3 Projected Water Demand and Supply (MCM/Year)

Year 1991 1995 2000 2005 2010

A. Demanda

- Municipal

- Irrigation

- Industry

255

800

43

300

1088

62

359

1088

101

426

1088

124

500

1088

150

Total Demand 1098 1450 1548 1638 1738

B. Resources

- Available

- Treated Waste-

waterb

740

37

820

52

974

69

974

93

974

110

Total Resources 777 872 1043 1067 1084

Total Deficitc 321 580 505 571 654

Source: MWI (1993)

a Projected demand is based on 1991 population (including about

310,00 returnees after the gulf war) and on a suppressed municipal

water demand scenario of 188 litre/capita/day to be attained by the

year 2005. b Adapted from UNDP Project Files and adjusted for 1991 estimated

population by DOS. c Calculated deficits assume no further development of water

resources.

3. REGULATIONS IN SEWAGE EFFLUENT REUSE

3.1 Introduction

Sewage effluent primarily consists of water, together

with organic and mineral matter in the form of gross

solids, suspended solids, colloidal particles and matter

in solution. Organic substances include fats, soaps and

synthetic organic chemicals from the process industries.

Wastewater might also contain chemical pollutants that

are potentially toxic to man, plants and aquatic life.

Heavy metals fall into this category. Sewage also

contains a variety of micro-organisms pathogenic to man

and other animals. These include pathogenic viruses,

bacteria, protozoa and helminths excreted from the bodies

of infected persons and thus posing health hazards to the

farm workers and consumers, where effluent is reused in

irrigation.

Moreover, the types of exchangeable ions and the effect

of total dissolved solids present in the sewage effluent

are of particular concern to the soil properties and

plant growth. A possible long term problem with

wastewater irrigation is soil salinization. This is of

particular importance in Jordan where high rates of

evaporation result in subsequent salt deposition and

accumulation in the soil profile.

Because of the nature of sewage and the potential hazards

associated with effluent reuse, guidelines have been put

forth to protect against public health hazards and poten-

tial environmental damage. This chapter presents the

health and chemical aspects of wastewater reuse and the

most widely accepted standards in this field, namely the

World Health Organisation (WHO) health guidelines and

Food and Agricultural Organisation (FAO's) guideline for

the evaluation of water quality for irrigation. Existing

regulations for treated effluent reuse in Jordan are also

discussed and reviewed closely with both WHO and FAO

standards.

3.2 Health Aspects of Wastewater Reuse

3.2.1 Infections caused by excreted pathogens

Excreta-related infections are communicable diseases

caused by pathogenic viruses, bacteria, protozoa and

helminths excreted in the faeces by infected persons and

may be passed on to others via the mouth, or the skin as

in the case of hookworms and schistosomes (52)

. These

infections are of particular concern in countries, which

have diarrhea diseases and nematodes infections, such as

Jordan.

Excreta related infections of public concern have been

divided into five categories according to their environ-

mental transmission characteristics and pathogen prop-

erties, table 3.1 (23)

. Many of the excreted pathogens can

survive in wastewater for some time, hence those which

can withstand conventional treatment processes, can

arrive at the field in numbers large enough for human

infection to be theoretically possible. However,

infection occurs only if an infective dose is received by

a susceptible host, and this depends on the following (16)

:

1. Survival time of the pathogen in the soil, on the

crop, in fish or in water.

2. The presence, for categories IV and V infections

(see table 3.1), of the required intermediate host.

3. The mode and frequency of wastewater application.

4. The type of crop to which wastewater is applied.

5. The nature of exposure of the human host to the

contaminated soil, water, crop or fish.

Table 3.1 Environmental Classification of Excreted Infections

Category and

epidemiological

features

Infection Environmental

Transmission

Focus

Major

Control Measure

I. Non-latenta;

low infective

dose

Amoebiasis

Balantidiasis

Enterobiasis

Enteroviral

infections

Giardiasis

Hymenolepiasis

Hepatitis A

Rotavirus infe-

ction

Personal

Domestic

Domestic water

supply.

Health educa-

tion.

Improved hous-

ing.

Provision of

toilets.

II. Non-

latent; medium

or high infe-

ctive dose;

moderately

persistentb;

able to multi-

ply

Campylobacter

infection

Cholera

Pathogenic Esc-

hericiacoli

infection

Salmonellosis

Shigellosis

Typhoid

Yersiniosis

Personal

Domestic

Water

Crop

Domestic water

supply.

Health educa-

tion.

Improved hous-

ing.

Provision of

toilets.

Treatment of

excreta before

discharge or

reuse.

III. Latent and

persistent; no

intermediate

host

Ascariasis

Hookworm infec-

tion

Strongyloid-

iasis

Trichiriasis

Yard

Field

Crop

Provision of

toilets.

Treatment of

excreta before

land applica-

tion.

IV. Latent and

persistent; cow

or pig as

intermediate

host

Taeniasis Yard

Field

Fodder

Provision of

toilets.

Treatment of

excreta before

land applic-

ation.

Cooking, meat

inspection.

V. Latent and

persistent;

aquatic and

intermediate

hosts

Chonorchiasis

Diphyllobothri-

asis

Fascioliasis

Fasciolopsiasis

Gastrodiscoidi-

asis

Heterophyiasis

Metagonimiasis

Opisthorchiasis

Paragonimiasis

Schistosomiasis

Water

Provision of

toilets.

Treatment of

excreta before

discharge.

Control of

animal reser-

voirs.

Control of

intermediate

hosts.

Cooking of

waterplants and

fish.

Reducing water

contact.

a Latency is minimum time from excretion by man to potential

reinfection by man.

b Persistence refers to maximum survival time of final infective

stage.

Source: Feachem et al. (1983)

Table 3.2 shows that almost all excreted pathogens can

survive in water, soil and crops for a sufficiently long

time to pose health risks to farm workers. Pathogens

survive on crop surfaces for a shorter time than in soil,

as they are less well protected from the harsh effects of

sunlight and desiccation. However, survival times can be

long enough in some cases to pose potential risks to crop

handlers and consumers, especially when they exceed the

length of the crop growing cycle, as is often the case

with vegetables (32)

.

Table 3.2 Survival of Excreted Pathogens (20-30o

C)

Type of pathogen Survival times in days

In faeces,

nightsoil

and sludge

In fresh water

and sewage

In the soil On crops

Viruses

Enteroviruses

< 100 (<20)a

< 120 (<50) < 100 (<20) < 60 (<15)

Bacteria

Faecal cliforms

Salmonella spp

Shigella spp

Vibrio Cholerae

< 90 (<50)

< 60 (<30)

< 30 (<10)

< 30 (< 5)

< 60 (<30)

< 60 (<30)

< 30 (<10)

< 30 (<10)

< 70 (<20)

< 70 (<20)

-

< 20 (<10)

< 30 (<15)

< 30 (<15)

< 10 (< 5)

< 5 (< 2)

Protozoa

Entamoeba histolytica cysts

< 30 (<15)

< 30 (<15)

< 30 (<15)

< 30 (<15)

< 20 (<10)

< 20 (<10)

< 10 (< 2)

< 10 (< 2)

Helminths

Ascaris lumbricoides eggs

Many months Many months Many months <60 (<30)

a Figures in brackets show the usual survival time

Source: Feachem et al.(1983)

3.2.2 Epidemiological evidence

The actual risk involved in agricultural use of

wastewater will be of public health importance only if it

results in excess incidence or disease transmission.

Available epidemiological studies, in this regard, have

been reviewed by Shuval et al.(1986). Their findings

indicate that (1) crop irrigation with untreated

wastewater causes significant excess infection with

intestinal nematodes in both consumers and farm workers,

(2) bacteria present a high actual risk and the viruses

little or no actual risk, and (3) treatment of wastewater

is a very effective method of safeguarding public health.

3.2.3 Microbiological quality criteria

Based on available epidemiological evidence concerning

agriculture use of human wastes, guidelines for the

microbiological quality of treated wastewater intended

for crop irrigation, were formulated and are outlined in

table 3.3 (52)

. The intestinal nematode egg guideline

value, designed to protect field workers and crop

consumers, represents a high degree of egg removal from

the wastewater (99.9%) in areas where helminth diseases

are endemic. If this guideline is complied with, all

helminths and protozoan cysts will also be removed to the

same extent.

The faecal coliform guideline value is considered more

than adequate to protect the health of consumers. Where

farm workers are the only exposed population, no

bacterial guideline are recommended, since there is

little or no evidence indicating a risk to such workers

from bacteria. A more stringent guideline value ( 200

faecal coliforms per 100 ml) is recommended where the

public may come into direct contact with lawns irrigated

with treated wastewater.

3.2.4 Technical options for health protection

Available measures for health protection can be grouped

under waste treatment, crop restriction, waste

application methods and control of human exposure (32)

.

Waste Treatment

Without supplementary disinfection, conventional

processes (plain sedimentation, activated sludge, and use

of biological filters, aerated lagoons and oxidation

ditches) are not able to produce an effluent that

complies with the recommended bacterial guideline for

Category A irrigation.

Table 3.3 Recommended Microbial Quality Guideline For Wastewater Reuse in Irrigation

a

Category Reuse

Conditions

Exposed

Group

Intestinal ne-

matodesb

(arithmetic

mean no. of

eggs per

litrec)

Faecal colif-

orms (geomet-

ric mean no.

per 100 mlc)

Wastewater treat-

ment expected to

achieve

microbiological

quality

A Irrigation of

crops likely to be

eaten uncooked,

sports field,

public parksd

Workers

Consum-

ers

Public

1 1000d

A series of stabiliz-

ation ponds designed

to achieve the

microbiological

quality indicated, or

equivalent treatment

B Irrigation of

cereal crops,

industrial crops,

fodder crops,

pasture and

treese

Workers 1 Not applicable Retention in stabiliz-

ation ponds for 8-10

days or equivalent

helminth and faecal

coliform removal

C Localized irriga-

tion of crops in

category B if

exposure of

workers and the

public does not

occur

None Not appli-

cable

Not applicable Pre-treatment as

required by the irri-

gation technology,

but not less than

primary sedimen-

tation.

a In specific cases, local epidemiological, socio-cultural and environmental factors should be taken into account, and these

guidelines modified accordingly. b

Ascaris, Trichuris and hookworms. c During the irrigation period.

d A more stringent guideline ( 200 faecal coliforms/100 ml) is appropriate for public lawns, with which the public may have

direct contact. e In the case of fruit trees, irrigation should cease two weeks before fruit is picked, and no fruit should be picked off the

ground. Sprinkler irrigation should not be used.

Source: WHO (1989)

Moreover, these systems are not generally effective for

helminth egg removal. A series of ponds with a total

retention time of 8-10 days can achieve adequate helminth

removal, and about twice that time is usually required in

a hot climate to reach the bacterial guideline level for

category A.

Disinfection, usually chlorination, of raw sewage will

reduce the numbers of excreted bacteria in the effluent

from a conventional treatment plant, if maintained at a

uniform level of disinfection efficiency. Addition of

polishing ponds to conventional treatment plants is a

more appropriate measure to upgrade its effluent quality

for agriculture use.

Crop Restriction

Crops are categorised according to the exposed group and

the required health protection, as follows:

Category A: Protection required for consumers,

agricultural workers and the general

public

Category B: Protection required for agricultural

workers only.

Category C: No protection is needed.

If effluent standard does not meet the guideline for

category A irrigation, it may still be possible to grow

selected crops without risk to the consumer. However,

restriction of crops to those in category B, will protect

consumers, but not farm workers. Crop restriction should

therefore be complemented by other measures such as

partial treatment, and controlled application of

wastewater or human exposure control.

Waste Application Methods

Localized (trickle, drip or bubbler) irrigation can give

the highest degree of health protection. Sprinkler

irrigation should not be used on vegetables and fruit,

unless the effluent meets the guideline for category A

conditions. Flooding exposes field workers to the

highest risk and should not be used for vegetables.

