| Landscape water plays an important role in the construction of the city,but because of the small area, poor liquidity, lack of self purification ability and other characteristics, landscape water is subjected to differernt degrees of pollution. Now, the biological method is widely used in the treatment of landscape water, and microbial treatment method is an efficient and advanced technology that rises rapidly in the word. Bacillus subtilis can decompose macromolecular organic into simple organic compounds, which as the carbon and nitrogen source of reduction of nitrate by aerobic denitrifying bacteria, while under the anaerobic conditions, the photosynthetic bacteria can remove the rest nitrogen in water.In this study, we performed in different stages by using three kinds of high efficient microbial, and in order to further improve the removal rate of pollutants, we immobilizated the three kinds of composite microbia, which explored an efficient method for treating micro polluted landscape water.We screened out efficient, targeted elimination of microorganisms from nature, and optimal environmental conditions were determined according to the effect of environmental factors on the removal capacity; In order to improve the purification effect, the macromolecular material degradation reaction of Bacillus subtilis and aerobic denitrifying bacteria was performed under the aerobic conditions, then added photosynthetic bacteria without oxygen to remove ammonium; For exploring the compound microorganism’ removal efficiency of pollutants from the actual landscape water, we composited two or three strains of the three microorganisms, Moreover, we immobilized the microorganisms using polyvinyl alcohol and sodium alginate for extending the work time and keeping high degradation activity of the pollutants removal. To studying the microbial degradation of immobilized microorganism balls on the actual water pollutants, we inputed the aerobic balls into the collected actual landscape water and,shaking cultured for a period of time,and then added the photosynthetic bacteria with anaerobic static culturing.The main conclusions of this paper are as follows:1,Screening and identification of strains of three kinds of high efficient degradation bacteriaBased on the molecular analysis of the strain, we identified three types of bacteria: Rhodopseudomonas palustris(Psb2), Pseudomonas stutzeri(D-3)and Bacillus subtilis (K-9).2, The degradation effect of water pollutant by the three strainsThe ammonium removal rate was between 35% and 95.88% of Psb2 to five different landscape water, suggesting that Psb2 could efficiently reduce the ammonia in water. After inoculating the purified D-3 into the denitrification performance of the assay medium 5 days, the total nitrogen concentration decreased from 124.15 mg·L-1 to 55.39 mg·L-1, the removal rate reached 55.4%; but the nitrate concentration changed from 120.15 mg·L-1 to 2.67 mg·L-1, the removal rate was 97.78%; nitrite concentration exhibited the trend of first increased and then decreased, but kept in the lower level. Inoculated K-9 into simulate micro polluted water after 7days, we found the concentration of organic matter decreased from 300.21 mg·L-1 to 32.0 mg·L-1, the removal rate was up to 89.3%; total nitrogen concentration decreased from the initial 15.04 mg· L-1 to 12.42 mg·L-1; while the concentration of nitrate was from 5.11mg· L-1 to 2.99 mg·L-1, the removal rate was 41.5%; nitrite concentration was remained at a low level.3, Effects of different environmental factors on the aerobic denitrification capabilityThere were significant effects of different carbon source, inoculation quantity, initial pH,carbon-nitrogen ratio(C/N), rotation speed and temperature on the D-3 growth and denitrification ability. The results showed that under the condition of the inoculation of D-3 was 1%(V/V), the initial pH value=7, sodium succinate as the carbon source, C/N=12, the speed was 120rpm with the maximum removal rate of total nitrogen and nitrate and the temperature was 30℃, the aerobic denitrification capability was the best.4,The removal pollutants effect of compound microorganism in the actual landscape waterPreparation the single strain (Psb2, D-3, K-9), combinated two strains (P+K, D+K, D+P) and three strains (P+D+K). Firstly, put the strains D-3,K-9 and the combination without Psb2 into the actual water with shaking culture, Psb2 static light cultured, and addied Psb2 in the the above cultures three days later, static cultured in the light for 3 days continuely, then mesured the content. The results show that the total nitrogen (TN) concentration of treatment with composited strain was lower than the single strain as well as lowre than the control,The total phosphorus (TP) and NO3- were almost unaffected by the single strain,but the TP and NO3- removal rate increased obviously with the composite compound microorganism. Strain K-9 had almost no effect on the degradation of NO2-, and the removal rate of P+D+K was significantly higher than the other combinations; the removal efficiency of NH4+ was good with three single bacteria and four kinds of combination. The removal effect of COD have little difference betweent a single strain and a combination of strains, the degradation rate was not high. In a word, the degradation effect of six kinds of pollutants by the combination microbial was significantly better than single strain.5,The removal effect of pollutants in the actual landscape water by Immobilized MicroorganisThe experimental results showed that the optimal composition percentage of immobilized ball was the concentration of polyvinyl alcohol (PVA) 10%(m/v), Sodium alginate(SA)3%(m/v), CaCl2 2%(m/v). Taken 1mL(1*108cfu. mL-1)wet bacteria to embed ball, with sterile water cleaning ball after filtration, put the aerobic microorganism ball in real water samples that collected and shaking cultured for three days, then added anaerobic microorganisms ball, static cultured under the condition of light for other three days, finally mensurated the content. The results showed that to both single strain and a composited strain that immobilized,the removal rate of six kinds of pollutants rates were significantly higher than the free strains, the combination of P+D+K had a better effect to removal of TN, the removal rate was 60.6%. There was little difference in the removal effect of TP for the seven kinds of immobilized microorganism ball, but the degradation rate of the composite ball was slightly higher than the single strain; The removal NO3- rate of Psb2 and K-9 was low, but the remaining pellets’ degradation rate was almost no difference, in which a combination of P+D+K removal rate is as high as 60.1%; the effect on the removal of NO2- and NH4+ of seven balls were efficient, however,the effect of COD degradation was not very good, but it increased significantly compared to the free microorganism,. |
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