Influence Of Landfill Structure On Landfill Gas And Temperature

Sanitary landfill remains one of the most principal methods of municipal solid waste disposal at the present time. But nowadays landfill technique just takes landfill as a passive storage waste place, the wastes in landfill were isolated with outside water and air. Moisture content in landfill was so low that it couldn't provide microorganism with feasible condition, organic compounds in wastes biodegradation was restricted. It takes long time that landfill reach stability. The pollution of the leachate and landfill gas is very large. These emissions can last for decades or even centuries and result in a significant negative impact on the environment. So, every country has taking measures to ameliorate landfill technique to accelerate landfill stabilization process and weaken leachate pollution. That controlling pollution of landfill from headstream is significative to leachate treatment Disposal function is an important function of MSW landfill. With the increasing of air and moisture content in landfill, compound organic material can be decomposed by microorganism quickly, so the s process of landfill site is accelerated. At the same time, the way of biodegradation of compound organic material take change because of oxygen the pollution of landfill gas descend largely and the leachate quality is improved. In this experiment the structure of traditional landfill was change to semi-landfill .with temperature difference between solid waste mertiral and surroundings, air inflow to landfill and diffused ventilation in pipe so that the air condition was improved In this way both change the landfill structure and bio-reactor landfill are used disposal function of MSW landfill to improve leachate quality and landfill stabilization.to afford theory basisTwo landfill installations (1×1.5×1.8m) were built according to semi-aerobic landfill and anaerobic landfill theories. One is semi-aerobic landfill, the other is anaerobic landfill to contrast. Many points which were used sampled gas and detect temperature were paved with gridding. After rubbish landfill being completed.φ(CH4),φ(CO2),φ(O2) temperature were detected statly the spatial-time variety of landfill gas and temperature were reseached with geostatistics theory. The influence of Landfill structure to landfill gas and temperature, the result were as follows:1. Landfill gas distribution. In semi-aerobic landfill installation. The variety of landfill gas spatial distribution was very big and symmetrical along with vent-pipe .In area that near vent-pipeφ(O₂) was high ,butφ(CH₄) andφ(CO₂) are low; In area that near vent-pipeφ(O₂)is low ,butφ(CH₄) andφ(CO₂) were high. In anaerobic landfill simulant installation. Landfill gas spatial distribution was very large and show anisotropic. That is to say the variety of landfill gas spatial distribution in vertical was larger than that in level. From up to downφ(CO₂) andφ(O₂) increased andφ(CH₄) decreased2. Dynamic variety of landfill.The variety process of semi-aerobic landfill could divided into four periods: slowly ascending period(2～12 weeks).fast ascending period(12～23 weeks).stability period(23～30 weeks) descending period (30～42 weeks) during measure stage the biggest value ofφ(CH₄) of 14.7% which appeared in the 23th weeks , that ofφ(CO₂) was 21.5% which appeared in the 23th weeks The variety ofφ(O₂) descended firstly ,then kept stability ,ascended at last ,its least value was 3.7% which appeared in the 23 th weeks stable stage. The landfill gas of anaerobic landfill also could divided into four periods, their variety were different from that of semi-aerobic landfill, the biggest value ofφ(CH₄) andφ(CO₂) in anaerobic landfill installation were separate 46.8% which appeared in the 32th weeks and 42.0% which appeared in the 26th weeks, theφ(O₂)of anaerobic landfill installation descended firstly then ascended , during most timeφ(O₂) was less than 1%.3. Temperature variety.During measure stage the temperature of upper middle and down level in both landfill installation all ascended firstly and reached the biggest value at the 105th day, then descended and reached the least value. The temperature of upper middle and down level in semi- aerobic landfill installation were different each other. But that in anaerobic landfill installation were very nearly, During all measure stage the difference among them were never more than 0.5℃. Because the installation was very small, the temperature of semi- aerobic and anaerobic landfill installation were impacted very seriously, the temperature variety of rubbish and that of room temperature were parallel nearly4. Influence of Landfill structure on landfill gas and temperature.Because semi-aerobic landfill installation fixed vent-pipe, most rubbish biodegrading are aerobic reaction, which accelerated rubbish biodegrading. So stability rate of semi-aerobic landfill was faster than anaerobic landfill, theφ(CH₄) in semi-aerobic landfill gas was less than that of anaerobic landfill gas. The influence of vent-pipe on landfill gas spatial distribution was very distinct such as variety of landfill gas bigger than that of anaerobic landfill gas and symmetrical along with vent-pipe. The rubbish of semi-aerobic landfill degraded fast and drastically which released more heat, so temperature of semi-aerobic landfill was higher than that of anaerobic landfill.