ASSESSMENT ON THE REMOVAL OF ORGANIC

CHEMICALS FROM RAW AND DRINKING WATER AT A

LLOBREGAT RIVER WATER WORKS PLANT USING GAC

F. PAUNE1, J. CAIXACH1*, I. ESPADALER1*M, J. OM2 and J. RIVERA1

1Laboratori d'Espectrometria de Masses, C.I.D.-C.S.I.C.; Jordi Girona, 18±26; E-08034 Barcelona,Spain and 2Servei de Recerca i Desenvolupament, AiguÈ es Ter Llobregat; E-08440 Cardedeu, Spain

(First received March 1997; accepted in revised form February 1998)

AbstractÐA screening study was conducted on samples from a Llobregat river water works plant(WWP) in order to establish a better treatment for the removal of organic pollutants. The Llobregatriver is a polluted river supplying water to Barcelona (Spain) and its surroundings with a population ofapproximately 3.2 million. A broad spectrum and high levels of organic chemicals were found in riverwater, including hydrocarbons, pesticides, surfactants, plasticizers and trihalomethanes. Despite a var-iety of treatment processes employed in the studied plant, a satisfactory removal of organic compoundsfrom water is not guaranteed. Given that, improvement in water quality is achieved with the implemen-tation of ®ltration with Granular Activated Carbon (GAC). Seven control column tests (CCT) withanalytical GAC were conducted in series with their seven respective large column adsorbers to deter-mine the performance of each GAC. Organic compounds from samples of raw and drinking water werecollected by passing approximately 1000 l of water through a column of analytical GAC (representingmonthly averages). Selected target compounds previously identi®ed in raw and drinking water (trihalo-methanes: bromoform; pesticides: terbutylazine and molinate; surfactants: polyethoxylated nonylphe-nols; plasticizers: diethyl phthalate and tri-n-butyl phosphate; halogenated compounds:trichlorobenzenes, 2-chloro pyridine; miscellaneous compounds: 2-ethyl hexanol, trimethyl-cyclohexe-none, bromo-trimethyl-benzenes, bromo-polyethoxylated nonylphenols) were studied to predict thebehavior of seven di�erent commercial GACs. These pollutants were e�ciently removed by using GACbituminous coal based. The determination of organic compounds was carried out by using Soxhletextraction and high-resolution gas chromatography with low resolution mass spectrometry (HRGC/LRMS) analysis. # 1998 Elsevier Science Ltd. All rights reserved

Key wordsÐactivated carbon, adsorption, drinking water, organic pollutants, GC/MS analysis

INTRODUCTION

Since the sixties, the Llobregat river has been highly

polluted by the e�uents from chemical, textile, gal-

vanic, paper and other industries located along the

Llobregat basin, a heavy industrialized zone in

Spain. Urban wastewaters and, less signi®cant, agri-

cultural runo� complete the large point and non

point sources into the river. Given that Llobregat

water is one of the most important sources supply-

ing drinking water to Barcelona area (with a popu-

lation of 3.2 million people) and water for industry

and agriculture, several works have been focused on

the identifying and monitoring organic pollutants

(Rivera et al., 1985a,b, 1986, 1987) in order to

assess health e�ects and to devise rational control

procedures. Furthermore, salt mine discharges in

the upper course of the river are responsible for

high levels of bromide ion in the water, leading to

the formation of high levels of brominated organic

compounds during chlorination processes (Ventura

and Rivera, 1985, 1986; Ventura et al., 1988). As a

result of this large-scale pollution and its potential

e�ects on human health, several works have dealt

with the toxicological impact of drinking water pol-

lutants (Romero et al., 1992, 1993) and on the

improving of water treatment.

Our study was accomplish in a water works plant

(WWP) that treats 1.3�105 m3/day and employs

several treatment processes including prechlorina-

tion, coagulation with aluminum polychlorosulfate,

¯occulation with polyacrylamide, settling, sand ®l-

tration and postchlorination. However, these pro-

cesses do not achieve a satisfactory water quality as

far as organic pollutants content. This study

assesses the implementation of a ®ltration method

based on Granular Activated Carbon (GAC) to

obtain better drinking water. According to the Safe

Drinking Water Act (1986) this method is described

as a feasible treatment technique for synthetic or-

ganic chemicals (McGuire et al., 1991).

