Study On Aerobic Fermentation Process Of Corn Straw And Its Application In Winter Greenhouse Heating

China is a big agricultural country and the output of the straw is about 900 million tons every year,but the utilization rate of it is very low.It is the unreasonable utilization and disposal that make the resource wasted and the environment polluted.Aerobic composting is a fast and efficient way to convert the straw into harmlessness and recycling.This composting produces a lot of heat that can not only kill bacteria but also is provided for the outside.Choosing corn straw as the raw material then using aerobic composting to obtain the organic fertilizer and heat can solve the problem about heat supply in rural areas in winter and deal with the straw surplus,which has broad utilization prospects.Now the researches of aerobic composting mainly concern on how to stimulating rotten degree and fertilizer efficiency,however,there are few researches on heat generation and heat recycling in the process of aerobic composting.Therefore,it is of practical significance in the comprehensive energy utilization of straw that improving the heat quality in the fermentation process and providing many ways for heat utilization.The aim of the study about the heat industry by aerobic composting of corn straw is to improve the performance of heat output in straw fermentation and get the heat recycling.From laboratory scale and pilot scale respectively,this study uses many ways to enhance the performance of heat output in straw composting process,such as by designing reactor、using microbial inocula and composting additives,optimizing the condition of the industry and so on.And warming the greenhouse by designing the structure of heat transfer makes the heat recycling preliminarily.The main research contents and results are as follows:On the laboratory scale,the reactor designed has accomplished the system of reactor ventilation,heat preservation,leachate collection and temperature detection.Using self-developed FJ bacteria and commercial EM bacteria has accelerated the start of aerobic composting process,and has improved the capacity of heat output.In the small-scale composting process,the temperature has reached above 50℃ all the day,and the composting material has reached the medium decomposing state too.Meanwhile,in the laboratory scale,it has studied by using different straw grain sizes(<0.2cm,L 3.5±1.5cm;W 0.5cm,L 7±2cm;W 3cm,L 4±1cm;W 0.3cm)、 different nitrogen sources(urea,cow manure,pig manure)and different composting additives(self-made enzyme,cellulase,rhamnolipid).It also has recorded the data of temperature,humidity,p H value,specific conductance,C/N,three elements and water content.Through optimizing data,it preliminarily accomplished the ratio of bacteria agent,additive formula in aerobic composting process,and the steps of composting,which can provide theories and experimental basis for follow-up pilot experiments.Then according to the laboratory scale composting data,it has done large-scale composting experiment.It chooses the composting site in a greenhouse of the vegetable industry in Bin County,Harbin.During the experiment,it has expanded the laboratory scale.The pilot-scale composting in Bin County has been about 60m3 and fermented a total of 9 tons of corn stalks.It has reached the core temperature of the reactor above70℃ in the condition of-34℃ outdoors.It has developed the system of water cycle to exchange heat and heating supply system,then it realized the heat transfer process in the fermentation heap,heat storage in the heat storage tank and to the soil in the greenhouse.In the process of heat recovery and heating supply,continuous and intermittent heat recovery methods are designed.It is found that the heat storage temperature of intermittent heat recovery is about 2℃ higher than that of continuous heat recovery.In terms of heating supply effect,by observing the plant height of the cucumber control group and warmed group in the greenhouse,the cucumber warmed group higher than 30 cm was 11% higher than the control group.It has found that the content of organic matter,nutrient,water content,heavy metal content and other indexes are in line with the national standard.Finally,according to the content of cellulose,hemicellulose,and lignin,it has converted into sugars(glucose,xylose and arabinose)in glycolysis exothermic process then estimated unit mass of dry matter production of heat,has calculated the material capacity of heat generation in the laboratory scale and pilot scale,in order to provide the process optimization direction of experiment and the thermal solutions for theoretical guidance.