CAST Process Nitrogen Removal Control And Management In A Chemical Industrial Park Wastewater Treatment Plant In Southern Jiangsu Province

The urban sewage treatment plant located in a chemical park adopts the CAST process,and its service area enterprises mainly include electronic processing,chemical,pharmaceutical,metal surface processing,and hazardous waste disposal.Due to the complex and varied types of enterprises,the scale of drainage is different,resulting in abnormal water ingress in sewage treatment plants.The production in the factory is unstable,especially in the control of TN.This study has formulated relatively complete external inspection measures and procedures to understand the composition and drainage characteristics of enterprises in chemical parks,which is conducive to the effective control of incoming water.External inspections have effectively prevented the phenomenon of illegal drainage or leakage of drainage units in service areas.From the source,the phenomenon of mixing industrial rainwater that has not met the standards with the rain and sewage pipe network is suppressed,thereby reducing the impact on the normal operation of the sewage plant,and making the TN of the sewage plant effluent reaches the standard.Besides,the improvement in the sewage treatment plant provides a guarantee for the stable operation of the sewage plant.Through the modification of the aeration tube,the DO concentration in the anoxic and aerobic sections can be accurately controlled,so that the TN of the effluent is stabilized at 7.67 ~ 10.0mg/L,which is 31.7% ~ 41.5% lower than the TN concentration of the effluent before the modification.After the external carbon source sodium acetate dosing system is modified,the carbon source required for microbial denitrification can be supplemented in time.The addition of online monitoring instruments such as ORP and DO has reduced the number of problems caused by the operation of the sewage plant due to untimely manual detection,and the TN removal rate of the sewage plant water has been effectively improved and guaranteed.When the influent of the sewage plant is impacted by a sudden high concentration of toxic and harmful wastewater,it is timely and effectively regulated.For example,when the impact of wastewater with a low C/N ratio occurs,it is possible to extend the CAST biological pool influent flow(anaerobic)time,reduce the aerobic aeration air volume of the biological pool,reduce the aerobic aeration time,and start the sodium acetate agent injection Adding a system and replenishing the water carbon source in time to increase the denitrification rate so that the TN of the biological pool effluent can be effectively controlled below 10mg/L.When the high-concentration organic wastewater impacts,the abnormal wastewater is first hit to the emergency tank;then measures such as reducing the water intake and increasing the aeration time are taken.When the impact of high nitrogen wastewater occurs,the abnormal wastewater is first driven to the idle CAST tank;the sodium acetate dosing device is started and supplemented with manual sodium solid acetate to timely supplement carbon sources and other measures to improve the denitrification effect.When the impact of metal ion wastewater occurs,the water feed operation should be stopped immediately to accelerate the discharge of activated sludge affected by heavy metals,and the number of bacteria should be supplemented until the TN data of the effluent returns to normal.