The Comportment of Selected Pharmaceuticals in Sewage Treatment Plants

The comportment of selected pharmaceuticals

in sewage treatment plants

B. ~trenn',M. ~lara',0. ~ans~ & N. ~reuzin~er' l Institute for Water Quality and Waste Management, Vienna University of Technology, Vienna, Austria. 2 Federal Environment Agency Ltd., Vienna, Austria.

Abstract

The effluent of sewage treatment plants have been shown to be a significant source of pharmaceutical residuals in surface water. In order to determine and optimise the efficiency of wastewater treatment plants and derive basic knowledge on the behaviour of pharmaceuticals, different treatment steps of a municipal sewage

treatment plant were investigated. Ths article deals with common pharmaceutical active compounds (PhAC) for hfferent applications which are known to occur in the effluent of wastewater

treatment plants. In particular, two antibiotics (Roxithromycin, Sulfamethoxazole), two analgesicslantiphlogistics (Diclofenac, Ibuprofen), the antiepileptic Carbarnazepine, the contrast meha Iopromide, the tranquilizer Diazepam and the lipid regulator Bezafibrate were selected.

The investigations have been performed on a low loaded full-scale activated sludge plant for nutrient-removal and phosphorus precipitation with a high sludge retention time (SRT) of more than 100 days. Since April 2001 grab samples of the influent and effluent were taken once every two months. Furthermore three

sampling periods over 10 days were performed in October 2001 and in May and July 2002. Daily composite samples of influent and effluent were taken during these sampling periods. A typical distribution over the year was observed for the

antibiotic Roxithromycin in the influent of the treatment plant. Certain substances which showed no or only part elimination in parallel performed lab scale experiments which were implemented with much lower SRT, seemed to be degraded in the full scale plant. These results confm the assumption

that the elimination of pharmaceuticals from waste-water correlates with the sludge retention time.

274 Water Pollution \//I: Modclling, Mca~uringand Prediction

1 Introduction

In Austria 11,567 medicines for human applications were licensed in January 2002.

For these medicines approximately 1,800 different active compounds are in use. In addition to human pharmaceuticals 1,055 veterinary products are accredited [l]. The annual described quantity for the most important pharmaceuticals amounts to more than 100 t per year.

Medical substances are developed to effect specific targets in the organism for a limited period of time. By way of excretion, exposure to the environment is suspected. Because of the continuous and wide spread exposure, even low concentration levels may cause effects on aquatic systems. For this reason, unexpected but significant impacts of pharmaceuticals have to be anticipated. Large quantities of medical substances which are used in human and veterinary medicine are suspected to enter rivers, streams and surface water through the eMuent of sewage treatment plants. Surface water can be polluted with these medical compounds by run-off fiom fields treated with dung or application of liquid mure. Pharmaceutical compounds are excreted fiom humans, malnly via urine and faeces, in unchanged form or as metabolites or conjugates. Other medical substances such as ointments and paints get into wastewater directly due to them being washed off Another, not negligible, pathway that contributes to pharmaceutical emissions into the environment is the qroper disposal of domestic sewage. Finally, the pharmaceutical manufacturers represent a sigmficant group concerning another source of environmental intake [2].Concentrations of medical substances up to several pg/l have been found in river water. The discharge of antibiotics into the environment is anticipated to cause the growth of resistant bacterial strains at sub-lethal concentrations [3]. For &IS reason it is necessary to reduce the risks of long-term exposure of pharmaceuticals to the environment and the risk to human health. To achieve this it is necessary to investigate the behaviour of frequently used pharmaceuticals in the different steps of wastewater treatment and to determine the efficiency of sewage treatment plants.

The reduction of uncontrolled releases to the environment through wastewater and possible strategies to increase the removal grade concerning the effluent are an especially important target which has to be developed. In the following paper the investigations of the determined Influent and effluent concentrations of a low loaded municipal wastewater treatment plant are described. The presented results are part of the investigations which were performed according to the EU project POSEIDON (EVK1-2000-00546).

2 Selected substances

In the following Table 1 the investigated pharmaceuticals and their consumed quantities in Austria in 1997 are displayed [4]. The most prescribed pharmaceuticals in human medicine are medicaments with paregoric and anti-inflammatory effects, so called analgesics or antiphlogistics. For example the analgesic Diclofenac whch is especially used to relieve symptoms of

