| Based on rate-limiting step in refuse decomposition, and inhibitory effects of organic acids accumulation and high ammonia concentration on microorganisms involved in refuse decomposition in landfill only with leachate recycle (RL), landfill was combined with treatment of leachate in the paper. Effective microorganisms (EMs) were selected from refuse in the Hangzhou Tianzhiling landfill. And the mechanism of rapid decomposition of refuse and biological nitrogen removal was investigated in the bioreactor landfills with EMs inoculation and the optimization of biological environment of landfill and its bioreactor effect. The main results were summarized as follows:(1) Twelve EMs were selected from different media and carbon sources according to their enzyme activities, growth rates and growth time before log phase. They were cellulose-degrading bacterium (CB2), casein-degrading bacteria (PB15 and PA5), starch-degrading bacterium (SB11), olive oil-degrading bacterium (FB4), cellulose-degrading actinomycete (CA5), starch-degrading actinomycete (SAg), olive oil-degrading actinomycete (FA9), olive oil-degrading fungi (FF6), cellulose-degrading fungi (CF4), starch-degrading fungi (SF2) and pectin-degrading fungi (PeFs). Based on the morphological and physio-biochemical characteristics, combining with the phylogenetical analyses of 16S rDNA sequence, the EMs were identified as follows: stains CB2 and FB4 as Cellulomonas sp., strain SB11 as Bacillus megaterium, stain PB15 as Brevundimonas diminuta, strain PA5 as Bacillus anthracis, strains CA5, SAg and FA9 as Streptomyces sp., strains CF4, SF2, FF6 and PeFs as Mucor sp..(2) Key groups of anaerobic bacteria involved in refuse decomposition, including hydrolytic fermentative bacteria, hydrogen-producing acetogenic bacteria, methanogenic bacteria, sulfate-reducing bacteria, and denitritying bacteria, were all present in fresh refuse tested, in which hydrolytic fermentative bacteria and denitritying bacteria were the main microorganisms, followed by sulfate-reducing bacteria and hydrogen-producing acetogenic bacteria, and the least was methanogenic bacteria. Hydrolytic fermentative bacteria grew fastest in trophic groups. And it was the main microorganism in landfilledrefuse in the first 60 days of the experiment.(3 )Cellulose is the dominant substrate in municipal refuse. However, during refuse decomposition cellulolytic anaerobes population (104~107cells/g dry refuse) was below hydrogen-producing acetogenic bacteria, hydrogen-producing acetogenic bacteria and methanogenic bacteria populations by a factor of 104,102 and 10, respectively.(4) EMs inoculation provided a means of optimizing environmental conditions within the landfill. Hydrolytic fermentative bacteria and hydrogen-producing acetogenic bacteria populations in landfill with EMs inoculation and leachate recycle (EML) reached their maximum values were about 90 days and 30 days earlier than those in RL, respectively. And they were about 210 days and 60 days earlier than those in conventional landfill (CL) and landfill initially adjusted to 75% moisture content (ML), respectively. Sulfate-reducing bacteria, cellulolytic anaerobes and methanogenic bacteria populations in EML were also more than others. And the activities of hydrolytic enzymes, containing cellulase, protease, amylase, lipase and pectinase, positively affected by EMs inoculation.(5) The chemical oxygen demand (CODcr) removal efficiency was good in upflow anaerobic sludge blanket (UASB) reactors. Influent CODcr concentration was the main factor affecting the CODcr removal efficiency at low organic loading rates. Average methane content of the biogas produced in the UASB reactors was 75%. It was 20%~ 30% higher than that for conventional landfill gas.(6) The degradation of landfilled refuse and organic pollutants in leachate was divided into two phases in the bioreactor landfill system (BL), which combined UASB reactor with landfill. The hydrolytic fermentation and acid-production phase mainly occurred in...
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