A pilot plant (PP) installed in the WWP uses the

same processes described above including GAC ®l-

tration. Seven control column tests (CCT) with ana-

Wat. Res. Vol. 32, No. 11, pp. 3313±3324, 1998# 1998 Elsevier Science Ltd. All rights reserved

Printed in Great Britain0043-1354/98 $19.00+0.00PII: S0043-1354(98)00108-0

*Author to whom all correspondence should be addressed.

3313

lytical GAC for control were conducted in series

with their respective large column adsorbers (PP) todetermine the performance of each GAC. The CCTwere previously tested by the authors for the analy-

sis of organic compounds in water (Rivera et al.,1987; Espadaler et al., 1997).

MATERIALS AND METHODS

Pilot treatment facility

The pilot treatment facility was located in a Barcelonaarea water works plant supplying water from theLlobregat river. The treatment train includes settling, pre-chlorination at break-point, coagulation with aluminumpolychlorosulfate, ¯occulation with polyacrylamide, sedi-mentation, sand ®ltration, and four pilot-scale adsorbers.Four GAC columns operate in parallel. The four GACcolumns ®rst tested were named F1, F2, F3 and F4. F1,F3 and F4 columns were subsequently replaced by F5, F6and F7. F2 column was maintained to monitor the poss-ible saturation phenomena. The uptake and behavior ofpollutants in these large columns (pilot plant) were con-trolled by small columns (100 g of GAC). Each large col-umn had a small column in series (Fig. 1). The smallcolumns were replaced monthly.

Granular activated carbon

The granular activated carbon (GAC) used wasextruded and bituminous coal based on di�erent U.S.standard mesh particle sizes. Both speci®cations and thecorrespondence of each GAC with the tested columns areshowed in Table 1.

Activated granular charcoal about 1.5 mm extra pure(Merck, Darmstad, Germany), was used for the controlcolumns (CCT). The carbon was treated at 2508C over-night in order to ensure the purity of blanks. Likewise,

Soxhlet extractions were used to verify the quality of theactivated charcoal. Blanks extract were tested by HRGC/LRMS.

Reagents

The solvents employed, dichloromethane (Baker,Deventer, The Netherlands) and diethyl ether (Carlo Erba,Milano, Italy), were glass bidistilled before use. The purityof the solvents was tested by concentration (100 ml to100 ml) and injection into a gas chromatographic-¯ameionization detector (HRGC-FID) and a gas chromato-graphic-electron capture detector (HRGC-ECD) with thesame chromatographic conditions as samples. BF3-metha-nol was obtained from Pierce (Rockford, U.S.A.). Florisilfor residue analysis (60±100 mesh, 0.15±0.25 mm) fromMerck (Darmstadt, Germany) was used as a chromato-graphic adsorbent. Florisil and granular anhydroussodium sulphate (Carlo Erba) were activated at 5008Covernight. Copper ®ne powder GR (Merck) for sulfurremoval was purchased from Merck and activated withHCl. Glass-wool was cleaned by extraction in a Soxhletapparatus with dichloromethane for 24 h. All glass ma-terials were cleaned with Extran AP 13 alkaline soap(Merck) by sonication for 5 min or chromic mixture anddried at 608C.Base-Neutral Surrogates Spike Mix (Supelco, Bellefonte,

Pennsylvania), bromoform (Chem Service, West Chester,Pennsylvania), polyethoxylated nonylphenols MOE 4(KAO, Spain), atrazine, lindane, 2-chlopyridine and tri-chlorobenzenes (Fluka, Buchs, Switzerland) wereemployed for recovery tests.Amberlite XAD-2 adsorber resin (Merck) of 20±50

mesh particle size was used in the recovery tests (Fig. 2).Before use, the amberlite was washed in a Soxhlet appar-atus with acetonitrile, methanol and ether, each for 48 h.Finally, the ether was displaced by rinsing Milli-Q water.

Fig. 1. Schematic diagram of the experimental set-up.

F. Paune et al.3314

Sampling

Raw and drinking water (including water works plantand pilot treatment facility) were continuously collected atthe rate of approx. 30 ml minÿ1 with CCT columns(48� 3 cm) ®lled with GAC (100 g), and sampled monthlyto allow averaged water pollutants (1000 l approximately).The duration of both series of tests was of six monthseach. The size design and condition of CCT was accordingto Guardiola (1985). The GAC was removed from the col-umn, dried at 308C, transferred into a Soxhlet extractorand extracted with 500 ml of freshly distilled dichloro-methane for 48 h.

