Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China; School of Civil and Environmental Engineering, Nanyang Technological University, 639798, Singapore; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China.
School of Civil and Environmental Engineering, Nanyang Technological University, 639798, Singapore.
Chemosphere. 2022 Mar;290:133298. doi: 10.1016/j.chemosphere.2021.133298. Epub 2021 Dec 16.
Freshwater sludge (FS) produced from drinking water treatment plants is generally filter pressed and disposed in the landfill. However, FS could be potentially reused. In this study, FS were processed into biochar and hydrochar via pyrolysis and hydrothermal carbonization, respectively. The sorption characteristics/mechanisms of FS and its derivatives (biochar-B300, B500 and B700 and hydrochar-H140, H160, H180 and H200) for the removal of three typical pollutants (i.e., lead (Pb), phosphorus (P) and enrofloxacin (ENR)) found in swine wastewater were investigated using batch adsorption tests and microstructural analyses. It was found that Pb sorption was relatively enhanced due to the increased electrostatic attraction and surface precipitation of Pb(OH) while the anionic phosphate adsorption relatively decreased as a result of enhanced electrostatic repulsion at higher solution pHs. Comparatively, ENR adsorption was less affected by solution pH probably due to dominance of physical adsorption evidenced by the good fitting of the BET isotherm model (R = 0.95). The maximum sorption capacities of Pb were in the order of B700≈B500 (71 mg/g)>B300 ~ FS(37 mg/g)>H140 ~ H160 (13 mg/g)>H180 ~ H200 (6 mg/g). The adsorption capacities for P were relatively lower: FS (47 mg/g)>B300 (38 mg/g)>H140 (27 mg/g)>B700 (37 mg/g)≈B500 (24 mg/g)≈H160 (23 mg/g)>H180 (16 mg/g)>H200 (14 mg/g). This study provides an understanding of the sorption characteristics and mechanisms of FS and its carbonaceous products for common cationic, anionic and organic pollutants and elucidates new insights into the reuse of FS for pollutant removal to achieve the waste-to-resource concept and enhance water quality, soil health and food safety.
从饮用水处理厂产生的新鲜污泥（FS）通常经过压滤并在垃圾填埋场处置。然而，FS 也可能被重新利用。在这项研究中，FS 通过热解和水热碳化分别转化为生物炭和水热炭。采用批量吸附试验和微观结构分析，研究了 FS 及其衍生产品（生物炭-B300、B500 和 B700 以及水热炭-H140、H160、H180 和 H200）对猪废水中三种典型污染物（即铅（Pb）、磷（P）和恩诺沙星（ENR））的去除特性/机制。结果表明，由于静电吸引和 Pb(OH)的表面沉淀，Pb 的吸附得到了相对增强，而在较高的溶液 pH 下，由于静电斥力增强，阴离子磷酸盐的吸附相对减少。相比之下，由于物理吸附占主导地位，ENR 的吸附受溶液 pH 的影响较小，这一点可以通过 BET 等温线模型（R=0.95）的良好拟合得到证明。Pb 的最大吸附容量顺序为 B700≈B500（71mg/g）>B300FS（37mg/g）>H140H160（13mg/g）>H180~H200（6mg/g）。P 的吸附容量相对较低：FS（47mg/g）>B300（38mg/g）>H140（27mg/g）>B700（37mg/g）≈B500（24mg/g）≈H160（23mg/g）>H180（16mg/g）>H200（14mg/g）。本研究提供了对 FS 及其碳质产物对常见阳离子、阴离子和有机污染物的吸附特性和机制的理解，并阐明了 FS 用于去除污染物以实现废物转化为资源的新概念，从而提高水质、土壤健康和食品安全。