Wawr- Pollurion VII: Moddhrrg, Mea~ur-rngattd Pwdicriorl 275

arthritis and such as lnflarnmation or joint pain is excreted with about 60 % as glucuronides through urine [5]. Ibuprofen is an anti-inflammatory drug whlch is often applied instead of acetylsalicylic acid (Aspirin@) and it is very common in use because it is prescription fiee. The tranquilizer Diazepam is used to treat anxiety as well as epilepsy and muscle spasms and causes sedation. The common trade mark for it is Valium@. The medxal substance Bezafibrate is applied as lipid regulating agent. It &bits the composition of cholesterol and triglyceride in the liver whereby the portion of these lipids is decreased in the blood. Bezafibrate is excreted mainly via urine, 50 % of the a-stered dose in unchanged form and 20 % in form of glucuronides

PI. Carbamazepine is used for the treatment of epilepsy. The drug is degraded in the liver to active metabolites which are as active as the parent drug. Only 2 to 3 % of the administered dose is excreted in unchanged fom From the antibiotics the substances Sulfamethoxazole and Roxithromycin were

selected as frequently used agents. The sulfonamide Sulfamethoxazole inhibits bacterial growth. Also Roxithromycin, a rnacrolide antibiotic, affects antibacterial wherefore it is used to treat many different lunds of infections. The drug gets mamly concentrated in the bile.

The contrast medium Iopromide contains iodine and is a very frequently used pharmaceutical for X-ray recording. Contrast media are used for X-ray representations of special body parts. The substance is usually better or worse absorbed by the X-ray than from the ambient body tissues. After application 90 to

100 % of the drug will be excreted in unmetabolised form.

Table 1: Examined drug compounds and quantities consumed in Austria in 1997

Diclofenac AnalgesicsIAntiphlogistics lbuprofen Tranquilizer Diazepam Lipid regulator Bezafibrate 4474 Antiepileptic Carbamazepine 6334 Sulfamethoxazole 963 Antibiotics Roxithromvcin No data available I Contrast medium lopromide 5386 I

3 Material and methods

3.1 Determination method

Two different detection methods were used for the analysis of the above mentioned compounds. Ibuprofen, Diclofenac and Bezafibrate were separated

and analysed by GC-MS detection after derivatisation with diazomethane and a clean up step by silica gel chromatography. LC-MS-MS was employed for the

276 Water Pollution \//I: Modclling, Mca~uringand Prediction

analysis of Roxithromycine, Sulfamethoxazole, Carbamazepine, Diazepam and Ioprornide. Ionisation of the analytes was done by electrospray ionisation in positive mode.

Prior to the sample extraction a surrogate standard ('josamycine, tylosine and dihydrocarbamazepine or meclofenamic acid) was added to the samples. Two different solid phase extraction phases (cyclohexane (CH)- and ENV+ - phase) were employed for LC-MS-MS sample preparation. The samples were acidified in the case of the C-18 and CH - solid phase extraction cartridges, whereas the addition of a neutral EDTA buffer solution was necessary for the ENV+ phase. The water samples were extracted and enriched by C- 18 solid phase cartridges prior to the analysis with GC-MS.

To overcome problems due to ion suppression in the LC-MS method, recoveries of the surrogate standard and measurements of multiple dilutions of the extracts were performed. The limit of quantification (LOQ) was set with 20 ng/l and the detection limit

(LOD) with 10 ngll.

3.2 Wastewater treatment plant and sampling

3.2.1 Wastewater treatment plant The investigated wastewater treatment plant (WWTP) serves a rural community in the South-East of Austria. The WWTP was designed for 7,000 population equivalents, whereas presently about 2,000 inhabitants are connected to the sewer system. The treatment plant is charged predominantly with domestic sewage from a separated sewer system without industrial influents and with strong seasonal fluctuations due to the local viniculture influence. Therefore it is typical for a wide range of WWTP realized in Austrian rural areas applying best available technology.

The sewage plant is operated with simultaneous sludge stabilization and simultaneous Phosphorus precipitation with FeC13 as well as intermittent nitrification and denitrification are performed. The WWTP consists of screen and grit chamber, two aeration tanks, V = 2 X 1,546 m2, and two secondary clarifiers,

V = 2 X 949 m2, for he final sedimentation. The excess sludge is removed very infrequently what effects a very high sludge retention time (SRT).

3.2.2 Sampling

The study started in April 2001, since that time grab samples of the in- and effluent were taken once every two months. Sampling campaigns were performed over a period of S and 10 days in October 2001 and May and July 2002. During these campaigns daily composite samples of the influent and effluent were taken by means of different automatic samplers simultaneously at both sampling sites. The samples were percolated by fluted filters and then sent to the analflcal institute (Federal Environment Agency Ltd. of Vienna). The effect of filtration was evaluated by application of standard solution. The analysis of only dissolved fractions is justified by the main influence of the deposited and partially filtered effluent to the aqueous environment.

Besides Chemical Oxygen Demand (COD), nitrogen, phosphoms, total suspended solids (TSS) and dry matter concentration were detected applying standardized methods. Mass balances have been generated to check the plausibility

of the obtained data.