Separation method

After extraction, the dichloromethane extract was con-centrated to approx. 1 ml by a TurboVap II evaporator(Zymark, USA). The fractionation was performed asdescribed by Coleman et al. (1980) modi®ed. The remain-ing residue was redissolved in diethyl ether (volatile frac-tion), carried to a ®nal volume with 8 ml ofdichloromethane and extracted with 5� 1 ml 0.5 MNaOH. The ether±dichloromethane layer (containing thebase and neutral compounds) was dried and cleaned elut-ing over a column containing sodium sulfate anhydrousand ¯orisil. The elemental sulfur S8 contained in theextracts was eliminated by contact with freshly activatedcopper (12 h). After eliminating S8, the extract was ®lteredand dried with sodium sulfate anhydrous, evaporated in aKuderna±Danish evaporator and then by a gentle streamof nitrogen to 1 ml before analysis by gas chromatographyand gas chromatography±mass spectrometry. The aqueouslayer Ð containing acidic compounds Ð was extractedwith 3� 2 ml of dichloromethane after adjusting the pH to2 with 4 M hydrochloric acid. After drying with sodiumsulfate, the dichloromethane extracts were evaporated todryness and analyzed as methyl esters after conventionalfree acids derivatization with BF3/methanol (Ventura etal., 1988). The residue non soluble in ether was dissolvedin dichloromethane, concentrated to 1 ml (non volatilefraction) and analyzed by fast atom bombardment massspectrometry (FAB/MS).

Apparatus

Gas chromatography was carried out on two KNK-3000 gas chromatographs (Konik, Barcelona, Spain)equipped with a ¯ame ionization detector (FID) and aTracor (Austin, TX, USA) electron capture detector(ECD) respectively, using nitrogen as the make-up gas. ADB-5 (J & W Scienti®c, Folsom, California) fused-silicacapillary column (25 m� 0.22 mm i.d.) with a 0.25 mm ®lmthickness was used with hydrogen as the carrier gas at alinear velocity of 35 cm/s. The FID temperature programwas from 608C (held for 0.7 min) to 2808C (held isother-mally for 10 min), at 48C/min; the injector and detectortemperatures were 2258C and 2908C respectively. TheECD temperature program was from 708C (held for0.7 min) at 208C/min to 1508C (held isothermally for1 min) and then to 3008C (maintained for 10 min) at 48C/min; the injector and detector temperatures were 2508Cand 3108C respectively. The injection mode was splitlessfor 45 s.

Table 1. General characteristics of GACs tested

Column tested Speci®cations

F1 Bituminous coal based8� 30 U.S. standard mesh particle sizeSpeci®c surface area (N2 BET): 1000 m2/gPorous distribution: >2.36 mm, 15% max.;<0.60 mm, 4% max.Iodine number: 950 mg/g minMethylene blue number: 230 mg/g min

F2 Bituminous coal based12� 40 mesh sizeSpeci®c surface area: 1100 m2/gPorous distribution: >1.70 mm, 5% max.;<0.425 mm, 4% max.Iodine number: 1050 mg/g minMethylene blue number: 260 mg/g min

F3 Extruded activated carbonTotal pore volume: 1.0 cm3/gPorous distribution: Non reportedIodine number: 1000 mg/g min

F4 Bituminous coal based12� 40 mesh sizeSpeci®c surface area: 1000±1100 m2/gPorous distribution: >1.68 mm, 5% max.;<0.42 mm, 4% max.Iodine number: 1020 mg/g min

F5 F1 replaced (fresh)F6 Vegetal carbon (coconut shell)

14� 30 mesh sizeSpeci®c surface area: 1100 m2/g minPorous distribution: Non reportedIodine number: 1000 mg/g min

F7 Bituminous coal based10� 20 mesh sizeTotal pore volume: 0.8 cm3/gPorous distribution: >2 mm, 5% max.;<0.85 mm 4% max.Iodine number: 1000 mg/g min

Fig. 2. Schematic diagram of recovery tests.

