Study On Biodegradability Of Three Crop Wastes In South China

As an important biomass energy material,crop wastes can be recycled and reused,which can not reduce environmental pollution,but create renewable new energy,and alleviate the energy crisis.However,crop wastes are recalcitrant to biomass due to complex and compact lignocellulose structure,which greatly limits the efficiency of biodegradation.In this paper,aiming at the problem of low biodegradation efficiency of crop wastes,this paper carry out anaerobic methane production potential and aerobic composting tests on different crop wastes through treatment measures such as freeze-vacuum drying,freezing and microbial agent,in order to provide a certain scientific basis for the research on the biodegradability of crop wastes.The main research results of this experiment are as follows:1)Three kinds of displacement method trace gas flowmeters are calibrated based on different gas flow rates.The results show that in the actual measurement process,the single measurement result of the displacement method trace gas flowmeter is not a fixed value,but has a significant correlation with the gas flow rate,that increases with the increase of gas flow rate.When the gas flow rate is too high,gas loss occurs,and the greater the gas flow rate,the more gas loss.Therefore,the displacement method trace gas flowmeter must be accurately and dynamically calibrated with the gas flow in the actual application process to achieve accurate gas measurement.2)The freeze-vacuum drying was used to pretreat the waste cured tobacco leaves.The results showed that the freeze-vacuum drying treatment could effectively relieve the rate limit of lignocellulose hydrolysis,increase the contact area of microorganisms,and improve the biodegradation efficiency of waste cured tobacco leaves.Compared with untreated,the fermentation period of waste cured tobacco leaves after pretreatment and curing did not change significantly,and the BMP was increased by 3.94%-11.73% respectively,which can significantly improve the economic and energy efficiency of tobacco waste.However,with the extension of freeze-vacuum drying time,the energy consumption increases,and the organic matter loss is serious.In future research,the relationship between production capacity and cost should be balanced,control the pretreatment time and optimize the process.3)After the fresh ramie and rape materials are frozen pretreatment,voids and cracks are formed between the cells,and erosion and dehydration appear,which can damage the surface structure of the materials.Among them,the methane production of leaf material was obviously better than that of stem material;the fermentation period of rape material was shorter than that of ramie material.However,after the pretreatment of the substrate,the cells were frozen,the tissue was damaged,and the organic matter was lost with the water during the thawing process,and there was no significant difference in BMP between the frozen pretreatment and the untreated.4)Under controlled composting conditions,organic fertilizer starter was added to compost waste cured tobacco leaves and rape leaves,respectively.It was found that the waste cured tobacco leaves and rape leaves had great aerobic biodegradability without obvious hysteresis,and the compost degradation could be completed after 28 days.The oxygen consumption rate and GI of each treated compost product met the compost maturity standard,the total nutrient content of nitrogen,phosphorus and potassium can reach5.35%～7.49%.