ASSESSMENT OF ENVIRONMENTAL STATUS OF THE KRISHNAMPATHY TANK

IN COIMBATORE

OBJECTIVEREVIEW OF LITERATUREKRISHNAMPATHY TANKMETHODS OF APPROACH REMEDIAL MEASURESREFERENCES

CONTENTS

To study Environmental status of Krishnampathy tank.

To assess water and soil quality of the stored water in the tank.

To list out various impacts of pollution around the tank.

To suggest suitable remedial measures for the abatement of the pollution.

 

OBJECTIVE

REVIEW OF LITERATURE

BAHIA DEL MAR LAKE RESTORATION

LOCATION:Bahia Del Mar is a 14 acre lake located in St. Petersburg, on the eastern coast of Florida at 19thcentury

PROBLEM :This lake system was severely stratified, with large amounts of organic material in bottom waters, extremely high nutrient levels and high concentrations of hydrogen sulfide causing a “rotten egg” odor, high biological oxygen demand and very low oxygen levels.

It was unsuitable for aquatic life and causes health risks-H2S

MEASURES TAKEN :

Aeration: Bathymetric Mapping provided accurate detail about the depths and volume. Two Vertex Systems, an LL 4XL5 Aeration System and a HF 4XL5 Aeration System with sound kits were installed in April, 2012 to provide adequate turnover rates.

Alum application: After extensive laboratory trials to determine the most effective application, Aquatic Systems applied two treatments of Alum at a rate of 60ppm to improve water clarity and reduce water phosphorus levels.

RESULTS DUE TO MEASURES :

BOD at the bottom of the lake went from 385 mg/l to 2.5 mg/l – a 99% reduction.

“Rotten Egg” Odor eliminated – Hydrogen sulfide in the water column went from >5 mg/l to 0 mg/l – a 100% reduction.

Oxygen at bottom of the lake went from 0 mg/l to 8 mg/l.

Turbidity went from 113 NTU to 8 NTU – a 92% reduction

Bottom water Phosphate went from 8137 µg/l to 35 µg/l – a 99% reduction.

Bottom water Nitrogen Ammonia went from 109,250 µg/l to 800 µg/l – a 99% reduction.

Algal abundance (Chlorophyll a) went from 87 µg/l to 24 µg/l – a 72% reduction.

BAHIA DEL MAR LAKE RESTORATION

KEZAR LAKE

Location: USEPA Region I/Sutton, New Hampshire. The Size of Watershed area 2770 ha and Lake area 73.5 ha.

Pollutant(s):Sediment phosphorus

Pollutant Source: Historical POTW discharges(Publicly owned treatment Works)

Control Measures: Aluminum salts injection and wetlands management

PROBLEM :

Phosphorus, the limiting nutrient for biological growth in the lake, existed in high concentrations (> 30 g/l) at a depth of 6 m during nearly the entire first year of study. Such high levels of phosphorus translate into poor water quality because of increased biological productivity.

The measures taken was injecting aluminum salts into the hypolimnion to inactivate the sediment phosphorus.

RESULTS DUE TO MEASURES :

The effectiveness of aluminum salts application rests on the ability of aluminum to form complexes, chelates, and insoluble precipitates with phosphorus, thereby removing it from the water column and depositing it in the sediment in forms unusable by phytoplankton.

Depending on pH, phosphorus concentration, aluminum concentration, and the rate at which additional phosphorus is supplied, aluminum salts can provide long-term inactivation of sediment phosphorus

Siruthuli have studied and observed the hydraulic details of tank and highlighted the problem as encroachment around the tank and abundant growth of water hyacinth, water spinach, duck weed, reed grass.

This NGO association have desilted the tank and removed the growth of water hyacinth for a period. But this had been only a temporary measure to treat the tank water.

STUDY OF TANK BY SIRUTHULI(2008)

A group of students have studied and analysed the characteristics of lake and mentioned the problem as :

The water was moderately hard and mainly the problem was Eutrophication that in turns leads to oxygen depletion, elimination of aquatic species.

The problem was caused due to urbanization, industrialization, dumping of solids.

There have not mentioned a suitable solution or suggestion to the problem identified.

