Toxicity screening, assessment, and reduction in an industrial wastewater treatment plant
Abstract:The toxicity reduction capacity of a central wastewater treatment plant (CWTP) receiving 21 000 metric ton/d of industrial wastewater was thoroughly investigated using a whole-effluent approach with a Microtox™ Toxicity Analyzer System. It was found that the highly toxic wastewater introduced into the CWTP was almost completely detoxified during secondary treatment with a recycled activated-sludge system. The removal mechanism was shown to be a combination of adsorption, volatilization, and biodegradation, the first two being more clear than the other. Fractionation of toxic streams within the treatment plant provided valuable information about the general characteristics of the toxicity-causing agents in the wastewater, namely that they were primarily composed of filterable and dissolved solids, volatile organics, and nitrogenous compounds. A toxicity reduction evaluation survey within the plant revealed that the observed Microtox™ toxicity could be readily removed by treatment with powdered activated carbon (PAC) and mechanical aeration at properly selected operating conditions. The correlation between toxicity removal and the applied PAC dose was found to be exponential and asymptotic to the ultimate effective toxicant concentration of the effluent. Reductions in chemical oxygen demand and dissolved organic carbon during PAC treatment were also related to the applied PAC dose and the initial concentrations of the parameter. Removal of volatile components of toxicity by aeration was correlated with detention time by a power function.
Document Type: Research Article
Publication date: 1998-09-01
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Water Environment Research� (WER�) publishes peer-reviewed research papers, research notes, state-of-the-art and critical reviews on original, fundamental and applied research in all scientific and technical areas related to water quality, pollution control, and management. An annual Literature Review provides a review of published books and articles on water quality topics from the previous year. Published as: Sewage Works Journal, 1928 - 1949; Sewage and Industrial Wastes, 1950 - 1959; Journal Water Pollution Control Federation, 1959 - Oct 1989; Research Journal Water Pollution Control Federation, Nov 1989 - 1991; Water Environment Research, 1992 - present.
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