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The Research on Oily-Wastewater Treatment by Immobilized Microorganisms

Author: GongYuanJiao
Tutor: BaoMuTai
School: Ocean University of China
Course: Analytical Chemistry
Keywords: Oily wastewater Sodium alginate Immobilized microorganisms Biodegradable
CLC: X703
Type: Master's thesis
Year: 2010
Downloads: 202
Quote: 2
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Abstract

Oil to bring huge economic benefits, but also on the ecological environment caused a huge threat. The hazards of oil pollution on the environment and human health has gradually attracted the attention of people, oil pollution control methods and techniques to become today's environment workers urgent need to address the problem. Use the microbial immobilization technique to repair the research results of the pollution of the environment, immobilized microorganisms also have some breakthrough technology in the field of oily wastewater treatment. So-called immobilization technique, refers to the use of physical or chemical means will be free of microorganisms or enzymes are positioned within the space defined area, to keep it active and can be used repeatedly to meet the need of the application of biotechnology in proliferation under appropriate conditions, can also . Immobilized micro-organisms, toxic substances tolerance and degradation of organic matter significantly improved. This thesis is focused on the immobilization technology in the oily wastewater treatment applications. In this thesis, the oily sewage as the research object, examines the existing two hydrocarbon degrading bacteria in the laboratory biodegradation; Sodium Alginate immobilized microorganisms and compare the immobilized bacteria free bacteria effect on the degradation of crude oil; chitosan biofilm methods do a preliminary study, to enhance calcium alginate microspheres strength is, provides a theoretical basis for the practical application of calcium alginate microspheres. Experimental study, the main conclusions of the study are summarized as follows: (1) through physiological and biochemical experiments, the laboratory has two petroleum hydrocarbon degradation bacteria W-1 and W-2 preliminary identification of Rhodococcus and Bacillus cereus. By measuring the growth curves of the two strains obtained W-1 and W-2 in a rich medium growth rate is faster, 7h achieve stable phase. Univariate analysis experimentally derived optimal growth conditions of the two strains, W-1: pH value of 7.5-8.5, a temperature of 35 ° C, salinity of about 2%; W-2: pH value of 7.5-8.5, temperature of 35 ° C and a salinity of about 4%. Compared with W-1, W-2 has a higher salt tolerance. (2) two strains for crude oil degradation rate decreases with the increase of the concentration of crude oil; W-1 and W-2 can adapt to the largest crude oil concentration of 0.3% and W-2 for crude oil degradation rate than W-1, respectively, 32% and 45%, respectively; when crude oil concentration exceeds 0.3%, the toxic substances in the crude oil significantly inhibited the growth of bacteria, the medium W: 1 and W-2 significantly reduced the number, or even impossible bioremediation ; the microbial crude oil degradation rate, as the degradation time growth gradually increased after 7 days the number of two strains of dynamic equilibrium, stabilized, the degradation rate of crude oil stabilized. W-1 and W-2 are substantially consistent with the best conditions for biodegradation of crude oil and the optimum growth conditions. (3) was measured at 25 ℃ activated carbon adsorption amount of bacteria W-2 10.9 × 108cell / g, so adding activated carbon not only give the microspheres to provide support to enhance the strength of the microspheres and through the adsorption of bacteria to enhance the effect of immobilization . Sodium Alginate containing activated carbon fixed-W-2 by single factor analysis of experiments, the optimal immobilization conditions: the crosslinking temperature 25 ° C; the crosslinking agent pH of 5-6; crosslinking time for 24h; entrapped bacteria volume of 6 mL (of embedding bacteria and gels volume ratio of 5:1). Obtained by the comparative tests, to add an inorganic salt can accelerate the immobilized W-2 activity recovery. (4) in the oil content is 0.3% of the inorganic salt medium, the immobilized W-2 can adapt to the degradation conditions were: temperature, 30 to 50 ° C; pH value of 6-9; ,2-5% of salinity, than the scope of the adaptation of the free W-2 (temperature 40 ° C, a pH of 7-8, the salinity of about 4%) is widened; the rate of biodegradation and free W-2 up to about 40%, immobilized W-2 for crude oil degradation rate can reach more than 70%, increased by 30% or more than the free W-2, the treatment effect was significantly better than the free bacteria. (5) sodium alginate low mechanical strength, easy to decompose shortcomings, the paper, in addition to add activated carbon, chitosan solution in the biofilm on the surface of the microspheres to enhance the strength of the immobilized microspheres. Experimental results show that when 85% deacetylation degree of chitosan solution, a concentration of 0.8% chitosan solution biofilm time for 1.5 h, the biofilm effect Preferably, the mechanical strength of the strongest and stirred, after a period of time , no damage. Biofilm, significantly improve the mechanical strength of the microspheres can be reused twice.

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CLC: > Environmental science, safety science > Processing and comprehensive utilization of waste > General issues > Wastewater treatment and utilization
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