72.石炭炉底灰を利用した下水汚泥焼却灰の安全化処理

抄録

Coated sewage sludge ash pellets were prepared by covering with bottom ash from a coal-fired boiler. Since the melting temperature of inner sewage sludge ash was lower than that of outer bottom ash, coated sewage sludge was heated rapidly in order to make only the surface of a pellets melt. The condition which let only the surface of pellets melt was decided, after each thermal conductivity of sewage sludge ash and bottom ash were measured. The elution test was carried out in hydrochloric acid and nitric acid solution for the sewage sludge ash pellets with and without bottom ash coating. The coating of sewage sludge ash completely suppressed the elution of arsenic ion in both solutions, while the sewage sludge pellet without coating caused a considerable amount of arsenic elution.