Control of Human Exposure

Selection of human exposure control methods depends on

the population group being at potential risk from

wastewater use, namely, field workers, crop handlers,

consumers and those living near the fields concerned.

Control Measures include protective clothing, appropriate

footwear, fencing of the site, maintaining high levels of

hygiene and the provision of adequate medical facilites.

3.3 Criteria Based on Chemical Constituents

Four problem categories have been identified for

evaluation of conventional resources of irrigation (22)

.

Table 3.4 presents FAO 's guidelines for interpreting

water quality for irrigation. These are equally

applicable to evaluate wastewater for irrigation in terms

of chemical constituents, such as the TDS, relative

sodium content and toxic ions.

Salinity

A salinity problem exists if excess soluble salts accumu-

late which make the soil sollution sufficiently concen-

trated to injure plants and impair productivity. As the

total dissolved salts in reused wastewater tend to be

higher than normal irrigation water, more soil, water and

cropping problems should be anticipated. The salt

content of an effluent depends upon the the initial

salinity of the municipal water supply, the rate of water

consumption and the type and quantity of salts released

through industrial, commercial and household wastes.

Salts in soil or water reduce water availability to the

crop and hence affect crop yield. Plant symptoms vary

with growth stage and are similar to those of drought.

To prevent harmful salt concentrations in the root zone,

it is Insert Table 3.4

Insert Table 3.4 cont'd

therefore necessary to remove excess soluble salts at the

same rate at which they are applied. This can be

achieved through the process of leaching.

According to FAO guidelines, table 3.4, water may be

classified into one of three categories- no restriction,

slight to moderate restriction and severe restriction for

use. Ordinarily, no soil or cropping problems are

experienced when using water with values less than those

shown for no 'restriction on use' (TDS < 450 mg/l). To

achieve full yield potential, increasing care in crop

selection and management is required with restrictions in

the slight to moderate range and TDS between 450 - 2000

mg/l, typical range of treated effluent in Jordan (Tables

5.1 and 5.13). Soil, and cropping problems or reduced

yields are experienced if water used equals or exceeds

the values for 'the severe restriction on use'. A

specially designed cropping pattern, in addition to a

high level of management skill are hence required for

acceptable production. For the estimation of crop

responses to the effluent and soil salinity use can be

made of the crop tolerance and yield potential data

presented in appendix 3.1.

The Infiltration Problem

The infiltration problem is mainly related to the

relative proportions of sodium ions to calcium and

magnesium ions, termed the Sodium Absorption Ratio (SAR),

and the total concentration of soluble salts in the

infiltrating water. Besides the toxic effect upon

plants, sodium affects soil structure through cation

absorption, mainly on the clay and fine silt fractions.

As the percentage of sodium rises in relation to other

cations, the clay disperses, thus filling the small pore

spaces and hence results in greatly reduced infiltration,

particularly at soil surface, decrease in water supply to

crop between irrigations and reduced soil aeration

capacity.

Generally the infiltration problem increases with high

salinity water and decreases with either decreasing

salinity or increasing SAR. Therefore, when evaluating

potential infiltration problem, both ECw and SAR should

be considered as they relate to the unfavourable changes

in soil chemistry.

Since reused wastewater is already high in sodium, the

resulting high SAR becomes a major concern in wastewater

reuse projects. This is enhanced by changes in the

calcium content of the applied water following

irrigation, at which time calcium becomes a part of the

soil-water. Calcium changes occur due to dissolution of

soil minerals into the soil-water thus raising its

calcium content, or to precipitation from soil-water,

usually as calcium carbonate, thus reducing the calcium.

Factors affecting such changes include dilution,

bicarbonate content relative to calcium, and carbon

dioxide content. An adjusted sodium absorption ratio

(adj RNa), appendix 3.2, evaluates these effects and

predicts more correctly potential infiltration problem

for irrigation water including sewage effluent. This adj

RNa can be substituted for SAR in the infiltration

guidelines of table 3.4 and read jointly with ECw of the

applied water. Following such guidelines, infiltration

problems are not expected to be encountered in Jordan.

The treated effluent quality with respect to ECw and SAR

do not pose any potential for unfavourable changes to the

soil chemistry (Section 5.3.1.2). In addition, the soils

in Jordan are generally sandy or silty loam with a clay

content of around 20% and appear to have good drainage.

Specific Ion Toxicity

A toxicity problem occurs within the plant when certain

ions from marginal quality water are taken up with the

soil-water and accumulate in the leaves to an extent that

result in damage to the plant and reduced yield. The

ions of most concern in wastewater are sodium, chloride

and boron. These ions, are also of particular concern to

wastewater reuse in Jordan (Section 5.3.1.3).

Sodium toxicity occurs as a result of relatively high

sodium concentrations in the water (high Na or SAR) or,

in more complicated cases, may invlove possible calcium

deficiency in the soil. However, sodium toxicity for

tree crops is often associated with sodium concentrations

(in the leaf tissue) exceeding 0.25 to 0.5 percent on a

dry weight basis. The toxicity guidelines use SAR as an

indicator of the potential for sodium toxicity problem

following surface irrigation with a particular quality of

water, table 3.4. The relative sodium tolerance of

several crops, expressed in terms of soil exchangeable

sodium (ESP) is given in table 3.5. For the estimation

of soil ESP corresponding to the long term use of water

of a given SAR use can be made of the nomogram in

appendix 3.3

Sodium ions can also be absorbed directly into the plant

through the leaves wet by sprinkler irrigation,

especially during periods of high temperature and low

humidity. Depending on the relative tolerance of the

crop, foliar injury may occur, (Appendix 3.4).

Chloride, although essential to plant, is toxic at high

concentrations. Chloride content of water is increased

through municipal use. Table 3.6 gives the known crop

tolerances to chloride. A chloride toxicity can occur by

direct leaf absorption during sprinkler irrigation and as

such speeds the rate of toxic ion accumulation. Injury

symptoms develop when chloride is taken up by the crop

and accumulate in the leaves during water transpiration

to an extent that exceeds crop tolerance. With sensitive

crops, these symptoms occur when leaves accumulate from

0.3 to 1.0 Insert Table 3.5

Insert Table 3.6

percent chloride (dry weight). Many tree crops, however,

begin to show injury above 0.3 percent chloride (dry

weight).

The most prevailing plant toxicity from using reclaimed

municipal wastewater is caused by boron originating from

domestic use of bleaches or from industrial plants.

Boron is essential to plants at very low concentrations

but becomes toxic at higher levels. Relative boron

tolerance of agricultural crops is given in table 3.7.

Generally, sensitive crops' yield or vegetative growth

reductions will occur at boron concentrations of 0.5 -

0.75 mg/l, moderately tolerant at 2.0 - 4.0 mg/l and

tolerant crops at 4.0 to 6.0 mg/l. Problems with high

boron concentrations in some of the treatment plants in

Jordan have been rectified after 1990, through government

regulations restricting its use in detergents.

Miscellaneous Problems

In addition to specific-ion toxicity, many trace elements

are toxic to plants at low concentrations. Suggested

maximum concentrations for these elements in irrigation

are shown in table 3.8. These concentrations are based

upon a concern in their long term build-up in the soil,

which could result in human and animal health risks, or

cause phytotoxicity in plants. Of all the trace elements

tabulated, cadmium could present the most serious health

concern because of its tendency to accumulate in human

and animal livers and kidneys causing renal tubular

damage, and because of the continuous intake of the metal

by plants for many years (14)

.

At high concentrations copper could be toxic to plants

and thus reduce yields and at even higher concentrations

could cause animal toxicity. Nickel could be phytotoxic

to plants at around 50 mg/kg of plant tissues and

molybdenum

Insert Table 3.7

Insert Table 3.8

could be toxic to farm animals. Although Zinc is

relatively non-toxic to humans and animals, it is heavily

implicated as a prime cause of toxicity in crops (51)

.

Like cadmium, its uptake by plants is greater when the pH

is below 6.5. It should be noted that heavy metals

concentrations in treated effluents in Jordan are still

below FAO's recommended guideline (Section 5.3.1.3).

However, regular future monitoring of effluent quality is

required to ensure it does not exceed the guideline

values as more industrial wastewater discharges get

connected to public sewers.

A further factor to consider in respect with wastewater

irrigation is the high content of nutrients. Wastewater

especially from domestic sources contains nitrogen with

values ranging from 10 to 50 mg/l, well below those

observed in most of the treated effluents in Jordan

(Tables 5.1 and 5.13 and Sections 5.3.1.4 and 5.4).

While most crops are unaffected by nitrogen

concentrations below 30 mg/l, sensitive crops may be

affected when nitrogen exceeds 5 mg/l. Excess nitrogen

affects crop production due to overstimulation of growth,

delayed maturity or poor quality. Values less than 5

mg/l may stimulate nuisance, growth of algae in streams

and lakes and may result in plugged valves, pipelines and

sprinklers and increased maintenance cost for clearing

vegetation from canals.

Where the microbial effluent quality permits the use of

sprinkler irrigation for trees and vegetables, scale

deposits on leaves or fruits could be of special concern

when using effluent water containing a high proportion of

slightly soluble salts such as calcium, bicarbonate and

sulphate. Although there is no toxicity involved, the

deposit reduces the marketability of fruit and foliage

and thus requires expensive treatment before marketing.

Clogging of drip emitters also presents a problem.

3.4 Existing Regulations for Wastewater Reuse in

Jordan

Prior to 1989, legislations in Jordan, issued under

Martial Law No. 2/1982, limited the agricultural use of

treated wastewater to forest trees, fruit trees and

fodder crops. In 1989, a more advanced version of the

law was issued which relates the types of crops with the

effluent quality for reuse. The ban on irrigation of

cereals and vegetables eaten cooked was removed, provided

the treated effluent meets the corresponding helminth and

bacterial guidelines presented in table 3.9 (25)

.

While the new standards are more in line with the

stringent WHO guidelines with respect to helminth egg

removal, the microbial guideline absolutely prohibits

treated wastewater irrigation of crops that are eaten

uncooked. However, the guideline accepts a less

stringent standard for treated effluent irrigation of

public lawns, when the potential public health risk

associated with direct access to such lawns, may be

greater than those with irrigation of vegetables eaten

raw (52)

.

Moreover, the new law does not allow the use of primary

treatment effluents for localized irrigation of trees and

industrial crops where exposure of workers and the public

does not occur. According to WHO guidelines, such crops

could be irrigated with effluents from primary sewage

treatment, unless otherwise required by the irrigation

technology. The government has already specified

secondary (biological) treatment as the minimum treatment

requirement regardless of the effluent intended use (25)

.

Since helminthic pathogens have been identified in

Jordanian wastewater (5)

, this necessitates the addition

of polishing ponds as a means to upgrade the treated

effluent quality to meet the helminth guideline value, a

task that has been undertaken by the Water Authority of

Jordan (WAJ).

It is realized that such stringent guidelines arise out

of concern to protect existing health standards, however,

overstringent regulations can result in either illegal

use of wastewater (for strong economic motives), creating

the same health risks as if they did not exist, or

causing unnecessary fear of prosecution or diseases and

thus dissipate potential water resources. In the absence

of local epidemiological studies that justify the use of

restrictive guidelines, a revised national standard,

following WHO guidelines of table 3.3, should be

afforded. In the meantime, a more integrated approach to

minimise health risks should be considered. This should

aim at integrating waste treatment, crop restriction,

control of wastewater application method and human

exposure in any wastewater reuse strategy.

Apart from the microbiological guidelines outlined in

table 3.9, there currently are no regulations issued by

the government that establish specific limitations on the

chemical composition of treated effluent for agriculture

use. However, Jordanian Standard Specification No.

202/1981 and WAJ regulations of September 1988

establishes effluent limitations that are applicable to

the discharge of industrial wastewater to the surface

waters and municipal sewage treatment plants,

respectively.

