The Implications of Disinfection Byproduct Formation in the Selection of A Disinfection Strategy

In order to meet future discharge limitations, the Sacramento Regional County Sanitation District must upgrade its wastewater treatment plant. Pilot facilities were operated as part of the Advanced Treatment Technology Pilot project. The project included a biological nitrogen removal (BNR) system, three filtration technologies (conventional granular media filter [GMF], a GMF with a preozonation step and a membrane filter) and three disinfection technologies (ultraviolet irradiation, ozone and chlorine). Chlorodibromomethane (CDBM) and dichlorobromomethane (DCBM) were monitored to evaluate if chlorine disinfection could meet discharge limitations. In addition, chloroform, bromoform, NDMA, bromate, haloacetic acids and aldehydes were monitored for all disinfectants. Both benchCscale and pilotCscale evaluations were conducted for each postCfiltration disinfection technology. When compared with chloramination, free chlorine disinfection resulted in higher CDBM and DCBM, but lower NDMA concentrations. Ozone disinfection generated higher concentrations of bromate, NDMA and aldehydes. Overall, UV disinfection resulted in the lowest concentrations for all DBPs tested.