1. PERSISTENT ORGANIC POLLUTANTS (POPs) IN WASTEWATER TREATMENT PLANTS SAMPLED BY SEMIPERMEABLE MEMBRANE DEVICES (SPMDs) Per-Anders Bergqvist, *Lijana Augulytė, *Violeta Jurjonienė and *Audronė Žaliauskienė Environmental Chemistry, Umeå University, Sweden and *Kaunas University of Technology, Lithuania Introduction Increased demands on municipal wastewater treatment around the world have increased the concern about the outgoing water quality from municipal wastewater treatment plants (MWWTPs). The diverse inputs leads to numerous kinds of pollutants found in the wastewater treatment process. Most efforts have been focused on reducing the effluent of the traditional parameters such as BOD, nitrogen and phosphorus, as well as some heavy metals. This study presents dissolved concentrations of a multitude of persistent organic pollutants (POPs) in two MWWTPs, in Ume å, Sweden (140.000pe) and Šiauliai, Lithuania (200.000pe). Materials and methods Sampling was performed using semipermeable membrane devices (SPMDs) in the incoming as well as outgoing water from both municipal treatment plants during a three-week sampling period. The sludge centrifuge water and air leaving the centrifuge were also studied in the smaller plant. The SPMDs are diffusive samplers that are used for measuring the truly dissolved concentration of pollutants in water and air. Sampling of incoming water in Umeå MWWTP Results and discussion Acknowledgements We thank Umeå university, Kaunas University of Technology, Swedish Institute and Erasmus program for support. Conclusions 1.SPMD is a good tool for passive sampling of the dissolved part of persistent organic pollutants in the high load pollution environment as municipal wastewater. 2.The conventional municipal wastewater treatment plants are not designed to treat water polluted with POPs. 3.Tendency for “Light” PAHs to decrease and “Heavy” PAHs to increase in the outgoing water in both plants. 4.Total concentration of Pesticides decreased during the treatment in Umea, but increased in Šiauliai treatment plant. 5. PCBs increased in both plants effluent water. 6. Šiauliai treatment plant was more polluted with PCBs and the PCBs originated from more fresh pollution sources. The table assess dissolved concentrations of persistent organic pollutants in Ume å and Šiauliai MWWTPs. The results indicated that not all the persistent organic pollutants entering the wastewater treatment is efficiently removed during the cleaning process, even if BOD is efficiently decreased. Dissolved concentrations of some POPs even increased. Musk compounds (mainly Galaxolide) in Ume å M WWTP were, by far, the most dominating group of pollutants in the samples. PAHs in the Swedish plant were elevated compared with the Lithuanian sampling, but opposite situation was detected for pesticides and especially PCBs. Compounds dissolved in water from MWWTPs Incoming (Ume å, March 2001 ) (ng/L) Outgoing (Ume å, March 2001 ) (ng/L) Incoming (Šiauliai, October 2001) (ng/L) Outgoing (Šiauliai, October 2001) (ng/L) Total PAH (  24) 120081290100 Total Musk (  4) 4100071000-- Total Pesticides (  17) 114.51753 Total PCB (  10) 0.240.641033 The “light” PAHs concentrations decreased between the incoming and outgoing water with average 97.5 % (Figure 1). On the opposite, the dissolved concentrations of “heavy” PAHs increased 3-4 times during the treatment (Figure 2). Air contamination with POPs in the in-door work environment originating from the evaporation during sludge centrifugation were identified (Figures 1 & 2). The pattern for both types of PAHs in the sludge centrifuge water was similar to outgoing water. PAHs pattern in vapor phase from centrifuge water resemble the water phase. Figure 1. “Light” PAHs in Ume å MWWTP Figure 2. “Heavy” PAHs in Ume å MWWTP Figure 3. PCBs in Ume å MWWTP Figure 4. PCBs in Šiauliai MWWTP Increased dissolved concentrations of the lower chlorinated PCBs were found in both MWWTPs in the outgoing water compared with the incoming water (Figure 3 & Figure 4). The PCBs with higher chlorination were detected nearly at the same range before and after the treatment process. The concentration levels of dissolved PCBs in Lithuanian MWWTP were approx. 50 times higher than the detected amounts in Swedish MWWTP. Since Lithuania samples are strongly dominated by tri- and tetra chlorinated congeners, a recent source is suspected in the catchment's area. By analyzing several more PCB congeners in the samples from Šiauliai MWWTP, we found the same trend but higher total concentrations. Since the dissolved concentrations increased in the effluent for many substances, unexplained behaviour involving formation or partitioning occurs in treatment plants. - not measured compounds In this study, SPMDs revealed a time weighted average (TWA) concentrations of dissolved PAHs, PCBs, organochlorine pesticides and Musk compounds. The samples were treated according to scheme presented below.