58-Aerobic Treatment of Pulp Mill Effluent in Batch and Continuous Reactors

Abstract

Batch and continuous studies were conducted for the aerobic treatment of black liquor from an agricultural residue based krafl pulp mill using pure cultures of bacterial strain Aeromonas formicans. Batch experiments were carried out in 500 ml Erlenmeyer flasks containing 200 ml of sterilized black liquor supplemented with nutrients at optimum concentration and pH. The results revealed that the strain was able to remove 70 to 78% of chemical oxygen demand (COD) and lignin, while the colour removal efficiency was around 86% in 10 days of retention time in batch process. To study the continuous treatment of black liquor on the laboratory scale, completely mixed, continuous flow aerated reactors were fabricated using plexi glass having a capacity of 6 litres. The removal efficiencies of COD, colour and lignin obtained in continuous reactors were 73, 88 and 77% respectively for 8 days detention period and these efficiencies were almost the same as obtained in batch studies.