Removal of organic chemicals using GAC 3315

Fig.3.Typicalgaschromatogram

ofcompoundsextracted

from

GAC

ofraw

waterfrom

theLlobregatriver

enteringthewaterworksplant.(1)2-chloro

pyridine,

(2)2-

ethylhexanol,(3)3,5,5-trimethyl-2-cyclohexen-1-one,

(4)1,2,3-trichlorobenzene,

(5)1,3,5-trichlorobenzene,

(6)diethylphthalate,(7)tri-n-butylphosphate,(8)terbutylazine,

(9)NPEO

n=

1,(10)NPEO

n=

2,(11)NPEO

n=

3.

F. Paune et al.3316

Fig.4.Typicalgaschromatogram

ofcompoundsextracted

from

GAC

ofdrinkingwater.

(1)bromoform

,(2)2-chloro

pyridine,

(3)2-ethylhexanol,(4)3,5,5-trimethyl-2-

cyclohexen-1-one,

(5)1,2,3-trichlorobenzene,

(6)1,3,5-trichlorobenzene,

(7)diethylphthalate,(8)tri-n-butylphosphate,(9)terbutylazine,

(10)NPEO

n=

1,(11)NPEO

n=

2,(12)NPEO

n=

3,(13)NPEO

n=

4,(14)bromoNPEO

n=

1,(15)bromoNPEO

n=

2,(16)bromoNPEO

n=

3,(17)chloro

NPEO

n=

1,(18)chloro

NPEO

n=

2,(19)chloro

NPEO

n=

3.

Removal of organic chemicals using GAC 3317

For HRGC-LRMS a MD-800 quadruple mass spec-trometer (Fisons Instruments, Manchester, UK) was used.The chromatographic conditions were the same as forHRGC-FID, except for the column length which was60 m. Helium was the carrier gas at a linear velocity of27 cm/s. For the electron impact ionization mode, the con-ditions were as follows: ionization energy 70 eV, massrange 45±450 m/z and a scan time of 1 scan/s. The datawas processed with the LAB-BASE Release 2.14 software(Fisons), which includes the spectra libraries NIST (62.235spectra) and Wiley (138.111 spectra).

The samples were analyzed by FAB/MS using aAutospec-Q instrument (VG, Manchester, UK). The resol-ution was set at 1000. o-Nitrobenzyl alcohol (NBA) wasused as the matrix, the cesium ion gun was operated at20 kV, the mass range was 200±1200 m/z and scan timewas 4 scan/s.

Recovery tests

To ensure the accuracy of GAC testing, we developed anumber of recovery tests for the di�erent steps of samplemanagement. First, we test the adsorption e�ciency of tar-get compounds by control GAC. We designed a low scalelaboratory test (Fig. 2) to ®nd out the recoveries for eachcompound. The system consisted in a closed loop with apump that provided a constant ¯ow of 15 ml minÿ1

through a CCT. The total volume of water that passedthrough the CCT was of 500 l. Twenty liters of Milli-Qdeionized water were recirculated 25 times from the tankto CCL and spiked daily with a 200 ml standard mixtureof target compounds Ð each at a di�erent concentrationto obtain amounts similar to PP e�uent water. The waterwas ®ltered in a hybrid column with GAC and XAD-2 toprevent pollutants which had not been adsorbed in CCTfrom recirculating, before returning to the tank.

In order to study the behavior of punctual inputs of dis-crete pollutants the same low scale test was used. We

simulated a spill by spiking 2.25 mg/l of lindane and wesampled tank water aliquots before and after passagethrough the carbon.The recovery in Soxhlet extraction and separation

method steps was performed by spiking the standard mix-ture of target compounds in dried GAC entering theSoxhlet and by spiking base-neutrals surrogates at Soxhletextract respectively.The recoveries of target compounds in control GAC

were the following: 30% for bromoform, 22% for chloro-pyridine, 17% for trichlorobenzenes, 102% for terbutyla-zine and 98% for NPEO n = 2. The recovery of punctualinput of lindane was 99%. The recovery of base-neutralssurrogates was from 40% for nitrobenzene-d5 to 95% for4-terphenyl-d14.

