Field Experimental Study Based On Landfill Gas Control Leachate Transport System Clogging

The landfill leachate pipeline clogging burst phenomenon has occurred frequently. In order to solve the problem fundamentally, the previous proposed "by Waste" thinking, and through laboratory simulation experiments demonstrated the feasibility of the idea.In this paper, based on previous laboratory experimental studies, Chengdu Changan landfill as the basis,the author further verificates the idea through field tests. Experiment uses gas emissions from Changan landfill chemically reacting with landfill leachate, by means of single-factor and orthogonal experiment method to evaluate the feasibility and the control method of using landfill gas removing leachate scaling ions. And we apply experimentally determined optimum conditions to the actual engineering design process. The research shows:1) Changan landfill leachate pH is around 8.0, calcium and magnesium concentration are about 300mg/L, high hardness leachate under alkaline conditions is easy to form a precipitate; The selected discharge port mixed landfill gas flow rate basically stable at 720ml/min, the content of CO2 is maintained at between 32 to 36%, which is able to meet the requirement of the test.2) Univariate result is that the smaller gas flow rate, the higher leachate pH, the appropriate intake air amount, compared with continuous intake mode, intermittent intake method, the better removal effect of scale-forming ions.3) The orthogonal experiments show that considering the actual situation, the continuous intake condition recommends optimal reaction conditions are:pH9.5～10.0, the gas flow rate 0.08L/min, the intake air amount 2L, this time for the removal of calcium ions is 77.83%; The intermittent intake condition recommends optimal reaction conditions are: pH9.5～10.0, the gas flow rate 0.08L/min, the intake air amount 1.5L, this time for the removal of calcium ions is 77.71%.pH on the degree of influence on the removal of calcium ions play a key role.4) According to the optimal conditions of orthogonal test, I preliminarily design the prevention and control to chemical blocking process scheme of leachate pipeline transmission:the volume of leachate aerating the reaction cell and sedimentation tank is at least 1280m3; Optimal the intake air amount under continuous intake and intermittent intake air conditions respectively 1812 m3/d and 1359 m3/d; Adjusting the pH of leachate required alkali about 10.87kg/d. Using this program, it can significantly reduce the risk of environmental pollution from chemistry blockage and burst pipes in the leachate pipeline process, with good economic and environmental benefits.