Anaerobic Treatment of Pulp and Paper Mill Effluents: An Overview of Applications

Since the early 1980s anaerobic treatment of industrial effluents has found widespread application in the pulp and paper Industry. Over 200 anaerobic plants are treating a large variety of different pulp and paper mill effluents. Amongst various anaerobic systems the UASB and IC are the most commonly applied anaerobic reactor systems. Anaerobic treatment is well suited for effluents originating from recycled paper mills, mechanical pulping (peroxide bleached), semi-chemical pulping and sulfite and kraft evaporator condensates. Advantages of anaerobic pretreatment are (1) net production of renewable energy (biogas), (2) minimised biosolids production (3) minimal footprint and (4) reduced emission of greenhouse gases. Via in-line application of anaerobic treatment in closed circuits (paper kidney technology) further savings on the cost of fresh water intake and effluent discharge levies are generated.