RESULTS AND DISCUSSION

Prior organic analysis

Figures 3 and 4 show typical gas chromatograms

of compounds extracted from GAC used in rawwater (from the Llobregat river entering the waterworks plant) and drinking water ®ltration respect-

ively. During the sampling period the main com-pounds identi®ed (see Table 2) includedtrihalomethanes, a wide range of plasticizers (phos-

phoric acid esters, dimethyl and diethyl phthalates),alcohols, linear alkylbenzene sulfonates C12 andC13 (LAS), alkylbenzenes from C2 to C5, dye car-

riers such as trichlorobenzenes and polyethoxylatednonylphenols. Other miscellaneous compounds suchas 2-chloropyridine, 3,5,5-trimethyl-2-cyclohexen-1-one and pesticides (terbuthylazine and molinate),

Table 2. Compounds detected in raw and drinking water. Chronic (C), frequent (F), accidental (A), not detected (n.d.)

Compound Raw waterDrinkingwater Compound Raw water

Drinkingwater

Trihalomethanes PlasticizersDibromochloromethane A A Dimethyl phthalate C CTribromomethane (bromoform) C C Diethyl phthalate C CAlcohols Other phthalates C C2-Buthoxy ethanol F F Phosphoric acid tri-iso-butyl ester C CButhoxyethoxy ethanol n.d. A Phosphoric acid tri-n-butyl ester C C2-Ethyl-1-hexanol C F Phosphoric acid 2-buthoxyethanol A F2-Butyl-1-octanol A n.d. Surfactants1-(2-Methoxy-1-methylethoxy) 2-propanol A F Polyethoxylated nonylphenols (NPEO)

n= 1C C

2-Ethyl-1-decanol A n.d. NPEO n = 2 C CDimethylethoxy ethanol n.d. A NPEO n = 3 C C2-Methyl-2,4-pentanediol A A NPEO n = 4 to n= 10 C CDibuthoxy methanol n.d. A Bromo NPEO n= 1 C CEthylhexyloxy ethanol A n.d. Bromo NPEO n= 2 C COctadecanol A n.d. Miscellaneous1-(2-Methoxypropoxy) 2-propanol F F 3,5,5-trimethyl 2-cyclohexen-1-one C C2-(2-buthoxyethoxy) ethanol F A 1,7,7-trimethyl 2-cyclohepten-2-one n.d. ABromo ethoxylate alcohol n.d A 1-methyl-4-(1-methylethyl)-cyclohexanol A n.d.Other alcohols F F Bisdimethylethyl-methyl phenol A n.d.Alkylbenzenes 2-Chloropyridine C CAlkylbenzene C2 n.d. A Propanoic acid ester F FAlkylbenzene C3 C C Benzaldehyde A n.d.Alkylbenzene C4 F F Ethyl benzaldehyde n.d. AAlkylbenzene C5 n.d. A Hydrocarbons F AAlkylbenzene C12/13 A n.d. Methyl phenyl etanone A n.d.Bromo alkylbenzene C3 F F Isoborneol A n.d.Bromo alkylbenzene C5 n.d. A Biphenyl A n.d.Chlorobenzenes Pesticides1,2,4-trichlorobenzene C F Terbuthylazine C C1,2,3-trichlorobenzene C C Molinate A A1,3,5-trichlorobenzene C C

Accidental, frequent and chronic have been calculated for <25%, 25 to 75% and >75% of presence with respect to all samples.

F. Paune et al.3318

hydrocarbons from C7 to C22 and terpenes (isobor-

neol) were also identi®ed. The gas chromatograms

of raw water samples showed as the main com-

ponents surfactants being polyethoxylated nonyl-

phenols the major ones (widely used non ionic

surfactants). These compounds and their degra-

dation products were largely described in the bibli-

ography (Stephanou and Giger, 1982; Giger et al.,

1984; Ball et al., 1989). The presence of these pollu-

tants is due to the existence of surfactant and textile

industries along the banks of the river, as well as to

other industrial activity and urban discharges.

These compounds were identi®ed from n = 1 to

n = 6 (degree of polyethoxylated chain) by HRGC-

LRMS, maximum identi®ed under our conditions.

Nevertheless, the non volatile extract was also ana-

lyzed by FAB mass spectrometry showing poly-

tethoxylated nonylphenols up to n = 15, with a

maximum in n = 7. Other compounds identi®ed by

FAB were ethoxylated tridecyl alcohol (TDAEO),

with a degree of ethoxylation from n = 3 to n= 14

and with a maximum in n = 4, ethoxylated lauric

alcohol (LAEO) and ethoxylated myristic alcohol

(MAEO), with a degree of ethoxylation from n= 3

to n = 12 and with a maximum in n = 5 (Fig. 5).

