Study On The Characteristics Of Respirogram Profiles Of Two Typical Nitrogen Removal Processes

As the continuous improvement of the emission standards of sewage treatment plants in China,the increasing attention of the good denitrification operation and control technology to be attracted.However,it is not clear how microbial activity changes under complex working conditions,which in turn leads to poor process control accuracy.For this reason,this study selected the actual sewage treatment plants with two typical denitrification processes(oxidation ditch,AAO)under the same influent conditions as the research object.The study analyzed the respirogram characteristics of activated sludge microbial activity,and clarified the operation of the denitrification process for the key control factors in the process,corresponding control measures are proposed.The respirogram technology was combined with water quality detection indicators and process operating conditions information to evaluate the denitrification effect of sewage plants,and established a simple and feasible new method that can be used for on-site monitoring.The reasonable operation and timely regulation of the treatment plant provide a reference for the optimization of the operation of the sewage plant.The main conclusions are as follows:(1)Through monitoring,it is found that the two denitrification processes have their own characteristics.The overall impact resistance of the AAO process is strong,and it owns strong ability and speed of recovery when suffering from shock.which can ensure long-term stable and up-to-standard overload operation;What’s more,because of relatively stability of the oxidation ditch process system,The ability to deal with abnormal situations is stronger,for the denitrification capacity of the system can still be guaranteed when the aeration system fails.(2)In terms of system stability,the on-site respiration ratio OURs/OURenc of the oxidation ditch process is higher than that of the AAO process when the system is impacted.What’s in common is,the OURs/OURenc of the two processes can reach the standard stably when the OURs/OURenc is 0.1-0.3 from the view of statistics,otherwise,both subtle difference lies to the quasi-endogenous respiration characteristics to maintain stable operation.The quasi-endogenous respiration ratio OURq/OURenc of the AAO process is 0.05-0.15,and the oxidation ditch is 0.1-0.2,When the oxidation ditch is impacted,the endogenous respiration rises more obvious.(3)As far as the denitrification effect is concerned,the endogenous respiration characteristics can better characterize the stability of the process and the denitrification effect.When the OURe/OURenc of the AAO process is less than 0.08 and the oxidation ditch is less than 0.05,the nitrogen removal efficiency of the two processes is relatively poor;the ratio of the AAO process is between 0.08-0.15,and when the oxidation ditch is between 0.05-0.15,the two processes have high nitrogen removal efficiency.The effluent quality is stable and up to standard;when the ratio of the two processes is higher than 0.15,the operation of the water plant is unstable.(4)In terms of ammonia removal,when the ammonia nitrogen degradation OUR/OURenc of AAO is 0.025-0.05,the effluent ammonia nitrogen is low.When the ratio is relatively low,the effluent ammonia nitrogen may exceed the standard.When the ratio suddenly rises,it indicates that the microorganisms have been severely impacted.In the oxidation ditch process,the ammonia nitrogen degradation OUR/OURenc fluctuates between 0.05 and 0.1.When the value is extremely low,the dissolved oxygen concentration may be insufficient,but the treatment effect is very perfect.When the value is high,it indicates that the autotrophic bacteria are affected.which should be adjusted in time.The AAO process COD degradation OUR/OURenc healthy interval is defined as 0.8-0.95,and the oxidation ditch process healthy interval is 0.8-0.9.When the ratio is in the healthy range,the COD of the effluent is low,and when it suddenly decreases,the microbial activity of the system is not good,and the effluent is likely to exceed the standard.(5)In the case of high-frequency shock,the effective control measures of the AAO process are:to control the inflow water flow(inflow shock);when the system is impacted by the influent water quality,such as the influent COD,too high ammonia nitrogen,and the low(less than 5)influent pH,which measures can be taken as:to increase the DO concentration,add external carbon source to the denitrification tank,increase the reflux ratio(AAO system),increase the DO concentration,adjust the sludge concentration to change the sludge load,and adjust the sludge age(oxidation ditch)system).