Step 4 - Cleaning With Citric Acid; Step 5 - Resume Normal Operation; Step 6 - Checking Permeability - ProMinent DULCOMETER PH-501 Assembly And Operating Instructions Manual

7.3.2.4 Step 4 - Cleaning with Citric Acid

This step is only required in case of inorganic fouling caused by the high hardness. The
recommended concentration is 2 g/L solution (up to 20 g/L).
Rinse membrane filter thoroughly with potable water to completely
remove NaOCl solution before treatment with citric acid. Mixing NaOCl
with citric acid releases toxic chlorine gas!
1. Turn off air scour
2. Confirm that the membrane tank (TNK-601) has been cleaned and refilled with water (Section
7.3.2.1).
3. Add Critic Acid into the membrane tank to a concentration of 2 g/L solution (up to 20 g/L) –
reducing the membrane tank to a pH of 2.0.
a. Volume of Critic Acid required can be calculated as follows. A starting dose for Critic
Acid would be 2g/L (up to 20g/L). For example: if using a 50% solution of Critic Acid,
approximately 3.2 L of solution would be required per m3 of membrane tank. Additional
Critic Acid may be required depending on the alkalinity of the water. The operator should
measure pH after addition of 2g/L and add more until the pH is 2.
b. TNK-601 holds approx. 8 m3 or 6000L.
4. Keep the membranes soaked in the citric acid solution for 2 hours (longer soak time
required if severe fouling is evident).
5. Drain spent citric acid solution, rinse membranes thoroughly with potable water and drain all
the rinse waters. Spent citric acid solution and rinse waters are drained.

7.3.2.5 Step 5 - Resume normal operation

Turn all equipment back to Automatic mode "A", and enable the membranes.

7.3.2.6 Step 6 - Checking Permeability

Normal permeability after cleaning: 200 to 300 LMH/bar.
Repeat the cleaning procedures If normal permeability is not achieved.
newterra O&M Manual
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