GIRE-097-2-2
47
b. Chemical cleaning with the chemical tank located above the membrane submerged
tank (Fig.VIII-2)
(i)
Confirm that the chemical injection valve is closed.
(ii)
Provide the chemical tank with specified amounts of the chemical.
(iii) Stop filtration, stop aeration, and close the filtrate valve.
(iv) Slowly open the chemical injection valve to inject chemicals.
(v)
After injecting the chemical, hold the equipment for 1 to 3 hours.
(vi)
Close the chemical valve, open the filtrate valve, and start aeration. Then,
restart filtration operation.
* The chemical may remain in the permeated water in an early stage of
filtration (for a period of 2 or more intermittent cycles). Send back the
permeated water to the raw water tank, or dispose of it in accordance with
applicable legal standards for waste disposal. Before restarting the normal
operation, check the pH and/or Cl concentration of the permeated water.
Fig.VIII-2 Chemical Cleaning with Chemical Tank Located
above Membrane Submerged Tank
c. Chemical cleaning with the chemical feed pump and relief valve (Fig.VIII-3)
(i)
Confirm that the chemical feed pump is stopped and the top of relief piping is
located at 1 m or lower height from membrane submerged tank water level.
(ii)
Provide the chemical tank with specified amounts of chemical.
Module
Manifold
Permeated
water valve
Chemical tank
1,000 mm (=10 kPa) or less
Low water level of
Membrane
Submerged Tank
Chemical
injection valve
