Study On The Biodegradation Technology Of Waste Water-Based Mud From The Drilling Plant In The Ocean

In this paper, the microbial diversity of waste water-based mud from offshore drilling was analysed, also its physical and chemical properties. A high efficient hydrocarbon degrading strain was screened from the waste water-based mud,and the influence of the culture condition on the degradation ability of this strain was investigation. A SBR devices and a aerobic fermentation device were designed, and their performances were investigation.The physical and chemical properties of waste water-based mud from Pinghu Oilfield were anslysed, and the result showed that its parameters, such as organic content, exceed the national emission standards. Also, the result of GC-MS showed that the pollutants contained hydrocarbons, acids and esters, and long-chain alkanes are the main pollutant.The bacterial 16S rRNA gene clone library was constructed to detect the hydrocarbon-degrading bacterial community diversity in the waste drilling fluid. The phylogenetic analysis indicated that most of clones were clustered inβ,γ-Proteobacteria with the phylotypes belong to y-Proteobacteria accounting for 78.6% of the clone library. The sequences closely related to moderate halophile Chromohalobacter sp. and Halomonas sp. were dominant in the bacterial community. The hydrocarbon-degrading bacteria were isolated from the waste water-based mud and evaluated by 2,6-DCPIP combining GC method.Based on the study of the degradation abilty of petroleum hydrocarbons in the waste water-based mud of the single strain and the mixture with the activated sludge, a high efficient hydrocarbon degrading strain was screened. The influence of pH, oil concentration, microbial quantity, experimental time on the degradation abilty of 3-Jun strain was studied. The result showed that the optimum culture condition were as follows:pH 8.0, glucose concentration 15 g·L-1, NaCl 0.8 g·L-1, NH4Cl8.0 g·L-1, KH2PO4 2.0 g·L-1, Na2HPO4·3H2O 1.2g·L-1, inoculum size 7%, temperature 25℃, rotation rate 160r-min-1. The SBR has a significant effect on the degradation of the oil in the waste water-based mud. The removal of COD was 87.11%, when the COD of the inflow was 1000 mg/L. The 3-Jun strain was added to the SBR system, and it could be found that the removal rate of COD reached 90.12%,3.01% higher than without dosing. And the degradation rate of the oil was also slightly has been improved.In the experiment of the aerobic fermentation, sawdust was used as the amendment, straw as the bulking, and peptone was used as nitrogen source. The forced aeration was at the rate of 0.07m3/h while the influence of the microbe soures on the process was thus investigated. The oil degradation rate was up to 50.45% after aerobic fermentation under the conditions of the mixture of the activated sludge and 3-Jun strain as the microbe.