An Experiment Study On Remedy Of Eutrophic Sediment Using Zeolite Capping Technology

Releasing ammonia nitrogen originated from sediments is the main cause of eutrophication of water bodies. Eliminating of nitrogen load in sediment is an effective way to control eutrophication of water bodies. In this study, sediments from the Yangzhou ancient entropic canal and Xi'an artificial entropic lake as the research objects, respectively. We investigated the feasibility of remedy polluted sediments capping zeolite inoculated isolated bacteria. This thesis focus on the contents that include the effect of low temperature on activity of screening predominant bacteria, the effect of heavy metal, flow turbulence, zeolite dose and ratio of sediment on remediation of zeolite capping technology. The results will provide theoretical basis for the practical application. The main results and conclusions are as follows:The result show that the mixed bacteria of HF3, HF7, WGX10, WGX18 and the mixed bacteria of HF7, WGX10, WGX15 has high removal efficiency of total nitrogen (43.1%) under 14.5℃. Therefore, these bacteria motioned above can be used eliminate to nitrogen load of sediment. The results show that metal content of sediment has little effect on eliminating nitrogen load using the zeolite capping technology. TN removal efficiency is 95.2% after 48days. TN concentration in overlying water reduced to 0.37mg/L and 91% of TN has been removed after 10 days in the simulation of the actual flow dynamic system in water. Although flow increases the releasing ammonia rate of sediment, the effect of water flow on TN removal efficiency was hardly observed in zeolite capping system.The results show that removal efficiency of TN increased as zeolite dosage increased. When the dosage of zeolite is more than 1.04kg/m2, 74.1% of TN will be removed. However, the dosage of zeolite were further increased, the TN removal efficiency changed little (84.7% of TN will be removed when the dosage of zeolite is 1.87kg/m2).The results show that there is a significant effect of ratio between sediments and water on NH4+-N release to overlying water. Under making the water 5L together with 300g sediments condition, the releasing rate of the NH4+-N is close to the releasing rate in the Yangzhou ancient canal. In this condition, TN has been removed 84% after 20days. Therefore, zeolite capping technology is effective to remedy of eutrophic sediment of Yangzhou ancient canal.