Technical Report No. 137
Stanford M. lwamoto, Michael J. Chun, Reginald H.F. Young, Gordon L. Dugan
The most common method of disinfecting waste water effluent is by chlorination which destroys pathogenic microorganisms in the waste water stream. A field study conducted at the Wahiawa Wastewater Treatment Plant on the island of 0’ahu, Hawaii was established to determine the effect of aeration on disinfection efficiency in the chlorine contact chamber. A range of chlorine dosages was applied to the waste water entering the contact chamber for aeration rates of 0, 2.36 X 10-3, and 4.72 X 10-3 std. m3/s (0, 5, and 10 std. cfm) of air. The chlorine demand and chlorine requirement of the waste water was then determined by measuring the chlorine residual and fecal coliform concentration in the effluent leaving the chlorine contact chamber. The addition of aeration into the chlorine contact chamber enhanced the disinfection efficiency of chlorine, while its effect on chlorine residual loss in the contact chamber was not readily apparent; however, a greater drop in the chlorine residual was observed for higher chlorine dosages during periods of aeration, in comparison to nonaerated conditions.