Citation:

Ryu, H., Y. Addor, N. Brinkman, M. Ware, L. Boczek, J. Hoelle-Schwalbach, J. Mistry, S. Keely, AND E. Villegas. Understanding microbial loads in wastewater treatment works as source water for water reuse. WATER. MDPI, Basel, Switzerland, 13(11):1452, (2021). https://doi.org/10.3390/w13111452

Impact/Purpose:

Water scarcity is becoming a global problem directly impacting drinking water quality and quantity throughout. The reuse of treated municipal wastewater has become a viable potential to relieve the ever-increasing demands of providing water for (non-) potable use. More recently, direct potable reuse (DPR) is being implemented in some communities and seriously considered in others, to solve the water scarcity issues. However, negative public perception and health concerns due to the uncertain quality of reuse water limit its widespread use and applications. With the emergence of technology that makes wastewater effluent a viable alternative source of potable water, additional research is needed to further characterize the microbial pathogens of concern present in effluents and the risks associated with exposure to these contaminants as they relate to DPR practices. The main objective of this study was to assess microbial quality of reclaimed water. In addition, we attempted to address the efficacies of treatment processes typically employed in municipal wastewater treatment plants, focusing on the removal or inactivation of waterborne pathogens from the influent to the effluent.

Description:

Facing changes in water demands and population size, particularly in the water scarce regions in the United States, the reuse of treated municipal wastewater has become a viable potential to relieve the ever-increasing demands of providing water for (non-) potable use. The objectives of this study were to assess microbial quality of reclaimed water and to investigate treatability of microorganisms during different treatment trains. Raw and final treated effluent samples from three participating utilities were collected monthly for one year and analyzed for various microbial pathogens and indicators. Results revealed that the detectable levels of microbial pathogens tested were observed in the treated effluent samples from all the participating utilities. Log10 reduction (LR) values of Cryptosporidium oocysts and Giardia cysts were few orders of magnitudes lower than those of human adenovirus and all the indicator organisms except for aerobic endospores which showed the least LR. Relatively high LR of the indicator organisms such as bacteriophages suggested that these microorganisms could be considered conservative viral indicators of human adenovirus during wastewater treatment processes. Overall, this study will assist municipalities considering wastewater effluent as another source of drinking water important data on the prevalence, occurrence, and persistence of waterborne pathogens of concern. More importantly, the results from this study will aid in building a richer microbial occurrence database that can be used towards revising reuse guidelines and disinfection practices for water reuse practices.

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