STUDY OF TANK IN 2006-2007

KRISHNAMPATHY TANK

KRISHNAM

PATHY TA

NK

The series of tanks in Coimbatore are Narasampathi tank, Krishampathi tank, Selvampathy tank, Kumaraswamy tank.

Series of tank in Coimbatore

During the survey, Krishnampathy tank was found to be the starting point of the pollution which then is transferred to rest of the tanks.

People used the tank water for their needs before decades and now it has become a sewage tank.

Need of water for people. Spreading health issues. Ground water contamination –wetlands.

Why Krishnampathy tank?

Present condition of tank

Krishnampathy tank is situated west of Coimbatore city near seeranaickenpalayam . The bund of the lake starts from the Sugarcane Breeding Institute and ends at TNEB sub station.

Latitude: 11° 00.283’ N and Longitude: 76° 55.237’ E.

KRISHNAMPATHY TANK

Catchment area: 26 Sq. Km (based on the watershed Atlas)Lake bed area – 178.00 acres (Originally as per Irrigation Memoir)Current Lake bed – 54.00 acres (AFPRO Study)

Storage capacity – 7.67 MCft (based on Irrigation Memoir)Water Level (FTL) – 11 m (based on Irrigation Memoir)Lake bund length – 1250 mLake shoreline length – 2800 m.

HYDRAULIC DETAILS

PARAMETERS STANDARD VALUE

INLET RESULT (MARCH)

INLET RESULT(JULY)

INLET RESULT(OCTOBER)

pH @27◦c 5-9 7.84 7.9BOD 30mg/l 690mg/l 80mg/lCOD 250mg/l 2800mg/l 600mg/lTDS 2100mg/l 1329mg/l 1176mg/lConductivity 0.0025S/m 0.2564S/m 0.2570S/m Total suspended solids

100mg/l

56 mg/l 33.32mg/l

Total hardness as CaCo3

3-4meq/l 14.97meq/l 49meq/l

Coliform 50-100cfu/100ml

112cfu/100ml 33cfu/100ml

Iron 3mg/l 0.60 mg/l 0.80mg/lTotal Alkanity as HCO3

180-240meq/l 9.83meq/l 500mg/l

mercury 0.01mg/l BDL BDLchromium 2mg/l 0.0114mg/l 0.018mg/lPhosphates 5mg/l 17.6mg/l 28.10mg/lSilica as SiO₂ 20mg/l 6.8mg/l 6.83mg/lNitrate as NO₃ 10mg/l 2.56mg/l 2.56mg/l

Water quality analysis of tank water

Comparison in various seasons

tds mg/l

tss mg/l

hardness mg/l

fe mg/l

phosphate mg/l

bod mg/l

cod mg/l

0

500

1000

1500

2000

2500

3000

standard

march

july

INFERENCE

It could be clearly seen that there is dilution in BOD,COD, coliforms ,hardness ,phosphate due to the seasonal variation

Study of seasonal variation gives the average quality of water for its further processing.

PARAMETER INLET WATER

OUTLET WATER

TDS mg/l 1329 1146TSS mg/l 56 14Hardness mg/l

437 338.4

Fe mg/l 0.6 0.8Phosphate mg/l

17 1.12

BOD mg/l 690 26COD mg/l 2800 190

Inlet and outlet water comparison

0

500

1000

1500

2000

2500

3000

inletoutlet

INFERENCE The levels of BOD, COD ,Hardness ,TDS are found to be reduced in the outlet water.This is due to the settling & uptake of metals and phosphates by weeds ,hyacinth ,reed grasses.

PARAMETERS OF SOIL STANDARD SAMPLE

pH 7 7.6

EC (dS per m) 8 0.8Available N (kg per

ha) 350 269Available P (kg per

ha) 15 67Available K( kg per

ha) 150 1254

Soil analysis around the tank

0200400600800

100012001400

standardsample

INFERENCELow nitrogen – low organic contentHigh P&K – alkalinity of soil.

From the above observation it is could seen that :

There is huge dumping of domestic sewage into the tank.

The presence of heavy metal indicate that there is minor level of industrial dump.

In particular –it has excessive amounts of dissolved salts organic matter and phosphate as its major pollutant.

From soil sample it is observed that soil has started to lose its nutrient content.

