Recycling of Pulp and Paper Industry Sludge with Saw Dust by Aerobic Composting Method

Studies were conducted to evaluate the feasibility of bioconversion of pulp and paper industry secondary treatment sludge with sawdust under aerobic conditions. The composting of the waste was carried out for a period of 90 days by mixing pulp and paper industry sludge (PS) with sawdust (SD) in the ratio of 3:1 and inoculating treatment 1 (T₁) with only cow dung whereas inoculating the treatment 2 (T₂) with cow dung and effective microorganisms (EM). The composting process showed satisfactory results with the cow dung and effective microorganism inoculum, i.e., Treatment 2 (T₂). The different chemical parameters like pH, EC, temperature and C:N ratio were analysed during the composting period. The C:N ratio showed a gradual decrease from 36.12 to 21.02 and 38.30 to 17.63 for T₁ and T₂ respectively on the 90th day of composting. The pH varied from 6.5 to 7.3 and from 6.8 to 7.6 in T₁ and T₂ respectively indicating a good compost quality. The EC values decreased gradually from 2.3 μmhos/cm and reached the value 1.2 μmhos/cm in both the treatments. The nutrient values like NPK were almost equal in both the treatments i.e. Though the nutrients levels were equal, the Treatment 2 (T₂) reached the compost stability at the 90th day whereas the Treatment 1 has not reached the stability or maturity at the 90th day, which is indicated by the C:N ratio. Therefore, it can be concluded that the pulp and paper industry sludge (PS) can be successfully converted into value added compost in the period of 90 days by cocomposting with sawdust (SD) in the ratio of 3:1 and by mixing with cowdung (CD) + effective microorganisms (EM) as inoculum.