复合缓释功能材料原位修复硝酸盐污染地下水的研究和应用

Research and application of composite slow-release functional materials for in situ remediation of nitrate-contaminated groundwater

针对我国地下水硝酸盐污染问题,以农业废弃物资源化利用为核心,耦合化学与生物过程,利用农作物秸秆和零价铁为主要原材料,辅以高渗透性材料和塑性粘结材料,按不同配比研发出一种用于去除地下水中硝酸盐的复合缓释功能材料.所研发复合缓释功能材料具有一定的强度和孔隙度,能够缓慢持续的释放碳源.将该材料用于室内模拟实验,以研究复合缓释功能材料与含水层介质(粗砂)填充比的不同对硝酸盐去除效果的影响,结果表明除材料与砂按1∶0时由于零价铁释放过多导致出水氨氮含量稍高外,其他各填充比对材料修复效果影响不大,硝态氮去除率均在85%以上;应用于野外原位修复,试验运行175天后,去除率高于70%,过程中没有产生亚硝态氮和氨氮的累积,为污染地下水原位修复提供了重要的技术支撑.

In recent years,due to the excessive application of agricultural nitrogen fertilizer,the unreasonable sewage irrigation,livestock farming and the waste emissions of industrial and agriculture,nitrate-contaminated groundwater is becoming an increasingly serious problem.The excessive nitrate in groundwater will be a terrible threat to the health of human,animals and plants.It is extremely urgent to repair nitrate-contaminated groundwater.In this paper,with recycling agricultural waste as the core,combined with the process of chemical and biological,and with cropstraw and Zero-Valent Iron as main materials,the composite slow-release functional material for groundwater nitrate removing is designed in different ratio.Wheat straw,attapulgite,reduced iron powder mixed in the ratio of 2∶4∶0.4ratio in inner and attapulgite∶diatomite∶cement with the ratio of 2.4∶0.8∶0.4in the shell have been optimized,the particle-strength of the material made in this ratio with low cost is big,and the surface of it is course.The material made in this ratio has been used in indoor experiment to study its nitrate removal ability,and results show that its nitrate removal efficiencyis over 85%.Permeable reactive barrier（PRB）is a new technology for in situ remediation.For the reason that there is no need to extract pollutants out of the ground and input energy constantly,PRB is widely used in foreign countries,while it＇s just in the start period in china in this field.That is why a PRB is constructed in the field.The quality of the water samples collected in fixed period are tested.Results show that,the developed material has worked well in the remediation of nitrate pollution of groundwater.The removal efficiency of this section is higher than 70%,and there is no nitrite accumulation happened during the process.The technology developed by this study is economic and efficient when used to repair nitrate-contaminated groundwater.This technology shows a very good practicability and popularization.This means that it will have a very good reference value for in situ remediation in large area for contaminated groundwater in our country.