Impact On Quality Of The Water Spinach And Heavy Metal Accumulation Of Soil Of Different Applying Sewage Sludge Amount

Urban sewage treatment plants were builted and puted into operation in the country among major cities as mushroom-like with the economy raise and the urbanization development of China. Of course ,it has played a positive role in the prevention and treatment of water pollution, but a potential problem resulting:sludge treatment and disposal.For a long time, there was a tendency in China that the light sludge treatment. According to statistics, it was about 9 million tons discharge every year fromin urban sewage treatment plants in China and increase rate of 20 percent an annual. A lot of unstability sludge dealing with unnormal way, it has become a heavy burden of sewage treatment plants and important sources of pollution that impact the urban and rural environment.Sludge contains a large number of organic compounds, heavy metals and pathogens, it was caused serious environmental pollution if emissionsed anywhere without treatment.In recent years,the content of heavy metals have decreased significantly in urban sludge. The green garden used was better land used for sludge composting.In order to found a broader way to land-use sludge, it is an important research for sludge composting application in vegetables and crops.Under the predecessors of sludge used before,first according to the amount of ertilizer applying, close to the production. It wsa layed a foundation to application sludge in vegetables bass that analysis the sample of vegetables bass in Huiji country of Zhengzhou City and discussion the content of heavy metals in different areas of soil; Second, the sludge of Xuchang sewage treatment plant was choosed to the test fertilizer,the test field in Xuegang vegetable bass, the focus analysised the impact on quality of the water spinach and heavy metal accumulation of soils in Huiji country through the different applying sewage sludge amount.;it was analysised the evaluation of soil environment quality through the sewage sludge in Henan Province using in agriculture..Finally,.Search the composting as the best fertilizer application and the application of life,provide was offered for resources usede of sludge in agricultural.The results are as follows:1.Evaluation of indexes of combined pollution which three out of four vegetable bass was beyong 1 in Huiji country, all grades more than the warning level.According to the national standard for evaluation of soil environmental quality showed that the degree of pollution in four vegetable bass was Xuegang than Huijiqiao than Qingzhai than Tielu;indexes of monomial of Cd was the highest in four areas respectivly,the pollution of Cd was serious than other heverymetals;Q-cluster results showed that six kinds of heavy metals that the soil of Huiji country were divided into two groups. Group one including Zn, Cr, Cu, Ni and Pb, they had common features of the pollution index what is lower; Group two includes Cd, it refers to the pollution index was higher;Relevance and principal component analysis showed that, Cd, Cu, Zn, Cr between Pb were significant relationship, there were several elements pollution, according to sewage irrigation 30 years past and application a lot of fertilizer now.2.Heavy metals accumulated of soil for sludge consecutive application four years, according to the model that predicte the security soil life, if the application amount for the food, content of Cd, Cr may be higher than national agricultural soils two standards in consecutive application sludge for one and ten years under 45t/hm2 treatment; the effect more obvious of short-term cumulative about Cu;long-term excessive use of sludge there also have accumulated risk although Zn, Pb, Ni short-term accumulation in the soil were not obvious.3. There was an obvious increase in the water spinach output with being applied sludge,the yield were hightest with 30kg/hm2 treatment,up than the blank treatment 102.80%.The content of nitrate were lowed national standard of food hygiene,in particular the application of sludge for many years to attention the potential risks, nitrate levels in vegetables will accumulated through the food chain role in the human body.4. Heavy metals content of water spinach shown the trend that with the increased amount of sludge, and Zn> Cu >Cr>Pb> Ni>Cd of different treatment.In the first harvest,content of Zn, Pb had exceeded the national food hygiene standards;In the second when,there had Cu,Cd and Cr;Arrived the third harvest all of six heavy metals content of water spinach had exceeded the national standard of food hygiene. In the future work,the curing treatment of heavy metals shoud be considered,use lime for instance;and be paied attention to avoid the leafy vegetable varieties to minimize the potential harm of heavy metal accumulation.5. Intake of six heavy metals of the per person per day lower than the ADI standard value. according to the moisture content of 95 percent in water spinach and the consumption vegetables of 400 grams per person per day.6. The content of heavy metals in the sewage sludge was greatly higher than that in the soil background, and had not achieved the national standard in 8 cities out of 17; also the sludge was used for agriculture made the soil into serious polluted risk in Cadmium and Zinc.The rate out of stander of Zn reached 41.2%.Cu, Cr, Cd has a different degree of occupation, Sewage may be different geographical nature with the local people's living standards, customs and industrial and agricultural nature.7. In the condition of applying 30t/hm2, under the safety and security soil pollution levels there had ten points for the sludge can be applied five years, six points for ten years,and twenty years late,the soil of all points may be pollution; the years of sewage sludge using in agriculture was less than fixed number if the content of heavy metals in soil was lower than the secondary standard of soil environment quality. 8. Proposed to reduce the concentration of Cd when the 17 points to the city sludge application of vegetables;Puyang, Hebi, Jiaozuo, Pingdingshan and Zhoukou, Xuchang, Zhengzhou seven points of the sludge can be used in food crops; Kaifeng, Sanmenxia, Xinyang, Luohe, Xinxiang five points of the sludge should not used in food crops but economic crops;Anyang, Luoyang, Zhumadian and Nanyang, Shangqiu five points of the sludge should not be used in economic crops, the proposal can be used in landscaping and other Area. However, no matter in any areas, it should be the establishment the long-term research of sludge, soil and environmental testing in order to determine the appropriate application of sludge and the application of life.