Results of a "Whole Effluent Assessment" study from different industrial sectors in Germany according to OSPAR's WEA...

The results of a Whole Effluent Assessment (WEA) of 8 wastewater samples from different industrial sectors as the German contribution to the OSPAR-WEA expert group are presented. The testing strategy followed the WEA principles described in the OSPAR WEA-Guidance document considering persistency (P), potentially bio-accumulative substances (B) and toxicity (T). All wastewater samples have been tested before and after a biodegradation test. The Zahn-Wellens test has been applied with wastewater indirectly discharged to a municipal treatment plant, the DOC Die away assay for wastewater directly discharged to surface water. The DIN standardized bioassays referred to in the German wastewater ordinance which partly are related to screening versions of the respective OECD guidelines have been applied. The potentially bio-accumulative substances (PBS) were determined by solid phase microextraction (SPME) and referred to the reference compound 2,3-dimethylnaphthalene. Generally low to moderate ecotoxic effects of wastewater samples have been determined with maximum values of LID(A)=8 in the algae test, LID(L)=24 in the luminescent bacteria test and LID(Egg)=6 in the fish egg test. Low levels of PBS were determined in the effluents after biological treatment. The Zahn-Wellens test proved to be a suitable screening tool for the biological treatment of wastewater samples. The mutagenicity of one wastewater sample from the chemical industry was investigated by additional chemical analysis and backtracking. A nitro-aromatic compound (2-methoxy-4-nitroaniline) used for batchwise azo dye synthesis and its transformation products are the probable cause for the mutagenic effects analysed.