Effect Of Biological Flocculation Sludge Hydrolysis Acidification Solution As Carbon Source On Denitrification Of Combined Process

Low carbon and nitrogen ratio is one of the reasons why most of our sewage treatment is not up to standard,and how to use the lowest cost to improve the efficiency of nitrogen removal is our research goal.This study combined the biological flocculation adsorption,hydrolysis and acidification and pre-denitrification biological aerated filter three processes on the campus sewage treatment.At first,sewage into the biological flocculation adsorption process to strengthen the primary treatment,and then hydrolytic acidification solution and effluent of sedimentation tank in the biological flocculation adsorption process together into the BAF system for advanced treatment.Before the operation of combined system,the three processes were launched in run-time sequence.After the start were completed,run the combined system.The effects of pH value and sludge inoculation amount on the hydrolysis and dissolution of flocculated sludge were studied respectively.The optimum alkaline pH and optimum sludge inoculation were determined.The nitrogen removal performance of the composite system was then studied when the process was stable.The removal of COD,NH₄⁺-N and TN in different working conditions was carried out to determine the optimal ratio.The material balance analysis of the carbon source of the combined system was carried out under the optimum ratio.The effects of pH value on the hydrolysis and acidification of flocculated sludge were studied.The results showed that the yield of SCOD,VFAs and PO43--P increased with time,and the maximum value was 1270mg/L?341mg/L and 38.73mg/L at pH = 11,respectively.The minimum dissolution of NH₄⁺-N and TN at pH = 11 was 48.86mg/L and 49.93mg/L,respectively.At pH = 11,?SCOD: ?VFAs: ??N?: ??P?= 155:47:6:5,??SCOD + VFAs?=1409mg/L,the hydrolysis and acidification effect is the best.Enough SCOD and VFAs and other organic matter generated,and ammonia nitrogen,phosphate release was not much.Therefore,the optimum pH for hydrolysis and acidification of biological flocculation sludge is pH = 11.In the same amount of sludge inoculation,the SCOD and VFAs increased with the time,and the sludge was inoculated at different sludge inoculation.When the inoculationt amount of sludge was 35%,the SCOD and VFAs of the unit mass were 87.53mgCOD/gVSS and 42.13 mgCOD/gVSS,respectively,and the yield of SCOD and VFAsdecreased at the 9th day.From the conversion rate of SCOD to VFAs,the conversion of VFAs in four cases was greatly reduced after 7 days of flocculation and sludge hydrolysis.Therefore,when the inoculation amount of sludge was 35%,the hydrolytic acidification effect of bioflocculation adsorption sludge was the best.When the ratio of gas to water was 4:1,the reflux ratio was 150% and the carbon source ratio was 1:60,the average concentrations of influent COD,NH₄⁺-N and TN in the raw water were 219.4mg/L,29.14mg/L and 35.98mg/L,respectively.The COD,NH₄⁺-N and TN concentrations were 97.4mg/L,21.89mg/L and 29.37mg/L,and the removal rates were 55%,24.9% and 18.37% after bioflocculation.The final effluent of COD,NH₄⁺-N and TN were 24.1mg/L,0.8mg/L and 6.46mg/L respectively.The total removal rates of COD,NH₄⁺-N and TN were 89%,97.09% and 82.01%,respectively.When the average concentration of COD,NH₄⁺-N and TN were 97.4mg/L,21.89mg/L and 29.37mg/L,the removal rate of COD was about 80%,the removal rate of NH₄⁺-N was about 96%.The removal rate of total nitrogen was the highest,and the removal rate of total nitrogen was about 80% when the ratio of carbon source was 1:60.Therefore,the pre-denitrification biological aerated filter with the best ratio of 1:60.When the biomass flocculation process was carried out,the COD content of the influent was 22000 mg/h,the effluent COD accounted for 43.83%;the COD content of the excess sludge was 0.44%;The COD content of the adsorption tank was 49.42%.The COD content of the activated regeneration tank was 6.31%.The effluent COD concentration of the process is relatively high,the removal of organic matter is not ideal,and the necessity of subsequent deep treatment is proved.Due to the addition of hydrolytic acidification solution into the pre-denitrification biological aerated filter system,the COD quality of influent COD is6820.5mg/h,and the effluent COD content accounts for 17.67%.The COD consumption of DN BAF pool is 30.92%;the COD quality of C/N BAF pool accounts for 44.17%.So the system to exclude the COD quality of 6326.25mg/h,accounting for 92.76%,did not get a complete balance.Based on the above results,this combination system can make up for the problem of low carbon and nitrogen ratio,and does not increase the cost.It is of great significance to study the denitrification performance.