Large fluctuations in influent flow
Low water temperatures during winters
Hydraulic overloading
Stringent discharge standards (Discharge Standard of Water Pollutants for Municipal Wastewater Treatment Plants DB11/890-2012).
Solution：Dosed MicroMotion®-N,to address nitrogen issues under low-temperature and high-flow conditions.
Processing Scale：100000m3/d
Treatment Effect：Influent ammonia nitrogen: 40–50 mg/L Effluent after biological treatment: <6 mg/L Final effluent ammonia nitrogen: <1 mg/L
Characteristics
Large fluctuations in influent flow
Low water temperatures during winters
Hydraulic overloading
Stringent discharge standards (Discharge Standard of Water Pollutants for Municipal Wastewater Treatment Plants DB11/890-2012).
Description
Based on preliminary on-site investigation conducted by our technical team, the coexistence of nitrate and nitrite was observed at the end of the secondary sedimentation tank and aerobic tank. Alkalinity at the end of the aerobic tank exceeded 240 mg/L, and the system demonstrated approximately 50% ammonia nitrogen removal efficiency. Thus, we identified the following key issues:
1. Nitrification rates were reduced due to low-temperature operating conditions.
2. Under the same low temperatures, the aerobic zone had insufficient retention time for complete ammonia nitrogen oxidation.
3. Residual alkalinity in the secondary sedimentation tank remained above 240 mg/L, indicating no alkalinity limitation during nitrification.
4. With 50% nitrification efficiency, it is unlikely that the system was significantly affected by toxic shocks.
Option
1. Based on data analysis and bench-scale testing, it was determined that low temperatures suppressed the activity of both nitrifying and denitrifying bacteria.
2. Ensured sufficient system alkalinity (alkalinity ≥ 7.14 times the ammonia nitrogen concentration), maintained dissolved oxygen levels above 2 mg/L in the aerobic zone, and kept pH between 8.0 and 8.5.
3. Increased sludge concentration to enhance biological enrichment capacity.
4. Dosed 2,000 kg of MicroMotion®- N to promote nitrification.
Result
After the corresponding adjustments, the ammonia nitrogen removal rate reached 90%, with biochemical effluent ammonia nitrogen consistently maintained below 6 mg/L. Following simple post-treatment steps such as disinfection, the final effluent met the discharge standards.
Service Content
Staff training and scheduled on-site support
Provision of standard operating procedures
Monitoring on-site data with 24/7 remote troubleshooting assistance
Periodic Service
