Behaviour of chlorinated phenolic compounds in bleach-plant, treatment-system and archipelago area

The environmental fate of chlorophenolic compounds and the influence of process changes for discharges were studied at a Finnish pulp mill during two years. Free and bound chlorophenols (FPCPs and BPCPs) and chlorinated methoxybenzenes (PCAs) were analyzed in samples of bleach plant effluent, and in the influent, effluent, and biosludge of an activated treatment plant, as well as in the discharge effluent. In addition, environmental samples, fish and sea water, were collected al various distances from the mill on the coast of the Gulf of Bothnia. The percentual chlorophenolic composition of effluents did not considerably change after the process stages. However, activated treatment considerably reduced the total concentration of chlo rophenolics. In process effluents, about half of chlorophenolic compounds were already bound and part of free chlorophenolics were subsequently bound to the biosludge in the activated treatmen plant. Nevetheless, in the discharge water, the rations of chlorophenolics were nearly the same a: before treatment. In sea water, the most widespread compounds were chloroguaiacols and 2,4,6 trichlorophenol. Seasonal variation was observed to affect the levels of chlorophenoics and methoxy benzenes in fish.