Institute of Hydrogeology and Environmental Geology, Zhonghua street No. 268, Shi Jiazhuang, hebei, China.
Environ Sci Process Impacts. 2015 Feb;17(2):389-97. doi: 10.1039/c4em00538d.
PTA wastewater discharged from a factory was selected as the research object in this project and CODcr was selected as the characteristic pollution factor. Static adsorption and soil column leaching experiments of silty clay and clayey soil were carried out to study the adsorption, bio-degradation and dispersion coefficient of CODcr in PTA wastewater. Hydrus-1D was used to build the convection-diffusion model to demonstrate the migration of PTA wastewater in the vadose zone. The results indicate that silty clay and clayey soil in the vadose zone can adsorb, degrade and impede the contaminants in PTA wastewater; however, the coefficient of adsorption and degradation were very low, they were down to 0.0002 L g(-1), 0.0003 L g(-1) and 0.0097 d(-1), 0.0077 d(-1) for silty clay and clayey soil, respectively. Under the virtual condition that, wastewater in the sewage pool is 5 m deep, CODcr concentration is 4000 mg L(-1), vadose zone is 21 m, PTA wastewater will reach the phreatic surface after 20.87 years. When wastewater in the sewage pool is 7 m with other conditions unchanged, after 17.18 years PTA wastewater will reach groundwater. The results show that there is a higher pollution risk for groundwater if we do not take any anti-seepage measures.
本项目选取工厂排出的 PTA 废水为研究对象，选取 CODcr 作为特征污染因子，通过粉质黏土和黏土的静态吸附及土柱淋溶实验，研究 PTA 废水中 CODcr 在包气带中的吸附、生物降解及弥散系数。利用 Hydrus-1D 建立对流弥散模型，模拟 PTA 废水在包气带中的运移。结果表明，包气带中的粉质黏土和黏土对 PTA 废水中的污染物具有吸附、降解和阻滞作用，但吸附、降解系数均较小，分别为 0.0002 L/g、0.0003 L/g 和 0.0097 d-1、0.0077 d-1。在污水池深 5 m，CODcr 浓度 4000 mg/L，包气带深 21 m 的虚拟条件下，PTA 废水需要 20.87 年才能到达潜水面。当污水池深 7 m，其他条件不变时，PTA 废水 17.18 年就可到达地下水。结果表明，如果不采取防渗措施，对地下水存在较高的污染风险。
