| Biodegradation is currently the most widely used in the field of wastewater treatment purification technology which use microbial metabolism to biodegrade the contaminates in the wastewater and achieve the purifying water. In recent years, immobilized microbial technology developed very quickly. This technology selectively fixed dominant strains, improved the degradation efficiency of the refractory organic matter. Due to the low temperature in the cold winter in the northern China, the efficiency of wastewater purification is very low. In order to improve the low temperature wastewater treatment effect and overcome the suspension cold-adapted bacteria vulnerable, easy loss and other issues, one of the most effective methods is breeding the dominant cold-adapted microorganism and immobilization. In this paper, cold-adapted were isolated and identified. The growth characteristics of the cold-adapted bacteria and the optimal conditions were studied. Finally, the immobilized cold-adapted bacteria were employed for biodegradation simulated wastewater at low temperature.(1) The samples for isolated bacteria came from a cold-water in Helong city, Jilin Province. After isolated, purified, primary screened and secondary screened, three dominant cold-adapted bacteria YB1, YB2 and YB3 were obtained. The three strains were identified by gram staining, physiological and biochemical characteristics, morphology of the colony and scanning electron microscope, combined with the 16 S r DNA sequence alignment results. The three isolates belong to Pseudomonas koreensis、Pseudomonas fragi and Pseudomonas lundensis, respectively.(2) The growth curve of every strain under different low temperature was determined. Meanwhile the biological characteristics of the three strains were studied. Furthermore, the optimal conditions for growth were measured. The optimum growth temperature of three strains was between 10 ℃~16 ℃; the optimal p H value of YB1 and YB3 was 7.0, YB2 was 8.0; the optimum growth shaking speed of YB1 and YB3 was 180 r/min, YB2 was 210 r/min.(3) The suspended single cold-adapted bacteria and mixed strains were used to treatment simulated wastewater. The results demonstrated that single strain and mix strains both exhibited degradation ability for removal contaminates in the water. The mix system of three cold-adapted bacteria showed the better degradation efficiency for COD, NH3-N and TP in simulated wastewater, the removal rates of COD, NH3-N and TP could were 67.46%、64.13% and 20.68%, under the condition of 8 for wastewater treatment 192 h.℃(4)The mixed cold-adapted bacteria was immobilized by the adsorption and embedding immobilization method, respectively. Adsorption method used a new polyurethane material AQUAPOROUSGEL to immobilize mixed cold-adapted bacteria( named HJ); the cold-adapted bacteria and strains-activated carbon were embedded by sodium alginate(named SAJ and SCJ, respectively). The degradation efficiency of different ways of immobilized bacteria was compared, and the optimal dosing quantity of immobilized bacteria was determined. The experimental results showed that HJ and SCJ treatment effect for low temperature wastewater were better than SAJ. The optimal dosing quantity of HJ and SCJ was 15% and 10%. Under the optimum conditions, HJ removal rate for wastewater of COD、NH3-N and TP reached at 96.14%、91.76%、63.15%; SCJ removal rate for wastewater of COD、NH3-N and TP reached at 89.89%、86.31%、31.9%. The results confirmed that immobilized mixed cold-adapted bacteria on the removal rate of pollutants in wastewater at low temperature were higher than the suspended mixed cold-adapted bacteria. Among them, HJ removal rate for wastewater of COD and NH3-N were more than 90%, the removal rate of TP was more than 60%. Therefore, the cold-adapted bacteria was adsorbed immobilized by the new polyurethane material AQUAPOROUSGEL had good engineering application value and practical application prospects. |
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