| In recent years,with the follow-up and attention to water pollution treatment,the high-salt wastewater treatment also received attention.The salt-tolerant bacteria screened from the high-salt environment,in addition to having an important position in the biotechnology of industrial production,can also be used to control pollution problems in industrial production.In seawater desalination,hazardous industrial wastewater treatment,environmental bioremediation,etc.,salt-tolerant bacteria also have broad application prospects.In the process of using biological methods to treat high-salt wastewater,it is a fast and effective method to directly screen for salt-tolerant bacteria or halophilic bacteria from a high-salt environment.Therefore,in this paper,a strain of salt-tolerant bacteria named WS-1 was selected from the leachate of hazardous waste landfill,and it was used as the research object to analyze the performance of the strain in the degradation of organic matter and the adsorption of heavy metals.WS-1 was used to strengthen activated sludge,and NaCl to simulate actual wastewater salinity,compared with non-inoculation and adding of screening mixed salt-tolerant bacteria,simulated SBR reactor by beaker experiment.With the salinity changing of high salt wastewater,the domestication cycle of activated sludge and the effects of wastewater treatment were studied by experimental design.In this experiment,three groups of devices were set,1#SBR as a control group,2#SBR as a single salt-tolerant bacteria WS-1 device,3#SBR as a mixed salt-tolerant bacteria device,which was screened from the landfill sewage treatment station activated sludge plus high salinity screening.At the same time,the effect of salinity on the acclimation cycle of activated sludge and the degradability of organic matter by WS-1 were evaluated and verified by electronic scanning electron microscopy and microbial diversity analysis.The WS-1 enhanced activated sludge under high salinity has practical significance in the treatment of high-salt wastewater.The main research results are as follows:1.That salt-tolerant bacteria WS-1 was identified as Staphylococcus sp.by 16S rDNA,Cocci,and Gram-positive bacteria.It grows best when the salt mass fraction was 0%-10%and the pH was 7.0.Its cumulative growth OD600 at 24h around salinity 5%was 2.01,and its cumulative growth OD600 at salinity 0%and 15%was 2.57 and 0.36,respectively.2.The salt-tolerant bacteria WS-1 has a certain degradation effect on phenol,and it can grow well in the range of phenol concentration from 0 to 1000 mg/L.Low concentration of phenol could promote the growth of strains,and high concentration of phenol could inhibit the growth of strains.Within 72 hours,the strain’s degradation rate of phenol was about 38%.3.Salt-tolerant bacteria WS-1 has a certain ability to remove Cd heavy metal ions.When the concentration of Cd2+was 1-5 mg/L,the growth of WS-1 was not affected.When the concentration of Cd2+reaches 10 mg/L,the inhibition of the effect was obvious,extending the growth cycle of WS-1.The Cd2+ removal rate of WS-1 at low concentration was about 90%,and the Cd2+ removal rate at high concentration is about 40%,and the effect was not obvious.4.The devices were operating well in the domestication of activated sludge,and all could operate stably while maintaining a high removal rate of organic matter and ammonia nitrogen.Among them,the specific effect,the initial 0%salinity stage,the organic matter and ammonia nitrogen removal rate of each device were not different,although there were fluctuations,but the overall stability,with the increase in the salinity of the device,2#SBR and 3#SBR were compared with the control 1#SBR has improved the removal rate of organic matter and ammonia nitrogen,the difference was not big in the low salinity stage,however,in the 3%salinity stage,the bacteria adding device is more than the control device,and the removal rate of organic matter and ammonia nitrogen was higher than the control device.Compared with the 1#SBR and 3#SBR,the average COD removal rate of 2#SBR were 84.69%,3#SBR,1#SBRwas 83.45%and 79.27%respectively.Moreover,high salinity had a greater impact on the removal rate of ammonia nitrogen than COD,and the removal average rate of 2#SBR was only 66.97%,and which of 3#SBR and 1#SBR was 68.97%and 64.40%,respectively.The sludge concentration and SVI of the three groups of devices were not much different during the operation period.With increasing the salinity in SBR,the sludge concentration descended first and then rose,SVI was high(100mL/g)in the initial salinity stage,which decreased with the increasing salinity,and then stabilizes at about 40mL/g.After acclimating the activated sludge for 107 days,the three groups of devices could remove pollutants in simulated high-salt wastewater at 3%salinity.The 2#SBR and 3#SBR had a shorter domestication period and stronger treatment performance than the control group.5.There were abundant bacterial groups in activated sludge in different devices.With the increase of salinity,the species diversity in 1#SBR and 3#SBR activated sludge showed a trend of increasing first and then decreasing,and which in 2#SBR showed a trend of decreasing first,then increasing and then decreasing.The dominant bacteria of 1#SBR were Proteobacteria,Patescibacteria,Chloroflexi,Bacteroidetes,Acidobacteria,Actinobacteria,Firmicutes,and Planctomycetes;2#SBR dominant bacteria included Proteobacteria,Planescibacteria,Bacteroidetes,Planctomycetes,Actinobacteria,Acidobacteria;3#SBR included Proteobacteria,Patescibacteria,Bacteroidetes,Chloroflexi,Actinobacteria,Plantomytomytes,Acidobacteria.The three groups of devices have roughly the same phylum,but differ in the specific relative abundance of each phylum.After acclimation,the number of dominant phyla and the number of dominant bacteria in the activated sludge of each device increased.Under the strengthening effect of salt-tolerant bacteria,the increase rate of activated sludge in the control group(1#SBR)after domestication was lower than that of the enhanced group(2#SBR and 3#SBR). |
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