efficiency of a biological activated sludge effluent treatment plant with extended aeration

The extended-aeration activated sludge process was chosen by a Finnish company to treat pulp mill effluents. Results obtained since the treatment plant was commissioned in early 1986 had been very satisfactory. As well as reducing BOD and suspended solids, the process had reduced chlorinated phenols markedly. Other higher molecular weight chlorinated substances were also removed by the plant, which was situated at the company's Jakobstad mill.