Study On Removing Ammonia And Nitrite From Wastewater Using Immobilized Composite Bacteria

In this study, two bacteria strains with the characteristic of removing ammoniaand nitrite efficiently were obtained from shrimp pond and its growth characteristicsare studied. The optimizing formula of the obtained strain mixed with others wasdetermined by Mixture design method. That compound bacteria immobilized methodand its functions on ammonia and nitrite removal are studied. The main results are asfollows:1Isolation and Identification of High Effective Microorganisms DegradingAmmoniaBacterra strains B25are obtained by using ammonium chloride and glucose assubstrate and based on its efficient removal of ammonia. The sequencing analyzingresults of16SrRNA shows that it is100%similarity with Bacillus megaterium. Theoptimal carbon and nitrogen ratio was20for the strain growth and the bacterialdensity can up to5.44×108cells/mL. The ammonia removal efficiency could be ashigh as89.09%. The result shows by orthogonal experiment that the optimalperformance of ammonia removal can up to88.26%under the condition of initialconcentration of bacteria0.15, carbon nitrogen ratio of10, pH7.5. The results showedthat the growth of the strain correspond with Gompertz model (R2=0.985)，and itsexpression is Y=0.184e368.636exp(-0.199t).2Isolation and Identification of High Effective Microorganisms DegradingnitriteBased on enrichment culture, separation and purification,26bacteria stains areisolated from shrimp pool. Staining is identified as Bacillus spp. with spore staining.By using nitrite nutritional medium strain BD6was obtained which nitrite removalreached100.00%and97.65%in primary screening and follwed rescreening. The16SrRNA sequencing results show that was99%similarity with Bacillus cereus andBacillus thuringiensis. 3Optimization of the formula of compound bacteria preparation using mixturedesignMixture design method is used to optimize the formula of mixedbacteria.The effects of the four strains of bacteria on OD600, ammonia and nitriteremoval are studied, and the regression model is established. Through theequation analysis, response values satisfies all expectation were optimized usingoptimization of Design Expert8.0, and the most excellent combinations ofBacillus sp. BD6, Bacillus sp. BZ5, Bacillus sp. B25and Vibrio alginolyticusVZ5are5.2%,22%,0%, and72.8%, respectively. Verification experiment on theformulation shows that the result is consistent with the prediction. The mixedbacteria can get a higher ammonia and nitrite removal in24h. Ammonia andnitrite removal rate can reach98.37%, and93.81%in72h, respectively. With theaid of analysis software, formulation of mixed bacteria could be optimized forseveral responses and the best formulation could be obtained.4Study on removing ammonium and nitrite nitrogen from wastewater byImmobilized microorganism within the composite carrierThe immobilized microbial beads were made by bacteria combined withcomposite carrier, which conbining with fine partical silica as adsorbent, polyvinylalcohol and sodium alginate as entrapment carriers. And its function onNH4+-N andNO2--N removal from aquaculture wastewater was determined. The experimentresults show that when the PVA mass percent is10%, SA3%, bacteria0.1%,4%, thecross-linking time36h, ammonia and nitrite removal rate can reach96%and98%in24h, respectively. The immobilized microorganism has characteristics of highmicrobial load and large specific surface area.