4 Results and discussion

In the course of the project the plausibility of the measured values were controlled by generating mass balances of phosphorus, nitrogen and COD. Beside data control the mass balances lead also to a characterization and illustration of the system

stability. Especially the phosphorus balance is a qualified instrument for control because phosphorus concentrations of the influent must be recovered in effluent and excess sludge in prorated distribution. The results of the phosphorus mass balance concerning mfluent- and effluent-concentrations as well as excess sludge production

showed a good correlation and confhmed the stability of the process. The WWTP is subjected to seasonal fluctuations because of the local viniculture. Hence the treatment plant was charged very low during the sampling campaigns in May and July 2002. Due to this low utilization the sludge retention time that was calculated

from the COD mass balance was obtained to be about 140 days. Within a project concerning investigations about the effects of infiltration of purified wastewater, influent and effluent samples as well as samples of the additional treatment steps of the WWTP were taken regularly over a period of one

Year [61. From the available results an annual fluctuation of the antibiotic Roxithromycin was observed. While during the summer months the influent concentrations were detected in the range of the limit of quantification, in wintertime a significant

increase of Roxithromycin was noticeable (Figure 1). Because the influent data of the sample taken in February 2002 is missing, no data is available for this time.

4Roxithromycin influent + ,Roxithrornycineffluent

S00 - l

g 150 .. ------

Figure 1: Concentrations of Roxithromycin in influent and effluent of the WWTP

278 Water Pollution \//I: Modclling, Mca~uringand Prediction

A similar but not so significant distribution was also observed for the antibiotic Sulfarnethoxazole. The residual substances did not allocate such an annual concentration rhythm.

The results (median, maximum and minimum values) of the three sampling campaigns performed in October 2001 and in May and July 2002 are displayed in Figure 2 to Figure 4.

Figure 2: Concentrations of influent and effluent of the WWTP sampling campaign 09.10.-16.10.2001

Figure 3: Concentrations of influent and effluent of the WWTP sampling campaign 06.05.-17.05.2002

- Influent Effluent

Figure 4: Concentrations of influent and effluent of the WWTP - sampling campaign 16.07.-22.07.2002

Generally it has to be annotated that the displayed reductions between duent and effluent concentrations do not differentiate between degradation or adsorption but describe the removal of the substance from the liquid phase. According to the concentrations displayed in Figure 3 and Figure 4 and the by means of the mass balances generated influent and effluent amounts, removal grades of the selected substances were calculated, see Table 2.

Table 2: Removal grade of the investigated substances during the

sampling campaigns in May and July 2002

Removal Substance May 2002 July 2002

Diclofenac 53 74 I lbuprofen I 99 I 99

Diazepam 100 * 100 * Bezafibrate 99 99

Carbamazepine 14 25 Sulfarnethoxazole 63 --

*... All effluent concentrations of Diazepam were analysed to be under the detection limit, whereas the Influent concentrations varied between the limit of detection and quantification. Hence an efficiency factor of 100 % was ensued.

No efficiency factors could be calculated for the antibiotic Roxithromycin. For Iopromide no qualified results were observed. All measurement values for duent and effluent concentrations were detected to be near the limit of quantification.

Iopromide was observed in very low concentrations only during the sampling

280 Water Pollution \//I: Modclling, Mca~uringand Prediction

campaign in October 200 1, with a maximum detection value of 550 ngll (Median value of 140 ng/l). During the other two samplings the analysed concentrations varied in the range of the detection limit. Altogether 25 influent and the same number of effluent samples were analyzed. Only 6 influent samples and 1 effluent sample resulted in hgher values than the limit of quantification of 20 ng/l. In 13 Influent and 17 effluent samples Iopromide was not detectable. The results of the remaining 6 influent and 7 effluent samples varied between the LOQ and the LOD.

Theses results can be explained by the lack of a hospital and radiology institute in the drainage area. Negative efficiency factors were calculated for the two antibiotics Sulfamethoxazole and Roxithromycin. Whde the influent concentrations were observed to be under the limit of quantification, low effluent concentrations were measured. This effect can be explained by the significant high sludge and hydraulic retention time of the WWTP. The sludge retention time describes the mean residual time of the microorganisms in the system. Due to the occurrence of disaggregations in the sludge incorporated substances can be discharged why several matters can be recovered in the effluent even though no measurable concentrations of the influent were found recently. For the analgesic Ibuprofen and the lipid regulator Bezafibrate removal rates of

