Application of toxicity identification evaluation procedures on wastewaters and sludge from a municipal sewage treatment works with industrial inputs

A comparison of influent and effluent wastewater toxicities to Daphnia magna was undertaken to determine the most representative aqueous fraction for future toxicity identification evaluation (TIE) studies. Wastewater samples originated from a wastewater treatment plant which receives mainly domestic wastewater and industrial effluents. The TIE results reveal that the key toxicant contained in the influent was 2-propylbezaldehyde oxime. Results suggest that greater attention needs to be given to the receiving influent containing 2-propylbezaldehyde oxime to avoid damaging the bacterial populations in the primary activated sludge process. In addition, in order to evaluate the applicability of the reuse of activated sludge as a fertilizer in agriculture, TIE studies were also performed on water extracts from surplus sludge.