真人做人爱试看一

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          Heavy metal characteristics of sludge of sewage treatment plants in Guangdong province

          Author: Taida machine       Release time:2016-08-17
          Reading guidance:In recent years, owing to rapid development of economy, environmental pollution is getting worse and worse. People gradually realize that non coordinated development of industries and environmental pro
                In recent years, owing to rapid development of economy, environmental pollution is getting worse and worse. People gradually realize that non coordinated development of industries and environmental protection coordination will threaten seriously human health and survival. In order to control pollution and slow down the deterioration of environmental impact on human beings, the country gradually construction of pollution treatment facilities for sewage treatment plant as representative. Relevant data shows that Guangdong province (city) have built the sewage treatment facilities. According to statistics, the province has built 239 urban sewage treatment facilities which can dispose about 13547000 tons. At the same time, sludge amount produced reaches to 2 million 470 thousand tons / year to 494 million tons, ranking first in the country. Restrained by the characteristics of the sludge and technical conditions, sludge treatment forms are single. Most of the dehydration is transported to landfill place or incinerated after dehydration process. This disposal method not only costs much money, but also waste resources. Even, cause secondary pollution.
               Sludge is a by-product produced in the process of biological waste water treatment. It is a aggregation formed by a variety of microorganisms of zoogloea and adsorption of organic and inorganic  matters. In the disposal process, by absorption of bacteria in the sewage treatment process, bacteria and minerals absorbed on the surface of the particles, and with some inorganic salts (such as phosphate, sulfate and etc.) co precipitation and a variety of ways, sewage in 50% ~ more than 80% of the heavy metals will be transferred in the sludge, if the sludge failed to get good disposal, will cause serious heavy metal pollution to the environment. At the same time, sludge containing heavy metals is influenced the sludge were dominated by farmland resources utilization, the main restraint factors.
               Guangzhou, Shenzhen, Foshan, Dongguan and Zhaoqing's main industrial sewage sludge of sewage treatment plant of heavy metal content was higher, and the amplitude of variation is larger. Compared with the national average of city sludge, heavy metals in sewage sludge which is lower than the national average level, but contains a large number of industrial waste water sludge is higher than the national average level and, some heavy metals is higher than the limit of sludge in China agricultural value, most of the heavy metals were significantly higher than the average value of agricultural soil in Guangzhou city. Because the characteristics of heavy metals in sewage sludge will be gradually accumulated after the agricultural city of Guangdong Province, 8 for the city sewage treatment plant sludge agricultural still has some risks, especially the risk of sludge containing a large amount of industrial waste water is high.
              In different sludge, the results of acid leaking are different. Among them, the highest leaking proportion of heavy metal are Zn and Ni respectively; the mean values of 25. 4% and 23. 8%, Cu and Cr leaching ratio is low, with an average of 2. 9% and 2. 8%, respectively, Pb has no is the highest of the two metals in leaching.Zn and Ni content of, mobility is very strong, the potential mobility and biological hazards of most worthy of attention.
              Sludge disposal and sludge disposal don’t keep same pace. Sludge disposal lags behind sewage disposal all the time. Sludge disposal is ignored for a long time. Recently, there are more and more pollution caused by sludge. Sludge disposal is paid attention to by government and citizens. At present, the sludge disposal in our country mainly adopt landfill. With the increasing amount of sewage treatment, sludge production increases day by day. The rapid development of economy makes the land become the most valuable resource, landfill disposal has been considered an unsustainable development. Therefore, the sludge resources as one of the main direction of sludge disposal, and large amount of sludge is rich in nitrogen and phosphorus and organic matter, the sludge has become a possibility. The study can be found, the more developed economy in the Pearl River Delta region, city sewage treatment plant is often part of the industrial waste water containing, or even a large amount of industrial waste water this leads to heavy metals, residual sludge produced in the waste water treatment process will contain high content of sludge utilization in agriculture which has certain risk. Therefore, in Sludge disposal of agricultural use, should be guided by the heavy metals in sludge concentration is lower than the harm plants, pollution of groundwater and surface water concentrations of principle, while addressing the leaching of heavy metals to reach standard of safe re-utilization of sludge.
           

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          真人做人爱试看一

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