Table 3.9 Microbial Quality Guideline For Wastewater

Reuse in Jordan

Reuse Type Intestinal

nematodes

Faecal colif-

orms

UNRESTRICTED

Irrigation of

crops to be eaten

uncooked.

Irrigation of

sports field, pub-

lic parks

Not allowed

1

Not allowed

200

RESTRICTED

Irrigation of cer-

eal crops, indus-

trial crops, fod-

ders and trees

1

1000

LOCALIZED

Irrigation of cer-

eal crops, indus-

trial crops fod-

ders, trees with

no exposure of

workers and the

public

Not allowed

Not allowed

Frequency of test-

ing

> 2 per month > 2 per month

Source: Al-Salem 1992

4. WASTEWATER REUSE IN JORDAN

4.1 Wastewater Quantities

In 1992, 45% of the population in Jordan were served by

sewer system. Large numbers of cesspits are, however,

still widely used and create groundwater pollution prob-

lems. Presently, most major cities and towns have sewage

collection networks and treatment plants. It is expected

that by the year 2010, the sewage service will reach

about 58% of the population, table 4.1.

Table 4.1 Percent Population Served and Projected Wastewater Quan-

tities

Year Population % Population

Sewered

Quantity

(MCM/Year)

1992a 4,024,080 45% 48.66

1995b 4,115,345 51.4% 61.30

2000b 5,270,067 54.3% 81.13

2005b 6,218,818 57.8% 103.71

2010b 7,321,785 57.9% 130.04

a Based on WAJ records (1992) b Adapted from UNDP Project files and adjusted for 1991 estimated

population by administrative division, published by DOS for the same

year.

The above estimated quantities and percentage population

served are based on the following assumption (Appendix

4.1):-

1. All potential properties within the existing

drainage areas will be connected to the wastewater

collection system by the year 1996.

2. An annual development of 1.4% in terms of 1991 esti-

mated served population will continue until 1996.

3. Expansion of the existing wastewater systems would

be in place by 1996; will reach about 70% of the

estimated urban population in the year 2005, and 75%

in the year 2010.

4. The per capita per day wastewater flow contribution

will continue to reflect the existing conditions in

the major urban areas until 1996, and will slightly

rise thereafter with increased water consumption.

Table 4.2 summarizes the projected wastewater quantities

by urban area, depicted in Appendix 4.1.

The actual volume of waste water available for effluent

reuse, table 4.4, will depend, however, on the

realization of wastewater development plans and

subsequently, the size of the population served. Other

factors include the actual quantities of municipal water

supplied to the users, their lifestyle and the type of

wastewater treatment plant (WWTP). Based on local

conditions, about 5% of conventional WWTPS inflows are

considered lost by evaporation from filter beds and

settling tanks. WAJ operation records indicate that

about 15%, 35% and 50% of waste stabilization ponds (WSP)

inflow is lost by evaporation and infiltration in

highland and lowland plants of Ma'an and Aqaba, respect-

ively, table 4.3.

Table 4.4 shows the estimated quantities of treated

effluent available for reuse, based on reducing

wastewater flows summarized in table 4.2, by the factors

shown in table 4.3. In calculating reuse potential,

wastewater discharges to cesspits and septic tanks

reaching groundwater, in addition to industrial

discharges not linked to the sewage system are not

considered part of the supply available.

Assuming that the effluent is reused on the lands

adjacent to the treatment plant and that the existing

treatment plants continue to serve the urban areas

outlined below, table 4.4 also shows the corresponding

areas that can be irrigated by the year 2010, based on a

cropping pattern similar to that prevailing in the

agroclimatic zone in which each treatment plant is

located. Underlying these Table 4.2 Estimated Wastewater Quantities by Urban Area, MCM/Year (1991 - 2010)

Urban Area 1991 1995 2000 2005 2010

Amman 30.557 37.078 40.201 50.794 64.468

Madaba 0.329 0.644 1.299 1.619 2.016

Zarqa 8.521 11.691 15.712 19.678 24.742

Irbid 2.027 2.810 6.358 7.868 9.724

Jarash 0.466 0.526 2.694 3.366 4.161

Ramtha 0.259 0.513 1.153 1.451 1.816

Ajlun 0.271 0.580 1.807 2.249 2.239

Mafraq 0.482 0.844 2.695 3.358 4.202

Salt 2.993 3.607 3.909 4.180 5.181

Karak 0.244 0.283 0.762 1.538 1.924

Tafila 0.175 0.377 0.497 1.003 1.255

Ma'an 0.303 0.709 1.039 2.104 2.633

Aqaba 1.535 1.633 3.006 4.498 5.684

Total Esti-

mated

48.144

61.295

81.132

103.708

130.043

Actual (WAJ

1991)

45.237

Adapted from UNDP Project Files and adjusted for 1991 estimated population.

Table 4.3 Estimated Reduction Factorsa for Effluent Reuse

Urban Area Reduction Factor Type of WWTP Serving

the Area

Amman 0.85 WSPb

Madaba 0.85 WSP

Zarqa 0.85 WSP

Irbid 0.95 CWWTPc

Jarash 0.95 CWWTP

Ramtha 0.85 WSP

Ajlun 0.95 CWWTP

Mafraq 0.85 WSP

Salt 0.95 CWWTP

Karak 0.95 CWWTP

Tafila 0.95 CWWTP

Ma'an 0.65 WSP

Aqaba 0.5 WSP

a Based on WAJ operation records (1991 and 1992) b Waste Stabilization Ponds c Conventional Wastewater Treatment Plant

Table 4.4 Estimated Quantities of Treated Effluent Reuse, MCM/year

(1991-2010) and the Corresponding Irrigated Areas in the

Year 2010

Urban

Area

1991 1995 2000 2005 2010 Irrigated Areas

(Ha) Year 2010

Amman 25.97 31.52 34.18 48.25 54.80 7288

Madaba 0.28 0.55 1.10 1.38 1.71 294

Zarqa 7.24 9.94 13.36 16.73 21.03 2797

Irbid 1.93 2.67 6.04 7.47 9.24 1424

Jarash 0.44 0.50 2.56 3.20 3.95 609

Ramtha 0.22 0.44 0.98 1.23 1.54 237

Ajlun 0.26 0.55 1.72 2.14 2.13 294

Mafraq 0.41 0.72 2.29 2.85 3.57 475

Salt 2.84 3.43 3.71 3.97 4.92 845

Karak 0.21 0.27 0.72 1.46 1.83 251

Tafila 0.17 0.36 0.47 0.95 1.19 163

Ma'an 0.20 0.46 0.68 1.37 1.71 240

Aqaba 0.77 0.82 1.50 2.25 2.84 326

Total

Estimated

40.94

52.21

69.31

93.25

110.47

15243

Actual

(WAJ

1991)

37.26

estimates is the assumption that wastewater flows would

be conveyed by closed pipes from the source and that drip

irrigation will be used. Assuming that one hectare of

irrigated land is adequate to support five persons(37)

,

then the total irrigated areas of 15243 ha would be

sufficient to produce food for 76213 people, about 1% of

the population in 2010.

4.2 Wastewater Treatment Plants in Jordan

There are fourteen WWTPs operating in Jordan, six of

which are WSPs, table 4.5. Other plants include extended

aeration, activated sludge or trickling filters. Sludge

comes out from conventional WWTPs and is disposed by land

application or dumping (21)

. Eighteen additional plants

are in the planning and design phases. Some will have

effluent flows available for reuse.

Table 4.5 Municipal Wastewater Treatment Plants in Jordan

Treatment

Plant

Year of

Start Up

Design

Capacity

m3/day

Type Receiving Water

As Samraa 1985 68000 WSP

d KTR

k

Mafraq 1988 1800 WSP Irrigation

Aqaba 1987 9000 WSP Irrigation

Ramtha 1988 2335 WSP Irrigation

Madaba 1989 2000 WSP Irrigation

Ma'an 1989 1335 WSP Landscaping,

Revegetation

Abu-Nuseir 1988 4000 RBC, ASe KTR

Baq'a 1988 6000 EF, SCf KTR

Irbidb 1987 11023 TF, AS

g Wadi Arab

Karak 1988 786 IT, TFh Wadi Karak, Irri-

gation

Tafila 1989 800 IT, TF Le-Ghoweir

Kufranja 1989 1800 IT, TF Wadi Kufranja

Saltc 1981 2442 EA

i Shu'eib Reservoir

Groundwater

Recharge

Jarashc 1983 1155 OD

j KTR

Source: Pride (1992) a Extension to As Samra is under study b Effluent is diverted to the Jordan Valley c Extension to Salt and Jarash is under study d Waste Stabilization Ponds e Rotating Biological Contactors, followed by Activated Sludge f Trickling Filters, Solid Contact g Trickling Filters, Activated Sludge h Imhoff Tank, Trickling Filter i Extended Aeration j Oxidation Ditch k King Talal Reservoir

4.3 Present Wastewater Reuse

Planned and deliberate use of treated wastewater (Direct

reuse) is still limited in Jordan. However, effluents

from WWTPs normally discharging to seasonal surface water

are reused in diluted form for restricted or unrestricted

irrigation (Indirect Reuse). The following types of uses

describes the situation in Jordan (25)

:-

1. Indirect (Intentional) Potable Reuse

Where sewage collection networks are not present, septic

tank and cesspool effluents infiltrate through the ground

layers and eventually reach the groundwater. In Seil

Zarqa area, treated effluent infiltrating into the

groundwater reservoir was estimated at 10 MCM/year in

1983 (26)

. Infiltration of polluted water seeping from the

floor of stabilization ponds in Aqaba is estimated at

4.24 mm/day (1992). This rate, however, is continuously

decreasing due to the self-sealing process of the floors

and embankments. Analysis of WAJ operation records on As

Samra WWTP indicates a total quantity of water recharged

through seepage in 1991, at about 1.24 MCM.

2. Intentional Groundwater Recharge for Non-Potable Reuse

The bulk of the effluent around Aqaba WWTP is being

applied to infiltration ponds to recharge brackish

groundwater aquifer. The same applies on Salt WWTP

effluent which recharges the aquifer below Wadi Shu'eib

Dam

3. Direct Irrigation Reuse

This is practised either on site or on the land adjacent

to the treatment plant. About 4 MCM/year are presently

used to irrigate fodders, cereals, fruit trees and

vegetables eaten cooked in As Samra, Ramtha, Mafraq,

Madaba and Ma'an.

4. Indirect Irrigation Reuse (Upstream of Dams)

About 700 ha of lands upstream of dams are irrigated with

treated effluent discharged to fresh surface water in the

Wadis and used for restricted irrigation, upstream of

King Talal Reservoir, Wadi Shu'eib Dam, and Wadi Arab

Dam.

5. Indirect Irrigation Reuse (Downstream of Dams)

Treated effluents discharged into the surface flow of

wadis and retained by dams are used for unrestricted

irrigation downstream of King Talal Reservoir in case of

As Samra , Abu Nuseir, Baq'a and Jarash treatment plants.

At Salt, the effluent is discharged to Wadi Shu'eib and

is partly used for the same purpose downstream of the

dam.

4.4 Wastewater Reuse and Health in Jordan

In 1981, it was believed, though not scientifically

proven, that an epidemic of cholera had been caused by

the use of water polluted with treated but not

disinfected wastewater for the irrigation of vegetables

eaten uncooked. Since then, all wastewater was required

to be treated and disinfected prior to discharge to

surface water. Restrictions on types of crops which may

be irrigated from sources likely to be polluted with

treated effluents were also imposed (19)

.

Apart from the information available on patients referred

to hospital clinics for the presence of intestinal infec-

tions, no cross sectional data exist on the community

prevalence of specific intestinal parasites in the

Jordanian population. Samples from patients visiting the

hospitals for non-parasitic medical care in 1988 showed

one per cent Ascaris, when tested for helminth eggs at

the Central laboratories of the Ministry of Health. In

Amman City, the average concentration of nematode eggs

per litre of raw sewage was 297, with Ascaris

lumbricoides being the dominant species at an average

concentration of 245 eggs per litre (6). Average egg

concentration in the raw sewage of Jarash, Salt and Abu

Nuseir was 150, 174 and 242 egg/litre, respectively.

