SIMULTANEOUS SEWAGE-SLUDGE DIGESTION AND METAL LEACHING - EFFECT OF TEMPERATURE

The effect of temperature on the simultaneous sewage sludge digestion and metal leaching process was studied in laboratory bioreactors of 20 l working volume. The results thus obtained showed that the process c an be employed efficiently for metal solubilization, elimination of in dicator microorganisms and sewage sludge stabilization at temperatures between 10 degrees C and 30 degrees C. Rates of pH reduction, sulfur oxidation, growth of thiobacilli, elimination of indicator microorgani sms and solids degradation were found to decrease with temperature. Lo w metal solubilization efficiency was observed at 10 degrees C; howeve r, metals were solubilized to below the recommended level. The solubil ization of organic matter and nutritive elements (N, P and K) was not significantly affected by the variation in temperature. The fertilizer value of sludge after leaching and digestion did not change significa ntly and remained the same irrespective of temperature.