Acute and Chronic Toxicity Of Chlorine By-Products In WWTP Effluent

A study was conducted to assess the formation and toxicity of disinfection by-products (DBPs) formed from the chlorination of municipal wastewater treatment plant (WWTP) effluent treated to Title 22 standards and reused for an industrial application. Because of concerns with toxicity upon eventual discharge to the environment, bench scale tests were conducted to determine the concentrations of trihalomethanes (THMs), haloacetic acids (HAAs), and Nnitrosodimethylamine (NDMA) and the effluent toxicity after disinfection.In addition to the baseline of non-disinfected effluent, five disinfection alternatives were studied: chloramination at two Cl2:NH3-N ratios, breakpoint chlorination, free-chlorination of a low-ammonia effluent, and bromamination. Disinfectant demand-decay, breakpoint curves, DBP concentrations, and chronic and acute effluent toxicity results are presented.In this study, the results of the toxicity testing indicated that none of the disinfection alternatives would likely impact the whole-effluent toxicity of the recycled wastewater when it is ultimately returned to the environment.