| In recent years, China's large-scale farms and the intensification of the constant increase in the number, result in growing problems of environmental pollution brought by livestock dung. According to statistics, by the year 2007, the total emissions of the animal dung in the whole nation had reached up to 30 million tons or more, and the total COD emissions were more than 77 million tons which are five times more than the total COD emissions of nationwide industrial and domestic wastewater. As for the pollution control of animal dung, the main technology to anaerobic fermentation of animal dung biogas units are widely used and increasingly concerned about. To the end of 2010, large and medium-sized biogas projects have reached 669.785 million cubic meters. Biogas slurry will be heavily produced with the development of large biogas project.Although biogas slurry is rich in COD, BOD, SS, total nitrogen, ammonia nitrogen, total phosphorus and other substances, biogas slurry as fertilizer nutrient contains several characteristics:its content is low and is inconvenient to use except its widely using. Those characteristics severely restrict the utilization of biogas resources, especially the biogas project taken by those large-scale farms produced a large number of biogas per day which would bring about serious environmental problems without timely consumption.In this paper, the nanofiltration membrane enrichment experiments are carried out with biogas slurry characteristics. The paper will focus on the following aspects: nanofiltration membrane concentration process, the concentration of the concentrated liquid and liquid ingredients by the impact, the use of concentrated solution developed series of organic liquid fertilizer. A pot study and concentrate made with nutrient solution of soilless cultivation of cabbage yield and quality. 1, Investigation and analysis of the Ningbo Yinzhou District, various large-scale farms of more than 50 biogas digesters biogas slurry, biogas slurry containing NPK and other elements and organic matter and active substances, but also found that the methane fermentation process and biogasproject management of biogas slurry composition has a greater impact.2, Determined the best enrichment process:raw biogas, multilayer grille, quartz sand filter, the security filter, nano filtration membrane enrichment, cyele of concentration for biogas of cow dung is 4 times,5-6 times is the most appropriate for pig manure, as adopting Nanofiltration membrane with the cut-off molecular weight of 90. Biogas concentrated solution can meet the needs of the development of liquid organic fertilizer.3, As the operating pressure, flow rate, temperature and other factors keep constant,membrane flux will decline with the extension of time, adopting the intercept liquid all cycle operation mode. Along with the increase of concentration ratio, concentrate pH rose, permeate pH dropped, conductivity of both all increase. Also found that the nanofiltration membrane has a high retention effect of divalent Ca, Mg, Fe and Zn ions.4, Amino acid soluble fertilizer products, developed through concentrate enrichment process and blends with technology, meet the NY 1429-2010 standard, and there is a good application.5, The output and chlorophyll content of cabbage in the Soilless cultivation cabbage experiment, adopting the concentrate of pig manure as soilless culture solution, are higher than the control group, which adopted Hoagland nutrition solution.The result showed biogas concentrate can be used as nutrient solution in soilless culture. |
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