Pulp and paper mill wastewaters normally contain very low concentrations of nitrogen, but many pulp mill aerated stabilization basin (ASB) treatment systems are operated with no supplemental nitrogen, while achieving high biochemical oxygen demand (BOD5) removal. A nutrient
mass-balance study, undertaken across one of the aerated lagoons in such an ASB system, found that a substantial input of nitrogen was occurring within this pond, amounting to approximately 600 kg nitrogen per day. Direct measurement of acetylene reduction (nitrogen fixation), both in the
pond and in a laboratory simulation, showed that bacterial nitrogen fixation was responsible for the input of nitrogen. Most of the nitrogen for bacterial growth within the lagoon was supplied by atmospheric nitrogen fixation, and, consequently, nitrogen fixation was critical to overall system
effectiveness. It appears that elevated dissolved oxygen concentrations may inhibit fixation. This may be an important constraint on the operation of such ASB systems, especially for the first lagoon, and represents a potential change to current thinking. The implications of bacterial nitrogen
fixation, with respect to the effective operation and control of kraft mill ASB systems, are discussed.
Water Environment Research® (WER®) publishes peer-reviewed research papers, research notes, state-of-the-art and critical reviews on original, fundamental and applied research in all scientific and technical areas related to water quality, pollution control, and management. An annual Literature Review provides a review of published books and articles on water quality topics from the previous year. Published as: Sewage Works Journal, 1928 - 1949; Sewage and Industrial Wastes, 1950 - 1959; Journal Water Pollution Control Federation, 1959 - Oct 1989; Research Journal Water Pollution Control Federation, Nov 1989 - 1991; Water Environment Research, 1992 - present.