The Efficiency Of The Membrane-covered Aerobic Composting System For Agricultural Wastes Treatment And Optimum Design Of The System

China produces a large amount of agricultural waste every year.Aerobic composting is an important way to realize the " Reclamation,Harmless and Reductive" treatment of agricultural waste.The semi-permeable film aerobic composting technology has more advantages than the traditional aerobic composting technology,which can alleviate the influence of odor on the surrounding environment,and increase the air pressure in the heap to facilitate the even contact of oxygen with the material.In this paper,corn stalks are taken as the main research object.Semi-transparent membrane anaerobic composts technology is adopted to select five auxiliary materials such as cow dung,peanut meal,alfalfa meal,cabbage and urea to be mixed with corn stalks for fermentation.The changes of multiple physical and chemical properties during composts are measured to study the effects of mixed composts of corn stalks and different auxiliary materials.The semi-permeable membrane was applied to the integrated fermentation silo,the on-line monitoring system was added,the stirring and aeration equipment was improved,and a semi-permeable membrane automatic aerobic fermentation silo was developed for the convenience of mechanization control.In the process of composting,white bacteria were found on the surface of groundnut meal,alfalfa meal heap and urea heap during the heating and high temperature period,but not in the manure heap,indicating that the functional bacteria of the fermentation of cow manure and plant-based waste might not be the same.The changes of water content,p H value,electrical conductivity,NO₃-N and total solid organic carbon of five kinds of compost all accord with the general law of fermentation.After 30 days of ferment,the NH₄-N content of cow dung heap,alfalfa meal heap and peanut meal heap are respectively 0.20 g/kg,0.70 g/kg and 2.16 g/kg.The NH₄-N content of peanut meal heap is higher than that of general composting fertilizer,which fails to meet the stability requirements of composting products.The germination index of cow dung heap,alfalfa meal heap and peanut meal heap were 165.2%,124.5% and 103.7% respectively,which were not harmful to seed germination but also promoted it.Through comprehensive evaluation of the ranching degree of the five piles,it can be found that although the decomposition degree of the straw is low,the manure pile has the highest safety and is completely decomposed by fermentation.Alfalfa meal reactor high temperature time,the final heap is black brown,good fermentation effect;Peanut meal nutrients release slowly,the final NH₄-N content is high,the heap is unstable,and it needs secondary fermentation or further aging.There was no obvious change in the material of cabbage pile and the fermentation effect was not good.Urea reactor fermentation is rapid,but because urea is quickly used up,the late microbial lack of nitrogen,most of the corn straw is not decomposed.In the experiment,it was found that the semi-permeable membrane could block the odor and improve the fermentation environment,but the stirring cost manpower,and the lack of stacking process,the heap surface and internal fermentation is not uniform.Therefore based on automatic control and membrane covering design,designed a automation membrane covering the aerobic fermentation silo,improved mixing and aeration system.Temperature sensor,humidity sensor and oxygen sensor are connected to the external PLC control system,according to the real-time monitoring data,automatically adjust operation,realizes the organic fertilizer aerobic fermentation process of precise automatic control.