In addition, brominated NPEOs up to n = 10 weredetected (Fig. 6). These compounds were previously

described by Rivera et al. (1987) and Ventura et al.(1988).Drinking water samples showed brominated tri-

halomethanes (THM) as the major species. The ori-gin and abnormal high levels of these compoundswere attributed to water discharges from salt works

upstream of the water works plant. 2-Chloropyridine was identi®ed in the spills of a cos-metic industry located in the upper course of the

river. 2-Chloropyridine is an intermediate com-pound of pyrithione synthesis, which is used in pro-ducts for capillary treatment. It has been reportedthat 2-chloropyridine is toxic (Dear®eld et al., 1993;

Anuszewska and Koziorowska, 1995).Terbuthylazine was a habitually detected pollutantwith a non point (from agriculture) and a punctual

origin (used as algicide in the refrigeration systemof a factory 30 km upstream of the water works).

Assessment of target compounds removal

According with the organic pollutants identi®edin prior analysis, we selected some of these (targetcompounds) to monitor their behavior in the seven

Fig. 5. FAB (+) mass spectrum showing the region of ethoxylated surfactants from non volatile frac-tion of F2. NPEO with n= 3±14 (M+ Na+=507 for n= 6); TDAEO with n= 3±13(M+Na+=399 for n= 4); LAEO with n= 3±12 (M+Na+=385 for n= 4). Di�erences between

degrees of ethoxylation are M+ Na+ of 44.

Removal of organic chemicals using GAC 3319

di�erent GACs tested on the basis of their chronicpresence in drinking water, the amounts detectedand/or their signi®cance in the potabilization pro-

cess. The target compounds included trihalo-methanes (bromoform), pesticides (terbuthylazine,molinate), surfactants (polyethoxylated nonylphe-nols), plasticizers (diethyl phthalate, tri-n-butyl

phosphate), halogenated hydrocarbons (trichloro-benzenes) and miscellaneous compounds (2-chloro-pyridine, 2-ethyl-hexanol, trimethyl-cyclohexenone,

bromotrimethyl-benzenes, bromo polyethoxylatednonylphenols). Bromoform, trichlorobenzenes andpesticides are included in the general environmental

quality standards for surface waters in di�erenteuropean countries and US.The average amounts and concentration range of

target compounds obtained from monitoring CCTare shown in Table 3. The variability in bothdetected concentrations in CCT and raw water were

due to randomness of the stream volume (from aMediterranean river with ¯oods and low-water sea-son) and spills. The change in the quality of raw

water entering the water works plant was clearlyin¯uenced by spills of extremely diverse origin andwas re¯ected in the wide range of concentrations

(Guardiola et al., 1991). Nevertheless, the continu-ously collected samples with CCT columns mini-mize this source of variability.

We observed an increase in chlorinated and bro-minated compounds in treated water with respect toraw water. In this way we can observe in treatedwater high amounts of bromoform, trichloroben-

zenes and bromopolyethoxylated nonylphenols(Fig. 7). The increase in bromoform and other tri-halomethanes, is due to the fact that the chlori-

nation of surface water produces brominatedtrihalomethanes when bromide is present in rawwater (Rook, 1974). This process has been studied

by a number of authors (Amy et al., 1991;Ko�skey, 1993; Adachi and Kobayashi, 1995;Schmidt et al., 1995). In the drinking water of

Barcelona, bromide, chlorine demand and total or-ganic carbon (TOC) have an important role in theTHM formation (Ventura and Rivera, 1985).

Fig. 6. FAB mass spectrum showing bromo NPEOs from F1. TDAEO with n= 4±12 (M+Na+=399for n= 4); NPEO with n= 3±12 (M +Na+=507 for n= 6); Bromo NPEO with n = 6±10

(M+ Na+=585 for n= 6). Di�erences between degrees of ethoxylation are M+ Na+ of 44.

F. Paune et al.3320

Furthermore, Reinhard and Ball (1985) reported

that the acidic and neutral metabolites of the alkyl-

phenol ethoxylates react during chlorination produ-

cing brominated and chlorinated products. Chloro

and bromo polyethoxylated nonylphenols (Fig. 4)

has been also described by Ventura et al. (1988).

