Study On Resource Utilization Technology Of Stale Waste In Landfill

The governance of landfill waste has become an important work for nearly two years of China's environmental protection.The reuse of stale waste is the key to ensure the smooth development of the landfill treatment.In this study,a municipal solid waste landfill in Beijing was taken as the research object.The particle size and physical and chemical characteristics of landfill samples were analyzed after multi-point sampling,screening and manual sorting according to different particle sizes,and exploring the resource utilization of different components of stale waste in formal landfill.The research results are as follows:1.The humus soil and combustible waste such as plastics are the main components of waste,which together make up more than 80% of the total mass of stale waste in landfills.The combustible waste such as plastic was mainly concentrated in more than 60 mm,the stale refuse from the group of 0~60mm were mainly humus soil.Therefore,the waste of the landfill can be screened by 60 mm to realize the coarse classification of humus soil and combustible waste.The calorific value of the combustible waste on the sieve can reach 23.13 MJ/kg.With reference to the control standards for urban wastes for agricultural use(GB8172-1987),the total nitrogen content of humus soil was low,and other indicators met the standards.2.According to the physical and chemical properties of the stale waste,the resource utilization of the combustible waste on the screen and the humus soil under the sieve is adopted.The research results are as follows:1)The pyrolysis and combustion characteristics of mixed samples of combustible waste and pulverized coal with different proportions were investigated.There is a big difference in combustible waste and pulverized coal in terms of pyrolysis and combustion characteristics.Combustible waste has high volatile matter,and it is mostly precipitated in the low temperature section.In contrast,pulverized coal has a higher fixed carbon and most of the weight loss occurred in the high temperature range.It can greatly improve the burn-off of combustible waste,after being mixed with pulverized coal.When the mass ratio of combustible waste to coal powder is 4:1,its burning rate reaches 88.4%,which also causes a violent reaction to occur and releases a large amount of heat and its maximum heat output reaches 10427 mw.2)The research on the humus soil under the sieve as the substitute raw materials for the cement kiln and the seedling planting substrateFirstly,in order to explore replacement potential for humus soil was used as one of the raw materials for cement kiln and the effect of cement performance after adding humus soil.In this study,the humus soil in landfill soil was taken as the research object.The humus soil was pretreated by thermal desorption at three temperature gradients of 400°C,600°C,800°C and three time gradients 20 min,30 min,and 40 min,and chemical characteristics for humus soil after thermal desorption treatment are analyzed.The results showed that the most of the heavy metals and chloride ions had a good removal effect after thermal desorption conditions at 600? and 800?.However,the enrichment of most of heavy metals occurred with the thermal desorption time growing longer.With the increased of temperature and time of thermal desorption,the removal rate of chloride ions was on the rise.The humus soil was used as one of the raw materials for cement kiln to participate in burden calculation.And combined with the "Environmental protection technical specification for co-processing of solid wastes in cement kiln"(HJ662-2013).Humus soil could achieve the greatest replacement potential with 13% replacement amount at thermal desorption condition of 600°C for 30 minutes.The performance of different cement products was analyzed with 0%,3%,6%,9%,and 13% ratios of incorporation of humus soil after thermal desorption treatment.The results show that the properties of clinker and cement with different mixing ratios meet the requirements of relevant standards.In addition,the strength of cement increased significantly after incorporation with humus soil.The highest strength levels could be achieved at 52.5 grade of Portland cement.Secondly,In order to explore the best blending ratio of humus soil as a planting substrate for landscaping,it compares the physical properties of different planting matrices with the quality of seedlings after cultivation.In this study,the application of humus soil can reduce the bulk density of the planting substrate.However,it has an adverse effect on porosity and aeration porosity,which is caused by an increase in the amount of humus incorporated.Each treatment compared with the control group CK1(soil: vermiculite = 5:1),with the addition of fertilizer,it reduced the porosity and aeration porosity of the planting substrate.The adding of humus soil can obviously improve the growth and development,emergence rate,fresh weight and dry weight of seedlings,but excessive incorporation will have a certain impact on the seedlings.Mixing humus soil and plain soil at a mass ratio of 3:2 can greatly improve the emergence rate of seedlings,in addition,the adding of humus soil will prolong the growth cycle of seedlings.The quality of the seedlings added to the sheep manure was significantly better than that of the chicken manure.Therefore,when the content of sheep manure is increased,it will cause the seedlings to grow weak.It is necessary to strictly control the dosage.