Experimental Study On Sludge Reduction And Denitrification Efficiency Of Multi-A/O Biofilm Reactor

People paid more attention to the water resource,with development of society and economy of our nation,and the urbanization speeded up.Active sludge process as an conventional treating wastewater technology,has more problem such as massive excess sludge,the inefficiency of nitrogen removal,etc.The new technology should be applied to settle the problem of conventional active sludge process.Multi-A/O biofilm process,coupling of the conventional biofilm technology and multi-A/O system,was more efficiency in treating wastewater.As a coupling process,the multi-A/O biofilm technology could reduce excess sludge,which was the characteristic of biofilm process,and improve efficiency of nitrogen removal.In this study,effect factors of sludge yield and nitrogen removal were investigated by a single factor test.What's more,the mechanization of reducing sludge yield,and improving efficiency of nitrogen removal in different conditions were studied.As the study of single factor in the multi-A/O biofilm rector,sludge yield was reductive with improving DO level.The DO was improved from 1mg/L to 5 mg/L,22.3% sludge yield could be reduced.Because the higher DO value could improve efficiency of sludge granule's aerobic decomposition.The sludge yield was reduced in the longer HRT.The sludge yield could be reduced 33.3% with improved HRT from 8 h to 16 h.In the longer HRT condition,the wastewater could fully contact with the microorganism,and the sludge could be decomposed thoroughly.The sludge yield could be increased by81.5% with improved sludge return ration from 0.5:1 to 2:1.The sludge yield could be increased by 223%,with the temperature changed from 25? to 10?.Water temperature descendant reduced the activity of microbial.On the other hand,the decrease of temperature leads to the death of a large number of microorganisms,resulting in an increase in sludge yield.In the single factor study of multi-A/O biofilm reactor,the efficiency of NH₄⁺-N removal could increase by 13.7% with the DO from 2mg/L up to 4mg/L,and the efficiency of TN removal increase by 5.9%.Higher DO value could improve the efficiency of nitrification.However,the excess DO could break anoxia condition reducing the efficiency of denitrification.the influent flow ratio of the reactor from 2:1 to 1:1,the average ammonia removal rate increased 1%,the TN removal rate increased by 10.6%.The influent flow was the major factor in distribution of the organic carbon source.The abundant organic carbon source could enhance the efficiency of denitrification,and effect removal of ammonia nitrogen,with nitrification without organic carbon source.The reflux ratio from 1:1 to 2:1,the average ammonia removal rate decreased 12.1%,the total nitrogen removal rate increased by 12.9%,which was mainly due to the nitrification liquid reflux for denitrification.But nitrate recirculation concentration was too high,could inhibit nitrification,resulting in effluent ammonia is higher.Based on the DOM detection and ORP value variation,the change of MLVSS/MLSS sludge parameters of biofilm,microscope and SEM analysis,the mechanism of sludge reduction could be researched.And along the changing of COD/TN/NH₄⁺-N/NO3--N,the changes between ammonia nitrogen,nitrate nitrogen and COD could be observed.And the nitrification,denitrification process and SND process could be obtained by the calculation in the reactor.Then,the reactor on the removal mechanism of nitrogen could be researched.The biodegradation of biological carrier is beneficial to the digestion of the in-situ sludge,and the sludge after digestion can release the organic carbon source and promote the subsequent biological denitrification.At the same time,in the process space,anoxic-aerobic repeated coupling,Which further improves the efficiency of sludge reduction and biological denitrification,and effectively achieves the coupling of sludge reduction and biological denitrification.