At present, the inoculation and commissioning of activated sludge are being carried out in the extremely low temperature environment of minus 10 ℃ in Harbin during winter, and special attention should be paid to maintaining microbial activity, controlling system temperature, and optimizing the commissioning cycle.
1, The core impact of low temperature on the commissioning of activated sludge
Microbial metabolism slowing down: Low temperature significantly reduces microbial enzyme activity, leading to a decrease in organic matter degradation rate, and the debugging cycle may be extended by 2-3 times (conventional debugging takes 20-30 days, and may take 60-90 days at low temperatures).
Deterioration of sludge sedimentation: Low temperature can easily cause sludge expansion, leading to sludge loss and affecting system stability.
Increased energy consumption: Additional heating is required to maintain water temperature, while aeration efficiency decreases, requiring an increase in aeration volume to meet dissolved oxygen demand.
2, On site rapid warming and insulation measures
Temporary heating scheme
-Steam/hot water coil heating: Install coils inside the aeration tank or secondary sedimentation tank, and circulate hot water through the boiler room or electric heating equipment (pay attention to the anti-corrosion of the coil material).
-Biological pool cover insulation: Cover the surface of the pool with rock wool or polystyrene board to reduce heat loss, and seal it with canvas or plastic film on the top of the pool.
-Preheating of incoming water: Utilize the waste heat from the factory area (such as air compressor cooling water) or electric heating devices to increase the incoming water temperature to 10-15 ℃.
Process adjustment and temperature increase
-Reduce aeration rate: Reducing aeration intensity can reduce heat loss, but it is necessary to ensure that dissolved oxygen is ≥ 2mg/L.
-Shortening sludge retention time (SRT): Proper sludge discharge can improve sludge activity, but excessive sludge discharge should be avoided to prevent microbial loss.
3, Key measures to accelerate the debugging process
Strain optimization
-Inoculate low-temperature resistant sludge: Priority should be given to selecting activated sludge from sewage treatment plants in cold northern regions (such as the existing sewage treatment plant in Harbin), whose microorganisms have adapted to low-temperature environments.
-Adding low-temperature microbial agents: supplementing with thermophilic microbial agents (such as Pseudomonas) can be customized through online shopping or contacting microbial preparation companies.
Nutrition and Environmental Regulation
-Increasing the carbon to nitrogen ratio (C/N): Microorganisms have an increased demand for carbon sources at low temperatures. It is recommended to adjust the C/N ratio to (10-12): 1 (usually 8:1).
-Control pH: Maintain pH at 7.0-8.0 to avoid insufficient alkalinity caused by low temperature.
-Intermittent aeration: Adopting a "2-hour aeration+1-hour stop aeration" mode to reduce heat loss while promoting microbial recovery.
Strengthen monitoring and emergency response
-Daily monitoring of key indicators: SV30,MLSS, Dissolved oxygen, effluent COD/NH3-N, adjust parameters in a timely manner.
-Backup heating plan: Prepare portable electric heating equipment or temporary steam boilers, plan to use steam pipes, insert them into water, and cope with extreme low temperature weather.
4, Prediction and optimization of debugging cycle
-Initial stage (1-20 days): Focus on increasing the sludge concentration to 3000-4000mg/L, and promote microbial adaptation through intermittent aeration and nutrient supplementation.
-Mid term (20-40 days): Gradually increase the load to 50% -70% of the design value, and monitor whether the processing efficiency meets the standard.
-Late stage (40-60 days): Run at full capacity, optimize aeration and sludge discharge to ensure stable effluent.
5, Economic suggestions
-Utilize existing facilities: prioritize the use of waste heat from the factory area (such as generator cooling water) for heating to reduce energy consumption costs.
-Staged debugging: Start the hydrolysis acidification tank first, use anaerobic heat production to increase water temperature, and then gradually connect to the aerobic system.
-Insulation material recycling: After debugging, remove the insulation material for subsequent winter maintenance.
precautions
Avoid directly adding high-temperature water (>30 ℃) to the aeration tank to prevent microbial death from heat shock. Difficulty in dewatering sludge at low temperatures requires adjusting dewatering machine parameters or adding coagulants. Pay close attention to the phenomenon of sludge floating up in the secondary sedimentation tank and take timely measures (such as increasing sludge discharge)