Table 4.6 shows the variety of helminths identified in

the Jordanian wastewater (5).

This table also indicates that there is a potential risk

in reusing inadequately treated wastewater that cannot be

overlooked wherever the existing treatment system is not

effective for nematode egg removal. Presently, there is

no reliable information available on the numbers of

farmers and farm workers irrigating with particular

treated effluent and surface water containing such efflu-

ent. In order to assess the actual health risks involved

in wastewater reuse and before any decision on the need

for an epidemiological study can be made, preliminary

studies are required to gather such information as (a)

current reuse practices, water sources, effluent

discharge and crops grown, (b) the size of the exposed

population, (c) behavioural patterns, (d) the degree of

soil and crops contamination and (e) the degree of

prevalence of intestinal parasite infections in selected

farm workers and their families.

Table 4.6 Helminthic Pathogens Found in As Samra Pond System

Helminth Common Name

Ascaris Lumbricoides Round Worm

Trichuris Trichiura Whip Worm

Ancylostoma Duadenale Hook Worm

Diphyllobothrium Latum Fish Tape Worm

Enterobius Vermecularis Pigworm

Hymenolepis Nana Dwarf Tape Worm

Schistosoma Haematobium Schistosoma

Taenia Saginata Beef Tape Worm

Schistoma Mansoni Schistosoma

Necator Americanus Hookworm

Trematodes Haematobium Schistosoma

Strongyloides Stercoralis Threadworm

Source: Al-Salem 1988

5. ASSESSMENT OF TREATED WASTEWATER QUALITY FOR

IRRIGATION

5.1 Introduction

Of all the treatment plants presently operating in

Jordan, As Samra stabilization pond (referred to in maps

2.1 and 2.2 as Kh.Samra) is the largest and the most

significant for agriculture reuse. The plant currently

serves about 76% of Jordan's sewered population (49)

, in

the heavily populated Amman and Zarqa region and as such,

accounts for 81% of the treated wastewater flows in

Jordan. By the year 2010, and assuming that As Samra

plant will be expanded to accommodate the increased

wastewater generated by greater Amman and Zarqa

localities at the targeted 75% population sewered (table

4.2 and appendix 4.1), it is expected that the

contribution of this plant will be as significant, at

about 69% (table 4.4). Effluent from As Samra, presently

discharged to Zarqa River is used to irrigate some areas

along the river. After it reaches King Talal Reservoir

(KTR), it is released for reuse in unrestricted

irrigation in the Jordan Valley, and continues to

constitute an increasing proportion of water used in that

area. Assuming no agricultural reuse upstream, most of

KTR stored water in 2010 will be effluent discharged from

As Samra.

The aim of the following sections is to review and assess

the quality of treated wastewater for the use in irriga-

tion, with special emphasis on As Samra effluent. Back-

ground information on the latter and the existing reuse

sites are first provided. The treated effluent quality

is discussed and assessed with respect to WHO and FAO

guidelines at the discharge point and at several sites

downstream, after dilution. The necessary irrigation

management practices are also outlined. Similar, but

more general assessment of the country's WWTPs effluent

quality will also be in order.

5.2 Background on As Samra Waste Stabilization Pond

As Samra treatment plant consists of three parallel

treatment trains, each composed of two anaerobic ponds,

four facultative and four maturation ponds, occupying

about 181 ha. The ponds, originally designed for an

average flow of 68,000 m3/day

(40), are overloaded and

receives an average influent of 128,000 m3/day (1992)

(Appendix 5.1). Compared with a BOD design load of

35,768 kg/day (41)

, the average BOD load has increased by

80% during the same year (49)

. Due to the excessively wet

year in 1992, with the subsequent increase in the

hydraulic loads discharged to the system, the biochemical

oxygen demand (BOD) removal efficiency of 76% reflects

more than 10% decrease to that of 1991, estimated at 85%.

In addition, the large increase in population and the

increased wastewater loads and diversions have adversely

affected the ponds performance, and hence the effluent

quality. Map 5.1 shows a schematic layout of As Samra

treatment plant and the sampling points where the

effluent has been monitored by RSS since 1986. It should

be noted in this regard, that the discharge point of the

treated effluent in As Samra is referred to in the water

analysis reporting as site 4.

5.2.1 Existing Reuse Sites of As Samra Effluent

- Zarqa River Area

A small portion of the effluent is used for on-site

irrigation of a variety of trees. However, over 1.24 m3/s

(1992) is discharged to Wadi Dhuleil, a tributary of

Zarqa River, which flows to KTR. The dilution of the

treated effluent in the Wadi is negligible as the latter

is dry for most of the year (19)

. The mean base flow of

the Zarqa River just upstream of the confluence (referred

to as site 5) is less than the flow of the effluent. By

the time the river reaches Jarash Bridge, 41 km

downstream of As Samra, it has Insert Map 5.1

a base flow of 1.0 to 1.5 m3/s. This, however, may fall

to 0.5 m3/s in dry years

(19). Effluents from Jarash

treatment plant discharged to Wadi Jarash flows into the

Zarqa River at Jarash Bridge (site 7), 2 km downstream

from the works. The effluent, averaging 1510 m3/day in

1992 (49)

, is diluted by 1:155 and 1:1150 by the flow of

Zarqa River in dry and wet weather, respectively,

although much of the Zarqa flow is effluent from As Samra

(Appendix 5.3). Upstream of Jarash Bridge, the surface

water containing effluents is used for restricted

irrigation of a few hundred hectares (ha). In addition,

a series of wells has been drilled beside the river and

are used to irrigate 120 ha of vegetables. Downstream of

the bridge, water is pumped from the river to irrigate

cooked vegetables.

Effluents discharged by Abu Nuseir and Baq'a treatment

plants eventually reach KTR through the two tributaries

of Zarqa River, namely Wadi Addananeer and Rumeimeen.

However, effluent from As Samra remains to contribute

about 33% of the total water received by King Talal

Reservoir during 1991 (Appendix 5.2). Due to the wet

climatic conditions prevailing in 1992, As Samra effluent

provided KTR with only 18% of its total inflow (Appendix

5.3). Both values, however, do not reflect losses due to

seepage, evaporation and irrigation estimated at 5,763

MCM/year (2). Other sources of inflow to KTR include

springs in the Zarqa River area, irrigation return flows

and industrial discharges estimated at 6500 m3/day

(25).

Industrial discharges are considered the greatest sources

of KTR pollution.

- Jordan Valley

Water stored in KTR is released for unrestricted

irrigation in the Jordan Valley. During dry seasons, the

Zarqa River flowing into KTR becomes essentially sewage

effluent (Appendices 5.2 and 5.3). Presently about 1100

ha are irrigated in the Jordan Valley using KTR water

alone, and some other 8,900 ha using KTR releases after

entering the King Abdullah Canal (KAC). There have been

complaints about the quality of this water for

irrigation. Treated effluents started to reach KTR in

1985. Records show that EC of KTR water started to

increase steadily since then. Organic pollution and

faecal coliform contamination is increasing. Various

studies have confirmed that KTR is in a hypertrophic

condition. Masses of algae bloom occur every spring and

most of the warm months of the year. KTR thermally

stratifies during summer periods from March or April each

year. RSS records on KTR shows that the water quality of

the bottom layer is not much different from the surface.

However, the risk of anaerobic conditions arising in the

lower layer is likely to increase progressively in the

future, and would have adverse affects on crops if it

contained phytotoxins (19)

.

KTR water is discharged from a bottom outlet referred to

in water analysis reporting as site 600 (Map 5.2). Its

water flows in an open stream to a point referred to as

site 650, 17 km downstream of the outlet where water is

impounded by a diversion weir. It is then partially

distributed through closed pipe network for unrestricted

irrigation in Zarqa Triangle Project. The rest of the

water is diverted to a canal that meets KAC near Mu'addi.

KTR Total Dissolved Solids from the outlet to the point

of rediversion (at site 650) is increasing. Saline

Springs and seeps reportedly contribute to the

degradation and hence may limit the usefulness of the

water.

5.3 Water Quality of As Samra Effluent and Selected

Sites Along the Zarqa River

The following sampling sites were selected for water

quality assessment. These include sites 3, 4, 5, 5.1, 7

on map 5.1, and sites 100 and 600 on map 5.2. Sites 3

and 4 represent the inlet and outlet of As Samra WSP,

respective-

Insert Map 5.2

ly, and are selected to evaluate the plant's removal

efficiency with regards to certain parameters. Sites 5,

5.1 and 7 represent the flow of As Samra effluent along

the Zarqa River and sites 100 and 600 represent KTR water

both at the inlet and outlet, respectively. While it is

realized that KTR water quality downstream from the

outlet becomes more saline before it is ultimately

distributed to the farmers in the Middle Jordan Valley,

it is assumed that measures to reduce the salinity load

of KTR water downstream of site 600 will be taken through

the construction of a pipe line currently proposed to

transport water from KTR to the Valley. This implies

that the water quality at site 600 should represent that

at the farm inlets presently using KTR water in Zarqa

Triangle Project.

Table 5.1 gives the water quality data measured at the

previously mentioned sampling sites based on the latest

reports provided by RSS (41,42)

. Parameters not included in

these reports were obtained using the latest available

information from other sources. Despite the

inconsistency involved in a few cases, it is believed

that the available data should provide, in broad terms, a

good indication of the water quality in each site and has

therefore been used to determine such factors affecting

As Samra effluent quality both at the discharge point and

as it travels to its final destination in KTR.

Effluents from the ponds (site 4) are high in total sus-

pended solids (TSS); 150 mg/l with a BOD-5 of 124 mg/l.

Higher TSS concentrations are observed during summer

(Appendix 5.4) due to the increased concentration of

algae in the effluent. As the water travels along the

stream course, successive reductions in the TSS results

due to the natural death of algae and the dilution effect

of the springs and rain water, especially at, and

downstream of site 5.1.

Table 5.1 Average Water Quality of As Samra Effluent and Selected Sites along the Zarqa River

Parameter Unit Sampling Site

3a

4a

5a

5.1a

7a

100b

600b

General

Para-

meters

TSS mg/l 388 153 139 93 111 81 19

BOD-5 mg/l 489 124 104 49 35 21 6

BOD-S(F) mg/l 227 58 - - 9 - -

COD mg/l 1012 354 278 140 91 75 17

SO4 mg/l 79 29 43 91 100 - -

NH4-N mg/l 73 79 76 35 21 13.9 2.82

NO3-N mg/l - 0.6 0.8 6.1 9 10.4 6.03

T-N mg/l 94 91 - 41 30 28.71 11.42

T-P mg/l 14.1 18.3 - 8.3 8.5 4.96 1.68

MBAS mg/l 23.3 11.9 8 2.9 1.2 0.74 0.37

B mg/l 0.4 0.61 - - 0.44 0.41 0.23

TDS mg/l 1041 1204 - 1173 1099 1088 762

EC US/cm 1748 1976 2008 1764 1611 1514 1049

DO mg/l - 5.2 6.1 7 8.2 - -

pH SU 7.4 8 8.2 8.1 8.2 8.1 8.1

Na mg/l - 192 - - 153 146 84

SAR - 4.34 - - 3.04 2.89 1.88

Heavy

Metals

Al mg/l 0.22 0.9 0.1c

As mg/l <0.02 <0.02 <.005c

Cd mg/l <.003 <.003 <.005c

Cr mg/l <.01 <.01 <.01c

Cu mg/l <.01-.03 <.01 <.01c

Fe mg/l .07c

Li mg/l .05c

Mn mg/l 0.17c

Ni mg/l <.05c

Pb mg/l <.02 <.02 <.02c

Zn mg/l <.01c

Hg mg/l <.0002-

.0008

<.0002-

.0009

<.0005c

micro-

biolog-

ical

Cloro

phyll-a

mg/l - 87 - - 14 9.56 0.88

TFCC MPN-

/100ml

8.6 x

106

2.7 x

102

1.2 x

104

4.8 x

103

6.9 x

103

2.02 x

103

3.5 x 101

Nematodes Eggs/l 3 0 - 0 - 0 0

a Source: RSS (1993a). The average is arithmatic mean of measurements taken between March 1992 - February 1993

b Except for heavy metals concentrations, source is RSS (1993b). The average is arithmetic mean for the period February 1992 - January 1993. TFCC is the geometric

mean for the same period. c

Source: RSS (1992). Data based on average values of heavy metals concentrations in KTR water during January 1991.

