GETTING A JUMP ON DISINFECTION BYPRODUCTS: A PRO-ACTIVE APPROACH FOR OPTIMIZING RECLAIMED WATER DISINFECTION

摘要

As communities grow across the United States, public utilities are faced with unique challenges in meeting future water demands on the front-end and higher level treatment of wastewater on the back-end. The traditional view of water and wastewater as separate and distinct resources is giving way to a more holistic approach, particularly as potable reuse is beginning to dominate the conversation of potential alternative water supplies. One critical component of this holistic approach is the optimization of wastewater treatment and production of high quality reclaimed water effluent. Providing high-level chlorine disinfection to protect against pathogen exposure is a key treatment step directly impacting reclaimed water quality. However, the formation of disinfection byproducts (DBPs) is an unintended consequence of disinfection with free chlorine. With regulatory agencies beginning to scrutinize and enforce DBPs limits in reclaimed waters, utilities are tasked with managing their treatment and operational processes to meet these limits. In this study, DBP formation potential testing of reclaimed water from a full-scale water reclamation facility was performed to assess the impacts of converting from UV to chlorine disinfection as part of a 20 MGD plant expansion. The DBP formation potential results were empirically modeled to develop an operations support tool for predicting the formation of DBPs as a function of process flows and the chlorine contact time. The DBP and modeling evaluation results demonstrated that dechlorination in conjunction with careful control of the chlorine contact chamber operation were vital for meeting regulated DBP limits. Thus, the developed modeling tool provides treatment operators a practical, proactive strategy for optimizing their disinfection process and improve their reuse water quality by helping maintain lower DBP levels.