Performance And Optimization Of A Sewage Treatment Process In Alpine Region

With the development of society and the guidance of national policies,sewage treatment process requirements continue to improve to meet people’s needs for water quality and environmental sustainability.In particular,the operating efficiency of sewage treatment plants in the high-cold regions of Northeast of China was greatly affected by climate and other environmental factors,and the aging of equipment caused the process to be in a low-efficiency operating state all year round.In order to ensure that the effluent quality meets the latest national standards along with reduce energy consumption and less maintenance costs,this study takes a urban sewage treatment plant in Heilongjiang province as the research object and conducts research and analysis on the actual operating data of the plant.The influent water quality often exceeded the original design index,the average concentration of suspended solids in the effluent of the hydrolysis acidification tank was as high as 126.26 mg/L,and the high energy consumption of the biological aerated filter process was carried out,therefore,the optimization plan was proposed.The influence of the hydrolysis acidification tank was studied from the muddy water boundary,load,temperature,etc.,the operation conditions of the hydrolysis acidification tank were optimized,and the best decontamination efficiency was determined when the muddy water boundary was 2~3 m,and the SS removal rate can be The removal rate of COD was up to 62%,and the removal rate of COD was 54.7%.The study found that the change of hydraulic load had little effect on the removal of organic matter,but it had a significant effect on the removal rate of SS.When the water temperature was as low as 5℃ and the HRT was 4.2 h,the removal rate of SS can still be maintained.About 46%,the COD removal rate can reach more than 27%,and the water temperature had little effect on the hydrolysis acidification tank;the study found that the thickness of the sludge layer should be appropriately increased during operation,and the middle sludge discharge should be the key method.Optimization of the water distribution pipeline by choosing DN50 PE pipe to replace the old pipeline,which improved the water distribution effects.After optimization,the SS concentration of the effluent from the hydrolysis acidification tank was 90.3 mg/L,and the average removal rate was 60.53%;the average COD concentration of the effluent was 247.2mg/L,and the average removal rate was 36.22%;the NH3-N concentration of the effluent was 38mg/L,and the average removal rate was20.57%;the effluent BOD/COD value has significantly increased from 0.38 to 0.44,with an increase of 16%.It was further strengthened with a new type of mixed water purifier to ensure the removal effect under low temperature and fluctuations in water quality.A new type of water purifying agent was selected to improve the removal effect during low temperature and water quality fluctuations,and the optimal dosage was determined to be 40L/h through experiments,and the new mixed agent containing polyaluminum chloride was generally better than the mixed agent containing ferric chloride.Through optimization,the SS removal rate of the hydrolysis acidification tank was up to 71.32%,the COD removal rate was up to 67.32%,the best removal rate of NH3-N was 48.59%,and the maximum removal rate of TP was 29.78%.In view of the low temperature characteristics of Northeast China,the water temperature conditions were analyzed and the study found that the COD removal efficiency of the biological aerated filter was the highest(89.13%)at 25℃,and the average removal rate dropped to 64.64% when the temperature was below 10℃;It has the greatest impact on denitrification.The average removal rate is 88.89% at25℃~30℃,and the denitrification efficiency was only 13.64% when it is lower than10℃.Through optimization,the backwashing scheme of the biological aerated filter was as follows: when air flushing alone,the air flushing intensity is 17 L/(m2·s);the air and water combined backwashing is determined to be 17 L/(m2·s)),8 L/(m2·s);when rinsing with backwash water,determine the water flushing intensity of 8 L/(m2·s);the backwash program should be optimized as follows: first air rinse for 10 minutes,then air and water mixed washing for 20 minutes,and finally water for 10 minutes.