I. Source control of pollution: reducing the pressure on filter media to retain pollutants
Enhanced influent pretreatment: When influent turbidity > 10 NTU, a pre-filter (coarse filter) should be used.
Control harmful impurities: Water containing oil should be pretreated by oil removal (such as an oil separator) to control the oil content of the influent to ≤5mg/L; in scenarios containing hard objects (such as slag), filter screens should be installed to intercept them and reduce filter media wear.
Stabilize influent water quality: Avoid the impact of wastewater with high turbidity and high concentration of chemicals. Set up a water quality buffer tank to maintain the influent turbidity ≤10NTU and pH value between 2 and 13.
II. Optimize operating parameters: reduce filter media wear
Reasonable control of filtration rate: Stabilize the filtration flow rate at 20-30m/h, avoid ultrafiltration operation exceeding 50m/h, reduce the impact and wear of water flow on the filter media, and at the same time allow impurities to be evenly distributed in the filter layer, rather than being quickly blocked on the surface.
Precisely set backwash parameters: control the backwash flow rate at 8
Avoid overload operation: The single tank's processing capacity should not exceed the rated value. In high-flow scenarios, multiple tanks should be connected in parallel to divert the flow, reducing the interception load of the filter media in a single tank and the impact of water flow.
III. Regular maintenance: Restoring filter media performance
Regular screening and replenishment: Open the tank every 6-12 months, take out the filter media and screen it to remove broken and pulverized fine sand particles (screening is required when the proportion exceeds 10%), and replenish with new filter media of the same specification to maintain the filter layer thickness at 100-300mm and ensure stable gradation.
Targeted chemical cleaning: Every 3-6 months, choose the cleaning method according to the water quality. When there is scale, rinse with 5%-8% dilute hydrochloric acid. When there is sticky organic matter, soak in an alkaline cleaning agent (such as sodium hydroxide solution) for 30 minutes and then backwash to remove the adhering substances on the surface of the filter media.
Cleaning filter media: If the filter media is still partially caked after backwashing, loosen it manually or rinse it with low-pressure water to prevent the caked area from expanding; check the drain outlet monthly to ensure that impurities are completely discharged during backwashing and do not remain at the bottom of the filter media.
IV. Operational detail optimization: reducing filter media damage
Stable operating conditions: Avoid frequent start-ups and shutdowns of the equipment. Before restarting after a shutdown of more than 24 hours, flush the filter layer for 5-10 minutes to remove microbial slime that has grown on the surface of the filter media and prevent rapid clogging after startup.
Avoid chemical corrosion: When treating water containing strong acids and alkalis, choose corrosion-resistant filter media (such as modified quartz sand) and rinse the filter layer with clean water regularly to reduce the erosion of the filter media by chemical residues.
Protect the filter layer structure: Do not strike the tank or shake it violently while the equipment is running, to avoid channeling (water flow short circuit) in the filter layer, which may cause local overload of the filter media.
V. Specific Measures for Special Scenarios
Water containing microbial slime: Regularly add bactericides (such as chlorine dioxide) to control microbial growth and prevent slime from coating the filter media and forming caking.
In low-temperature outdoor environments: In winter, ensure proper insulation to prevent the filter layer from freezing and expanding, which could cause the filter media to break. When shutting down, drain the water from the tank.
