PRB技术同步去除地下水中硝酸盐和镉

为评估可渗透反应墙(PRB)技术同步去除复合污染地下水中硝酸盐和重金属的可行性，选取蛭石、活性炭、固定化微生物为PRB反应介质，采用批实验和柱实验在不同填装方式及不同水力停留时间等条件下，考察PRB技术对硝酸盐和Cd2+的同步去除效果。结果表明：PRB介质为蛭石或活性炭与固定化微生物组合型填料时，Cd2+对PRB去除复合污染水体中的硝酸盐影响甚微，可实现高效的同步去除；当进水NO3-N浓度为50 mg·L-1、Cd2+浓度为10 mg·L-1时，活性炭与固定化微生物的组合型反应介质对NO3-N和Cd2+去除率分别可达93.13%和95.80%，蛭石与固定化微生物的组合型反应介质对NO3-N和Cd2+去除率分别可达92.70%和99.50%，经处理后的水质可达到地下水Ⅲ级质量标准(GB/T 14848-2017)。以蛭石+固定化微生物、活性炭+固定化微生物作为反应介质的PRB技术可以实现NO3-N和Cd2+的同步去除，该技术可应用于处理硝酸盐和重金属复合污染地下水。

Synchronous removal of nitrate and cadmium from groundwater using permeable reactive barrier technology

In order to assess the feasibility of synchronous removal of nitrate and heavy metal in groundwater using permeable reactive barrier (PRB), vermiculite, activated carbon, and immobilized microorganisms were selected as the medium for PRB reaction. The synchronous removal efficiency of nitrate and cadmium using PRB technology was investigated under various filling methods and hydraulic retention times by batch experiments and column experiments. The results showed that Cd2+ had slight effect on the removal of NO3-N, and synchronous and high effective removal of Cd2+ and NO3-N occurred when the vermiculite or activated carbon and immobilized microorganism were selected as the PRB media. When the concentrations of NO3-N and Cd2+ were 50 mg·L-1 and 10 mg·L-1, respectively, the removal rates were up to 93.13% (NO3-N) and 95.80% (Cd2+) for PRB with combined medium of activated carbon and immobilized microorganisms, and up to 92.70%(NO3-N) and 99.50%(Cd2+) for PRB with combined medium of vermiculite and immobilized microorganism. The PRB treated water quality could meet the third level of national quality standard of underground water (GB/T 14848-2017). Therefore, the PRB technology with the combined reaction medium of vermiculite and immobilized microorganism or activated carbon and immobilized microorganism has a satisfactory synchronous removal efficiency of NO3-N and Cd2+ in groundwater, which can be applied to treat the groundwater polluted by nitrate and heavy metals.