So, what should sewage treatment plants check and how should they check? Some supervisors have summarized a set of "Key Points for On-site Inspection of Sewage Treatment Plants" based on their on-site inspection experience.
1. Key points for central control system inspection
Key operating parameters: check the data such as dissolved oxygen (DO), sludge concentration, oxidation-reduction potential (ORP) of the biochemical pool shown in the central control system to judge the operation of the sewage treatment plant.
2. Key points for water inlet inspection
Overflow port: on-site inspection of the overflow port location and overflow method of the sewage treatment plant.
Influent water quality: The influent water should be gray-black and have a weak rotten smell.
3. Key points for pretreatment inspection
Adjustment tank: Check the size of the adjustment tank and check whether the adjustment tank can meet the water volume requirements. Check on-site whether the adjustment tank is equipped with an overflow port, understand the overflow situation and check the relevant ledger records.
4. Key points for biochemical inspection
Activated sludge settling performance: The on-site detection method is to take the mixed liquid of the aeration tank into a 1L measuring cylinder, let it stand for 30 minutes, and see the proportion of the volume of the precipitated sludge formed to the volume of the original mixed liquid.
Sludge characterization and concentration: The color of normal sludge is generally yellow-brown and has a muddy smell.
5. Key points for the secondary sedimentation tank inspection
Secondary sedimentation tank sludge settling performance: The thickness of the supernatant in the secondary sedimentation tank during normal operation should be no less than 0.5m-0.7m.
6. Key points for effluent disinfection inspection
7. Key points for effluent inspection
Effluent water volume: The effluent water volume should be close to the influent water volume, with an error of no more than 10%. Calculate the effluent volume through online monitoring data.
8. Key points for sludge verification
Sludge properties: The dehydrated sludge of a sewage treatment plant that operates normally is yellow-brown, has a muddy smell, does not stick to the hands, and forms lumps.
9. Key points for online monitoring verification
Data transmission and storage: Abnormal conditions include long-term lack of online monitoring data without justifiable reasons, and the change range of online monitoring data fluctuates slightly around a fixed value for a long time.
1. Details of the pretreatment section
The operation of the fine screen needs to pay attention to: regular flushing of the screen slag; high-pressure water flushing; configuration of a pressure pump and a water storage tank; and the corresponding height of the baffles on both sides.
The operation of the aerated grit chamber needs to pay attention to: control of the aeration volume; cleaning of the sand outlet corridor; and statistics on the operation and sand separation of the sand-water separator.
The operation of the cyclone sand settling tank should pay attention to: the good function of the sand lifting system; check the speed of the stirring impeller; and count the sand discharge of the sand-water separator.
2. Key points of biological treatment section details
The activated sludge settling ratio should focus on observing: settling process; mud-water boundary; supernatant; density of precipitated sludge.
Inspection of external reflow in biological pools should be checked: check whether the operating current, voltage, vibration of water pump guide rails, etc. are working properly; check whether the external reflow sludge is evenly mixed with the influent; check the mixed liquid mud-water separation structure, mud level and liquid level in the pump room, etc.
3. Key points of details in the deep treatment section
Problems that are prone to occur in high-efficiency sedimentation tanks: loose sludge floating; easy to breed green algae; dead corners of sludge, causing sludge floating; prone to inclined tube collapse.
The types of filtration are: V-type and D-type filter tanks with filled filter media; filter cloth filter tanks with filter cloth; ultrafiltration membrane filter tanks with membrane separation; active sand filtration with fluidized filter bed; denitrification deep bed filter tank with denitrification function.
4. Key points of details in the sludge treatment section
The moisture content of various types of sludge in sludge treatment: primary sedimentation tank sludge: 95~99%; biochemical residual sludge: 99%; deep chemical sludge: 95~99%; mud cake: 60~80%.
During the PAM preparation process, attention should be paid to: drug powder spillage; water-drug ratio; maturation observation; drug efficacy cycle.