Screening,Identification And Calcium Adsorption Of Calcium-resistant Microorganisms In Gelatin Wastewater

The main reasons that the adsorption method has been favored by the public are that it has good metal removal effect,and no secondary pollution.Bacteria are the largest group of microorganisms because of their many species and wide distribution.They have been widely used as adsorption materials for metal ions.The characteristics of high calcium and high chemical oxygen demand,the gelatin wastewater was difficult to be treated and the problem of large a mount of excess sludge.Therefore,gelatin processing wastewater was used as material to screen and identify calcium resistant bacteria.The growth and calcium adsorption capacity of bacteria were optimized by response surface method.The adsorption mechanism was studied by SEM-EDS and FT-IR.The main results are as follows:?1?The results showed that the dominant bacteria in the primary sedimentary wastewate was Hydrogenophaga,the dominant bacteria in the aerobic wastewater and the secondary sedimentary sludge were uncultured-bacterium-p-WS6,and the dominant bacteria in the discharge wastewater was uncultured-bacterium-p-Saccharibacteria.The microbial community structure of different wastewater treatment units was obviously different,and the similarity of microbial community composition of aerobic wastewater and secondary sedimentary sludge was the highest.In addition,Rheinheimera was positively correlated with Ca²⁺,ammonia nitrogen and pH.There was a significant negative correlation between the uncultured-bacterium-c-Candidatus-Moranbacteria and total nitrogen.There was a significant negative correlation between the uncultured-bacterium-p-Saccharibacteria and chemical oxygen demand.Alkalibacterium was positively correlated with total nitrogen and chemical oxygen demand.?2?The results of screening and identification of calcium tolerant microorganisms showed that when the concentration of calcium ion was 50 mg/ml,three strains of calcium tolerant bacteria were screened out from four samples,respectively numbered N1-4,N3-1and N3-4.After identification,they were successively as follows:vibrobacillus pantothenicus,Bacillus niabris and vibrobacillus pantothenicus.?3?The optimal growth conditions of calcium tolerant microorganisms were as follows.The strain N1-4 were initial calcium concentration 2.97 mg/L,temperature 35.61?,and pH7.98.The strain N3-1 were initial calcium concentration 1.41 mg/L,temperature 37.2?,and pH 8.31.The strain N3-4 were initial calcium concentration 0.99 mg/L,temperature 35.35?,and pH 4.15.?4?The results of single factor experiments showed that the optimum temperature of N1-4,N3-1 and N3-4 were 30?,28?and 28?,pH were 5,6 and 6.Under the suitable temperature and pH conditions,the optimal adsorption conditions of strain N1-4 were as follows:adsorption time 77.01 min,initial calcium concentration 148.02 mg/L,and biomass dosage 0.83 g/L.The strain N3-1 were adsorption time 70.72 min,initial calcium concentration 130.19 mg/L and biomass dosage 1.52 g/L.The strain N3-4 were adsorption time 72.70 min,initial calcium concentration 141.98 mg/L and biomass dosage 1.30 g/L.?5?SEM-EDS analysis showed that strain N1-4,N3-1 and N3-4 had serious deformation,rough surface,protuberance and sediment.Compared with the bacteria before adsorption,after adsorption,there were not only carbon and nitrogen peaks,but also calcium peaks.FT-IR analysis showed that-OH,-NH,-PO₄,C-N,C-C,-CH₃,-CH₂,-C=O,C?C,S=O and P=O may participate in the adsorption of calcium.