Sludge Solubilization and Reduction of Excess Sludge Production in Night Soil Treatment Plants using Chemical and Biological Treatments

A novel sludge solubilization process was applied to the reduction of excess sludge production in night soil treatment plants. Chemical and biological treatments were used to reduce excess sludge. In the first step, the sludge was pretreated with alkali to enhance biological reduction. In the second step, the sludge was reduced by biological treatment. Many kinds of sludge degrading microorganisms were integrated into the sludge. The solubilization properties of batch treatment with alkali were evaluated in terms of the excess sludge in two night soil treatment plants. Successive treatments of alkali and biological solubilization were conducted. The excess sludge was solubilized approximately 30-50 % during the experimental period. This solubilization efficiency indicated that this process was able to reduce excess sludge production in night soil treatment plants.