生物淋滤法脱除城市生活垃圾焚烧飞灰中的重金属:底物浓度的影响

通过接种嗜酸性硫杆菌复合菌株(氧化亚铁硫杆菌与氧化硫硫杆菌)并采用序批式试验，研究了底物浓度(硫粉投加比例)对城市生活垃圾焚烧飞灰中重金属生物淋滤脱除效果的影响．结果表明，5g／L的硫粉投加比例对重金属的去除与底物利用最为有利．在此条件下淋滤处理飞灰15d，Cd、Zn、Cu、Pb的去除率分别可达到89．7％、81．8％、72．6％、29．3％，硫粉的利用率达到65．2％．TLCP毒性试验表明，飞灰的重金属毒性被有效脱除．飞灰中重金属的去除或溶出主要依赖于硫杆菌生物氧化S^0所导致的浆液酸化．

Removal of Heavy Metals from MSWI Fly Ash Using Acidithiobacillus Strains: Effects of Substrate Concentration

A mixed culture of Acidihiobacillus ferrooxidans and Acidihiobacillus thiooxidans was used to leach heavy metals from MSWI fly ash (municipal solid waste incineration fly ash) to render them nonhazardous. Batch experiments were conducted to optimize substrate concentration for the bioleaching process. Results showed that substrate concentration significantly influenced solubilization of heavy metals and biooxidation yield of added sulfur. The optimum substrate concentration was 5g/L. After 15d of bioleaching, 89.7% of Cd, 81.8% of Zn, 72.6% of Cu and 29.3% of Pb were extracted from fly ash with the addition of 5g/L elemental sulfur and bacterial inoculation. Moreover, final yield of sulfur oxidation obtained 65.2%. TCLP(Toxicity Characteristic Leaching Procedure) tests confirmed that the bioleaching process resulted in the solubility reduction of Cd, Zn, Cu and Pb to below the regulatory limits. Results also suggested metal solubilization was mainly dependent on the acidification of fly ash suspension resulted from biooxidation of added elemental sulfur.