Eight issues to be considered in the design of "MBR membrane system"
1. Fouling Resistance FR-MBR membrane flux design
(1) Generally designed sludge concentration <10g/L;
(2) When arranging membrane modules, the convenience of maintenance and management needs to be considered;
(3) Flux: In industrial wastewater treatment, the general 1/2 domestic wastewater flux is provided, but the actual selection needs to be analyzed in combination with specific wastewater types and water quality characteristics.
2. Fouling Resistance FR-MBR membrane system material selection and membrane module form
(1) PVDF material (mainstream material), PP material, PES material, PTFE material
(2) Hollow fiber membrane ((submerged) curtain/column), flat membrane (plate (submerged), higher cost), tubular membrane (tubular membrane (external), higher cost
3. Operating costs and energy consumption
(1) The operating cost is a special consideration in engineering design.
(2) The operating cost of FR-MBR: a. The performance of the water pump: related to the membrane module and TMP; b. Aeration: membrane aeration, generally using large bubble aeration; biological aeration, generally Use micro-bubble aeration;
① Small-scale MBR, biological aeration and membrane aeration can be combined, and the large bubble method is used to ensure the scouring of the membrane module, but the energy consumption is slightly higher.
②Medium-sized and large-sized MBRs need to be set separately, which not only ensures the scouring effect on the membrane module, but also reduces energy consumption.
③ Excessive membrane aeration will result in decreased membrane life and damage to membrane components.
(3) Cleaning of the membrane: the proportion is very small;
(4) Membrane replacement: It is related to the membrane material, the technical level of the membrane manufacturer, and the quality of maintenance.
4. Fan and aeration pipe
(1) For the protective film, an oil-free compressor should be used.
(2) Due to the problem of the impact load of industrial wastewater, sufficient dissolved oxygen is required, that is, there is a sufficient surplus of fans.
The aeration pipe is easily blocked, and cleaning equipment needs to be installed. When designing the piping, the cleaning water should be prevented from flowing into the fan. The blower pipeline should be higher than the water surface to prevent washing water from flowing into the blower.
5. Automatic control method and monitoring
(1) Usually PLC control is adopted, the necessary electric/pneumatic valves are configured, and the dosing device runs automatically.
(2) Automatic valves should have signal feedback to determine whether the switch is in place.
(3) Design monitoring indicators: TMP, water quality, turbidity, etc.
6. Odor, noise and humidity problems
(1) Due to the large amount of aeration, the odor, noise and humidity of the MBR workshop are large.
(2) Odor: As required, the top of the reaction tank is covered to make it airtight, and a centrifugal blower is used to extract the odor into the odor removal device.
(3) Noise: use a soundproof cover, or choose a low-noise fan.
(4) Humidity: Add a dehumidifier or strengthen ventilation as needed.
(5) Temperature: can not exceed 40 ~ 45 degrees.
7. Chroma problem and removal
(1) The current MBR membranes all use ultrafiltration/microfiltration membranes, which have a low retention effect on chroma.
(2) The chromaticity of raw water: pretreatment, adding coagulant or decolorizing agent, reducing the chromaticity to a reasonable range in advance, and then entering the MBR to continue decolorization through biodegradation.
(3) The membrane effluent sometimes has chromaticity. Ozone, activated carbon and other methods can be used to continue decolorization.
8. Convenience of post-operation and maintenance of anti-pollution FR-MBR membrane (configured with cranes, cleaning pools, etc.)
(1) Consider the convenience of membrane module cleaning;
(2) Consider the convenience of membrane module replacement;
(3) Operators' daily maintenance, daily maintenance, etc.