Bromine chloride as an alternative disinfectant to chlorine of human enteric viruses and other pathogens in water and wastewater

Abstract

Bromine chloride (BrCl) was evaluated as an alternative disinfectant to chlorine by comparing the inactivation of human enteric viruses and indicator bacteria in water and wastewater by bromine chloride and chlorine. Preliminary studies were conducted under ideal laboratory conditions. In nitrogen-free buffer at pH 6.0, BrCl found to be two to three times as effective as chlorine in inactivating more than 5 logs of poliovirus. Furthermore, BrCl retained its disinfecting ability over a wide range of pH. The primary sit8 of action of BrCl on poliovirus was the virus protein; and infectious RNA was recovered from poliovirus in which more than 3 logs of virus had been inactivated by 0.3 mg/l of BrCl. Bromine chloride was less affected than chlorine by the presence of interfering compounds such as NH 4Cl and glycine, added to the water. Under simulated field conditions in the laboratory, a 5 mg/l dose of BrCl inactivated more than 5 logs of poliovirus in sewage effluent whereas the equivalent dose of chlorine inactivated only 2 logs. Disinfection of wastewater by BrCl and chlorine was also studied under field operating conditions by using a model chlorine contact chamber at a sewage treatment plant to treat large volumes activated sludge sewage effluent. An 8 mg/l dose of BrCl was determined to be more effective than an equivalent dose of chlorine in inactivating more than 4 logs of several types of human enteric viruses added to the effluent as well as viruses naturally present in sewage. BrCl was shown to require a shorter contact time and resulted in unstable residuals as compared to chlorine. Bromine chloride was also shown to be equally effective in inactivating human enteric viruses and coliform bacteria. Chlorine was more effective in inactivating human enteric viruses and coliform bacteria. Chlorine was more effective in inactivating coliform bacteria than viruses. Preliminary experiments also indicate that BrCl is a more effective disinfectant than chlorine of giardia cysts in water. Additional studies demonstrated that residual BrCl was less toxic than residual chlorine for fish. It is concluded that BrCl was a more effective disinfectant than chlorine of human enteric viruses and indicator coliform bacteria in water and wastewater and is therefore strongly recommended as an alternative disinfectant to chlorine.