The Isolation Of The Facultative Anaerobes For Degrading Oil-Field Wastewater And The Study Of Multiphase Taxonomy For A New Bacterium

Oil-field wastewater is a kind of degradation-resistant wastewater with complex components,which is harmful to the environment if it is not treated.Currently,the biotechnology is a widely used,economical,and non-secondary treatment method.In this paper,the activated sludge in the ABR anaerobic treatment system for treating oil-field wastewater is taken as the research object.A combination of the traditional cultural method and the molecular biology technology is used to identify and study the characteristics and effects of partially culturable microorganisms in the ABR reactor,and a new strain discovered from the activated sludge are classified by the polyphaser taxonomy.The results are obtained as follow:(1)Nine different facultative anaerobic species were isolated from the ABR reactor,which are marked as B2?E1?H2?H3?P2?Q1?Q2?Q3?I2,respectively.It is determined that H3 belongs to the genus Bacillus,and B2,H2,Q3 have the highest similarity with Bacillus subtilis,P2 belongs to Bacillus licheniformis,E1 and I2 are Pseudomonas,and Q1 and Q2belong to Stenotrophomona sp.PG16 and Pantoea.The isolates are common degrading bacteria used in the treatment of oil-field wastewater by utilizing organic pollutants for the growth and metabolism.(2)A new strain of genus Clostridium marked YB-7~T was isolated in the activated sludge.The characteristics were described as follow:YB-7~T is a Gram-positive,strictly anaerobic rod-shaped bacterium,and the growth condition is pH 5.0-12.0(optimally pH 7.0),temperature 20-45?(optimally 37?),NaCl concentration 0-5%(optimally 5%).The main fatty acids(>5%)are C16:0,iso-C13:0 and iso-C15:0,while the polar lipids of YB-7~T are phosphatidylglycerol,phosphatidylethanolamine,phosphatidylethanolamine,phosphatidylglycerol,phosphatidylcholine Base,two unknown aminophospholipids and two unknown phospholipids.YB-7~T was named Clostridium beihaiensis sp.nov.,which was deposited at the China General Microbiological Culture Collection Center and Korean Culture Collection numbered CGMCC12214 and KCTC 15555,respectively.(3)A degradation test of oil-filed wastewater by the single factor analysis was operated to determine to get the optimal conditions for the degradation of oil-field wastewater.The best degradation effect can be achieved at the conditions of temperature 35?,inoculum concentration 3%,pH 7.0,and reaction time 48 h.In the further study,the orthogonal analysis of response surface shows the optimal degradation conditions as follow:pH=7.02,temperature34.89?,inoculation 3.76%,time 48.98 h,and the maximum degradation rate predicted by the model was 94.58%.The actual TOC degradation rate was obtained after a verification test,which can up to 94%indicating that the model has a high accuracy.This study determined the optimal conditions for the biodegradation of the oil-field wastewater,which has improved the degradation efficiency in the oil-field wastewater treatment system.The study of a new strain including discovery,identification and description has enriched the resources of the degrading bacteria in oil-field wastewater.