Cause
Short sludge age:
The generation cycle of nitrifying bacteria is relatively long. If the sludge retention time (SRT) is too short, nitrifying bacteria cannot effectively aggregate in the system, resulting in weakened nitrification.
Poor sludge return or excessive sludge discharge can also reduce sludge age and affect nitrification efficiency.
Excessive load:
When the organic load or ammonia nitrogen load is too high, nitrifying bacteria are at a disadvantage in competition with heterotrophic bacteria and cannot fully carry out nitrification.
Insufficient sludge volume during the initial start-up of the system, or short system retention time, can also lead to excessive load.
Inappropriate external environment:
Insufficient dissolved oxygen (DO): Nitrification requires sufficient oxygen, and when DO is below 2.0mg/L, nitrification will be inhibited.
Abnormal pH value: Nitrifying bacteria are sensitive to pH value, with an optimal range of 8-9. Exceeding this range will affect their biological activity.
Inappropriate temperature: Nitrifying bacteria can carry out normal physiological metabolic activities within the range of 5-35 ℃. When the temperature is below 5 ℃ or above 40 ℃, their activity will be inhibited.
Equipment malfunction or improper operation:
The malfunction of the aeration equipment resulted in insufficient DO.
Abnormal reflux system, affecting sludge reflux and mixed liquid distribution.
The control system malfunctioned, causing the process parameters to deviate from the normal range.
Emergency response methods
Pause or reduce inflow: Reduce system load and provide opportunities for nitrifying bacteria to recover.
Increase aeration rate: Increase dissolved oxygen levels to support the activity of nitrifying bacteria.
Adjust reflux ratio: Increase the internal reflux ratio appropriately to improve nitrification efficiency.
Maintain a suitable pH value: Adjust the pH value within the range suitable for the growth of nitrifying bacteria by adding acidic and alkaline substances.
Stop sludge discharge: to avoid further loss of nitrifying bacteria.
Solution
Adjust sludge age:
Extend the sludge retention time, avoid excessive sludge discharge, and ensure effective aggregation of nitrifying bacteria in the system.
Optimize the sludge return system to ensure smooth sludge return.
Reduce load:
Reduce the inflow load and lower the concentration of organic matter and ammonia nitrogen.
Increase system dwell time and improve processing efficiency.
Activated sludge can be added during initial start-up to quickly increase sludge concentration.
Optimize external environment:
Increase dissolved oxygen levels to ensure DO is between 2.0-3.0mg/L.
Adjust the pH value to the optimal range for nitrifying bacteria (8-9).
Control the water temperature within an appropriate range (5-35 ℃) to avoid the impact of extreme temperatures on nitrifying bacteria.
Strengthen equipment maintenance and management:
Regularly inspect key equipment such as aeration devices and reflux systems to ensure their normal operation.
Strengthen control system maintenance to ensure stable process parameters.
Improve the skill level of operators, strengthen training and management.
Add nitrifying bacteria culture medium:
After confirming the stability of the system, nitrifying bacteria culture medium can be added to accelerate the recovery of the nitrification system.
Select the appropriate culture medium for nitrifying bacteria and add it according to the actual situation of the system.
Strengthen water quality monitoring and early warning:
Regularly monitor the effluent quality, promptly detect and handle any abnormal situations.
Establish a warning mechanism to monitor and alert key indicators in real-time.