The effluent organic pollution load, measured as BOD

ranges between 75 and 234 mg/l. Based on adopted

Jordanian standards for treated effluent quality, As

Samra ponds should achieve a mean BOD-5 filtered 29 mg/l (12)

, as compared with an average of 59 mg/l during the

study period. The high influent BOD-5 concentrations of

819 mg/l and 1254 mg/l representing Amman and Zarqa,

respectively, indicate very strong sewage discharged to

the ponds. Underlying the effluent BOD-5 quality are a

low per capita per day domestic water consumption

estimated at 99 litres and increased hydraulic loads

discharged into the system with the subsequent reduction

in the ponds BOD removal efficiency. Despite the

subsequent reductions in the BOD-5 concentrations

downstream of As Samra, Appendix 5.5 shows a general

increase in its concentration at site 7 since the water

quality programme started in 1986, thus indicating a

reduction in the stream's self purification capacity.

Considering the average effluent Chemical Oxygen Demand

(COD) of 354 mg/l, it is clear that the effluent quality

is below the 60 - 100 mg/l desired effluent. The high

influent COD due to industrial wastes discharged to the

sewer system, in addition to the reduced removal

efficiency discussed above contribute to the

deteriorating effluent quality.

The increase in SO4 concentrations in sites 5, 5.1 and 7

has not yet been studied. It is, however, expected that

with the anaerobic decomposition of sulphate - containing

organic compounds and the subsequent release of H2S,

clogging problems in localised irrigation may occur.

The ammonium nitrogen (NH4-N) concentrations in As Samra

effluent of 79 mg/l compared with an effluent

concentration of 73 mg/l indicates the lack of oxygen

necessary for nitrification. This is also confirmed by

the low nitrate nitrogen (NO3-N) concentrations in the

effluent. As

oxygenation of the former and dilution along the stream

and in KTR occur, a subsequent decrease in NH4-N takes

place with a simultaneous increase in NO3-N

concentrations.

The high input of total nitrogen (T-N) and total

phosphorous (T-P) from As Samra ponds provide nutrients

to KTR (Appendices 5.6 and 5.7). Other sources include

phosphate mining activities in the catchment area, and

wastes reaching Zarqa River. RSS analyses of KTR water

during the study period indicates that KTR is

hypereutrophic. As a result various species of algae are

present in its water. High concentrations of algae are

also found in As Samra effluent and along the Zarqa

River. The algae population of the former is dominated

by Phacus, Euglena and Chlamydomonas species; the natural

resident population of highly polluted ponds. The algae

population of the river at site 7 is dominated by the

Diatoms; typically residents of river sediments. The

presence of chladophora, however, reflects relatively

high nutrients content. The chlorophyll-a concentrations

which are indicative of the algae population, show a

marked decrease of this parameter downstream of As Samra.

Presently, As Samra plant is removing 49% of Methylene

Blue Active Substance (MBAS) in its ponds. Previous data

on the wastewater at As Samra show increasing

concentrations; from 28 mg/l to 50.1 mg/l between 1986

and February 1990 (Appendix 5.8). Despite the general

decrease in the effluent MBAS concentrations since 1988,

it remains

fairly high on aesthetic grounds, since very small

concentrations are sufficient to cause foaming at all

sites.

Increasing concentrations of boron were observed until

1991 (Appendix 5.8). This situation, however, has been

rectified by government regulation restricting the use of

boron in detergents, and hence explains the decrease in

boron concentrations at all sites since then.

Evaporation from the ponds increase the TDS concentration

at the discharge point of As Samra relative to that at

the inlet. Averaged over the study period, RSS records

show TDS concentrations representing Amman and Zarqa

sewage, at 1127 and 1672 mg/l, respectively. Chemical

analysis of different water samples in these cities show

corresponding average TDS values of 465 and 1027 mg/l.

Assuming TDS increments due to one cycle of use similar

to that found in Israel at 370 mg/l(15)

, an average 284

mg/l of TDS would therefore be attributed, during the

same period, to industrial sources and low per capita

domestic water consumption. Higher contributions are,

however, expected during the dry periods when water

rationing is practised country-wide.

Increase in TDS and EC values are observed in site 4 and

sites 4 and 5, respectively. This is due to the evapor-

ation of water from the ponds and along Wadi Dhuleil. As

the effluent gets diluted, subsequent decrease in these

values occur.

The water downstream of As Samra becomes more enriched

with oxygen due to increased aeration. The PH values of

the water at all sites indicate a tendency towards

alkalinity. As for the heavy metal concentrations, table

5.1 indicates that they are below the detection limits in

both As Samra effluent (site 4) and the Zarqa River (site

7).

The faecal coliform removal from an influent mean level

of 8.6 x 106 MPN/100 ml to a final effluent level of 2.7 x

102 MPN/100 ml after chlorination indicates that As Samra

ponds are not performing as well as a conventionally

designed and constructed stabilization pond system.

Monitoring of the effluent before chlorination by RSS

during the study period shows that it has 1.4 x 105

MPN/100 ml, in comparison with 1027 MPN/100 ml in 1986.

Review of WAJ monthly operation records for 1992

indicates a maximum hydraulic load of

141,542 m3/day discharged into the ponds in February of

that year. Based on WAJ estimates of the sludge depth in

each anaerobic pond of the three treatment trains, the

effective volume of the ponds is found 2.46 MCM. Hence,

the actual retention time achieved in the ponds is

approximately 17 days as compared with the designed 40

days. Other factors affecting faecal coliform removal in

As Samra ponds have been identified by Saqqar (44)

. The

latter found that the rate of die-off of faecal coliform

was an inverse function of BOD-5 loading, its

concentration in the pond and pond depth and a direct

function of pond water temperature pH and retention time.

According to WHO guidelines, a total retention time of at

least 16-20 days are required in a hot climate to reduce

bacterial numbers to the guideline value of 1000 MPN/100

ml. Clearly, there is a need to identify the same under

the local conditions of the plant during summer and

winter periods.

In the circumstances, effluent chlorination is applied to

maintain a faecal coliform level 1000 MPN/100 ml, in

the discharge to Wadi Dhuleil (site 4). This is believed

to be costly and unreliable due to the irregular

availability of chlorine gas. Considering the 10-15 mg/l

rate at which the latter is dosed into the final

effluent, over 1-2 tons of chlorine are on average

released daily into wastewater rich in organic material,

and hence pose the possible contamination of the effluent

with the "suspected carcinogenic" trihalomethanes (THMS).

Regrowth of faecal coliform occurs in the chlorinated

effluent downstream of As Samra discharge point in Wadi

Dhuleil (site 5), due to the high BOD and NH4-N

concentrations and hence further hinders disinfection.

Other factors contributing to the growth include waste

disposal and runoff, agricultural operations and

livestock feeding in the area.

RSS analysis for the intestinal nematodes; Ascaris,

Trichuris, Ancylostoma and Necator indicate their absence

in sites 5.1, 100 and 600 due to their complete removal

in passage through As Samra system, as confirmed by WAJ

operation records. This is due to the sufficiently long

retention time in the ponds for at least 17 days during

the peak winter flow.

Finally, retaining the incoming water in KTR has the

general effect of improving its quality with regards to

all the parameters discussed. This is contributed to (a)

additional mixing of the inflows with rain water and the

surface water reaching the reservoir, (b) consumption of

nutrients by the algae in KTR, (c) natural bacterial and

algal die-off, (d) decomposition of organic compounds and

(e) precipitation of suspended solids during the

retention period.

5.3.1 Suitability of water for irrigation

Table 5.2 summarizes the average values of the water

quality parameters, most relevant to agricultural use,

during the irrigation period (April 92 - October 92).

Although winter irrigation is practised in the Jordan

Valley, it is believed that except for dry years, the

water quality during this period will be more critical

for irrigation. Monthly variations of all the parameters

values are expected. However, deviations from the

average would not be sufficient to push the water quality

into a different category of use. Hence the average

values shown in RSS records are again thought to be

adequate for the general purpose of determining the

suitability of water at all sites for irrigation.

Table 5.2 Water Quality of As Samra Effluent and Selected Sites

along the Zarqa River during the Irrigation Period (4/92

- 10/92)

Perimeter Unit Average during the Irrigation Period

(April - October)

4a 5

a 5.1

a 7

a 100

b 600

b

EC

TDS

SAR

Na

Cl

B

NH4-N

NO3-N

T-N

HC03

PH

TSS

TFCC

Intestinal

Nematodes

dS/m

mg/l

-

me/l

me/l

mg/l

mg/l

mg/l

mg/l

mg/l

su

mg/l

MPN/100ml

Eggs/l

2.058

1312

4.6

9.12

11.1c

0.67

91

8.1

182

49

2.137

74

0.5

8.2

160

1.2 x

104

1.828

1251

40

8.1

103

5.8 x

103

0

1.67

1137

3.2

7.21

0.46

27

7.55

8.1

117

8.1 x

103

1.66

1144

3.19

7.05

9.17

0.45

31.51

6.81

8.3

89

3.19 x

103

0

1.01

722

1.75

3.27

4.43

0.21

9.83

4.64

8.17

12

1.81 x

101

0

a Except for chloride concentration, source is RSS 1993a

b Source: RSS (1993b)

c Source: WAJ Operation Records (1991)

5.3.1.1 Suitability Using ECw and TDs

The quality of the water with respect to ECw and TDs

represent a slight to moderate (SMR) restriction on use

at all sites. Assuming that irrigation water is the only

source of salt, the long term influence of continuous

irrigation with the given water quality at any site can

be predicted using the equation ECe = X * ECw (22)

where,

ECe = soil salinity, dS/m

ECw = salinity of the applied water, ds/m, and

X = concentration factor

Assuming a 40 - 30 - 20 - 10 percent crop water use

pattern from the upper to lower quarter of the rooting

depth, and a 15% leaching fraction, with a concentration

factor of 1.5, table 5.3 shows the expected soil salinity

resulting from the irrigation water salinity of all

sites.

Table 5.3 Suitability of As Samra Effluent and Zarqa River Water

for Irrigation using ECw and TDS

Sampling Sites

Effect 4 5 5.1 7 100 600

A. Degree

of restr-

iction on

use:

ECw

TDS

SMRa

SMR

SMR

-

SMR

SMR

SMR

SMR

SMR

SMR

SMR

SMR

B. Long

term

effect on

soil sal-

inity ECe,

dS/m

3.1

3.2

2.7

2.5

2.5

1.5

a Slight to Moderate Restriction on Use

The corresponding crops' relative yield can be calculated

using the following equation (31)

:-

Yr = 100 - B( k - A)e Error! Switch argument not

specified.where,

Yr = relative yield

B = the percent yield decrease per unit salinity

increase above the soil salinity threshold

Ke = electrical conductivity of an extract of a saturated

soil paste, which is equivalent to ECe,

dS/m, and

A = the soil salinity threshold i.e. the maximum

allowable salinity without yield reduction

below that for non-saline conditions.

Based on A and B values presented in Appendices 5.9, 5.10

and 5.11, the relative yields of all crops known to the

study area, given the water quality in each site and a

leaching fraction of 15%, are shown in table 5.4.

