Enhanced Performance Of SBR By Immobilized Aerobic Denitrifying Bacteria

Conventional biological denitrification is the removal of nitrogen in water using the nitrification of the self-cultivation microorganism and the nitrification of heterotrophic microorganisms.Since these two types of microorganisms have different demand for oxygen,in order to achieve the desired denitrification effect,it must provide advantageous environmental conditions,resulting in an increase in the area of sewage treatment facilities,and the processing cost is increased.The previous research of the research group found that inoculating aerobic denitrifying bacteria with both iron oxidation and aerobic denitrification functions into SBR reactor has a certain strengthening effect on biological denitrification,but it is difficult to achieve the ideal denitrification effect due to the easy loss of functional microorganisms or lack of competitiveness.In this study,a heterotrophic nitrifying aerobic denitrifying bacteria with iron oxidation function was screened from SBR reactor with sponge iron,After embedding with polyvinyl alcohol and sodium alginate,it is added to ordinary activated sludge system and biological sponge iron system to analyze its enhanced denitrification effect.The main research results are as follows:(1)Through the primary screening of BTB medium,the re screening of aerobic denitrification performance and the screening of iron oxidation function.A heterotrophic nitrification aerobic denitrifying bacterium B-2 with good iron oxidation and aerobic denitrification was obtained.There was almost no accumulation of nitrite nitrogen during the culture of strain B-2,and the removal rates of nitrate nitrogen and total nitrogen reached79.1%and 71.9%respectively.According to the colony morphology,physiological and biochemical characteristics and 16S r DNA sequencing analysis,the strain B-2 is Pseudomonas putida.(2)Pseudomonas putida strain B-2 has good ability of heterotrophic nitrification and aerobic denitrification.When ammonia nitrogen or nitrate nitrogen is the only nitrogen source,the removal rate of total nitrogen reaches 77.50%and 99.38%respectively.(3)It was found that the growth characteristics and denitrification of Pseudomonas putida strain B-2 were affected by carbon nitrogen ratio,nitrate concentration,initial p H and carbon source types.The optimum aerobic denitrification conditions of Pseudomonas putida strain B-2 were as follows:C/N is 25,nitrate concentration is 80 mg/L,p H is 7.5,and carbon source is sodium succinate.(4)The embedding conditions of Pseudomonas putida strain B-2 were optimized by orthogonal experiment.It was found that the optimum mass fractions of polyvinyl alcohol(PVA),sodium alginate(SA)and boric acid calcium chloride were 11%,2%and 2.5%respectively.The immobilized pellets prepared under the optimum embedding conditions have good mechanical strength,biological activity and aerobic denitrification ability.After shaking for 24 h at the speed of 200 rpm,the small ball was not damaged or deformed;The immobilized Pseudomonas putida strain B-2 has good mass transfer performance and nitrogen removal efficiency.In the improved denitrification medium,the growth status and denitrification ability are not different from that of Pseudomonas putida strain B-2 itself.(5)After ordinary activated sludge system(referred to as ordinary sludge system)and biological sponge iron system(Biological Sponge Iron System,referred to as BSIS system)are biologically strengthened with immobilized Pseudomonas putida strain B-2 pellets,the removal rate of NH4~+-N can reach 100%,and there is almost no accumulation of NO2~--N in the effluent after adding additional carbon source.Compared with 1#reactor(ordinary sludge system),the addition of sponge iron increased the TN removal effect of 2#reactor(BSIS system)by 16.5%,the addition of immobilized B-2 pellets increased the TN removal effect of3#reactor(biological enhanced ordinary sludge system)by 14.3%,and the TN removal effect of 4#reactor(biological enhanced BSIS system)increased by 26.4%under the synergistic enhancement of sponge iron and immobilized B-2 pellets.(6)The effects of sponge iron dosage,influent p H,dissolved oxygen,temperature and water exchange ratio on the denitrification effect of immobilized bio enhanced ordinary sludge system and BSIS system were studied.When the dosage of sponge iron is 135 g/L,the TN removal rate of immobilized reinforced BSIS system is the highest,and the average TN removal rate is 75.6%;the optimum influent p H is 7.5.At this time,the average TN removal rates of immobilized enhanced ordinary sludge system and immobilized enhanced BSIS system are 73.1%and 80.9%respectively;under aerobic conditions,the average removal rates of TN were 71.0%and 77.8%,respectively;the optimum culture temperature was30℃,and the average removal rates of TN were 77.0%and 83.4%,respectively;the optimum water exchange ratio is 40%,and the average removal rates of TN are 78.0%and 86.2%respectively.