Study And Application Of High Temperature Aerobic Bio-drying Technology For Domestic Waste

Chinese domestic waste has the complex characteristics of "high water content,high organic matter,high mixing degree and low calorific value",in which the water content is the key factor to restrict its harmless,reducing and recycling.The common technologies for reducing the water content of domestic waste are mechanical drying,heat drying,biological drying,etc.,but there is still room for improvement in investment,energy consumption,operating cost,operational stability and drying efficiency,and environmental friendliness.Among them,the high temperature aerobic biological drying technology is to use the garbage released heat from the process of organic matter degradation of high temperature aerobic microbial flora,forming a continuous stable high-temperature environmentin the dry silo,making the waste liquid water evaporate into gaseous water,and then the ventilation system change the dry silo of low-temperature and humid air into high temperature and humidity gas and then discharge the gas.(In the dry silo,the low-temperature and humid air is changed into high temperature and humidity gas,and then the gas is discharged from ventilation system)The process to quickly remove most of the water from the waste.Currentlyaerobic composting and other common aerobic bio-drying technologies,that have been widely applied in China and other countries,have many problems such as low drying temperature(35～45°C),low speed,long cycle,poor drying effect,low product calorific value,hard to recycle..To improve the biological drying temperature is the breakthrough point to solve this series of problems.Therefore,to carry out the engineering research of high temperature biological drying technology,to build a high temperature aerobic biological drying technology system to adapt to the national conditions,It has guiding significance for the sustainable development of domestic waste treatment in China to "waste resources,waste to energy".In this paper,the researcher performed many types of high temperature aerobic biological drying process performance tests,through systematical researches about drying process and factors that influence its effect,drying product’s application suitability as well as drying flue gas pollution control,to determine the engineering operating conditions of high temperature aerobic drying process.On this basis,we performed the establishment of high temperature aerobic biological drying technology mathematical model and Process control methodand the high temperature aerobic biological drying technology mechanism and optimization control strategy research by the application of environmental biology,biochemical reaction kinetics,thermodynamics and other principles.On the basis of constructing high temperature aerobic biological drying technology system,this paper further puts forward a series of high temperature aerobic biological drying technology scheme,such as high temperature flue gas,solar energy and other waste heat auxiliary,small integration,flue gas dedusting desulfurization and denitrification.Through the engineering case analysis,this paper also performs the technical and economic evaluation of the process.The results are as follows:(1)High temperature aerobic biological drying is a kind of drying method suitable for Chinese domestic waste,and the temperature range is 50℃～70℃.(2)During high temperature aerobic biological drying process,the water content of garbage is gradually decreased from about 58.9% to about 18.6%,which is more than 50%,and the low calorific value of garbage is decreased from about 9000kj/kg to 18000kj/kg.(3)The main factors that affect the drying of high temperature aerobic are organic matter content,microbial strain,ventilation volume,warehouse structure,oxygen concentration,particle size,and the thermal insulation property of the silo,wwherein the high temperature aerobic microorganism strain,ventilation volume and silo structure are the decisive external factors.(4)the concentration of NO and SO in the discharge gas of the high temperature aerobic biological drying process is lower than the emission standard limit of the air pollutant Comprehensive emission standard(GB 16297-1996);High temperature aerobic biological drying process does not produce leachate,and the impact on the surrounding environment is small,which do not need to support special wastegas and wastewater treatment facilities.(5)After high temperature aerobic biological drying process,treated domestic waste can be made into refuse derived fuel(RDF).RDF’s combustion process is stable,and its combustion pollutant emission concentration is low.The products of high temperature aerobic biological drying can be used as a clean and efficient new energy source.The RDF/coal blending mass ratio should be controlled within 5～10%.(6)During the high temperature aerobic biological drying process,the variation of temperature of waste is consistent with the growth of microorganism,which proves that the energy used for biological drying is from the high temperature aerobic microorganism’s decomposition of organic matter in the waste.()(7)High temperature aerobic biological drying technology can shorten the biological drying cycle to 7d;the drying process can be divided into temperature rise period,high temperature period and temperature drop period.The durations of each period are 0.6d,5.6d,0.8d;water removal is mainly at high temperature.(8)The control strategies at various stages of high temperature aerobic biological drying: At the early stage,meeting the oxygen supply and heating up rapidly are the main control basis.At the middle stage,setting the oxygen supply to establish a dynamic balance between the maximum heat release of microorganism and ventilation and dehumidification absorption of heat is the main control basis.At the later stage,meeting the need for ventilation and dehumidification and rapidly reducing the temperature of waste are the main control basis.(9)The technology can be used in the existing waste incineration and comprehensive treatment plant renovation project.The transformation of some of the project investment is about 30,000 yuan/t,processing costs is about 23 yuan/t,the new economic benefits of about 66 yuan/t.(10)Using this high temperature aerobic biological drying technology,China’s domestic waste can use the "collection ～ Aerobic biological Drying ～ compression ～ transshipment" of the shipping mode and "coarse crushing + high temperature aerobic biological dry +RDF fuel Manufacturing + fuel incineration(or comprehensive utilization)" treatment and disposal model,fundamentally improve the efficiency of domestic waste disposal in China.Chinese government’s supporting and encouraging policies to the environmental protection industry provide a huge supply market for waste treatment.High temperature aerobic biological drying technology adapts to this change of market demand.It is a efficient,economical,practical waste biological pretreatment method and a solution to the “three high and one low” problem of Chinese domestic waste.There will be a broad application market for this technology.