College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China; Guangdong Provincial Key Laboratory of Agricultural & Rural Pollution Abatement and Environmental Safety, Guangzhou 510642, China.
South China Institute of Environmental Sciences, MEE, Guangzhou 510642, China.
Sci Total Environ. 2022 Mar 1;810:151294. doi: 10.1016/j.scitotenv.2021.151294. Epub 2021 Oct 29.
Biogas slurry has the problems of having a low concentration, having a large production volume, and containing many small-molecule organic pollutants. During the fertigation process of biogas slurry, many small-molecule organic pollutants may pose potential pollution risks to groundwater. In this study, the ultrafiltration membrane technology was used to separate small-molecule organics in the biogas slurry to prepare ultrafiltration concentrated biogas slurry (UCBS). To research the impact of UCBS and raw biogas slurry (RBS) on the small-molecule organic pollution of groundwater, a laboratory soil column simulation leaching device was used to conduct leaching experiments with 4 types of UCBS and RBS in acric ferralsols and hydragric anthrosols for two quarters (8 fertilization periods). The results of the study show that both UCBS and RBS caused nitrate pollution to groundwater. UCBS has a lower risk of organic pollution to groundwater than RBS. Irrigating UCBS in hydragric anthrosols has a higher risk of organic pollution of groundwater than that in acric ferralsols. Analysis of the molecular weight distribution of dissolved organic matter (DOM) in the leaching solution showed that the organic pollutants were mainly small molecules <10 kDa. According to 3D excitation-emission matrix (3D-EEM) analysis, the main organic pollutants in the leaching solution were fulvic acid, microbial protein metabolites and humic acid organic compounds. The research results show that the pretreatment of biogas slurry by ultrafiltration can reduce the risk of small-molecule organic pollution of groundwater in land application, which can provide a new scientific basis to standardize biogas slurry land application technical guidelines and reduce groundwater pollution.
沼液具有浓度低、产量大、含有多种小分子有机污染物等问题。在沼液施肥过程中，许多小分子有机污染物可能对地下水造成潜在的污染风险。本研究采用超滤膜技术分离沼液中的小分子有机物，制备超滤浓缩沼液（UCBS）。为研究 UCBS 和原沼液（RBS）对地下水小分子有机污染的影响，采用实验室土柱模拟淋溶装置，用 4 种 UCBS 和 RBS 在赤红壤和水稻土中进行淋溶实验，每个土柱淋溶 2 个季度（8 个施肥期）。研究结果表明，UCBS 和 RBS 均会造成地下水硝酸盐污染，UCBS 对地下水有机污染风险低于 RBS，UCBS 在水稻土中的淋溶对地下水的有机污染风险高于赤红壤。淋溶溶液中溶解性有机 matter（DOM）的分子量分布分析表明，有机污染物主要为小分子<10 kDa。根据三维激发-发射矩阵（3D-EEM）分析，淋溶溶液中的主要有机污染物为富里酸、微生物蛋白代谢物和腐殖酸类有机化合物。研究结果表明，超滤预处理沼液可以降低沼液土地利用对地下水小分子有机污染的风险，为规范沼液土地利用技术规范、减少地下水污染提供了新的科学依据。
