Ecotoxicity of purified industrial waste water

Abstract

Purified industrial waste water (PIWW) has been evaluated for probable toxicity using test-systems with Pseudorasbora parva (topmouth gudgeon) and Lepidium sativum L (garden cress). The acute toxicity of PIWW was calculated according to mortality of Pseudorasbora parva in dilutions 1, 5, 10, 25, 50, 100 and 200 times, and distillate water (DW) was used as a control. The LC50 has been calculated after 96 h of treatment and it was at approximately 8x (7.69) times dilution of PIWW. The toxic effect of PIWW with and without copper ions, added as CuSO4 have been measured using Lepidium sativum L. The comparison of the toxic effects of the same concentrations of copper in PIWW and DW, mixed and non-mixed contamination has been evaluated. It was found that Cu+2 has inhibitory effects on the root’s and stem’s growth of Lepidium sativum L seeds, and that effect appears in concentrations over 2 mg/l Cu+2. The 50% inhibition of root’s growth in DW was EC50=7.26 mg/l of copper ions, while for PIWW that concentration was EC50 =17.23 mg/l Cu+2. The calculated EC50 for stem’s growingin DW was 54.57 mg/l Cu+2 and 72.07 mg/l Cu+2 in PIWW. The observed EC50 differences in DW and PIWW perhaps are due to the formation of ligand compounds among copper cations and other impurities in the waste water and hence as consequences the reducing of free Cu+2 or their bioavailability, hereafter reduce copper toxicity. It was registered that PIWW diminished growth inhibitory effect of copper ions on Lepidium sativum L seeds lessening its amount by involving free Cu+2 in complexes with other waste products.