College of Earth Sciences and Engineering, Hohai University, Nanjing 210098, PR China.
Bioresour Technol. 2012 Oct;121:169-75. doi: 10.1016/j.biortech.2012.06.084. Epub 2012 Jul 4.
Solid residues (SRs) are important byproducts of sub- and super-critical water gasification of sewage sludge (SS). In this study, the quantitative evaluation of heavy metals (HMs) in SRs, compared with SS, is applied in terms of potential ecological risks, pollution levels, and both bioavailability and eco-toxicity. The results show the bioavailability and eco-toxicity of HMs in SRs decrease, although the total concentration of HMs increased, particularly in the bioavailable fraction of Cu, which decreased nearly 97%. The geo-accumulation and potential ecological risk index indicated that the gasification process increased contamination by two levels (to the maximum), while the overall risk was in keeping with SS. However, based on the risk assessment code, each tested HM exhibited lower environmental risk after gasification, especially for Cd, which drastically dropped from 66.67 (very high risk) in SS to 0.71 (no risk) in SRs, with a reaction temperature of 375°C for 60 min.
固体残留物 (SRs) 是污水污泥亚临界和超临界水气化的重要副产物。在这项研究中，从潜在生态风险、污染水平以及生物可利用性和生态毒性方面，对 SRs 中重金属 (HMs) 与 SS 中的重金属进行了定量评估。结果表明，尽管 HMs 的总浓度增加，但 SRs 中 HMs 的生物利用度和生态毒性降低，尤其是 Cu 的生物可利用部分，几乎减少了 97%。地积累和潜在生态风险指数表明，气化过程将污染程度提高了两个等级（最高级别），而整体风险与 SS 保持一致。然而，根据风险评估准则，每种测试的 HM 在气化后表现出较低的环境风险，特别是 Cd，其从 SS 中的 66.67（高风险）急剧降至 SRs 中的 0.71（无风险），反应温度为 375°C，时间为 60 分钟。