In order to obtain a tolerable degree of yield loss, not

exceeding that recommended by FAO at 10%, salt removal by

leaching is necessary. The minimum leaching requirement

Insert Table 5.4

needed to maintain the targeted yield is estimated as

follows:-

LR = EC

5 EC - EC

w

e w

Error! Switch argument not specified.

where,

LR = Leaching requirement, fraction

ECw = As previously defined

ECe = the average soil salinity as measured on a soil

saturation extract and corresponding to 90%

yield target.

Table 5.5 shows the recommended leaching requirement for

all crops given the target yield and ECw at each site.

The actual crop production will, however, depend on the

amount of leaching provided. Depending on the exact crop

rotation adapted, the most sensitive crop should be used

for leaching requirement assessment.

Given the usual inefficiencies of water application, the

water losses due to deep percolation, normally between

15% for drip irrigation and 50% for some of the surface

irrigation methods, almost always satisfy the leaching

requirements for salinity control presented in table 5.5.

Hence, the actual extra water needed to accomplish

leaching will ultimately depend on the irrigation method

used as determined by water quality and health

requirements, and the estimated contribution of effective

rainfall in leaching, based on local conditions. Factors

that should be considered in such an assessment include

average monthly evapotranspiration, mean monthly

rainfall, antecedent soil moisture condition and its

water-holding capacity, infiltration rate of the soil and

rainfall intensity. Based on annual precipitation

amounts in Seil Zarqa area and the Middle Jordan Valley

of about 400 mm and 180 mm respectively, it is expected

that a certain amount of natural leaching would have

occurred in both areas (though

insert table 5.5 here

to different extents) by the onset of the irrigation

period under study which should not be neglected. Winter

leaching can be enhanced even in a dry year by early

winter irrigation to refill the soil profile with water

before the rain. The latter will then complete the soil

water replenishment and accomplish all or part of the

required leaching with almost salt-free water.

It is important to realize that the potential yields

given in table 5.4, do not provide accurate quantitative

values representing those interactions which might

influence crop response to salinity. Actual yield

response depends on other factors such as specific ions

concentration, climatic and soil conditions, water

availability, crop variety and stage of growth. While

such values are not exact, they are however used to

predict the relative effect of salinity on the different

crops, assuming other factors are not limiting.

Potential yields will be further decreased by increased

salinity in the surface soil during germination and early

seedling stage. With a leaching fraction of 0.15, and a

40-30-20-10 crop water use pattern, the soil salinity in

the upper quarter of the rooting depth will be maximum,

when using site 5 water, at 1.6 ds/m. This is, however,

less than the maximum recommended by FAO at 4 to 5 dS/m.

Hence, given the water quality at all sites, it is

unlikely that the crop production potential will be

affected by slowed germination and reduced crop stand,

unless high salt concentrations are indigenous in the

soil and/or poor drainage conditions exist. While the

latter poses no problem due to adequate natural and

artificial drainage in the area, the former could result

in complete failure of some crops, especially in the

Middle Valley, where the occurrence of saline soils is

quite common, hence necessitating reclamation leaching to

restore soil productivity.

Salinity Control

The control of the salts in the soil can be achieved by

controlling the water movement in the soil. This

involves several interrelated factors such as (a)

quantities and distribution of rainfall, (b) quantities

and qualities of irrigation water, (c) prevailing

drainage conditions, (d) methods of irrigation and

leaching practices, (e) land preparation for better water

distribution (f) timing of irrigation to prevent

excessive root zone depletion and water stress (g) types

of crops and (h) soil type and topography (11,22)

.

Leaching practices

Provided that crop tolerance is not exceeded for extended

or critical periods of time, leaching can be done

at any time, soil and crop monitoring should hence be

useful to determine the need for leaching. The following

procedures are suggested for increasing the efficiency of

leaching and reducing the amount of water needed:-

1. Leach during the early irrigation season since the

evapotranspiration losses are lower.

2. Use tillage to slow overland waterflow.

3. Use sprinkler irrigation at an application rate

below the soil infiltration rate since unsaturated

flow is known to be more efficient than saturated

flow for leaching.

4. Use alternate ponding and drying instead of

continuous ponding. The former is more efficient in

leaching and less wasteful, though more time

consuming.

5. Schedule leachings, where possible, at periods of

low crop water use. Alternatively, after the

cropping season.

6. For low infiltration rates, preplant irrigation or

off-season leaching should prevent excessive water

applications during the crop season.

Irrigation methods

The method of irrigation directly affects the way salts

accumulate in the soil. With furrow irrigation using the

moderately saline water of all sites, it is difficult to

obtain a satisfactory stand of the crops, as the salinity

may concentrate five to ten times on top of the ridges

and hence affect germination. Placement of seed to avoid

areas likely to be salinized are therefore required. In

general, less problems are encountered with border

irrigation (11)

. Basin irrigation with good land levelling

is the most suitable for salinity leaching. Land

levelling is hence essential to furrow, border and basin

irrigation. Inadequate leaching may also be caused by

differences in the rate and time available for

infiltration.

Since the depth of water applied with surface irrigation

methods cannot be easily adjusted per irrigation, more

frequent irrigation for salinity control may result in an

unacceptable increase in depth of water applied and a

corresponding decrease in water use efficiency. Hence,

it may be easier to increase the frequency of irrigation

with sprinklers or drip rather than with surface

irrigation. However, given the chloride and sodium ions

concentrations in the different sites' water, the high

temperatures and low humidity during the irrigation

period, leaf burn of sensitive crops are expected with

sprinkler irrigation. These crops are listed in tables

5.6 and 5.7. Night sprinkling has proved effective in

reducing or eliminating both sodium and chloride toxicity

due to foliar injury. Other management options include

avoiding periods of high wind, moving of laterals with

the main wind direction, increasing sprinkler rotation

speed and rate of application if the soil infiltration

rate permits.

Drip irrigation has provided better yields with higher

salinity water (ECw>1 ds/m), due to the daily

replenishment of the water used by the crop and the low

moisture tension levels maintained throughout the season.

However, salt may accumulate at the outside edges of the

area wetted by emitters and might be moved by rain into

the root zone. It is therefore recommended that regular

irrigations continue during a rain and that new plantings

in the salty areas should not be made without prior

leaching. Careful management of drip irrigation systems

is required to decrease clogging of emitters (see section

5.3.1.5). Filtration is needed to prevent immediate

clogging by large particles and rapid granular filtration

is recommended to remove particles with irregular shapes.

Chemical pretreatments with oxidants and flocculants

might also be needed.

5.3.1.2 Suitability using ECw and SAR

Both salinity and the relative sodium content (SAR) in

the water at all sites do not present any degree of

restriction on use. However, as discussed in section 3.3

of this report, the SAR values based on the percentage of

sodium relative to the Ca and Mg ions concentrations in

the applied water, does not take into account changes in

calcium concentration following irrigation. For this

purpose the adj RNa should be used. However, RSS data

during the irrigation period do not allow such an estima-

tion. A quick review of the annual average values of Na,

Ca, Mg and HCO3 concentrations in sites 100 and 600 indi-

cates adj RNa at 3.7 and 2.27, respectively. These values

are higher than the average SAR values given in table 5.1

for both sites. However, given the ECw of the water, no

unfavourable changes to the soil chemistry would be

expected and hence infiltration problems are not foresee-

able, even when using clay soils.

5.3.1.3 Suitability using specific ion toxicity

a) Chloride ions

Assuming that the soil salinity consists predominantly of

Cl salts accumulated from the irrigation water, then

multiplying the maximum allowable soil salinity without

yield reduction (soil salinity threshold) given in the

salt tolerance tables of Appendix 3.1 by 10 gives the

crop tolerance to Cl- salinity in me/l

(31). Accordingly,

all annual crops in site 600 are not sensitive to the

chloride ions at the concentration given in table 5.2.

However, carrots, beans and turnips are expected to

suffer from yield reductions due to Cl- salinity, given

the average chloride concentration of As Samra effluent

at 11.06 me/l. To control chloride with ordinary surface

methods of irrigation a minimum leaching requirement of

28% will be required for beans and carrots and about 32%

for turnip in site 4.

The FAO toxicity guidelines of table 3.4 indicate a

severe restriction on use of As Samra effluents for

surface irrigation of most tree crops and woody plants

and a slight to moderate restriction on use in sites 100

and 600. Previous quantitative data on the maximum cl-

concentrations permissible in the irrigation water (table

3.6) indicate a possible leaf injury of the tree crops

shown in table 5.6 when applying surface irrigation.

Hence, adequate leaching will be required. Estimates of

the latter indicate that if salinity leaching is met, it

will be more than sufficient to leach chloride ions.

Based on relative tolerance of selected crops to foliar

injury (Appendix 3.4), table 5.6 also shows the crops

expected to suffer from leaf burn when using sprinkler

irrigation. The list is not all inclusive as many crop

tolerances to chloride are not yet all documented.

Table 5.6 Potential effect of cl- using As Samra Effluent and Zarqa

River Water

Effect of Cl-

Sampling Sites

4 100 600

A - Surface Irri-

gation

- Degree of restr-

iction on use

- Annual crops

likely to suffer

yield reduction

due to cl- sali-

nity

- Fruit crops lik-

ely to develop

leaf injury

Severe

Beans; LRb=28%

Carrots; LR=28%

Turnip; LR=32%

Rough Lemonc,

Sour and Sweet

Orangec, Stone

Fruitsc,d

,

Grapesc,d

SMRa

Turnip;

LR=25%

Sweet Oran-

gec, Stone

Fruitsc,d

,

Grapesc,d

SMR

-

Straw-

berryc,d

B - Sprinkler Irri-

gation

- Degree of

restriction on

use

- Tree crops

likely to

develop foliar

injury

SMR

Almond, Apricot,

Citrus, Grape,

Pepper, Potato,

Tomato, Alfalfa,

Barley, Corn

(maize), Cucum-

ber

SMR

Almond,

Apricot,

Citrus,

Grape, Pep-

per, Pota-

to, Tomato

SMR

Almond,

Apricot,

Citrus

a Slight to Moderate restriction on use b Leaching Requirement c Leaching for salinity is sufficient to meet chloride leaching d Sensitivity to chloride depends on variety.

b) Sodium ions

Except for site 600, the SAR of the water indicate a

slight to moderate restriction on use for surface

irrigation of most tree crops and woody plants. Those

relevant to the local climate and sensitive to the given

water quality are listed in table 5.7. They are

extracted from the relative sodium tolerance values

presented in table 3.5, and based on estimates of the

soil ESP expected to result from long-term use of the

given water SAR in each site (Appendix 3.3). Depending

on the specific crop tolerance to Na+,

Sodium injury can occur following surface irrigation for

an

extended period of time (many days or weeks) when

accumulation of toxic levels of Na+ is reached in the

leaves. Adequate leaching to maintain a low soil SAR is

therefore required. It is expected, however, that water

allocated for leaching of cl- whenever needed should be

sufficient to leach sodium ions. Crops likely to develop

foliar injury when using overhead sprinkler irrigation

are also listed in table 5.7.

