真人做人爱试看一

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          There are many obvious problems in agricultural application of sludge. Experts call on change

          Author: Taida machine       Release time:2016-08-24
          Reading guidance:The control standards for pollutants in agricultural sludge (gb4284-84), which was promulgated in 1984, has played a guiding role in the control of urban sewage sludge. However, there are many problems
              The control standards for pollutants in agricultural sludge (gb4284-84), which was promulgated in 1984, has played a guiding role in the control of urban sewage sludge. However, there are many problems in this standard from the present point of view:
          1. The control of heavy metals is too strict
             Because the city was a small amount of generated sludge, the related research work of heavy metals accumulation is very weak, limiting the concentration of standard value is not according to our specific situation according to the test result, but the reference to foreign standards. This is obviously not good for our crops, soil, climate and other basic conditions, and control all kinds of heavy metal concentration values are the lowest in developed countries to reference the standard value. Therefore, China's agricultural sludge heavy metal control standard is almost the same standard in most strictly. At that time, developed countries have only just promulgated or are making the standard of land use related city sludge, and China in the lack of adequate the accumulation of science make hasty agricultural sludge pollutant control standards (gb4284-84), apparently will encounter many practical problems. In accordance with this standard, the city sewage in our country is very much Mud can not land use. In fact, in does not cause the pollution of the environment under the premise, as long as it does not exceed the environmental capacity of urban sludge land use should encourage urban sludge land use. Recently, in the sewage treatment industry has "urban sludge" renamed "biological solid" and the name have been widely accepted in the different industries. Even in the official publication of the United States Environmental Protection Agency (USEPA) will also "urban sludge" renamed "bio solids", to avoid for a long time, people of urban sludge) bad impression, promote urban sludge land use.
          2. The restraint standard of Zn and other matters doesn’t comply with china’s national condition
              According to the statistical analysis of existing data, 55% city sludge samples exceed the standard Zn content, if the strict implementation of national standard gb4284-84, the city sludge can not only take the land use, landfill or incineration and other disposal methods. In fact, considering the situation of our country, which is a huge waste of resources. According to the second national soil survey data, China has 49 million Hm2 farmland zinc deficiency, total cultivated land of 51.1%. obviously, Zn content standard of sewage sludge in China's agricultural city standard is too strict. The city sewage treatment industry concerned have paid attention to China's problems in municipal waste water treatment plant emission standards news group (Draft) will limit the city sludge heavy metals in agricultural standard was modified. In the modified standard, raise the limit standard of Zn to 3000mgpkg (ph615 Soil). According to this standard, the exceeding standard rate of Zn in existing sample is only 9%. But this just a control of urban sewage treatment plant pollutant discharge standards, rather than for municipal sludge in the formulation of the standard, so the standard of urban sludge land using (not just narrowly "farm") in many of the problems and not refined.
          3. when sewage sludge is used for landscaping, waste to improve the forefront lack of heavy metals and other pollutants control standard. With reference to the current standard formulation method, for agricultural, range land, and landscaping, improved abandoned land should develop a refinement of the corresponding standard, should not be a standard application in all cases;
          4. no consideration was given to the control standards of pathogenic pollutants. In order to make the urban sewage sludge land use more safe, we should continue to improve and develop the control standards of pathogenic pollutants in municipal sewage sludge and municipal sewage sludge.
          5. in our current control standard only on agricultural sludge pollutant concentration limit, but on sludge up to accommodate many pollutants did not clearly defined. Even urban sludge concentration of heavy metals did not exceed the control standard, if long-term excessive use may also cause some harm to the soil properties and ecological environment.
               The control standard of agricultural pollutants in sludge has been carried out for in the city nearly 20 years. At the early 80s of 20 century, the sewage treatment industry is not developed, the function of the standard also is not very prominent. Now, there are millions of T city sludge produced every year in China, city sludge treatment and disposal has become the city sewage treatment industry the "bottleneck", therefore it is urgent to establish a set of norms, feasible standard of land use management and guidance of city sludge. The National Environmental Protection Bureau data show that in 1998 the city sewage sludge compost and land use has high sludge production reach city 53%, 2010 will rise to 70%. from the United States the development situation, land use it is an important way to solve the problem of city sludge. Therefore, according to the actual situation of our country, after the city sludge harmless treatment of land use is suitable for our country An important way of national conditions, however, so far, the urban sewage sludge content, form and its behavior in the soil and other scientific issues are required to carry out a more systematic, in-depth field experiment.
              Related experts said that the current agricultural sludge pollutant control standards there are many unreasonable places, especially in heavy metal and pathogen control standard of need as soon as possible to improve. Therefore, the relevant functional departments should as soon as possible formulation of the new standard, in the control of urban sludge land use environmental risk at the same time, and actively promote China's urban sludge resource utilization.
           
                    
           
           
           
           

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          真人做人爱试看一

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