危险废物焚烧飞灰固化体的长期稳定性试验研究OACSTPCD

To understand the applicability of different solid waste toxicity leaching methods for evaluating the long-term leaching behavior of solidified fly ash from incineration of hazardous waste,a study was conducted on the solidified fly ash from a disposal center in Hangzhou.The study examined leaching behaviors of solidified heavy metals in different leaching processes,analyzed the factors affecting the leaching process and applicability of the leaching methods,and proposed testing suggestions to the long-term stability of the solidified bodies through:1)leaching toxicity tests of the solidified fly ash with three standard methods;2)multiple extraction procedure(MEP)tests,3)pHstat leaching test;4)alternate dry-wet leaching tests simulating natural environmental conditions;and 5)tests examining influence of hazardous waste leachate on leaching behavior.The results indicated that pH was a key factor affecting the leaching toxicity of the solidified fly ash.The existing standards HJ557,HJ/T299 and HJ/T 300 cannot accurately assess potential risks of heavy metals in the solidified fly ash.The multiple extraction procedure(MEP)could extract metals from the unstable heavy metals from the solidified fly ash in a weakly acidic environment,serving as a reference for evaluating the stability and environmental risk of heavy metals.The pHstat leaching test not only allows the assessment of the leaching toxicity of the solidified fly ash at different pH values,but also measures the acid neutralization capacity of the solidifiedfly ash,providing insight into the potential leachability of heavy metals from the solidified fly ash over a long time.