Conditions Optimization Of Proteiniphilum Acetatigenes PSB-W EPS And Its Removal Of Heavy Metals And Phosphorus

Among the main strains used in sewage treatment,photosynthetic bacteria have the advantages of non-toxicity,strong reproduction,high efficiency and environmental protection.Moreover,the strain has EPS as a biological resource,which can play an effective role in sewage treatment.In the process of using biofilm treatment of sewage,EPS is a common microbial by-product,at the same time,EPS has biological phosphorus removal and adsorption of heavy metals can be used in water purification function,in the field of sewage treatment plays an important role.The content of EPS is affected by many factors.In order to make full use of this biological resource and get the best EPS,it is necessary to optimize the culture medium and fermentation conditions of the strain,which lays a foundation for the study of biological phosphorus removal and heavy metal adsorption in wastewater purification.Therefore,in this study,EPS produced by laboratory photosynthetic bacteria Proteiniphilum acetatigenes PSB-W was used as the experimental material to optimize the culture of high-yield EPS of the strain,including the optimization of medium and fermentation conditions.Through the treatment of different forms of phosphorus and heavy metals,the effect of EPS in phosphorus removal and the adsorption efficiency of heavy metals were preliminarily discussed,in order to provide a basic theoretical basis for the study of EPS in sewage treatment.The results obtained in this paper are as follows:(1)Firstly,the effects of different types and concentrations of carbon sources,nitrogen sources and inorganic salts on the extracellular polymer content were investigated,and the optimal medium composition was obtained.The Box-Behnken design level was determined according to the single-factor experimental results.Response surface analysis was performed on the extracellular polymer content produced by the strain.The optimal medium combination formula was 3g/L malic acid,0.8g/L ammonium chloride and 3g/L calcium carbonate.On this basis,the content of extracellular polymer was 80.63±0.65mg/L.(2)Analysis of the different temperature,light intensity,initial inoculation quantity of extracellular polymer content,the influence of filter to get the optimal culture conditions,according to the results of single factor experiment,the Box-Behnken Design level,according to the Design optimization of the production of extracellular polymers BBD fermentation conditions,by setting for five different gradient of single factor test.Through response surface analysis on the content of extracellular polymer,the optimal fermentation conditions were determined as follows:light intensity of 4000 Lux,inoculation amount of20%,and temperature of 30?.Through verification experiment,the content of extracellular polymer was 81.59±0.73mg/L.3)EPS adsorbs heavy metal ions in water through a large number of negatively charged adsorption sites.Therefore,the EDTA method was used to extract PSB-WEPS of Proteiniphilum acetatigenes.The effects of p H value,dosage of EPS,adsorption time and initial metal concentration on the adsorption rule of Cu²⁺and Pb²⁺ions on the EPS structure were studied,and the adsorption efficiency of EPS on copper and lead ions was also studied.The results showed that when p H was 6,heavy metal adsorption time was 50min,and EPS dosage was 96.6mg/L,the adsorption efficiency of EPS on heavy metal ions reached the best.When the concentration of copper ion and lead ion is less than 30mg/L,EPS is always in the rapid adsorption stage,and when the concentration is higher than 30mg/L,the adsorption efficiency of EPS gradually tends to balance.The adsorption capacity of EPS on Cu²⁺and Pb²⁺is different.In terms of the adsorption of single metal by EPS,the adsorption rate of Pb²⁺by EPS is higher than that of Cu²⁺.4)Five different concentration gradients of orthophosphate and pyrophosphate were set.By comparing TP_strainswith EPS strain and TP_EPSstrain,the results showed that in 40 mg/L orthophosphate concentration,the proportion of TP_EPSof EPS in TP_strainswas 30.1%.At 40mg/L pyrophosphate concentration,the proportion of phosphorus storage capacity TP_EPSof EPS to TP_strainswith phosphorus removal capacity was 21.2%,which was 8.9%lower than that of 40 mg/L orthophosphate.At other concentrations,the ratio was lower than that of orthophosphate.Under different treatments,the yield m_(strain),protein content m_(protein)and polysaccharide content m_{(polysaccharide)}in EPS were determined,and the principal components in EPS and the dephosphorization amount of the strain were linearly fitted.The results showed that there was a negative correlation between protein content in EPS and PSB-W phosphorus removal under the treatment of orthophosphate and pyrophosphate,and the linear relationship was general.There was a positive correlation between polysaccharide content in EPS and phosphorus removal by photosynthetic bacteria PSB-W,and the linear relationship was good.The correlation between polysaccharide content and strain dephosphorization was stronger than that between protein content and strain dephosphorization.Under the treatment of different forms of phosphorus,the correlation between polysaccharide content and protein content on the removal of orthophosphate was more obvious than that of pyrophosphate.In this study,EPS produced by Proteiniphilum acetatigenes PSB-W was used as the research object,in the aspect of culture optimization,from the carbon source,nitrogen source and inorganic salts from three aspects:optimize the culture medium and temperature,initial inoculation quantity,light intensity optimize the fermentation conditions,three aspects to give full play to the extracellular polymer laying a foundation for the biological resources.By studying biological phosphorus removal and heavy metal adsorption,the purification mechanism of Proteiniphilum acetatigenes PSB-W extracellular polymer in wastewater application was preliminarily explored,providing a new direction for future research on wastewater purification.