Modeling Trihalomethane Formation Potential from Wastewater Chlorination

The deletion of federally mandated fecal coliform limits has led many states to review and modify their wastewater disinfection requirements. One issue in analyzing wastewater disinfection is the discharge of potentially carcinogenic halogenated organics formed during the chlorination process. This research investigates the formation of one class of the halogenated organics, the trihalomethanes. The applicability of using drinking water trihalomethane formation models for use with wastewater effluent is examined. Three models are compared for predictive capability by using measured trihalomethane values from previous research data. The results show that a previously developed model is applicable for use based on assumptions stated. Results provide environmental managers with worst case predictions for a range of wastewater treatment plant WWTP parameters. Predictions indicate that trihalomethane formation from the chlorination of wastewater is typically lower than the Safe Drinking Water Act trihalomethane standard of 100 ugL. The worst case model predictions reach, and in certain extreme cases, pass the standard of 100 ugL. This level of trihalomethanes formed is minimized if aeration of the receiving bodies of water occurs. Based on this research, the risk of forming trihalomethanes as disinfection by-products from chlorination do not outweigh the benefits gained from proper chlorine disinfection of effluent. Wastewater, Wastewater disinfection by-product modeling, Trihalomethanes chlorination by-products, Chemical modeling.