External Pressure Ultrafiltration Is Made of PVDF Hollow Fiber Membrane

Parameters

Operation parameters

External pressure ultrafiltration is made of PVDF hollow fiber membrane and has the following characteristics:

High flux, effectively reducing the usage of membrane modules.

Uniform pore size distribution, efficient removal of bacteria and particulate matter, and effective guarantee of effluent quality.

High strength and high chemical resistance, reduce membrane damage caused by chemical corrosion or biological decomposition, effectively prolong the mission of the membrane.

Maintenance cleaning (MC) is more effective than backwashing and dosing (CEB) in reclaimed water reuse projects.

Pay attention to each time: preferably ≥20min (circulation + soaking) Frequency: according to the situation (it is also common for reclaimed water once a day)

Cleaning agent: 200-500ppm NaCLO (can be adjusted to pH6 by adding acid) or alkali (0.2%NaOH)

When there is a tendency to scale, an additional pickling step (0.1% HCL or 1% citric acid) can be added.

1. Timing of chemical cleaning of PVDF membrane:

Common Judgment Criteria: (any of the following)

①. The water production is more than 25% lower than the initial water production,

②. Transmembrane pressure difference (TMP) reaches 0.8Bar (initial TMP is generally within 0.2Mpa)

Transmembrane pressure difference (TMP) calculation method: Cross-flow (influent + concentrated water) / 2-permeate dead end filtration: influent - permeate and finally subtract the height difference (that is, the height of the permeate pipe - the inlet pipe) )

2. The cleaning method:

①: Pickling (generally 5-10 hours) Purpose: To clean inorganic pollution

Start the cycle for 1-2 hours → soak for 3-8 hours → drain → rinse to neutral

 (In the initial cycle, if it is not dirty, you should change the medicine immediately, and pay attention to maintaining the concentration of the medicine)

Use agent: 0.2% HCL or 1-2% citric acid solution (pH 1-2)

②: NaCLO cleaning: (generally requires a longer time of 12-24 hours) Purpose: cleaning organic pollution

Start the cycle for 1-2 hours → soak for 4-8 hours → cycle for 1-2 hours → soak for 6-12 hours → exclude → rinse to neutral

Use agent: 1000-3000ppm of the solution on the market (10%-12%) In order to maintain stability, the general pH value is 10.5-12. If used directly, the effect is very poor. Acid (HCL/citric acid) should be added. When the pH value is 6, the effect is the best, and CL2 (chlorine gas) may be generated below pH 5. 

Pay attention! !

The proportion of HCLO and CLO- is the same at pH 7.4 in NaCLO solution. CLO- is the main body at pH 7.4 and above, and at pH 9, 95% are CLO- oxidation and sterilization effect is poor. At weakly acidic pH 5-6, HCLO accounted for 95%. best effect. The oxidation and bactericidal properties of HCLO are 80 times that of CLO-.

③ NaOH cleaning：Only after washing with NaCLO several times, there is still no recovery. Only consider using NaOH washing (generally do not need to be used) NaOH washing should be separated from NaCLO washing (high pH value will affect the oxidation and sterilization performance of NaCLO.)

Concentration of 4% NaOH (pH14) is generally 12-24 hours (the method is the same as NaClO)

3. Cleaning sequence:

Mainly depends on the water quality: generally according to the first pickling and then NaCLO cleaning.

(If alkaline washing is required, it should be placed at the end. If the salt content of the water is high and the hardness is high, the high pH value will cause calcium and magnesium ions to scale on the membrane surface, which may harden the membrane filaments and cause breakage. Silk.)

4. The quantity of cleaning solution: generally according to (40L per membrane + volume of pipeline)*120%

5. Precautions when cleaning:

①. When the initial solution is dirty, it must be discharged. Refill supplements.

②. Whether the cleaning is effective or not depends on whether there is something washed out (that is, whether the discharged solution is dirty or not, especially when cleaning organic matter, it will generally be very dark)

③. The best water for dispensing is RO product water, and the worst is ultrafiltration product water.

• Package size

The membrane modules are added with glycerin protective liquid, and they are individually packaged when leaving the factory. The membrane modules are wrapped in plastic film bags, sealed and placed in a rigid cardboard box with shock-proof and fixing measures.

• Storage (use) precautions

If the membrane module is not installed and used temporarily, it should be stacked on a flat and clean indoor floor, away from cold and heat sources, to ensure that there is no corrosion and pollutants around; the storage temperature is controlled at 5-40 °C, and the recommended storage temperature is 20-35 °C .

• Warranty

Keep the membrane modules in the original packaging as much as possible. Under the above storage conditions, unopened new membrane modules can be stored for 2 years.

• Disclaimer

The indicators and data given in this document are based on our existing technical knowledge level and practical experience and are for reference only. The specific guarantee indicators are otherwise agreed in the technical agreement or supply contract

Subject to agreement. It is the user's responsibility to test the products purchased by our company to verify whether they are suitable for their respective proposed processes and uses, and to achieve the intended purpose.

The conditions and methods of using the company's products are beyond the control of our company, therefore, our company is not responsible for the results and damages arising from the use of such information and data. Our company technical support and

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