Dubey Monika, Mohapatra Sanjeeb, Tyagi Vinay Kumar, Suthar Surindra, Kazmi Absar Ahmad
Department of Civil Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India.
NUS Environmental Research Institute, National University of Singapore, 1-Create Way, #15-02 Create Tower, 138602, Singapore.
Environ Pollut. 2021 Jan 15;273:116515. doi: 10.1016/j.envpol.2021.116515.
Sludge generated at sewage treatment plants is of environmental concern due to the voluminous production and the presence of a high concentration of emerging contaminants (ECs). This review discusses the fate of ECs in sewage sludge treatment with an emphasis on fundamental mechanisms driving the degradation of compounds based on chemical properties of the contaminant and process operating conditions. The removal of ECs in sewage sludge through various treatment processes of sludge stabilization, such as anaerobic digestion (AD), composting, and pre-treatment methods (thermal, sonication, and oxidation) followed by AD, are discussed. Several transformation mechanisms and remediation strategies for the removal of ECs in sludge are summarized. The study concludes that pH, sludge type, and the types of functional groups are the key factors affecting the sorption of ECs to sludge. During conventional waste stabilization processes such as composting, the degradation of ECs depends on the type of feedstock (TOC, N, P, C/N, C/P) and the initial concentration of the contaminant. In AD, the degree of degradation depends on the hydrophilicity of the compound. The estrogenicity of the sludge may sometimes increase due to the conversion to estrogenic compounds. The pre-treatment techniques can increase the partitioning of ECs in the soluble fraction resulting in enhanced biodegradation up to 10-60%. However, the formation of by-products and loss of OH· to scavenging under high organic content during advanced oxidation processes can make the process uneconomical and require further research.
污水处理厂产生的污泥因其大量产生以及存在高浓度的新兴污染物（ECs）而引发环境问题。本综述讨论了ECs在污泥处理中的归宿，重点关注基于污染物化学性质和工艺操作条件驱动化合物降解的基本机制。讨论了通过污泥稳定化的各种处理工艺，如厌氧消化（AD）、堆肥以及预处理方法（热、超声和氧化）后再进行AD，去除污水污泥中ECs的情况。总结了污泥中ECs去除的几种转化机制和修复策略。研究得出结论，pH值、污泥类型和官能团类型是影响ECs吸附到污泥上的关键因素。在堆肥等传统废物稳定化过程中，ECs的降解取决于原料类型（总有机碳、氮、磷、碳氮比、碳磷比）和污染物的初始浓度。在AD中，降解程度取决于化合物的亲水性。污泥的雌激素活性有时可能会因转化为雌激素化合物而增加。预处理技术可以增加ECs在可溶部分的分配，从而使生物降解增强10%至60%。然而，在高级氧化过程中，高有机物含量下副产物的形成以及·OH被清除导致其损失，可能会使该过程不经济，需要进一步研究。
