Experimental Research On Fluid Production And Process Simulation Of Geochemistry Migration And Transformation

Leachate and landfill gas (LFG) are released continually in the process of landfill stabilization, which causes a series of resources and environment problems. It can provide theoretical basis and practical methods for municipal solid waste (MSW) harmlessness and resource that fluid production and geochemistry migration and transformation are researched by paying equal attention to MSW harmless disposal and resource development, that new bioreactor landfill technology and process are further explored.This dissertation was based on theoretical analysis, took simulation landfill device of different type and different similar scale as the experiment platform, took indoor simulated landfill experiments as main research methods, combined with on-site survey and mathematical modeling, researched fluid production and geochemistry migration and transformation in the process of landfill MSW degradation from the new viewpoint of unified harmless disposal and resource. In the dissertation, biogeochemistry migration and transformation mode of carbon element was constructed, quantitative relationship and characteristics among solid, liquid and gas evolution in the landfill were revealed, fluid production rule of landfill MSW degradation influenced by various factors was found out, artifcial induction theory of biomass was established, the effects of water migration on biogeochemistry activities and its mechanism were studied, eventually new technology of precision controlled anaerobic batch bioreactor landfill was put forward, and structure and operation mode of precision controlled anaerobic batch bioreactor landfill was constructed. By the research of this dissertation, main conclusions were drawn as follows:①Biomass loss is the basic reason of landfill secondary pollution and low LFG resource level. The key theory of manual intervention and MSW harmlessness and resource are the decrease of biomass loss and the increase of biomass gas transformation rate.②High reaction temperation and methanogens metabolism ability can promote rapid hydrolysis of solid biomass. The long-term leading role of hydrolysis acidification leads to increase of cumulative biomass loss; however, metabolic activity of methanogens can decrease it. Landfill system entering stable gas production stage rapidly, promoting cooperative metabolism between methanogens and non- methanogens are important measures of biomass loss decrease and biomass gas transformation rate increase.③In the case of regular leachate emission, the production rate of leachate and LFG are in line with the exponential function Y=A0*e-kt and Y'=V0*e-k't respectively. The potential of leachate production (A0/k) is mainly influenced by reaction temperature, the potential of LFG production (V0/k′) is influenced by water content, reaction temperature, microbial inoculation and MSW particle size. The attenuation constant of leachate production rate (k), the maximum day production rate coefficient of leachate (ηandη/k) have a significant effect on prediction results of leachate production rate.④In the process of MSW degradation, the mechanism of artificial induction gas production includes improving hydrolysis rate of solid biomass, decreasing loss of liquid biomass, promoting rapid consumption of methanogens on liquid biomass, and forming stable cooperative metabolism between non-methanogens and methanogens. Integrated multi-mode artificial induction is the effective way for implementing resource utilization of biomass.⑤It is difficult to form suitable biogeochemistry environment for methanogens in the case of regular leachate emission, which makes against rapid consumption of methanogens on hydrolysis acidification products, inhibits MSW degradation seriously. In the case of rainfall infiltration simulation, continuous washing of infiltrating water makes solid organic matter hydrolyze rapidly, meanwhile cumulative net leaching amount of CODCr increases significantly, which makes against the pollution control of leachate in landfill. In the case of leachate total recirculation, it is easy to form suitable biogeochemistry environment for methanogens, which is benefical to cooperative metabolism between non-methanogens and methanogens, accelerates leaching and removal of solid organic matter.⑥Precision controlled anaerobic batch bioreactor landfill can form suitable biogeochemistry environment for methanogens rapidly, promote hydrolysis and decomposition of solid organic matter, shorten landfill stabilization period, improve leachate quality, increase cumulative production and production rate stability of LFG and CH4, and CH4 concentration in LFG greatly. Besides, in this mode, biomass gas transformation rate increases obviously, loss rate decreases significantly, which are very important to improve potential of LFG resource and reduce landfill secondary pollution.