Beijing Key Laboratory of Water Resources & Environmental Engineering, China University of Geosciences (Beijing), Beijing 100083, China; College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
Beijing Key Laboratory of Water Resources & Environmental Engineering, China University of Geosciences (Beijing), Beijing 100083, China.
Sci Total Environ. 2022 Aug 25;836:155549. doi: 10.1016/j.scitotenv.2022.155549. Epub 2022 Apr 28.
Sewage sludge, including those after biological or thermochemical treatments, has the potential to be used as fertilizers for recycle of resources. However, its potential ecological risk is also of great concern to policy making. This study employed comprehensive ecological risk assessment (ERA) methods to evaluate the risk caused by the toxic metal(loid)s in sewage sludge throughout China. The conventional geo-accumulation index and potential ecological risk index revealed that cadmium (Cd) and mercury (Hg) were of significant concern in treating sewage sludge before land application, but chromium (Cr) and zinc (Zn) were preferred by potential affected proportion (PAF) and overall risk probability (ORP) of species sensitivity distribution (SSD). Because SSD considered both the community and the ecotoxicity of toxic metal(loid)s, it was more advantageous and promising in assessing ecological risks caused by land application of sewage sludge. Based on the predicted no-effect concentration (PNEC) of toxic metal(loid) calculated by hazardous concentration that cause death of 50% of species (HC50) by SSD, the maximum allowable disposal amount (MADA) of sewage sludge in the whole China indicated that chromium (Cr) should be totally eliminated because of its high risks in the present background soil. After excluding Cr, the MADA of sewage sludge in China was 3.24 × 10 t and 6.47 × 10 t under land application scenarios with high and low ecological risks, respectively. Additionally, the MADA could be increased by mixing sewage sludge with deeper soil in wider areas. This study emphasized that local laws and regulations on land application of sewage sludge and the subsequent ERA system need to be addressed in the future.
污水污泥，包括经过生物或热化学处理的污泥，具有作为肥料回收资源的潜力。然而，其潜在的生态风险也引起了政策制定者的极大关注。本研究采用综合生态风险评估（ERA）方法评估了中国污水污泥中有毒金属（loid）造成的风险。传统的地质累积指数和潜在生态风险指数表明，在土地应用之前，镉（Cd）和汞（Hg）是处理污水污泥时需要特别关注的元素，但铬（Cr）和锌（Zn）则是受潜在影响比例（PAF）和物种敏感性分布（SSD）整体风险概率（ORP）所青睐的元素。由于 SSD 同时考虑了有毒金属（loid）的群落和生态毒性，因此在评估污水污泥土地应用所造成的生态风险方面更具优势和潜力。基于 SSD 计算的物种半数致死浓度（HC50）引起的有毒金属（loid）预测无效应浓度（PNEC），全国污水污泥的最大允许处置量（MADA）表明，由于当前背景土壤中的高风险，铬（Cr）应被完全消除。在排除 Cr 之后，在高和低生态风险的土地应用情景下，中国污水污泥的 MADA 分别为 3.24×10^4 和 6.47×10^4 t。此外，通过在更广泛的区域将污水污泥与深层土壤混合，可以增加 MADA。本研究强调，未来需要解决有关污水污泥土地应用的地方法规和随后的 ERA 系统。