Table 5.7 Potential effect of Na

+ using As Samra Effluent and Zarqa

River Water

Effect of Na+ Sampling Sites

4 7 100 600

A. Surface irrigat-

ion

- Degree of

restriction on

use

- Crops likely to

develop sodium

toxicity

SMRa

Deciduous

fruits

Beans

Maize

Peas

Grapefruit

Orange

Peach

SMR

same as

site 4

SMR

same as

site 4

None

same as

site 4

B. Sprinkler

irrigation

- Degree of

restriction on

use

- Crops likely to

develop foliar

injury

SMR

Almond

Apricot

Citrus

Grape

Pepper

Potato

Tomatoe

SMR

same as

site 4

SMR

same as

site 4

SMR

Almond

Apricot

Citrus

a Slight to Moderate Restriction on Use

c) Boron Toxicity

Table 5.8 indicates that the concentration of this

element is within the acceptable limits for many crops

that can be grown in the study area. However, at the

given Boron concentration in As Samra effluent (site 4),

some very sensitive and sensitive crops can be affected

(table 3.7). Boron toxicity is hence inevitable when

growing lemon using such effluent. Since documented

tolerance of various crops to boron is based on a maximum

permissible concentration range in the soil-water, it

becomes quite difficult to identify the specific

concentration at which boron toxicity would occur, if at

all, given the water quality of each site. Depending on

the crop tolerance, it can be generally stated that the

boron concentrations pose toxicity potential to sensitive

crops in site 4 and to very sensitive crops elsewhere

(table 5.8). Use of the more tolerant crops is therefore

recommended if adequate leaching cannot be provided.

Table 5.8 Potential effect of Boron Using As Samra

Effluent and Zarqa River Water

Effect of Boron Sampling Sites

4 7 100 600

- Degree of

restriction on use

- Expected Crop

Toxicity

- Potential crop

Toxicity due to

Boron sensitity

None

Lemon

Grapefruit

Orange

Apricot

Peach

Cherry

Fig

Grape

Onion

None

Lemon

None

Lemon

None

Lemon

d) Trace elements

The concentrations of all the trace elements measured by

RSS (table 5.1) indicate no restriction on use at all

sites. However, continuous monitoring of these

parameters is required as more industries get connected

to the sewer system. Presently, out of the 108 wet-type

industrial operations, fifty are connected to Amman -

Zarqa sanitary sewers and 53 discharge to surface water.

Although many industries have on-site treatment

facilities, they seem to be inadequate and hence might

affect As Samra performance. Despite government

industrial limitations approximately one half the

industries are violating waste discharge Requirements (40)

and trace elements such as Fe, Pb, Mn, Zn, Cu, Cr and Cd

have been reportedly increasing in Amman - Zarqa basin.

Monitoring of industries compliance is hence necessary.

Management of Toxicity Problems

Management options to reduce toxicity and improve yield

include leaching in a manner similar to that for

salinity. Leaching requirement in excess of that

determined by salinity is needed to remove chloride ion

toxicity where beans, carrots and turnip are grown using

As Samra effluent, and for turnip using Zarqa River water

at KTR inlet (site 100). The corresponding leaching

requirement have been listed in table 5.6. Boron

toxicity of lemon is expected using As Samra effluent.

Since Boron leaching is more difficult than that of

chloride and sodium and requires about three times as

much leaching, lemon trees should not be grown using such

effluent.

As discussed earlier, FAO 29 guidelines do not indicate

the specific concentration at which boron toxicity might

occur. Crops sensitive to boron at concentrations less

than those of the different sites' water, have been

categorized as crops with potential crop toxicity and are

listed in table 5.8. Exclusion of such crops could be

considered, depending on local experience with their

tolerances to boron. Other options include blending of

water supplies if possible. Increasing the frequency of

irrigation reduces the severity of a toxicity problem.

Land grading, profile modification and adequate drainage

are essential practices that offer better control and

distribution of water for proper leaching. Finally,

managing toxicity to sprinkler irrigation has been

discussed in section 5.3.1.1.

5.3.1.4 Suitability using T-N and T-P

The total nitrogen concentration of the water at site 4,

5.1 and 100 (table 5.2) present severe restriction on its

use for irrigation, whereas that at sites 7 and 600 indi-

cate a slight to moderate restriction on use. The

quantity of nitrogen contained in As Samra effluent is

excessive even by the standards of tolerant crops.

Considering the T-N concentration at 91 mg/l (1 mg/l = 1

kg/1000 m3) and assuming a cropping pattern similar to

that prevailing in the climatic area in which the plant

is located, a weighted average effluent application of

479 mm/year would provide an average of 435 kg nitrogen

per hectare. This, however, far exceeds the amounts

reported to have adverse effects on such crops as oranges

and potatoes (15)

. Excess nitrogen application will affect

the yield and product quality of tomatoes for processing,

potatoes, citrus, peaches, apricots, apples and grapes (15,

18). Table 5.9 shows the average amounts of nitrogen

applied by irrigation given the T-N concentrations at the

different sites. These values, however, may be well

exceeded depending on the crop water application rate.

Research in Israel indicates that N-concentrations of

about 15-20 mg/l are required in the effluent in order

not to exceed the requirements of most crops. The

amounts of nitrogen required by different crops vary.

Typical nitrogen requirement for some crops are presented

in table 5.10. Some of the nitrogen not used by the crop

will leach out of the soil, mostly as nitrate, hence

posing undesirable nitrate pollution of the groundwater.

Based on annual average T-P concentrations during the

study period (table 5.1), the amount of phosphorus

applied by the water of the different sites is estimated

in table 5.9. Again As Samra effluent has excess

phosphorous which is more than that required by all the

crops listed in table 5.10. Despite the limited

information on the effect of irrigation with phosphorous

rich effluents, many soils are successfully irrigated

with sewage effluents having P - concentrations of about

5-10 mg/l (mostly as PO4).

Table 5.9 Average Amounts of Nitrogen and Phosphorous provided by As Samra Effluent and

Selected Sites along the Zarqa River (kg/ha)

Site Nitrogenc Phosphorus

d

kg/ha

Site 4a

Site 5.1a

Site 7a

Site 100a

Site 600b

435

192

129

151

52.6

88

39

40

23

9 a Weighted average application rate representing the cropping pattern in Zarqa River area = 479 mm/year.

b Weighted average application rate representing the middle Jordan Valley = 535 mm/year.

c Based on T-N concentrations during the irrigation Period (table 5.2).

d Based on T-P concentrations during the study Period (table 5.1).

Table 5.10 Nutrients uptake rates for various crops

Crop Uptake (kg/ha)

Nitrogen Phosphorous

Alfalfa

Barley

Corn

Potatoes

Wheat

224-538

71

174-193

230

56-91

22-34

17

19-28

22

17.0

Source: Bouwer and Idelovitch (1987)

The fertilizer value of As Samra effluent (site 4) and

KTR water (site 600) have been estimated by Al-Salem

(1992) at US$ 213 per 1000m3 and US$ 42, respectively.

This adds up to about US$ 8.9 million considering 1991

flows, almost the value of fertilizers Jordan imported in

1986. This suggests that the fertilization action of the

water at all sites should not be ignored. Depending on

the crop nutrients requirement and their availability in

the soil, evaluation of the different nutrients content

with respect to crop suitability can be made on an

individual crop basis for each site and hence, subsequent

decisions on the need for dilution and supplemental

fertilizers can be made.

A tailoring in the supply of nutrients is required for

nutrient control. This arises from the sigmoid pattern

of plant growth. During the active growth period an

abundant supply of nutrients should be provided, while

the lowest is required during the initial growth and

ripening stages. Blending or changing water supplies (if

possible) should be helpful. Such an alternative during

the ripening period will also minimize the pathogen

contamination of crops. During the period of low

nutrient requirements, light irrigation would be

advisable, whereby the minimum depth required to supply

the crop water demand shall be applied. If water applied

nutrients are still excessive, irrigation to cause a

moderate but increasing water stress as the crop

approaches maturity is required. During the non-

irrigation season, crop rotations should be planned to

utlize the residual nutrients in the soil.

Other options for nutrient control include control of the

sources of nutrients in the Zarqa River catchment area

including the overuse of fertilizers and restricting the

use of phosphorous in industrial detergents. Treatment

procedures to remove nutrients from the sewage include

denitrification, phosphate precipitation, ammonia,

volatization. These processes, however, might be

prohibitively expensive for irrigation. Other options

include soil aquifer treatment (SAT) via groundwater

recharge (18)

, if applicable. The latter is achieved using

rapid infiltration basins to put primary or secondary

sewage effluent underground, and wells or drains to

collect the sewage water after it has become renovated.

5.3.1.5 Suitability using TSS, TDS and pH

The concentration of these elements in the water at all

sites presents high potential for the clogging of

emitters in drip irrigation systems (Appendix 5.12).

Table 5.11 expresses this potential in terms of degree of

restriction on use. Plugging of emitters can be

decreased if the system is properly planned and designed.

A complete water analysis should therefore be conducted

before a system is designed. Water quality tests needed

include major inorganic salts, hardness, suspended

solids, TDS, BOD, COD, organic matter, microorganisms and

others (22)

.

Table 5.11 Influence of Water Quality on the Potential for Drip

Clogging Problems Using As Samra Effluent and Zarqa River

Water

Para-

meter

Degree of Restriction on Use

Site 4 Site 5 Site

5.1

Site 7 Site

100

Site

600

TDS

pH

TSS

SMRa

severe

severe

-

severe

severe

SMR

severe

severe

SMR

severe

severe

SMR

severe

SMR

SMR

severe

none

a Slight to moderate restriction on use

The main cause of clogging is solid particles in suspen-

sion. Filtration can prevent immediate blockage by

removing particles longer than the width of the emitter

flow path. Granular filtration helps remove particles

with irregular shapes. Other methods include efficient

backwashing of the filters and flushing the ends of the

line and installing long laterals when the topography

permits (18)

. Algae and other growths enhanced by the high

nutrient levels in all sites would also contribute to the

clogging problems. Use of oxidants such as chlorine or

chlorine dioxide is an effective control measure, though

costly and requires careful management to use safely.

Precipitation of calcium carbonate enhanced by high

temperatures or high pH is another cause of plugging.

Control of pH, or cleaning the system periodically should

prevent deposits build-up to such levels where clogging

might occur.

5.3.1.6 Suitability using microbiological quality

The faecal coliform guideline is met due to chlorination

in As Samra and to the long retention time in KTR before

water is discharged at site 600. The intestinal nematode

eggs are completely removed in As Samra WSP and are not

present downstream. Crop restriction on using effluent

from As Samra can therefore be relaxed, provided that a

uniform and predictable level of disinfecting efficiency

can be ensured or that the treatment plant is upgraded to

perform as originally intended to meet the faecal

coliform requirement without chlorination. Continuous

monitoring is required to determine whether the effluent

is complying with the guidelines during the irrigation

season. Crop restriction along the Zarqa River is

necessary and the government regulations in this regard

are justified. Measures to reduce the faecal coliform

contamination include waste containment facilities to

prevent livestock manure and waste from running off

directly into the River water. Table 5.12 shows the use

conditions of the different sites' water and the added

measures required for health protection, with respect to

application methods and control of human exposure.

Adopting category A crops in sites 5, 5.1, 7 and 100 can

be permitted provided that subsurface or localized

irrigation is used. Besides using water more efficiently

and producing higher yields, it prevents any

contamination from reaching the crop or the workers and

hence the health of both consumers and workers is

protected. However, clogging of emitters is a serious

problem (section 5.3.1.5), hence filtration is required.

Decisions on crop restriction is influenced by the demand

for the crops allowed, profitability, market pressures in

favour of the excluded crops and the crop production

potential. Crop selection and controlled application

methods as means of health protection require strong

institutional framework. Present experience with crop

restriction in Jordan shows it is being successfully

enforced. A possible problem for the future is the

increase in the irrigated areas as more effluent is dis-

charged along the Zarqa River. Increased capacity to

monitor and control compliance with regulations should

therefore be afforded. Farmers must be advised on the

need for crop restrictions. Other health protection

measures are shown in table 5.12. It should be noted

that the potential health risks involved in the use of

sites 5, 5.1, 7 and 100 water are further reduced by

technical factors involving the detention of water in

storage ponds. Experience with farmers in Jordan

indicate the use of the latter before water is

distributed through sprinkler or drip irrigation. In

addition the normal use of sand filters in drip

irrigation provides additional tertiary treatment at no

expense and therefore, can be used with more confidence.

