I. Common Problems and Solutions for Sewage Screen Operation
1. Screen Blockage
(1) Fault Phenomenon:
· The water level difference between the front and back of the screen increases significantly (>0.3m)
· The flow rate through the screen decreases abnormally
· Screen slag accumulates and slag removal becomes difficult
· The pump makes abnormal noise and efficiency decreases
(2) Cause Analysis:
· A sudden increase in the amount of garbage (e.g., during the rainy season)
· Improper selection of the bar gap
· Unreasonable slag removal frequency setting
· Failure of the slag removal equipment
(3) Solution:
*Immediate measures:
Start manual scavenging to clear the blockage in time
· Adjust the slag removal frequency and increase the number of slag removals
· Check the slag removal equipment and troubleshoot
*Long-term Improvement:
· Select the appropriate bar gap according to the water inlet characteristics
· Install a combination of screens of different specifications (coarse, medium, and fine)
· Add a crusher to pre-process large debris
· Establish a slag removal warning mechanism (water level difference alarm)
*Preventive Measures:
· Regularly check the operation status of the screen
· Establish slag removal operation procedures
· Equip necessary spare equipment
· Strengthen source control to reduce the entry of large pieces of garbage
II. Common problems and solutions in the operation of grit chambers
1. Sand accumulation problem in grit chambers
(1) Fault phenomenon:
· Severe sand accumulation at the bottom of the chamber, reducing the effective volume
· Overload of sand removal equipment
· Obvious sand-carrying phenomenon in the outlet water
· Increased equipment wear
(2) Cause analysis:
· Excessive sand content in the influent
· Improper setting of sand removal frequency
· Inefficient sand removal equipment
· Insufficient stirring or aeration intensity
(3) Solution:
*Immediate measures:
· Increase the sand removal frequency and remove the accumulated sand in time
· Check the sand removal equipment to ensure normal operation
· Adjust the aeration or stirring intensity
*Long-term improvement:
· Optimize the selection of sand removal equipment (pump suction, air lift, etc.)
· Install a sand-water separator to improve sand removal efficiency
· Set up a reasonable automatic sand discharge control program
· Regularly desilt the pool bottom
*Preventive measures:
· Regularly test the sand content of the influent
· Establish sand discharge operating procedures
· Strengthen equipment maintenance
· Optimize operating parameter settings
III. Other common problems and solutions
1. Equipment wear problems
(1) Manifestations:
· Wear and deformation of the screen tooth rake
· Wear of the sand settling tank agitator blades
· Increased wear of the pump body and pipelines
(2) Solutions:
· Select key components made of wear-resistant materials
· Regularly check and replace wearing parts
· Establish equipment maintenance files
· Prepare sufficient spare parts
2. Operating parameter imbalance problems
(1) Manifestations:
· Unstable flow rate through the screen
· Improper flow rate in the sand settling tank
· Inaccurate water level control
(2) Solutions:
· Regularly calibrate monitoring instruments
· Optimize the automatic control system
· Establish a parameter adjustment mechanism
· Strengthening Operations Personnel Training
Case Studies
Case 1: Screen Clogging Problem at a Municipal Wastewater Treatment Plant
Problem: Screen clogging frequently occurred during the rainy season
Solution:
1. Added coarse screens as the first line of defense
2. Installed an automatic water level differential control system
3. Established a rainy season emergency plan
4. Results: Screen clogging issues reduced by 80%
Case 2: Sand Accumulation in Sedimentation Basins
Problem: Severe sand accumulation in the sedimentation basins necessitated monthly desilting and dredging.
Solution:
1. Switched to pump-type sand removal equipment
2. Added a sand-water separator
3. Optimized sand removal control procedures
Result: Continuous sand removal achieved, eliminating the need for desilting and dredging.