Monitoring of the ecotoxicological hazard potential by polar organic micropollutants in sewage treatment plants and surface waters using a mode-of-action based test battery

Abstract

We propose and evaluate a mode-of-action based test battery of low-complexity and in-vitro bioassays that can be used as a routine monitoring tool for sewage treatment efficiency and water quality assessment. The test battery comprises five bioassays covering five different modes of toxic action. The bioluminescence inhibition test with Vibrio fischeri and a growth rate inhibition test with the green algae Pseudokirchneriella subcapitata are measures of non-specific integrative effects. A second endpoint in the algae test, the specific inhibition of the efficiency of photosynthesis, gives an account of the presence of herbicides. An enzymatic assay covers an important aspect of insecticidal activity, the inhibition of the acetylcholine esterase activity. Estrogenic effects are assessed with the yeast estrogen screen (YES) and genotoxicity with the umuC test. Three field studies, each lasting six to seven consecutive days, were undertaken at a sewage treatment plant (STP) in Switzerland. Samples were collected in summer and late autumn, under dry and rainy conditions. None of the bioassays gave positive results with raw water in whole effluent toxicity testing. Therefore, water samples from various sites during wastewater treatment and from surface water were enriched with solid-phase extraction. The focus was on non-volatile compounds of average to moderate hydrophobicity, a range that includes most pesticides, biocides and pharmaceuticals. Various polar solid phases were evaluated for their extraction efficiency, disturbance by matrix components and overall performance. We finally selected a mixture of a polymeric sorbent and a C18-sorbent, Lichrolut EN and RP-18 or, alternatively, Empore SDB-RPS disks. All bioassays gave clear and robust responses with the SPE extracts. With the bioassay data the treatment efficiency of the STP can be assessed with respect to different modes of toxic action and accordingly different groups of micropollutants. Furthermore, the data allowed for a comparison between the effluent and the receiving river. In all bioassays the primary effluent had a strong effect and this effect was reduced after passing the STP. Treatment efficiency was high (typically over 90%) but varied from bioassay to bioassay, which is expected because each bioassay detects different types of micropollutants and therefore we cannot expect a common answer.

Treatment of micropollutants in municipal wastewater: Ozone or powdered activated carbon?

“…These two approaches can be seen as complementary for evaluating the effects of the effluents: the first mentioned assays are very sensitive and focus on the effects produced by specific pollutants, while the second assays evaluate the long-term toxicity of the effluent, including the effect of very polar compounds not well extracted during the enrichment process, such as ozonation byproducts (Stalter et al, 2011). For the first approach, two bioassays were performed on enriched samples: the Yeast Estrogen Screen (YES) to evaluate the estrogenicity (Routledge and Sumpter, 1996) and the Combined Algae Assay to evaluate the global toxicity and the presence of photosynthesis inhibitors (Escher et al, 2008b). For the second approach, a fish early life stage test (FELST, OECD, 1992b) with rainbow trout was performed by exposing the fish for 67 d to the effluent from the different treatments under flow-through conditions.…”

“…It also limits the impact of the matrix components and metals, which are partially separated during the extraction . 7-d composite samples were enriched using SPE as described in Escher et al (2008b) and as presented in Table S2, SI. Briefly, 200 ml (influent samples) or 500 ml (all others) were enriched 200 and 500 times respectively using LiChrolut® EN-RP18 cartridges (Merck, Germany), and then stored in 1 ml of a solvent mixture (~50% ethanol, ~50% acetone and methanol) at -20°C until analysis.…”

Review of risk from potential emerging contaminants in UK groundwater

“…Escher et al (2006) estimated the removal efficiency of pharmaceuticals and hormones in separated urine using both bioassays and chemical analysis. This approach was extended to the ecotoxicological effects of polar micro-organics in effluent and receiving surface waters (Escher et al, 2008). …”

Uptake and release kinetics of 22 polar organic chemicals in the Chemcatcher passive sampler

“…In addition to the 23 channel loaded disks, a set of six SDB disks was loaded with 1 L of spiked channel water using a vacuum disk manifold system [24]. Two disks served as a reference (t 0 ), and the other four disks were placed in the circular tank.…”