PROBLEMS

METHOD

S OF C

LEANIN

G UP

Reformation Techniques

Preventive measures Ameliorative measures

Inlake Out lake

physical

biological

chemical

physical

biological

chemical

•Aeration•Hypolimnetic • drinage•Bottomsealing

Phosphorous

precipitation

Species manuplat

ion

• Mechanical

• Sediment removal

•Activated

carbon •Ammonia strippin

g• Ion removal

Primary works to be done :

Building of embankments-so as there is no external solid disposal at the site.

Laws against waste disposal. Removal of hyacinth & weeds using as bio-compost

Desilting should be done before remediation.

Primary measures…

Suggestions for remediation of sewage water

SEWAGE TREATMENT PLANT REED BED SYSTEM

Setting up of sewage treatment plant at the inlets and treating water before it is sent into the tank.

We have collected data of population that disposes its sewage into the tank.

Sewage treatment plant

Places Population(2011 CENSUS)

Estimated Discharge per day

Vadavalli 39906 5985900

P.N.Pudur 10152 1522800

Seeranayakanpalyam 57065 8559750

Total Estimated discharge = 1,60,68,450 litres per day

For the above mentioned population with calculations for average increase in future, sewage treatment plant could be planned.LAYOUT OF SEWAGE TREATMENT PLANT

REED BED SYSTEM

REED BED

SYSTEM

Reed bed system is process of treating the water so as to reduce the levels of BOD ,SS,COD, phosphates and heavy metals.

Principle: The Reeds has the ability to transfer oxygen from its leaves, down through its stem and out via its root system in the gravel bed.

This encourages micro-organisms that digest the pollutants in sewage to colonise the area.

REED BED SYSTEM

The reason to consider this system is : The use of reed bed produces a secondary treated effluent .

It also poses less of a risk to human health . Minimal operating cost due to low energy required.

possible treatment solution for the removal of recalcitrant compounds

Mechanical Aeration is not necessary and is substituted by plant respiration.

Initial capital costs for the construction of the system would be comparable with any of the conventional systems.

Hence it does not harm the environment

Why reed bed system..??

A sample water of 250 l was taken for the experiment.

Experimental setup :Materials used: Gravel 4kg Sand 15kg Vermiculate 17kg Soil 20kg Reeds used: Arundo donax, Typha angustifolia

Commonly called as Wild cane &  Bulrush .

Materials Used

Reeds used

Arundo donax

Used for:Strong metal-tolerance (arsenic,mercury, cadmium and lead).

As, Cd and Pb in shoots of giant reed is low while metal concentration in roots is high.

Translocate the metals absorbed into the shoot and to accumulate metals in the stalk and leaves above the root concentration without showing any toxic effects .

The requirement for reed bed system :

The residence time is most important criteria

It is calculated by,

Residence time = Reed Bed Volume X porosity /Daily Wastewater Generation.(input)

=732.8*0.4/250=2 daysLonger the residence time higher is the effect of filtration.

Residence time

Experimental Setup

Reeds were grown over layers of soil, vermiculate, sand& gravel for 1 week.(specifications of layer shown in the fig)

A week later after reeds were grown, the sample sewage water was sent through the set up for study.

Waste water is passed at constant flow rate of 8ml/min.

Water passes through various layers of bed and then saturated and sent out through outlet.

The outlet water sample is analyzed and studied.

Procedure

The results of the study are

Results & discussion

Parameters Treated Inlet chromium mg/l BDL 0.011

tss mg/l 6.72 56hardness mg/l 200 600

fe mg/l 13.8 0.6phosphate

mg/l BDL 17bod mg/l 110 690cod mg/l 500 2800coliform cfu/100ml 23 112

0

500

1000

1500

2000

2500

3000

treatedmarch

Inference

From the above graph it could be seen that there is decrease in level of BOD, COD, SS, coliforms which lie within the standard levels.

The reeds also digest the heavy metal in the waste water.

Thus, this method proves to be effective one for treating sewage water.

Layers of reed bedPlanting of reeds

Growth of reeds

Our experimental set up

From the above observations it could be seen that

Directing the sewage into a separate sewer system is not possible because of high population and tedious work s involved in laying them up.

So,waste water has to be treated before it is let inside the tank so reed bed system seems to be comparable with the sewage treatment plant economically and environmentally.

The quality of outlet remains the same.

conclusion

THANK

YOU