| The pollution is becoming more serious because of sewage and heavy metal waste water discharged into the water,but the traditional sewage treatment methods are relatively expensive,technical difficulty,ineffective,easy to cause secondary pollution and other issues.Duo to the advantages such as high efficiency,low operating cost,easy to popular and no second pollution,microbial wastewater treatment technology has become hot spots in the field of water pollution research and development.Wetland rhizosphere microorganisms probably play a core role in purifying wastewater in the constructed wetland,for it has high diversity,adaptable mutation ability,strong metabolic activity and with strong degradation and adsorption capacity of pollutants.Screening out efficient strains and applied to sewage treatment will be high practical value.10 efficient strains had been isolated from the rhizosphere soil of Thalia dealbata Link,Vetiveria zizanioides L.,A.donax var.versicolor in sewage treatment plant of Wuyishan city.And then identification,morphological observation and both physiological and biochemical characteristics of the selected strains were measured.And high efficiency strains were applied to different concentrations of sewage,TN,NH4+-N,COD,TP and heavy metal elements are adopted as endpoints for sewage determination,changes would be tested after vaccination within 48h(every 12h determination once),then removal rate in each group after 48h would also be calculated to determine the purification efficiency.Results are as follows:1)Screening,identification,physiological and biochemical characteristics of high efficient strains47 strains of bacteria,41 strains of fungi and 8 strains of actinomycetes were isolated and purified from rhizosphere soils of three kinds of wetland plants(Thalia dealbata Link,Vetiveria zizanioides L.,A.donax var.versicolor).Through the selection of dominant strains,sewage tolerance test and degradation rate comparison,and sequence analysis of the obtained rDNA sequence,finally obtained 5 highly effective bacteria(B2(Bacillus cereus),B5(Bacillus thuringiensis),B19(Bacillus megaterium),B21(Bacillus thuringiensis),B35(Bacillus cereus))and 5 high-performance fungi(F9(Westerdykella dispersa),F1 6(Aspergillus niger strain),F25(Penicillium janthinellum strain),F26(Aspergillus iizukae),F30(Paecilomyces lilacinus strain))Among them,strains B2,B5,B35,F9 and F16 were screened from the rhizosphere soil of A.donax var.versicolor,B19,B21 and F26 were screened from rhizosphere soil of Vetiveria zizanioides L.,F25 and F30 were screened from rhizosphere soil of Thalia dealbata Link.Different strains had different tolerance to salinity,pH and temperature.strains B2,B19 and B35 could be cultivated with the salinity of 0%-5%,B5 and B21 were 0%-1%,and the optimum salinity for strains growth was 0.5%.B19 could be cultivated with pH:5-9,the optimum pH was 6,B5 and B21 could be cultivated with pH:5-8,the optimum pH was 7,B2 and B35 could be cultivated with pH:5-9,the optimum pH was 7.Strain B19 could be cultivated with temperature of 10℃ to 40℃,B5 and B21 were 20℃ to 40℃,B2 and B35 were 20℃ to 50℃,and the optimum temperature for strains growth was 30℃.All strains except for B5 had protein hydrolysis characteristics,of which B19 had the highest ability.All strains except for B19 had grease hydrolysis characteristics,of which B5 had the highest ability.All strains had grease hydrolysis characteristics,of which B2 and B19 had the highest ability.2)Evaluation of purification ability of TN,NH4+-N,COD and TP under the treatment of rhizosphere efficient strainsThe degradation rates of TN in waste water were 53.75%-75.73%in high concentration,58.00%-80.67%in medium concentration,58.65%-74.55%in low concentration under the treatment of 10 rhizosphere efficient strains,F26,B19 and B21 was the efficient strains of high,medium and low concentrations sewage respectively.The degradation rates of NH4+-N in waste water were 33.00%-63.98%in high concentration,27.5%-72.05%in medium concentration,35.36%65.54%in low concentration under the treatment of 10 rhizosphere efficient strains,F16,F30 and B21 was the efficient strains of high,medium and low concentrations sewage respectively.The degradation rates of COD in waste water were 36.55%-62.14%in high concentration,39.91%-68.96%in medium concentration,40.5%-66.85%in low concentration under the treatment of 10 rhizosphere efficient strains,F26,F26 and B2 was the efficient strains of high,medium and low concentrations sewage respectively.The degradation rates of TP in waste water were 22.15%-50.15%in high concentration,33.71%-50.16%in medium concentration,32.28%-52.15%in low concentration under the treatment of 10 rhizosphere efficient strains,F16 was the efficient strains of high,medium and low concentrations sewage.However,compared with other indicators,the degradation of TP had the poor effect,indicating that the microbial is not the main factor in the removal of TP.In addition,the removal rates of TN,NH4+-N,COD and TP were higher in the medium concentration sewage after 48h,which indicated that strains had greater degradation ability under the medium concentration.Based on the analysis of three concentrations,the concentrations of TN,NH4+-N,COD and TP were significantly decreased with the extension of processing time,the degradation rates of TN,NH4’-N,COD and TP were significantly higher than CK under the treatment of efficient strains,of which F16,F26,F30 and B21 were the best strains for degrading TN,NH4+-N,COD and TP in different concentrations sewage.The results of multivariate analysis of variance showed that the degradation rates of TN,NH4+-N,COD and TP in sewage were significantly affected by different treatment time and different sewage concentrations.The optimal removal efficiency of TN and NH4+-N were the medium concentration sewage and 48h,the optimal removal efficiency of COD and TP were the low concentration sewage and 48h.3)Evaluation of purification ability of heavy metal under the treatment of rhizosphere efficient strainsThe adsorption rates of Pb2+ in waste water were 27.30%-52.27%in high concentration,32.17%-56.07%in medium concentration,32.17%56.07%in low concentration under the treatment of 10 rhizosphere efficient strains,F26,B19 and B19 was the efficient strains of high,medium and low concentrations sewage respectively.The adsorption rates of Cd2+in waste water were 29.63%-56.00%in high concentration,31.53%-59.23%in medium concentration,31.03%-58.70%in low concentration under the treatment of 10 rhizosphere efficient strains,B19,F9 and B19 was the efficient strains of high,medium and low concentrations sewage respectively.The adsorption rates of Cu2+ in waste water were 29.03%-55.73%in high concentration,29.83%57.73%in medium concentration,35.10%-59.00%in low concentration under the treatment of 10 rhizosphere efficient strains,F25 was the efficient strains of high,medium and low concentrations sewage.The adsorption rates of Zn2+in waste water were 29.67%-56.73%in high concentration,31.27%-58.10%in medium concentration,36.00%60.27%in low concentration under the treatment of 10 rhizosphere efficient strains,F16 was the efficient strains of high,medium and low concentrations sewage.In addition,the removal rates of Pb2+,Cd2+,Cu2+,Zn2+were higher in the low concentration sewage after 48h,which indicated that the strains had greater removed ability under the low concentration.Based on the analysis of three concentrations,the concentrations of heavy metals were significantly decreased with the extension of processing time,the adsorption rates of heavy metals were significantly higher than CK under the treatment of efficient strains,of which B19,F25,F9 and F16 were the best strains for adsorbing heavy metals in different concentrations sewage.The results of multivariate analysis of variance showed that the adsorption rates of heavy metals in sewage were significantly affected by different treatment time and different sewage concentrations.The optimal adsorption efficiency of heavy metals were the loe concentration sewage and 48h. |
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