Microbial decolourisation of pulp and paper mill effluent in presence of nitrogen and phosphorus by activated sludge process.

The effect of pH, nutrient and aeration was studied on the removal of colou r and reduction of BOD, COD and heavy metals with addition of readily avail able source of nitrogen and phosphorus in concentration of 1.0 g/L. Recalci trant compound was effectively degraded by active microbial consortia. The isolated bacteria were indentified as Pseudomonas putida (S1), Citrobacter sp. (S4) and Enterobacter sp. (S5). These organisms not only decolourised e ffluent upto 97% but reduced BOD, GOD, phenolics and sulfide upto 96.63, 96 .80, 96.92 and 96.67% respectively within 24 hrs of aeration and the heavy metals were removed upto 82-99.80%. The TSS and TDS were sharply reduced du e to degradation. The absorption maxima was also decreased to 90%. However, in control without the microbial consortium no noticeable change was produ ced.