99 % were observed during all sampling campaigns. The antiepileptic Carbamazepine did not show significant reduction between influent and effluent concentrations. According the results of the three samplings this substance passes the wastewater treatment steps without appreciable adsorption-, degradation or metabolisation processes. The efficiency factor for the antibiotic Sulfamethoxazole was analysed to be 63 % during the sampling campaign in May 2002. This value is comparable to results of lab scale test facilities that have been performed with different sludge retention times [7]. The results that have been gathered during the other two samplings were observed to be under the limit of quantification or of detection respectively. Contrary to the parallel performed lab scale experiments [8], the analgesic

Diclofenac showed a removal of 53 % and 74 % in the WWTP. Due to that fact it is assumed that according to the significant high sludge retention time special microbial pathways are accumulated whch are able to degrade Diclofenac. To confim these results further experiments according the WWTP and lab scale plants are performed. In Figure 5 the distribution of the removal rates concerning three low sludge retention times and the sampling results of the WWTP with a significant high SRT of 140 days are displayed. The mentioned results of lab scale facility experiments at

SRT Id, 16d and 35d are extracted ftom [7, 81. The distribution of Ibuprofen and Bezafibrate indicates a hgh degradation up to 99 % with increasing SRT what is appropriate to the Monod-relation. The removal of Sulfamethoxazole decreased with a SRT higher than 16 days. The removal of Diclofenac was observed to be significant higher with 53 % and 74 % at the investigated WWTP. Ths behaviour

indicates to a relation between the high SRT in the treatment plant and the growth of special microorganisms what effects the conspicuous elimination of Diclofenac.

+ .Dlclofenac + .Ibuprofen +Betafibrat - *- Sufamethoxazol

0 20 40 60 80 100 120 140 160 Sludge Retention Time related to 20'12 Id]

Figure 5: Removal rates of the investigated pharmaceutics in relation to the sludge retention time at 20°C

5 Summary

The investigated pharmaceuticals indicate different removal rates during the wastewater treatment. Comparing the results of the three sampling campaigns of the

WWTP the substances Ibuprofen and Bezafibrate evinced the best removal rates. In contrary the antiepileptic Carbamazepine appeared neither to be degraded, adsorbed nor metabolised in the different steps of the treatment plant, what confirms the results of lab scale experiments [7].

Finally, two different behaviours among the selected substances were observed. Some substances were removed nearly completely after the wastewater treatment and the relation between influent and emuent concentrations indicated efficiency factors up to 99 %. Among these pharmaceuticals specific behaviours were observed including the high sludge retention time of the determined WWTP. The antibiotics were removed partially and are showing an annual fluctuation. Other substances like Diazepam and Carbamazepine passed the WWTP in nearly unchanged concentrations. For these pharmaceuticals no conspicuous alteration could be detected in all three sampling campaigns. Concerning the results it has to be annotated that during these sampling campaigns only filtrated samples were analysed. Hence no qualified statements concerning the particulate fractions can be made. Furthermore some substances are slightly water soluble, e.g. Diclofenac, what can implicate to underestimated influent concentrations because of the lackmg suspended solids fraction. Besides some substances that are known to have hgh adsorption potentials to the sludge are also not included in this balance. At last specific substances are able to metabolise during the treatment steps and can not be recorded in form of these intermediate

282 Water Pollution \//I: Modclling, Mca~uringand Prediction

fractions. Hence it is possible that as a result of these metabolisms decisive quantities have not been found in the effluent. This article describes frrst evaluations of a low loaded rural WWTP. Further investigations should enhance the knowledge of the behaviour of the selected pharmaceuticals in the wastewater treatment process especially by means of a very low loaded plant characteristic.

Acknowledgement

This work was granted by the EU, in the course of the project POSEIDON,

Assessment of Technologies for the Removal of Pharmaceuticals and Personal Care Products in Sewage and Drinking Water Facilities to Improve the Indirect Potable Water Reuse; EVK1-2000-00546

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aquatischen Systemen, Wiener Mitteilungen, Bd. 178,2002 [4] Sattelberger, R.; Arzneirnittelriickstande in der Umwelt. Bestandsaufnahme und Problemdarstellung. Umweltbundesamt Wien, Report 162, 1999 [5] Scharf, S., Gans, O., Sattelberger, R.; Arzneimittelwirkstoffe im Zu- und

Ablauf von Klaranlagen, Umweltbundesamt Wien, Bericht UBA-BE-201, 2002 [6] Kroiss, H.; Auswirkungen der Versickerung von biologisch gereinigtem Abwasser auf das Grundwasser, 2002

[7]Clara, M., Strenn, B., Kreuzinger, N.; Verhalten ausgewahlter Pharmazeutika in der ~bwasserreini&n~,Wiener Mitteilungen, d. 178, 2002 [g] Clara, M., Strenn, B., Kreuzinger, N.; The Elimination of Selected

Pharmaceuticals in Wastewater Treatment, 2ndInternational Conference on Water Resources Management 2003, Gran Canaria, 2003