Application And Mechanism On Treatment Of Landfill Leachate With Compound Micro-organism Preparations

As the economy develops and urban population expands in China, the production of Municipal Solid Waste (MSW) is increasing. At present, China is still employing landfill as the primary method for MSW disposal, which may generate a large amount of poisonous and harmful leachate that is of complex composition and poor biodegradability, and thus have a great and lasting impact on the surrounding eco-environment if not treated. Therefore, control and treatment on the pollution resulted from the leachate has become a major issue in the current environmental protection field.The selection of strains has a very large impact on the treatment effect in biochemical process.Therefore, the choice of strain has become one of major issue for biochemical treatment of leachate.The paper aims to compare the effect of treatment under different dosing methods (adding directly, adding after sterilization, not adding) by domesticating three compound microorganisms and to probe into such influential factors, deducing the original flora may be beneficial in dealing with the original leachate.Through single factor experiments and orthogonal analysis,affection the HBH-ⅡCOD on removal levels in leachate are descending order: inoculation>pH value>reaction time>aeration time. affection the MCMP COD on removal levels in leachate are descending order: pH value>reaction time>inoculation>aeration time. affection the EM COD on removal levels in leachate are descending order: pH value>inoculation>reaction time>aeration time.The best optimal conditions are obtained for the three kinds of bacteria, adopting up bio-biofilm experiments, to compare the treatment effect three kinds of bacteria on the leachate, and selecting a strain of comparative advantage. Appling in leachate pre-treatment or advanced treatment to enhance the pollutant removal effectiveness in view of physico-chemical method, contrast to biochemical and physicochemical methods. analysing the pros and cons of different combinations comparison biochemical with physico-chemical method (physico-chemical method after biochemical, biochemical after physico-chemical method), from the treatment effect and cost-effectiveness analysis, and obtain the best treatment process.Making use of PCR-DGGE fingerprint analysis technology, the strain DNA fragments are extracted, purified, PCR amplification, DGGE separation, and 16S rDNA sequencing, compare the sequencing results with NCBI gene bank, analyzing the biofilm diversity and structural changes in the process of micro-organisms, having determined the relationship between microbial species, taking advantage of molecular biology means to explore the mechanism of microbial agent and try to explain the mechanism of microbial agents from the role of the process.Through the study of various aspects of the above, arriving at the following main conclusions:①The treatment for adding directly is superior to adding after sterilization or no-adding, this also shows that the original flora contain to deal with some of the beneficial micro-organisms in leachate.②Through single factor analysis, orthogonal experiment and comprehensive analysis of verifying experiments, HBH-Ⅱon treating waste leachate are: reaction time 96 h, aeration time 24 h, the proportioned volume of HBH-Ⅱand water 1/8000 (VHBH-Ⅱ: Vwater=1/8000), pH value 8.5. MCMP on treating waste leachate are: reaction time 72 h, aeration time 36 h, the proportioned volume of MCMP and water 1/8000 (VMCMP: Vwater=1/8000), pH value 8. EM on treating waste leachate are: reaction time 72 h, aeration time 36 h, the proportioned volume of EM and water 1/10000 (VEM: Vwater=1/8000), pH value 8.5.③With respect to preferred strains, as for removal of COD, BOD, NH4+-N and TN, there should be: EM>HBH-Ⅱ>MCMP. as for removal of TP, there should be MCMP>EM>HBH-Ⅱ. after comprehensive consideration, it is deemed that EM bacterium is the best in treating waste leachate, EM strains are selected to be the object in the subsequent researches. removal rates of COD, BOD, NH4+-N TN, TP reach 71.25%, 77.41%, 86.16.%, 86.82%, 47.25% respectively.④Biochemical water treatment through the follow-up Fenton (original pH=5, amount of FeSO4·7H2O increased to 0.03 mol·L-1, reaction time 3 h, nH2O2:nFe2+=3: 1), COD ultimately may reach 91.54%, while the concentration of the discharged water is 382.85 mg/L that meets Class III Standard in Integrated Wastewater Discharge Standard (GB8978-1996). After reaction, the value of BOD5/COD increases to 0.68 or so. Thus the biodegradability of waste leachate has been much promoted, and this may facilitate the subsequent treatments on the waste water in the pipe network. The removal rate of NH4+-N and TN in the discharged water is relatively low, only reaching 90.54% and 88.76% respectively, while TP, with a concentration of 1.56 mg/L in the discharged water.⑤The effect shows tbiofilm tailrace treatment by means of three kinds of physico-chemical method. Fenton oxidation (removal efficiency of COD 68.48%, removal efficiency of NH4+-N 18.37%) than in oxide and clay-lime hydration should be better. Comparative test also finds, The effluent parameters are approximately quite for two kinds of technologies that are Fenton+EM Biochemistry and EM biochemical+Fenton technology,the removal rates of NH4+-N, TN, TP are about 90%. the effluent higher biodegradability is obtained by way of EM biochemical+Fenton process, which is more favorable for subsequent to deal with in urban sewage treatment system. In the same removal conditions roughly, EM biochemical processes of pharmaceutical+Fenton treatment cost more than Fenton+EM biochemical processes is low 18.3%, about 4.55 yuan/ton.⑥Through DNA extraction, PCR amplification and DGGE separation. using BLAST program, analyzing the microbial community diversity of the System, as well as the dynamic change of different communities in the process of biofilm forming, and the result comes that the similarity of all sequence and 16S rDNA sequence in the database ranges from 94% to 100%, and the stains in the community structure also vary as the conditions and environment change. Some strains start dying of biological metabolism. With overall consideration, the time for early biochemical biofilm formation should be controlled within approximately eight days. The diagram of DGGE electrophoresis indicates, by the changes of bright bands and density, that the participation of strains has changed the original community structure of the microorganisms in the waste leachate. The strain represented by band 4 is 99% homological with Uncultured Firmicutes which show their advantages more obviously from the eighth day of biofilm forming. Some strains have good homology with the compared strains, but have no other strains of close genetic relationship on the phylogenetic tree.⑦Means of molecular biology analysis showed that the removal of pollutants from the the leachate was closely related to the amount of EM added,However, the contribution of original strain in leachate can not be ignored part of in the common function come from the EM strains and leachate itself role. The medicament of EM, based on its own functions, may enhance the structural evolution and functions of the communities, better the treatment system, And finally through the EM medicament and leachate in the joint action of the original flora leachate treatment systems to achieve increased performance and improved. After the success of hanging in the biological membrane, the reaction system formed by some bacteria and some of the original EM pose new strains of bacteria communities, this new strain of dealing with leachate communities play a decisive role. The practices of utilizing strong oxidants directly, alkali pretreatment will obviously damage some beneficial bacterioflora in original leachate directly. therefore, the traditional way of pretreatment process is worthy of deliberation.