| Due to the increasingly high level of urbanization, a significant increase in the urban population, so that water consumption increases, resulting in sludge production increased year by year. Agriculture accounts for a large proportion of our national economy, the annually crop straw is very large. Arable land produce a large number of crop stalks. It will take up a lot of land resources if random stacking. It will exacerbate the degree of air pollution if the straw was combusted. The municipal sludge compost and straw, not only make the water in sludge decreased quickly, but also make full use of sludge microorganisms, a large number of nutrients. This method also make straw decomposition. It is an effective and comprehensive way of using sewage sludge and crop stalks.The municipal sewage sludge and three kinds of common crop straw(wheat, corn, cotton stalk) in Shandong Province as material. First of all, used Chinese cabbage seeds germination index to determine both compost maturity. Then under the laboratory conditions optimized three straw respectively and municipal sewage sludge composting process parameters. Then carry out the field experiment, the pilot and demonstration of municipal sewage sludge and straw composting system were carried out. The heap compost pile as organic ingredients, with a certain amount of inorganic fertilizer, production of organic inorganic compound fertilizer and its application in pot experiment, to study the effect of fertilizer. At last, the economic benefit, environmental benefit and social benefit evaluation of municipal sewage sludge and straw compost were combined with the actual production and living conditions. The goal is to comprehensive use the municipal sewage sludge and utilization of straw, develop and optimize forced ventilation static pile of urban sewage sludge and straw composting system. Produce of organic- inorganic compound fertilizer, obtain good economic, environmental and social benefits. The main conclusions of this paper are as follows :(1) Forced aeration static pile urban sewage sludge and straw composting reactor is one of the effective way of using municipal sewage sludge and straw resources. The mixed composting can be a very good comprehensive utilization of city sewage sludge and waste straw. It will reduce the pollution of the environment and produce good economic and social benefits.(2) Under laboratory conditions get optimum parameters which were optimized for three kinds of crops straw and city sludge compost respectively:Wheat straw and sewage sludge compost: water content of the mixture was 65%, the ratio of straw and wet sludge mass ratio was 1/3, and the grain size of wheat straw was 0.5 cm;Corn straw and sewage sludge compost: water content of the mixture was 65%, the ratio of straw and wet sludge mass was 1/3, and the diameter of corn straw was 2 cm;Cotton straw and sewage sludge compost: the moisture content of the mixture was 60%, the mass ratio of straw and wet sludge was 1/2, and the diameter of cotton straw was 2 cm.(3) Composting parameters according to the laboratory research. The treatment of municipal sewage sludge and wheat straw, corn straw and cotton straw composting have experienced a temperature rise period, the high temperature duration, temperature reduction and mixture maturity period in four stages. Can reach the Ministry of "Environmental Protection of The Urban Sewage Treatment Plant Sludge Disposal Pollution Prevents on Best Available Technology Guide " and the Ministry of "Health of The Fecal no Harm Health Standard"(GB7959-87) high temperature and the duration of the three kinds of straw and sewage sludge composting treatment can reach 50 to 60 centigrade high temperature, and more than seven days or more.(4) After the completion of the composting, the changes of the indexes of the compost were analyzed. The results are as follows:The water the composting rate fell below 45%. Has reached the national Ministry of housing and development and Reform Commission jointly issued the "Urban Sewage Treatment Plant Sludge Treatment and Disposal of Technical Guidelines(Trial)" requirements.Compost products has tested by Zheng Ze Detection Technology Co., Ltd. Three kinds of compost of organic matter content was more than 40%, the organic matter content of cotton straw and sewage sludge composting matter even more than 70%. Three kinds of composting products total nutrient content(total nitrogen, P2O5 and K2O) are more than 5%, cotton straw and sewage sludge compost nutrient content of more than 12%. Organic matter and nutrient content all reached the national standard of the agricultural industry "Organic Fertilizer"(NY525- 2012) requirements.Sludge has been tested by Zheng Ze Detection Technology Co., Ltd., the contents of heavy metals in line with the requirements of the " urban sewage treatment plant sludge disposal of agricultural mud "(CJ / T 309-2009). Therefore, the content of heavy metals in organic fertilizer is in line with the national requirements.In summary, confirmed by field composting experiments and laboratory conditions to study the composting parameters feasible, can be used in engineering practice.(5) The city sewage sludge and three straw after composting products and inorganic fertilizer mixed with a certain proportion, made of organic inorganic compound fertilizer on spinach as experimental subjects for organic inorganic mixed fertilizer experiment. The results showed that the application of organic inorganic compound fertilizer could increase the plant height of 6%~20%, increase the crude 10%~26%, and increase the biomass of rape 5%~20%.(6) Forced aeration static pile of urban sewage sludge and straw composting technology to municipal sewage sludge and straw both difficult to deal with waste resource utilization, finally made of organic fertilizer or organic-inorganic compound fertilizer, the economic benefits significantly, environmental benefits and social benefits obtained recognition of the broad masses of the people, with broad prospects for development.In summary, in the condition of forced ventilation, it is an effective way to combine the municipal sewage sludge and straw compost, which can be used as an effective way to optimize the composting parameters. Because the compost is smaller, has no treatment and composting of odor. The compost parameters are applied in practice, and the optimization and adjustment should be carried out according to the practice. |
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