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Study On Zero Effluent Of Piggery Wastewater Through Co-composting With Straw And Piggery Wastes

Posted on:2004-07-31Degree:MasterType:Thesis
Country:ChinaCandidate:X Q TanFull Text:PDF
GTID:2121360092497171Subject:Soil science
Abstract/Summary:PDF Full Text Request
Trials about compost with maize-straw, rice-straw and wheat-straw were executed to treat pig wastewater and anaerobically digested effluent in winter and summer. The compost technology can consume large amount of pig wastewater, which showed that it is possible to make industrialized pig farm not to discharge piggery wastes. So the technology has good environmental benefits and social benefits, and the most important is that it offers an economic feasible model of piggery wastes treatment.The results as follow:The composts kept longer high-temperature duration even under the condition of high moisture content (80%) than those conventional composts. The treatments added pig wastewater kept longer high-temperature duration than the treatments added anaerobically digested effluent. The composts with the maize-straw and the rice-straw had longer high-temperature duration than the composts with the wheat-straw. Blast was the best way to provide oxygen for compost and control temperature of compost among blast, turnover and blast+turnover, while turnover was the worst. Temperature of composts in summer was higher than that in winter, which indicated that circumstance temperature had obvious influence on the temperature of composts.There was an acidification phase in early period of composts with maize-straw and rice-straw, after that pH rose to more than 8. However, composts with wheat-straw were in acid state during the whole composting course in winter.The amount of bacteria was dominant, followed by mildew, yeasts and actinomyces during composting in summer. Cellulose decomposing enzyme activity increased in early period and decreased gradually later. The catalase kept at a higher activity in early period and decreased quickly later, then kept at a lower activity stably. The urease kept at a loweractivity in early period and increase quickly after 70 days.In the end of compost, the C/N rations of different treatments were dropped from 32-54 to 10~20, and T values of composts were less than 0.5, so composts were mature. The contents of nitrogen, phosphorus and potassium were increasing continuously during composting, in the end, the contents of total nitrogen, total phosphorus, total potassium reached 1.73-1.92%, 0.60-0.85%, 1.81-2.71% respectively in winter, and reached 2.71-3.04%, 0.73-1.75%, 1.89-2.98% respectively in summer. The total contents of nitrogen, phospHors and potassium added up to 4.22-5.31% in winter and 5.66-7.25% in summer. The potassium contents of composts containing rice-straw were higher than those of treatments without rice-straw. The contents of nitrogen, phosphorus and potassium of treatments added pig wastewater were higher than those of treatments added anaerobically digested effluent. And the contents of nitrogen, phosphors, and potassium were higher than that of most other conventional composts.All parasite eggs were killed in every treatment. Sanitation index of treatments met the national standard of China Sanitary standard for the non-hazardous treatment of night soil (GB7959-87), except the colititer of composts with wheat-straw in winter and the compost added anaerobically digested effluent in summer. With the exception of Pb and Cd contents, heavy metal contents of treatments in winter met the national standard of China Control standard for wastes for agricultural use (GB8172-87), while all heavy metal contents of treatments in summer met the standard.The wastewater consumption rates during composting were 5.94-6.65 in winter and 9.23-9.62 in summer. The rates of dry matter loss were 65-69% during composting. The composting process reduced the mass and the volume of materials by more than 83-86% and 86% or so respectively. This composting method had a good effect on reducing of the mass and volume of materials, and condensing the pig wastewater.
Keywords/Search Tags:Zero discharge, Industrialized pig farm, High-temperature aerobic composting, Piggery wastes, Straw
PDF Full Text Request
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