Moreover, a decrease in the concentration of

NPEOs was observed. The increase of trichloroben-

zenes and presence of bromotrimethyl benzenes

(Fig. 8) are probably due to the presence of BTX

industrial solvents in raw water. Other byproducts

coming from surfactant and phthalate degradation

are methoxy, buthoxy and other etoxylated alcohols

(Table 2), and of di(ethylhexyl) phthalate such as 2-

ethyl hexanol.

With the implementation of the GAC (CCT) the

concentration of all compounds is reduced in drink-

ing water, except for NPEOs in some samples and

Fig. 7. Electron impact mass spectrum of bromopolyethoxylated nonylphenols.

Table 3. Average and concentration range of target compounds in control column tests for ®rst (F1 to F4) and second (F2 to F5) batch.

Raw water Drinking water F1 F2 F3 F4

BromoformConcentration range 0±142.7 64.9±2252.7 37.3±3735.2 75.6±1812.7 40.4±2113.5 25.7±3189.6Average 31.8 599.8 761.5 561.8 583.4 749.82-ChloropyridineConcentration range 6.3±283.0 7.1±363.2 8.5±701.1 7.6±641.9 8.4±555.7 3.6±627.3Average 68.5 89.6 189.2 136.1 156.9 149.4TrichlorobenzenesConcentration range 0.2±374.0 2.9±752.3 0.2±330.3 0.3±69.3 2.1±223.2 1.1±104.4Average 96.8 146.0 67.0 16.9 61.5 20.8TerbuthylazineConcentration range 0.42±2.96 0.24±1.50 0.13±3.10 0.11±3.60 0.34±4.30 0.59±1.50Average 1.20 0.81 1.07 1.04 1.63 0.90Polyethoxylated nonylphenols n=2Concentration range 24.4±820.0 10.3±198.0 1.1±390.1 0.6±182.6 11.3±266.2 0.4±268.8Average 215.3 55.7 125.8 53.7 95.9 86.7Bromo polyethoxylated nonylphenols n=2Concentration range 0.34±21.60 3.32±103.20 0±19.10 0±5.70 0.63±9.00 0.20±7.70Average 5.04 25.68 4.35 1.64 3.6 2.53

Raw water Drinking water F2 F5 F6 F7

BromoformConcentration range 6.3±69.0 376.9±1103.8 229.8±543.6 3.2±887.2 43.8±540.7 50.0±642.1Average 30.8 661.8 420.8 284.2 240.0 285.82-ChloropyridineConcentration range 5.44±58.43 31.79±75.93 3.89±60.22 0.10±19.76 0.84±22.94 1.45±38.08Average 27.89 60.05 36.79 6.04 11.63 19.95TrichlorobenzenesConcentration range 2.52±8.53 6.27±17.48 1.68±10.73 0.12±1.84 0.40±1.65 0.24±4.02Average 5.86 12.05 6.90 0.52 0.92 2.33TerbuthylazineConcentration range 0.03±0.16 0±0.24 0.05±0.33 0±0.06 0±0.06 0±0.06Average 0.09 0.14 0.14 0.02 0.04 0.04Polyethoxylated nonylphenols n=2Concentration range 1.72±80.10 2.21±33.74 1.27±31.01 0.07±29.31 1.56±84.95 0.48±66.93Average 27.62 11.72 18.16 6.27 22.75 18.36Bromo polyethoxylated nonylphenols n=2Concentration range 0.18±2.13 0.81±11.51 0.03±0.98 0±1.53 0.09±2.12 0.05±2.23Average 1.15 3.77 0.66 0.33 0.74 0.79

Removal of organic chemicals using GAC 3321

bromoform and 2-chloropyridine in the ®rst batch.

The behavior of these compounds in the ®rst batch

is probably due to the phenomenon of saturation of

GAC. In this phenomenon the column releases the

pollutants adsorbed previously because of the com-

petitive e�ects of a background of organic com-

pounds. A number of studies have been published

for competitive adsorption (DiGiano, 1987; Ying et

al., 1990; Oxenford and Lykins, 1991; Smith, 1991;

Sorial et al., 1994; Cerminara et al., 1995). On

many occasions we observed the phenomenon of

inverse adsorption of bromoform with respect to

the total contaminant charge, especially in the col-

umns with the best removal e�ciencies. Competitive

adsorption due to the presence of other organic

compounds like NPEOs and trichlorobenzenes

probably reduces carbon capacity for some other

target compounds.

