Bioaccumulation in fish of chlorinated phenols from kraft pulp mill bleachery effluents.

Abstract

During the last ten years the gross water pollution caused by oxygen consuming organic substances in the effluents from the pulp and paper industry has been considerably reduced. The greatest remaining pollution problem in the pulp industry is connected with the bleaching process. In this process the pulp is treated first with chlorine or a mixture of chlorine and chlorine dioxide in several steps and thereafter with strong alkali in order to extract the colored breakdown products of lignin from the pulp. The effluents from this multi-step bleaching procedure partly possess a strong ~rownish colour and generally constitute about half of the total effluent volume from a kraft pulp mill. This means that only in Sweden the kraft pulp bleacheries discharge about 300 million m 3 of waste water per annum. To get a detailed description of the chemical composition of the very complex mixture of different organic compounds discharged from the cellulose pulp mills is a formidable task, still to a great extent refractory to fulfilment. An interesting approach to this problem has recently been used by the Canadian workers LEACH and THAKORE (1973, 1975), who concentrated their identification work on those compounds that could be shown to cause clear-cut biological effects on aquatic organisms. In their studies on effluents from the first extraction step in kraft pulp bleacheries, LEACH and THAKORE (1975) were able to show that almost the total acute toxic effect to rainbow trout was exerted by a limited number of resin acid derivatives and chlorinated lignin breakdown products. The compounds responsible for 90 percent of the acute toxic action to fish were mono- and dichlorodehydroabietic acid, tri- and tetrachloroguaia col and epoxystearic acid. This result relates of course only