The Theoretical Study On Land Application System For Wastewater And Its Demonstration

Water resource has become the primary problem of global resource environment in 21^st century. Therefore, land application system, as a superior wastewater treatment and re-utilization system, is fully acknowledged again by its advantages and is developed rapidly in the aspect of its technology, the application area and scope and its research. In this regard, soil microorganism and heavy metal are the most concerned research scope in the system, on the opposite, the transition and transformation discipline of nitrogen and phosphor is less researched. Also, the ineradaptation of the entire system needs the evidence of examination, which limits the development of land application in its practice.Nitrogen works as a primary contaminant in the wastewater research for the eliminating pathways and effect. But, Nitrogen may work as a very important nutriment absorbed and utilized by the plants in the land application system, which leads to the very unique transition and transformation discipline of nitrogen in this system.In this report, the original and development of the land application system, which current condition of utilization was concluded, were retrospected in home or abroad. The developed direction was put forward for its utilization in water resource.The pathway of elimination of amino-nitrogen(NH₄⁺-N) was analyzed by the systemic device, promotor, operation and detect after the experimental facilities of the land processing system were constructed. And the associated measure for enhancing efficiency of nitrogen removed was concluded. The function of every processing unit of the facilities was analyzed. The classified statistics was done by detecting the distribution of nitrifying bacteria and nitrosobacteria of the samples from the system.The adsorption volume of NH₄⁺-N were detected in the primary saturated soil column or non-saturated soil column by interior( or indoor) test. The regularity of nitrogen moving and transformation was studied by different irrigated methods for winter wheat using this land processing system. Dry weight, root density, production,and cellular membrane permeability of winter wheat was respectively compared in sewage or fresh water irrigation.Utilization of sewage land application system was verified by studying water collection or meadow irrigation and comparing the biological number, proline quantity, cellular membrane permeability, catalase activity under grass in meadow.In the last chapter, the Sino-US cooperation project of wastewater land application system on anti-desertification in the desert area illustrates that the technology of land application system is very useful and effective if designed and operated correctly. It can be used in the area for solving the shortage of water resource, be beneficial to grassland recovery, the improvement of ecological environment, the promotion on economic development and as far as it can also be beneficial to anti-desertification. The demonstration project is of great significance in the regard. The conclusion of the entire project is abstracted from each related aspect in the sight of practical application, the aspects, which need to strengthen and improve, is also listed here.Overall, the paper is on the line of the water resource reuse through wastewater land application system, from the introduction of its development to theoretical research work as a study basis of this paper. The study of this paper supplements the vacant research area of land application, which is verified by the numerical value. Meanwhile, the feasibility study of grass-soil land application is also valued by the grass, as well as the adaptation study. The practical project if further testified that the comprehensive land application system is effective to water resource utilization, grassland recovery, anti-desertification, and is of high value on the social, economic and environmental benefit.