1. Large fluctuations in influent flow
2. Low water temperature during winters
3. Complex influent composition
4. Vulnerable to shock loading
Solution：MicroMotion®-N and MicroMotion®-Den were applied to address nitrogen-related issues under low-temperature conditions in winter.
Processing Scale：40000m³/d
Treatment Effect：Influent total nitrogen: 80–120 mg/L, effluent total nitrogen: 6–12 mg/L; Influent ammonia nitrogen: 70–110 mg/L, effluent ammonia nitrogen: <2 mg/L
Characteristics
1. Large fluctuations in influent flow
2. Low water temperature during winters
3. Complex influent composition
4. Vulnerable to shock loading
Description
The low water temperature significantly inhibited nitrification and denitrification processes, which led to ammonia nitrogen and total nitrogen levels not meeting discharge standards.
Option
1. After data analysis and bench testing, low temperature was identified as the cause of suppressed activity in nitrifying and denitrifying bacteria.
2. Ensured sufficient system alkalinity (alkalinity > 7.14 times the ammonia nitrogen concentration), maintained aerobic dissolved oxygen above 2 mg/L, and kept pH between 8.0 and 8.5.
3. Maintained dissolved oxygen below 0.5 mg/L and pH between 7.0–7.5 in the anaerobic zone; ensured the carbon-to-nitrogen-to-phosphorus (C: N:P) ratio met the 100:5:1 requirement.
4. Insulated and covered the biological tank with tent film to maintain water temperature at 10–13°C, thereby enhancing microbial activity.
5. Dosed 1500 kg of MicroMotion®-N and 500 kg of MicroMotion®-Den.
Result
After commissioning, the ammonia nitrogen removal rate reached 99%, with effluent ammonia nitrogen consistently maintained below 2 mg/L, well under the discharge limit.
The total nitrogen removal efficiency ranged between 88–93%, with effluent total nitrogen consistently maintained below 10 mg/L, meeting the discharge standard of 15 mg/L and ensuring stable and compliant system operation.
Periodic Service
