Maintenance and cleaning of mbr membrane of mbr membrane module

After the MBR system is used for a period of time, because the contaminants accumulate on the membrane surface and the pressure difference between the membranes rises, the membrane module needs to be cleaned and maintained. The initial pressure difference between the membranes is about 10KPa. After the MBR membrane module has been filtered for a period of time, when the membrane When the pressure difference is 20KPa higher than the initial stage, it is necessary to clean with chemical solution. When the transmembrane pressure difference reaches 35kPa, restorative cleaning must be performed. When the membrane flux cannot be recovered effectively through restorative cleaning, off-line chemical cleaning should be considered.

Regular online chemical cleaning of MBR can keep the MBR system running stably. At the same time, after 2 years, the water flux of the membrane system is about 90-95% of the original initial state.

MBR system online chemical cleaning maintenance steps:

In order to ensure the good water production performance of MBR membrane, the membrane should be cleaned regularly online. If the transmembrane pressure difference reaches or exceeds 35 kPa, the recovery effect will be greatly affected.

The recommended online chemical cleaning method is: maintenance cleaning once a week, restorative cleaning once a month, and pickling at least once every six months.

(1) Type and frequency of medicine cleaning

 Commonly used liquid medicines are sodium hypochlorite, citric acid, and oxalic acid solutions.

① Maintenance cleaning: once a week, 500 ~ 1500 mg/L sodium hypochlorite aqueous solution, the concentration of the chemical solution is subject to actual engineering needs;

② Restorative cleaning: once a month, 2000-3000 mg/L sodium hypochlorite aqueous solution;

③ Pickling cycle: once every six months or according to the specific pollution of the membrane filament, 1 to 2% (mass fraction) of citric acid or oxalic acid solution.

( 2 ) Dosage

The amount of medicament used per square meter of membrane area is 2 to 4 L, plus the amount required to fill the drug delivery pipeline.

( 3 ) Online chemical cleaning steps

① Stop filtering and aeration: first turn off the water production pump and close the water production pneumatic valve for the corridors that need to be cleaned. After 1 to 2 minutes, close the aeration. It must be confirmed on site that the aeration has been completely closed. The water inlet and backflow of the corridor are also closed, and then the valve of the medicine supply pipeline is opened;

② Adding chemical solution: In areas with low water temperature, you should consider heating the cleaning solution appropriately. Increasing the temperature can improve the cleaning effect. The recommended cleaning solution temperature is 25 ~ 35 ℃. Open the liquid medicine injection tube and inject the liquid medicine; add the liquid medicine in three times, each adding one-third of the amount of the medicine, the way of adding: the first dosing is 5 minutes, and the rest is 5 minutes; after that, the second dosing is done , Dosing for 5 minutes, and stand still for 5 minutes; do the third dosing, dosing for 5 minutes, and then close the corridor drug supply valve;

③ After the dosing is completed, let it stand for 1 to 1.5 hours, and then empty aerate (only aeration does not produce water) after 0.5 to 1 hour, open the corridor for water inflow and return, and restore the water production to the automatic state.