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Preliminary Study On Ammonium Nitrogen Removal By Modified Walnut Shell Biochar Combined With Strain A.baumannii AL-6

Posted on:2018-03-31Degree:MasterType:Thesis
Country:ChinaCandidate:X L HuangFull Text:PDF
GTID:2321330536468861Subject:Master of Engineering
Abstract/Summary:PDF Full Text Request
Ammonia nitrogen pollution is one of the main factors that cause eutrophication of rivers and lakes,which is the important indicator of water pollution control.In order to deal with the severe problems of ammonia nitrogen pollution,it is very importance to explore efficient methods of removing it.Compared with ordinary biochar,modified biochar has the advantages of larger pore size,specific surface area,better environmental stability and so on,and thus has better adsorption performance.The modified biochar can be used as the carrier of microbial growth,combined with microorganisms to remove ammonia in water,so as to achieve more efficient and stable deamination of ammonia effect.In this study,the effects of the modified walnut shell biochar,A.baumannii AL-6 and the combination strain AL-6 were investigated on initial ammonia nitrogen concentration,pH,temperature and other factors.The single factor experiment was used to optimize the biomass,preparation conditions and modification methods.The Experimental results showed that: The effect of walnut shell as raw material of modified biochar was better than that of peanut shell and corn stalk,with its adsorption rate of 19.38 %.The modified biochar of walnut shell with NaOH pre modification and Mg2+ modification was denoted as "NMC” biochar.When the initial concentration was 100mg/L,the absorption reached the highest rate of 65.42%.For effect of pyrolysis temperature,the initial concentration of 250mg/L was used,the NMC at pyrolysis temperature of 450℃ showed better adsorption effect than those prolysed at 300 ℃ and 600 ℃.At the pyrolysis temperature of 450℃,the removal rate of NMC reached 8.04mg/g,and the adsorption efficiency was 59.3%.Using NMC to adsorb ammonia nitrogen in water,the following conclusions were drawn: With the increase of initial ammonia nitrogen concentration,the adsorption capacity increases gradually,and the adsorption rate decreases gradually.The adsorption effect of NMC modified walnut shell under different pH conditions was best at pH value of 7,using initial concentration of 100 mg/L the adsorption rate was 74.0%.Under different temperature conditions,the highest adsorption occurred at the temperature of 30 ℃,the adsorption capacity was 4.94 mg/g,and the removal rate was 66.33%;According to the adsorption kinetics equation,NMC modified walnut shell biochar conforms to the quasi-second order kinetic equation,the equilibrium adsorption capacity is 1.34 mg / g,the adsorption process is mainly controlled by the diffusion within the grain,but not the control step.A heterotrophic nitrifying strain AL-6 was isolated from the conventional denitrification process and activated sludge by alternate method of flat streak method and liquid selective medium.After identification of the 16 S rRNA gene sequence,it was determined that the strain belonged to the genus Acinetobacterbaumannii.Using the strain A.baumannii AL-6 to study the removal of ammonia nitrogen,the following conclusions were drawn: With the increase of the initial ammonia concentration,the adsorption capacity gradually increases and the adsorption rate decreases.At the pH value of 7,the optimum strain A.baumannii AL-6 was grown,and the efficiency of ammonia nitrogen removal was the highest to 96.67%.When the experimental temperature was 20 ℃,the strain was inhibited and the removal rate was the lowest,which was 7.23%.At the experimental temperature of 30 ℃,the growth rate of the strain AL-6 was the best,reaching 96.82%.Through the study of combined biochar and bacteria to remove ammonia nitrogen,the following conclusions were drawn: as the initial concentration of NH4+-N increases,the adsorption capacity increases gradually,and the removal rate gradually decreases.When the pH value was 7,the best removal effect of combined modified walnut shell biochar and AL-6 bacteria was occurred,with the removal rate of 98.05%;Also the best effect occurred when the experiment temperature was 30℃,with the removal rate of NH4+-N of 96.24%.The combination of modified walnut shell biochar and AL-6 bacteria can achieve the better ammonia removal effect in shorter time with the advantages of early rapid adsorption onto NMC.The removal effect can take full advantage of the adsorption of NMC and strain AL-6 biodegradation.And thus,NMC modified walnut shell biochar can form a system with AL-6 bacteria,as NMC modified walnut shell biochar can not only adsorb ammonia nitrogen,but also the growth carrier of strain AL-6.
Keywords/Search Tags:A.Baumannii Strain AL-6, NMC Modified Walnut Shell Biochar, NMC Modified Walnut Shell Biochar Combined With Strain AL-6, Removal Rate
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