磷对深型土壤渗滤系统中氮的迁移转化作用机制研究

发布时间：2018-05-22 16:32

本文选题：土壤渗滤系统 + 氮　；参考：《武汉理工大学》2015年硕士论文

【摘要】：生活污水的大量排放、水体富营养化以及土壤缺磷等环境问题启发人们走出了一条资源化道路——生活污水灌溉农田。这种将生活污水变废为宝、实现污染物环保化、资源化的污水回用方式即是本文将要研究的土壤渗滤技术的一种实际应用。土壤渗滤系统中,反硝化作为脱氮的限制步骤,因其厌氧条件通常发生在土壤深层,而由于浅层土壤对磷强烈的吸附截留作用,是否使得深层土壤中因为磷营养元素的缺乏,从而抑制了反硝化菌的活性、限制了反硝化过程,造成土壤的脱氮效果不理想的现象有待研究。基于以上两点,本课题以土壤渗滤系统为主体,结合假设——磷作为深层土壤中反硝化作用限制因子的可能性,探讨磷在深型土壤渗滤系统中对氮的迁移转化作用机制。实验采用直径0.3m、高2.0m的PVC有机玻璃柱模拟地下土壤渗滤系统,在玻璃内装填深2.0m的取自北京顺义实验基地的原位土,加灌含有不同磷浓度的模拟生活污水,研究磷在不同磷负荷条件下的迁移转化变化规律,及其对氮迁移转化的影响。该深型土壤渗滤系统对污水中铵态氮和磷有非常好的去除效果,出水稳定均达到一级A标准。除去前期的调试阶段,系统稳定后对它们的去除率可分别达80%、99.9%,并不受磷负荷的影响,至少在实验阶段,磷负荷不影响系统氮、磷最终出水水质,但是对氮、磷的去除过程有影响。土壤对磷有强烈的吸附固定作用,是去除磷的主要方式,增大磷负荷能促进上表层土壤磷的迁移转化作用;较高的磷负荷能加大垂直迁移距离,同时加快上表层土壤对磷的吸附饱和,加强其在土壤中穿透力。土壤对氮的去除主要是依赖其硝化-反硝化作用;提高磷浓度能加快浅层土壤的脱氮速率,尤其是反硝化速率;土壤中氮、磷的净化达标都需要一定的土壤厚度来完成。实验中三种磷浓度条件下,当进水磷负荷为30mg/L时,土壤表层的脱氮速率更高,是三种情况下,氮和磷均达标所需最小深度值也最小,为0.8m。
[Abstract]:The environmental problems, such as the discharge of domestic sewage, eutrophication of water body and phosphorus deficiency in soil, have inspired people to find a way to make use of domestic sewage to irrigate farmland. It is a practical application of the soil leachate technology which will be studied in this paper to convert the domestic sewage into a treasure to realize the environmental protection of pollutants and to recycle the sewage. In soil leachate system, denitrification is the limiting step of denitrification, because its anaerobic condition usually occurs in the deep layer of soil, but because of the strong adsorption and retention of phosphorus in shallow soil, does it cause the deficiency of phosphorus nutrient element in deep soil. Therefore, the activity of denitrifying bacteria was inhibited, the process of denitrification was limited, and the phenomenon that the nitrogen removal effect of soil was not ideal need to be studied. Based on the above two points, the mechanism of phosphorus migration and transformation to nitrogen in deep soil leachate system was discussed by taking soil leachate system as the main body and hypothesized phosphorus as the limiting factor of denitrification in deep soil. An underground soil leachate system was simulated with 0.3m diameter and 2.0m high PVC organic glass column. The in-situ soil with a depth of 2.0m was filled in the glass, and the simulated domestic sewage containing different phosphorus concentrations was added to the soil in situ, which was taken from Shunyi Experimental Base in Beijing. To study the change law of phosphorus migration and transformation under different phosphorus loading conditions and its effect on nitrogen transport and transformation. The deep soil leachate system has a very good removal effect on ammonium nitrogen and phosphorus in sewage, and the effluent stability is up to the first class A standard. Apart from the early commissioning stage, the removal rates of the systems after stabilization can reach 80 / 99.9, respectively, and are not affected by the phosphorus load. At least in the experimental stage, the phosphorus load does not affect the final effluent water quality of the system nitrogen and phosphorus, but for nitrogen, Phosphorus removal process has an effect. The soil has strong adsorption and fixation to phosphorus, which is the main way to remove phosphorus, increasing phosphorus load can promote the transfer and transformation of phosphorus in the topsoil, and higher phosphorus load can increase the vertical transport distance. At the same time, the adsorption saturation of phosphorus in the topsoil was accelerated, and its permeability in the soil was strengthened. Soil nitrogen removal mainly depends on nitrification-denitrification; increasing phosphorus concentration can accelerate the denitrification rate of shallow soil, especially denitrification rate; the purification of nitrogen and phosphorus in soil requires a certain soil thickness to complete. Under the three phosphorus concentration conditions, when the influent phosphorus load was 30mg/L, the denitrification rate of the soil surface layer was higher, and the minimum depth required for both nitrogen and phosphorus to reach the standard was the smallest (0.8 m) under the three conditions.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703;X144

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