Study On Impact Of Crop And Soil To Sewage Sludge Application

Land utilization is increasingly considered as a positive and effective method for sludge disposal. This method take use of a large number of rich nutrients and organic matter from sewage sludge to improve soil structure and supply crop nutrient, which can not only take the appropriate use of the sludge resources and solve the problem of sludge, but also will not endanger human's health because toxic and harmful substances such as heavy metals and organic pollutants can not enter the food chain.In this paper, take the example of dewatered sewage sludge from ShiWeiTou treatment plant in Xiamen. The study focus on the impact of grapefruit trees and soil after sludge application, which provide theoretical guidance to sludge application of Xiamen City and guarantee the safety. The paper includes the analysis of sewage sludge in Xiamen, the impact of content of heavy metals in crops after sludge application, the impact of content of heavy metals in soil after sludge application and safety evaluation in the soil after the application.The results of the research show that: the nutrient content in ShiWeiTou treatment plant are slightly higher than the nutrient content of farmyard manure, which fertilizer efficiency better. Sludge application can promote the growth of grapefruit tree, the use of sewage sludge does not affect the content of heavy metals in tree leaves and grapefruit pulp, the concentration of heavy metals in leaves in strong in the flesh, the heavy metals in tree leaves and fruit is relocated, the accumulated sludge application a year later, the heavy metal content of indicators in flesh is still in the safety limits.The application of sludge will increase the concentration of heavy metals in soil, 0 ~ 15 cm soil layer of sludge application of the heavy metal content increased significantly larger than 15 ~ 30 cm layer of soil, Cu, Zn and Ni take the biggest difference between the rate of increase that Sludge in the main concentration of heavy metal elements 0 ~ 15 cm in the soil layer. Cd in the soil is considered as the limiting factor whose largest concentration decide the age of urban sludge land application, if the largest continuous application is 30 t / (hm2.a) to the farmland, the largest application period will be 11.53 years.In this paper, enrichment analysis model are used in safety evaluation of the soil. After one year application of sewage the soil was still clean. Finally, According to the process of the subject put forward some suggestions.