The Study On Microorganism Community Structure In Bio-deodorization Biofilter Of Petrochemical Company

Nowadays, with the improvement of living standards, people become more sensitive to environmental problems caused by odors. Petrochemical exhaust are toxicity and harmful to bodies since it contained a variety of compounds of benzene, aromatic hydrocarbons, inorganic and organic sulfide and ammonia. It becomes more and more important to deal with them efficiently.With deep research in bio-deodorization technology and related areas, biological treatment of odors is attracting attention due to its benign eco-friendliness, energy-savings and low operating costs. At present, biofilter is the most popular, extensive-using method in bio-deodorization technologies. Microorganism capable of deodorization is the key of bio-deodorization in biofilter system. Microbial community structure will be influenced by the changes of the device operating conditions and micro-environment, and demonstrate the different metabolic characteristics.The goal of this research is to study the odor treatment effiency of bio-deodorization biofilter in Shanghai Petrochemical Company as well as the microorganism diversity and structure on the biofilm in biofilter by using conventional microbiological methods and molecular biology methods and SEM. The conclusions were drawn as follows:1. The removal rate of the hydrogen sulfide was maintained at around 98% in biofilter during whole process .After a month of acclimation, the average removal rate of ammonia and VOCs (volatile organic compounds) could be reached to 85.17% and 88.5% respectively. The biofilter has shock resistance ability against high-loading and concentration odor.2 The results of microbiological experiment showed that the heterotrophic bacteria was predominated in biofilm, the next is fungi. Compared the removal rate of the odor components with the changes of microorganism amount, it is found that the microorganisms amount of the stalk and cortex reached the maximum after a month running, meanwhile the removal rate of odors reached the stable stage, The functional microbial amount increased a lot after one month acclimation which lead to the improvement of decomposition and the removal rate. There was an an slowly increased trend of Actinomycetes number which proved that the biofilter was becoming more mature and stable.3 The identification results of pure culture microorganisms showed that the most bacteria isolated were Bacillus; Fungi had more groups, thereinto 25% wasPenicillium, and meanwhile there existed Trichoderma, Aspergillus and other groups. These microorganisms have good acclimatization and are widespread in soil, water and plant tissues. They maybe play important role in treating odors.4 In the study of biofilter's microbial community structure using single strand conformation polymmorphism (SSCP), the optimal operatin conditions were as followings, 10% gel concentration (acrylamide-bisacrylamide[49:1]), adding 5% urea, PCR product was digested by lamda exonuclease, the dilution of the product is 1:1 ,the sample quantity of the PCR product applied in electrophoresis is 10μL, during electrophoresis, the voltage is 150V, with 4℃ constant temperature, electrophoresis 12h .The results showed that the microbial diversity and similarity were gradually increased with the running time, illuminated the microbial community structure in filter gradually become stable.5 After the bands cutting of SSCP fingerprint, and purification, re-amplification, sequenced, and compared in the genebank, the results showed that more than half of the bands represent the uncultured bacteria; they were quite different from the pure cultured isolations. Bacillus is the dominant bacteria, accounts for 33.3%, which give the same results with pure culture methods. At the same time, in the biofilter there exist many rhizobium strains, suggesting that the inner microorganism groups in root played a role in the treatment of odor.6 The results of microscopy and SEM of biofilm showed that biofilm became thickening with the running time extended, and the color gradually deepened. There were more protozoa, such as nematodes and rotifers as well as bacteria, streptococcus, filamentous could be clearly observed in SEM photographs, indicating that the microbial diversity on filter surface were aboundant with the time went on.