Application Of Bio-augmentation Technology To The Mature Landfills Leachates

With the fast economic development in China, urbanization is becoming more and moreserious. However, landfills leachates are being piled up day by day which is a big concern.Nowadays, there are mainly three ways to deal with this problem; it includes Biologicalmethod, Physical chemistry method and Land-coating method. Leachate from maturelandfills is typically characterized by high ammonium （NH4+） content, low biodegradability（low BOD5/COD ratio） and high fraction of heavy metals and large organic molecules suchas humic and fulvic acids. According to the National conditions and technical capabilitiesin China, biological treatment of leachate is undoubtedly the most cost-effective alternativewhen compared to other treatment options. Nevertheless, mature leachate effluents areknown to contain recalcitrant, thus, biological processes are not efficient in these cases.This problem can be improved or even solved by bio-augmentation technology.Bio-augmentation technology is the technology which aims to increase the biomass bymeans of adding some special bacteria to the system. This technology endows the originalbacteria to have stronger adaptability to the poisonous environment, shortens the adaptationtime and results in the better treatment efficiency eventually. According to the currentsituation of mature leachate in Changchun, we employed the method of increasing theconcentrations of NH4+N, humic acids and heavy metals(Mn²⁺Cd²⁺Cr³⁺)respectively.Three dominant strains were domesticated and isolated from leachate subsequently and thetreatment efficiency was measured by Chemical Oxygen Demand（COD）and the16SrDNA method was employed to identify every dominant strain. In the meanwhile, weintroduced the technique of Orthogonal experimental design to optimize the way thedominant strains treated the landfills leachates, the conditions in the Orthogonalexperimental design are as follows; experiment temperature、pH、the amount of thedominant strains and the amount of the Phosphorus. The result indicated pH was the mostimportant factor compared with the others and PH=7was the optical condition. Pre-treatments of Microwave and ultrasonic were applied to investigate the effect of theseprocesses on the subsequent biodegradability improvement. For this, different scenarioswere tested with regard to reaction time of10、30、60and120minutes and temperature of30、40、60and80℃. Ultrasonic power intensities were30W、40W、50W、60W、70W. Microwave power intensities were160W、320W、480W、640W respectively. Theresult indicated the optical temperature for the pre-treatments was between30-40℃,considering the treatment efficiency and the environment--friendly issue. We also usedfour screening mediums （yeast extract medium、tomato juice modified medium、Potatoextract glucose medium、Ethanol modified medium）to look for the potential dominantstrains and we got three dominant strains labeled1、2、3. Afterwards, three geneticsequences were tested and shown by the16S rDNA technology. Biological kinship wasdescribed by Biological evolution trees. Unfortunately，however，all the three dominantstrains did not show close genetic relationships with other bacteria（Pseudomonas bacteria、Heterotrophic denitrification bacteria、Bacillus.etc） Starch hydrolysis experiment andIMIC experiment were conducted to further examined the Metabolism of the potentialdominant strains.As described above, we utilized the method of increasing the concentrations of NH4+N,humic acids and heavy metals(Mn²⁺Cd²⁺Cr³⁺)and obtained the respective dominantstrains; The method of Chemical Oxygen Demand（COD）was employed to evaluate everydominant strain biodegrability; Pre-treatments of Microwave and ultrasonic were applied toimprove the effect of these processes on the subsequent biodegradability; Three potentialdominant strains were obtained by using four related screening mediums whose geneticsequences were tested and shown by the16S rDNAtechnology and their biological kinshipwas described by biological evolution trees.