Abstract
The need for larger quantities of high quality water have imposed a great demand on the fresh water resources. This has. led to increasing reuse of wastewater, sometimes with complete recycling. The recognition that pathogens may be transmitted via such waters has led to the development of disinfection practices for both municipal water supplies as well as for effluents to be discharged into rivers and lakes. An attempt was made to standardize and determine some of the parameters governing disinfection of effluents using the f2 coliphage and poliovirus 1. It was found that the activated sludge effluent from the Guildford Sewage Treatment Plant required far less chlorine for reduction of viruses than the levels reported in the literature. This reflected on the quality of the effluent and showed the need to characterize it before any attempt for disinfection. Threshold values for residual disinfectants needed to achieve 4 log inactivation of virus were determined for a pH range of 4-9, 3 temperatures (5C, 15C and 25C) at selected pH's and various amounts of organic matter contents. The disinfecting potentials of bromine chloride and peracetic acid were compared to those of chlorine. Bromine chloride was found to be more effective because it produced the active hypobromous acid at the normal pH of the effluent. Another advantage of bromine was that its by-products were recently proved to be less stable than those of chlorine and therefore presented less of a problem in receiving waters. Peracetic acid, on the other hand, had other advantages over halogens; its by-products, acetates, were non-toxic, the effluent had no demand for it because there were no side reactions with nitrogenous compounds, and it provided the effluent with better protection from secondary contaminations.