In the second batch, owing to an increase in ¯ow

of the river, all the compounds present minor con-

centrations and GAC showed a better behavior.

The results indicate the best adsorption capacity for

column F2 in the ®rst batch and for F5 in the sec-

ond batch (Fig. 9). Using the multifactor ANOVA

statistical test, in the second batch signi®cant di�er-

ences (con®dence level of 95%) were detected

between F5 and treated water for all the com-

pounds, except terbuthylazine (due to the very low

concentration of this herbicide and its intrinsic

variability). F5 showed smaller average concen-

trations for all compounds, except for bromoform,

which was best adsorbed by F6. It should be

pointed out that the lower concentrations in these

columns (CCL) indicate a good uptake of pollu-

tants by pilot plant (PP) columns. The averaged

values observed for 2-chloropyridine in drinking

water were reduced approximately a 90% using F5

CCT. Moreover, trichlorobenzenes were practically

eliminated after F5 passing. Similar trend was

observed for bromo NPEOs. In the second batch,

F2 (not replaced since the ®rst batch) showed the

worst behavior, due to saturation. In the multiple

range analysis, F2 di�ered signi®cantly from treated

water and from all other CCT, for trichloroben-

Fig. 8. Electron impact mass spectrum of 1-bromo-2,4,5-trimethyl-benzene.

Fig. 9. Bar diagrams of the target compounds adsorbed inCCT columns for ®rst batch (upper ®gure) and secondbatch (lower ®gure). Results are expressed as a ratiobetween every column with respect to the column thathave the lower values of adsorption in each batch (the col-umn with the lowest values have the ratio 1). The lower isthe amount adsorbed of a compound in a CCT columnbetter is adsorbed by PP column, and consequently the

behavior of the charcoal tested is better.

F. Paune et al.3322

zenes and 2-chloropyridine. Bromoform was alsopoorly adsorbed in this column. In the ®rst batch,

there were no signi®cant di�erences between GACs,because the dates were not balanced and conse-quently the potency of test was lower. Nevertheless,

F2 showed the lowest levels of pollutants except forterbuthylazine, being furthermore one of the bestresults over CCT columns. This result for terbuthy-

lazine is due to the low levels found in water, theirrandomness and the complexity of the GCMS chro-matograms. These results suggest a better pore size

distribution in the GACs F2 and F5, as describedin the bibliography (Urano et al., 1991; Ebie et al.,1995).

CONCLUSIONS

According to the aim of this study, a wide rangeof organic pollutants in raw water from theLlobregat river has been detected. These chemical

compounds attained high levels of concentration insome cases.We observed a large formation of THM within

other chlorinated and brominated compounds in

the chlorination process at WWP. Moreover, exper-imental results provide evidence of the presence oforganic bromo derivatives such as bromo alkylben-

zenes and bromo NPEOs in natural waters pollutedwith brominated salt discharges, when BTX sol-vents and NPEOs react with ion bromide. There

are few bibliographic references of these com-pounds.A number of pollutants were transformed or

degraded by fragmentations of their chains. FromNPEOs and LAEOs, a degradation have beenobserved into bromo and chloro NPEOs or meth-oxy, buthoxy and other ethoxylated alcohols. And

also from BTX solvents alkylbenzenes werefounded.Comparing the results of six characteristical

di�erent GACs, we select the most e�cient GACfor removing organic compounds. Considering thetypology of raw water from Llobregat river (a

widely industrialized river), the bituminous coalbased GAC, 12�40 U.S. mesh size (F2) showed animproved capacity for drinking water treatment asregards organic pollutants. As is well known, the

classic treatment of raw water with high contents oforganic pollutants clearly impairs the quality ofdrinking water as regards organic micropollutants,

leaving unacceptable taste and odor characteristics,and posing a serious risk to public health. By con-trast, GAC implementation clearly enhances the

quality of drinking water. Nevertheless, the controlof the saturation phenomenon for each speci®cGAC should be borne in mind.

This long term experimental set-up provides a re-liable comparison of di�erent charcoals for asses-sing the removal of organic compounds, whilstkeeping in mind the high temporal variability in

concentration range and type of compounds due tothe randomness of stream volume from a

Mediterranean river and spills.

AcknowledgementÐThis work has been partially ®nan-cially supported by AiguÈ es Ter-Llobregat.

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