Ultrafiltration Combined with Biological Treatment
Ultrafiltration of the effluents of paper industry reduces TOCI from 50% to 35-45% (3 kg/tonne pulp), which can be further reduced to 2 kg/tonne pulp, by combining ultrafiltration with oxygen bleaching. The effluent, however, is still acutely toxic, so that further biological treatment is needed. Following biological methods are available : (i) use of aerated lagoons, which are expensive: (ii) fungal treatment, particularly filamentous fungi (e.g. white-rot fungus = Phanerochaete chrysosporum), which can be filtered off and recirculated to the process.