Aerosols can result in transport of viruses and bacteria

when sprinkler irrigation with the more inferior water

quality in the above mentioned sites is used. However,

studies conducted in areas with similar climatic

conditions could not find any conclusive epidemiological

evidence of adverse health effects on the farm workers (46)

. Viruses and bacteria in aerosols inactivated by warm

temperatures, low humidity and sunlight; typical climatic

features of the study area during the irrigation period,

will further reduce the risk if it exists. For further

protection, arrangements can be made to operate the

sprinklers after the agricultural workers have left the

fields. The natural die-off of pathogens in the field

constitutes additional safety when the water is applied

to the crops and soil provides a further reduction of

pathogens within a few days after application.

Table 5.12 Conditions of Irrigation Use of As Samra Effluent and Zarqa River Water

Sampling

Site

Conditions of Use Application Method Control of Human Exposure

Sites 4 and

600

Category A Cropsa

- irrigation of all

crops including

those to be eaten

uncooked, sports

fields, public

lawns.

- Any irrigation method 1. Health Education

2. Provision of adequate potable

water supplies

Sites 5, 5.1,

7 and 100

Category A Crops - Subsurface or localized

irrigation

1. Health Education

2. Provision of adequate potable

water supplies

3. Irrigation channels, pipes and

outlets should be clearly marked

5. Outlet fittings designed to prevent

misuse.

Category B Crops

- Cereal crops,

industrial crops,

fodder crops

and pasture

- Fruit trees

- Crops eaten

after cooking

- Sprinkler irrigation is

allowed if there is a

buffer zone of 50-100m

from houses and roads

- Sprinkler irrigation

should not be used.

Irrigation should stop

2 weeks before harvest

and no fruit should be

picked off the ground.

- Border irrigation or

flooding should not be

used. Where sprinkler

irrigation is used,

minimum distance is

50-100 m from houses

and roads

1. Same as 1 to 5 above

2. Adequate medical facilities

3. Immunization of highly exposed

groups if feasible, e.g. immuniz-

ation against typhoid and pro-

tection against hepatitus A

a Provided that reliable disinfecting efficiency is ensured. Alternatively, As Samra treatment plant should be

upgraded to control faecal coliform. Regular monitoring of the effluent during the irrigation period is required.

5.4 Other Treatment Plants Effluent Quality

Table 5.13 shows the effluent quality for all the other

treatment plants in Jordan. It should be noted that the

levels of total dissolved solids achieve the requirement

of slight to moderate restriction on use for all

effluents. High nutrient concentrations are also

observed and almost always present severe restriction on

use. Clogging problems when using drip irrigation are

inevitable due to high TDS, pH and TSS in most of the

treated effluents. Except for Abu Nuseir treatment

plant, faecal coliform levels exceeding WHO guideline are

found in effluents of all treatment plants and hence may

constitute health risks for consumers and farmworkers.

WAJ operation records do not provide information on the

number of nematode eggs in the effluents. However,

studies made on wastewater reuse and helminths

infestation in Jordan (9) suggest that the( stabilization

pond system could achieve complete nematode egg removal.

This includes treatment plants at Mafraq, Aqaba, Ramtha,

Madaba and Ma'an. Conventional WWTPs (activated sludge

and trickling filter) are unable to achieve complete egg

removal unless secondary treatment is followed by slow

sand filtration, storage or the effluent is upgraded in

polishing ponds. Presently, Baq'a, Karak, Tafila and

Kufranja treatment plants meet the nematode egg guideline

through their removal in polishing ponds. In the absence

of such lagoons, effluents from Irbid, Jarash and Abu

Nuseir contain nematode eggs and hence are only suitable

for irrigation of category B crops provided that exposure

of workers and the public does not occur. Table 5.14

shows the recommended conditions of effluent reuse for

each treatment plant, based on the WHO microbiological

quality guideline. In addition the degree of restriction

on use given the available chemical analysis is

indicated.

Table 5.13 Average Water Quality, by Treatment Plant, 1992

Treatment

Plant

TDSc

mg/l

NH4-Nc

mg/l

T-Nc

mg/l

PO4c

mg/l

T-Pc

mg/l

pHc

Su

TSSc

mg/l

TFCCb

MPN/100 ml

Intestinal

Nematodes egg/l

Mafraq 1058 130 - 58 - 7.7 171 unsatisfactory satisfactoryd

Aqaba 964 47.1 - - - 7.5 95.1 24-460000c satisfactory

d

Ramtha 1225 124 41 7.5

(1)

227 240-2400c satisfactory

d

Madaba 1214 117.4 43.4 - 8 260 240000-390-

000c (2)

satisfactoryd

Ma'an 1127 82.4 - 32.3 - 7.8 192 460-110000c satisfactory

e

Abu Nuseir 851 - - - - 6.5 25 satisfactorye unsatisfactory

e

Baq'a 1069 - - - - - 112 77-2400c

(2)

satisfactorye

Irbid - - - - - 7.8 46.6 - unsatisfactorye

Karak 757 37.3

(5)

33

(4)

6.2

(1)

64.7 240-2400c

(5)

satisfactorye

Tafila 863 49.4

(2)

37.7 7.6 46.2 2400

(1)

satisfactorye

Kufranja 762 20.4 - 23.6 7.2 32 unsatisfactory c

satisfactorye

Salt 708 1.3

(3)

46

(3)

29

(1)

- -

62 <3-724c satisfactory

e

Jarash 916 36.7 23 7.4 36.6 23-40000c unsatisfactory

e

a As Samra Treatment Plant not included

b There is no indication whether the faecal coliform count

represents the effluent after or before chlorination c Source: WAJ Operation Files (1992)

d Suggested by Al-Salem and Tarazi (1992)

e Source: Pride (1992)

Not all data are available on a monthly basis - Numbers between brackets indicate the number of months (n) used to obtain the

average, where n 5

Table 5.14 Degree of Restriction on Use, by Treatment Plant

Treatment Plant TDS Nutrients pHa

TSSa

Microbiological

(Reuse Condi-

tions)

Mafraq SMRb

Severe SMR Severe Category B

Aqaba SMR Severe SMR SMR Category B

Ramtha SMR Severe SMR Severe Category B

Madaba SMR Severe SMR Severe Category B

Ma'an SMR Severe SMR Severe Category B

Abu Nuseir SMR - none none Category C

Baq'a SMR - - Severe Category B

Irbid SMR - SMR none Category C

Karak SMR Severe none SMR Category B

Tafila SMR Severe SMR none Category B

Kufranja SMR SMR SMR none Category B

Salt SMR Severe - SMR Category A

Jarash SMR Severe SMR none Category C

a Degree of restriction on use of drip irrigation

b Slight to moderate degree of restriction

6. CONCLUSIONS AND RECOMMENDATIONS

* The vast depletion of renewable resources in Jordan,

the high cost of developing additional water

resources and the increasing demand on limited water

supply suggest that wastewater reuse should play an

important role in supplementing conventional

resources.

* The estimated amount of treated effluent available

for reuse by the year 2010 will constitute about 40%

of the country's renewable groundwater resources and

hence should save the same amount of fresh water for

drinking purposes. Additional benefits accrue from

the agricultural production under wastewater reuse

schemes and employment opportunities. The

wastewater quantities produced by the year 2010

would be sufficient to support the income of 12,194

families, about 1% of the population of Jordan in

2010.

* Wastewater recycling through agricultural schemes

should be given priority. This should occur as near

to the sewage treatment plant as possible to

minimize evaporative losses. Other benefits include

protection of groundwater and surface waters from

pollution, use of available nutrients and organic

matter as fertilizer and soil conditioner and hence

reduce the eutrophication of receiving waters. It

also ensures the protection of the effluent from

further contamination and ensuring that it does not

transmit disease from one area to another.

* The Jordanian regulations with regards to the

microbial guideline governing effluent reuse are

rather strict and should be revised in the light of

WHO guidelines until improved epidemiological

information permit the adoption of national

standards.

* Before an epidemiological study can be made, it is

important to gather information on the size of the

exposed population, current reuse practices,

behavioural patterns, the degree of soil and crop

contamination and the degree of prevalence of

intestinal parasite infections in selected farm

workers and their families.

* The major treated effluent discharges in Jordan

come from As Samra WSP. The increased

hydraulic and organic loadings on the treatment

plant has adversely affected the ponds

performance. As a result water quality of As

Samra effluent, Zarqa River and KTR have

deteriorated. Priority actions should,

therefore, concentrate on upgrading the ponds

such that the effluent is suitable for

agricultural reuse.

* Treated effluent from the 14 wastewater treatment

plants in Jordan varies in quality. Low per capita

per day domestic water consumption is believed to

contribute partially to high TDS levels in the

effluents. The concentrations of the total

dissolved solids in all the treated wastewaters

generally achieve the requirement of slight to

moderate restriction on use for irrigation. Similar

effect is also observed for As Samra effluent as it

travels from the upper part of Zarqa stream to its

point of reuse in the Jordan Valley.

* High TDS, TSS and/or pH values are expected to

result in clogging of emitters in drip irrigation.

Use of large orifices emitters, filtration,

backwashing of the filters and flushing should help

in this regard.

* If treated effluents are to be used for irrigation,

constant monitoring of all the parameters relevant

to agricultural reuse should be ensured. Additional

parameters, not presently measured for all treated

effluents, should include ECw, SAR, Cl, Na, B, heavy

metals, T-N, T-P, TFCC and intestinal nematodes

during the irrigation period.

* High chloride ion concentrations are particularly

noted in As Samra effluent and to a lesser degree at

KTR inlet and outlet. This may affect sensitive

annual and fruit crops when using surface

irrigation. Sprinkler irrigation will particularly

affect some tree crops leaves.

* High levels of sodium concentrations measured for As

Samra effluent and along the Zarqa River indicate

the possibility of sodium toxicity of sensitive

crops. Foliar injury when sprinkler irrigation is

used will mostly affect sensitive trees.

* Boron concentration in As Samra effluent is particu-

larly harmful to citrus, some stone fruits and other

crops.

* Increase of industrial discharges into As Samra

treatment plant and Zarqa River warrant the need for

future monitoring of industries compliance with

existing regulations.

* Very high nitrogen concentrations are observed in

almost all treated effluents. This will delay

maturation of fruits and deteriorate crop quality.

In addition, the high T-N concentration of As Samra

effluent partially contribute to the eutrophication

of KTR. Other sources include phosphate mining

activities and wastes reaching Zarqa River.

* Evaluation of the suitability of the treated

effluents for irrigation is warranted on a case-by-

case basis so that appropriate crop and application

method selection can be made. Soil and crop

monitoring is required to prevent salinity build-up

and determine the need for leaching. If crop change

to more tolerant crops with regards to specific ions

is not contemplated special management practices to

reduce toxicity are needed. These include proper

leaching and night sprinkling.

* If blending of water supplies is not possible,

control of nutrients in the effluent is recommended.

Options include denitrification, ammonia

volatization. These could, however, be

prohibitively expensive for irrigation. Other

options include restricting the use of phosphorous

in industrial detergents and crop selection.

* Faecal coliform levels exceeding WHO guideline are

observed in most of the treatment plants and along

the Zarqa River. Intestinal nematodes are present

in effluents of the conventional treatment plants of

Irbid, Jarash and Abu Nuseir. The addition of

polishing lagoons as intended by WAJ should allow

the use of such effluents for Category B irrigation,

unless the total faecal coliform is controlled by

efficient disinfection. In the absence of such

measures, health protection can be achieved by crop

restriction, wastewater application techniques and

human exposure control.

* Regulations using a permit system on a case-by-case

basis which consider the use, the application method

and area of application may be appropriate to avoid

squandering resources and marketing pressures in

favour of excluded crops. This should be backed up

with health education campaigns and increased

capacity to monitor and control compliance with

regulations.

* Future design of wastewater treatment plants should

consider the suitability of the effluent for

wastewater reuse.

* It is recommended that a comprehensive feasibility

study for any reuse project should be made. Factors

should include crop type, irrigation method, soil

type, health and environmental aspects.

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