TORAY MBR
Instruction Manual
06-G-MB2-NHPAF-220801
50 of 63
6. Chemical Cleaning Procedure
(1) Element Chemical Cleaning Procedure
To begin the cleaning process slowly inject the chemical via the filtrate water nozzle into the
elements until the cleaning solution flows through the membranes.
Do not apply pressure
in excessive of 10 kPa (100 mbar) when injecting the cleaning chemicals
. Some
recommended cleaning chemical injection methods are shown below.
a. Chemical cleaning with the chemical tank located at the bottom (Fig.VIII-2)
(i)
Confirm that the chemical injection valve is closed and that the chemical feed
pump is in the off position.
(ii) Using the chemical tank, mix the desired amount of chemical solution.
(iii) Discontinue the filtration process and associated module aeration. Next close
the filtrate water valve.
(iv) Start the chemical feed pump and check to make certain the pump is sufficiently
primed, and the chemical is being pumped to the elevated cleaning chemical
injection tank.
(v) Slowly open the chemical injection valve to start injecting the chemical.
(vi) After injecting the specified amount of chemicals to the elements, stop the
chemical feed pump.
(vii) Allow the membrane elements to soak for 1 to 3 hours.
(viii) After soaking,
close the chemical injection valve, open the filtrate valve, and start
the module aeration. Finally, resume normal filtration process.
*
When starting up the MBR after a chemical cleaning, some residual cleaning
chemical may be present in the filtrated water for 2 or more filtration cycles. It
is recommended that the filtrate flow be directed back into the raw water tank
until no residual cleaning chemical is detected. Before directing the filtrate
from the raw water tank back to the normal filtrate discharge line, test the
filtrate pH and chlorine concentration.
Fig.VIII-2 Chemical Cleaning with Chemical Tank Located at the Bottom
Module
Low Water Level of
Membrane Tank
Chemical
Injection Valve
Filtrate
Water Valve
Chemical
Feed Pump
Chemical Tank
Vent
1,000 mm (=10 kPa) or less
