WRRCTMR No.52 Algal Growth Potential of Waste Water Effluents in Hawaiian Receiving Waters

Abstract

A laboratory study was conducted to determine the algal growth potential (AGP) of secondary domestic effluents on stream and marine waters in Hawaii. AGP methods developed by the Environmental Protection Agency were used with effluent-receiving water mixtures representative of nutrient levels found in existing effluent disposal situations. Results of this study are indicative that growth response follows similar patterns for conventional biologically-treated effluents in the four fresh receiving waters tested, with peak growth occurring at a 20% dilution of the effluent. Peak growth conditions occur at a lesser dilution, 40%, in sea water, but this would be an uncommon existing environmental situation in light of outfall design objectives and current practice. Field conditions exist in fresh receiving streams in Hawaii where the effluent dilution is 20% or less, so in situations of excessive stimulation or at lesser dilutions, some inhibition of planktonic growth occurs. The growth potential response of "standard" test alga with Hawaiian waste waters and receiving waters has been demonstrated.