Abstract
In an evaluation of health and environmental effect in wastewater reuse, one of the important parameters is the toxicity of reclaimed wastewater. We applied bioassay using cultured human cell lines to the samples from three experiments: 1) decay process of activated sludge, 2) ultrasonication of activated sludge, 3) aerobic degradation process of ultrasonicated activated sludge. The bioassay results showed that 1) aerated activated sludge increased the toxicity of the filtrate of sludge, 2) the dose-response relationships of hydrophilic organic matter obtained during activated sludge decay process were almost identical and they had approximately same 50% Effective Concentration (EC50). The comparison of dose-response relationships obtained from several samples in this research showed that 1) the hydrophobic organic matter detached from activated sludge showed toxicity in 30hours and they were degraded biologically, 2) the toxicity in decay process of activated sludge depended mainly on the hydrophilic organic matter released from activated sludge cells. We examined the toxicity of Lipopolysaccharide(LPS) and the mixture of LPS and activated sludge before and after aeration. The mixture after the aeration showed more intensive toxicity than before aeration.
