| Livestock manure is an important source for Rural Area Non-Point Pollution. With the development of industry and agriculture, and the expansion of intensive farms, The use of additives in the breeding process is becoming more and more common. In the pig raising period, the right amount of copper can promote the growth of pigs and enhance the ability to resist disease. But excessive amounts of trace elements will enter the environment and accumulate in the environment with the waste, and this will cause heavy metal pollution in soil, which through food chain can affect human health. At present, copper pollution and potential risk has been highly concerned by the state.Aiming at the pollution and control of copper in pig industry, the following studies were carried out in this paper:(1)The speciation and the residue characteristics of copper in the pig manure were analyzed in several pig farms in different regions of Chongqing by way of taking a sample at random, and discussed the change of speciation of Cu and the influence to the environment in the conventional process. The research involved: 1)Feces of different kinds of pigs:the feces of piglets, fattening pigs and sows; 2)Sewage sample: biogas residue and biogas slurry in the process of solid-liquid separation; 3)feeds: the feeds of piglets, fattening pigs and sows; 4)the feces before and after composting. Several methods of controlling copper pollution from source are put forward.(2)Have carried out pretreatment for the removal of copper in the piggery wastewater, and compared the removal and inactivation effect of Calcium hydroxide, PAC, PFS on copper in wastewater, have determined the optimum coagulant selection, dosage and process parameters such as agitation rate as well.(3)Carried out the chemical-leaching experiment. Study the effect of leaching time, leaching solid concentration, acid type on the leaching efficiency, and analysed the effect of leaching effluent on the subsequent process. And the application of chemical leaching were exploredThe main results are as follows:(1)The content of copper in feeds and feces of each sampling point showed that the content of copper is piglets>fattening pigs>sows. Sequential extraction adapted showed that although the available forms of copper in feces of piglets is in lower proportion, but the content is large, so it is more likely to be greatest threat to the environment.(2)The copper in the wastewater can enrich in the biogas residue through the biogas process, and the speciation of copper in biogas residue is more stable compared with feces of pig. Because the content of copper in the biogas slurry is far below the 0.5mg/L, refers to the ?Integrated wastewater discharge standard?, so there is no need to further removal of copper.(3)Measure of cooper source in copper pollution: 1)Organic copper additive to replace copper sulfate; 2)Equilibrium ratio of various additives; 3)Strict control of copper in feed.(4)PAC, PFS, calcium hydroxide can passivate the copper in the wastewater, and pretreatment can reach the standard. When adopted calcium hydroxide, adding amount of 15mg/L can reach the standard(<0.5mg/L).(5)The optimum leaching time is 3h. when adopt hydrochloric acid for chemical leaching, the leaching efficiency of sow and fattening pig manure is better than piglet manure. For the chemical leaching method, the higher the concentration of solid of manure, the lower efficiency of chemical leaching is. So the lower concentration of solid may be adopted in chemical leaching. with the decrease of pH, the COD, NH3-N,TP of leaching effluent increase. |
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