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Chlorine Disinfection of Blended Municipal Wastewater Effluents
Citation:
BOCZEK, L. A., C. H. JOHNSON, AND M. C. MECKES. Chlorine Disinfection of Blended Municipal Wastewater Effluents. WATER ENVIRONMENT RESEARCH. Water Environment Federation, Alexandria, VA, 82(12):2373-2379, (2010).
Impact/Purpose:
To inform the public.
Description:
Blending is a practice used in the wastewater industry to manage wet weather events when the influx of storm water to municipal treatment facilities could compromise the hydraulic capacity of the facility’s biological treatment system. To prevent this, wastewater is treated through primary clarification with flows in excess of the hydraulic capacity of the secondary system being directed to effluent disinfection. Just prior to disinfection, the primary clarified effluent is “blended” with effluents which have been treated through the secondary system. The combined or “blended” effluents are then disinfected prior to being discharged to receiving waters. We evaluated the effectiveness of chlorine to disinfect blended effluents. Experiments were conducted at bench scale on primary and secondary effluents and three ratios of primary to secondary effluent (1:9, 3:7 and, 5:5) from three publicly owned treatment works. We found that blending 10% or more primary effluent with secondary reduces the efficacy of chlorine disinfection. We also found that coliphage survived chlorine disinfection of blended effluents better than bacterial indicator organisms, and we provide a simple empirical model for predicting indicator organism densities following chlorine disinfection.
