Extraction Test And Evaluation Method Of Landfill Gas For Municipal Solid Waste Landfills

Landfills in China have an annual capacity of13.2billion m3landfill gas (LFG), and LFG includes greenhouse gases, poison or smelly gases, it is flammable and combustible. So landfills need to carry out LFG collection engineering, and which has two key works—forecast of LFG and evaluation of LFG. But at present, we still don’t have a perfect forecast and evaluation method of LFG. With doing the extraction test and theoretical analysis, this paper presents a forecast and evaluation method of LFG.This paper divids the method into three parts:The first part is the gas model and its parameters. It chooses the appropriate gas model based on the analysis of the existing gas model. It discusses the two key parameters of the gas model---the potential LFG generation capacity (L0) and the LFG generation rate (k). It gets the relationship between L0and the components of waste. The second part is the extraction test and analysis of k. It introduces the results of extraction test, and shows the influence of leachate level to influence radius of extraction well and steady flow in extraction test. It confirms the value of k from the test data. The third part is the evaluation of LFG collection rate. It studies the gas migration with the one-dimensional steady-state model for gas pressure distribution in layered waste landfills. It also uses the numerical simulation software COMSOL to analysis two-dimensional steady-state pressure distribution and the influence radius of extraction well. It gets the relationship between LFG collection rate and the leachate level. Combining with the above three parts, this paper did a forecast and evaluation of LFG of two landfills in China.Parameter analyses using the presented method show that:the value of L0of waste with typical components is122m3/t in China. The value of k is0.20a-1in Shanghai Liming landfill, and the influence radius of extraction well is between10.42m and15.52m. Reduce leachate level can effectively improve the LFG collection rate. Control landfill cover conditions and lechate level is two effective measures to improve the LFG collection.