真人做人爱试看一

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          It should be attached importance to apply the heavy metal disposal to agricultural field of urumqi.

          Author: Taida machine       Release time:2016-08-19
          Reading guidance:Chinas urban sewage treatment plant sludge with the continuous improvement of Chinas urban sewage treatment rate, the yield a dramatic increase in the. According to related statistical data shows, ever
               China's urban sewage treatment plant sludge with the continuous improvement of China's urban sewage treatment rate, the yield a dramatic increase in the. According to related statistical data shows, every year in our country sludge generated volume of more than 3 * part, the sludge problem is becoming more and more serious. Sludge contains rich organic matter, nitrogen, phosphorus, potassium and other nutrients, so the sludge become resources disposal of sludge is one of the effective ways, but enrichment of heavy metals in the sludge will to sludge bring potential risk to the environment. Many studies show that, toxicity of heavy metals not only with the total amount of heavy metals is related to, a greater degree by the chemical speciation of decision.
               There exist eight sewage treatment plants in urumqi. 2011 sewage treatment about 1.5 * 108t, sludge produced about 1.5 x (according to the moisture content of 80% of the total), of which a considerable number of no properly. Without effective treatment under random emissions, extremely easy to groundwater, soil, air, etc., causing secondary pollution, a direct threat to environmental safety and public health. Xinjiang soil organic matter content is low, fertility is low, and the urban sludge is rich in the organic matter, nitrogen and phosphorus and other nutrients, application will significantly increase soil nutrients, reduce chemical fertilizer application amount. If the sewage plant sludge for agricultural use, can produce certain environmental and economic benefits.
               By the representative of Urumqi's two sewage treatment plant sludge quality analysis, determine the possibility of Urumqi sludge in agricultural use. Two sewage sludge is neutral, not by adjusting the pH is suitable for sewage sludge sludge. After mechanical dewatering or natural drying, the moisture content is still higher than in 70%, a semi solid state for sludge transportation and agricultural increases the difficulty of China's agricultural mud standard moisture content below 60%. Therefore, the two sewage sludge need to be further dehydrated in a farm before, and this will increase the cost of agricultural sludge. Chinese agricultural mud meets the standard of nutrient elements in the sludge, the sludge has high organic matter, high N, high P, low k, which is consistent with other studies. So the sludge must pay attention to potassium balance problems at the time of application.
               All sludge adopted should meet sludge standard of CJ/T 309-2009and also meet agricultural utilization standard in America and EU. However, the Zn and Cd content of HD sewage plants has been beyond relevant standards.   Low compared to other provisions of standard 309 cj/t 2009 a sludge heavy metal control limits to be strict in the United States and the European Union standards, a class a sludge allowed to use crops are vegetables, food crops, oil crops, fruit trees, forage crops, fiber crops, B class a sludge allowed to use crop oil, fruit trees, forage crops, fiber crops, prohibit applied to vegetables and food crops. And our country urban sludge of heavy metals in Urumqi, two wastewater treatment plant sludge in Cu and Pb, Zn, Cd content is higher, especially in sludge CD content is about China's urban sludge CD average content of 1. 5 times, the Urumqi municipal sewage sludge for agricultural use especially should pay attention to the Cd pollution problem.
               The heavy metal content of sludge and effective state affect directly to its utilization methods. It will also affect agricultural utlization of sludge. Effective content should be paid much attention to. Urumqi City Zn and Cu in sludge mainly in residual and organic bound fractions, the other three forms a smaller proportion; Pb and Cd in the residual fraction, carbonate bound and Fe Mn oxide fractions. According to the morphology of the bioavailability of the various chemical forms are divided into effective state, potentially effective state. And not by the state. The State likely to be absorbed by organism, including exchangeable and carbonate fractions; potential available including Fe Mn oxide and organic bound, they are the direct provider of heavy metals; not available generally refers to the residual, basically no bioavailability. Two sewage sludge factory in Zn, Cu not use state proportion was above 50%, its bioavailability is low, the sludge is advantageous for the.Pb, CD two elements of bioavailable and potentially effective state and the proportion in 50% In the above, there is a strong biological availability, while CD, Pb for biological hazards, there is a potential risk, in the sewage sludge should be paid attention to.
           
           
           
           

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          真人做人爱试看一

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