OPERATION REGULATION OF WASTEWATER TREATMENT PLANT WITH LOW CARBON-TO-NITROGEN RATIO INFLUENT BASED ON WHOLE PROCESS ANALYSIS METHOD

In order to make the effluent of a wastewater treatment plant(WWTP) reach the emission standard, the whole process test was carried out. After analyzing the changes of pollutants along the process as well as the characteristics of activated sludge and assessing the current status of process operation, basic data for optimal regulation was provided. The study found that the BOD₅ to total nitrogen (TN) ratio of the influent was only 2.45, which belonged to low carbon-to-nitrogen ratio influent. In addition, the activated sludge characteristics test found that the denitrification potential was 9.0 mg/(g·h), and the relative abundance of denitrifying bacteria was high. Therefore, insufficient carbon source in the influent and unreasonable dosing site of external carbon source were the main reasons for the poor nitrogen removal effect of the WWTP. The total nitrogen of the effluent was reduced from 32.0 mg/L to 12.7 mg/L by changing the carbon source dosing site, reducing the aeration volume of the biochemical reaction tank and increasing the amount of carbon source dosing, which realized the standard discharge of total nitrogen. In addition, the anaerobic phosphorus release potential increased from 1.3 mg/(g·h) to 2.6 mg/(g·h), which meant that the biological phosphorus removal capacity had also been greatly improved. This study provided a way to discover and solve problems in WWTPs with effluent exceeding the standard, which provided references for controlling operation and reaching standard for discharge of WWTPs with low carbon-to-nitrogen ratio influent.