TORAY MBR
Instruction Manual
06-G-MB2-NHPAF-220801
39 of 63
2. Operating Parameters
The performance of the “NHPA Series” varies depending on raw water quality and site
specific operating conditions. In order to achieve stable “NHPA Series” operation, it is
recommended that various operating parameter values be monitored and recorded regularly.
The following operational parameter values should be recorded regularly.
(1)
Scouring air flow rate (blower air flow)
(2)
Diffusion pressure (blower discharge pressure)
(3)
Filtrate water flow rate
(4)
Trans-membrane pressure (TMP)
(5)
Liquid temperature in the membrane tank
(6)
DO (dissolved oxygen) concentration in the membrane tank
(7)
pH in the membrane tank
(8)
MLSS in the membrane tank
(9)
Raw water quality (BOD, COD, turbidity, T-N, T-P, etc.)
(10) Filtrate water quality (BOD, COD, turbidity, T-N, T-P, TSS etc.)
(11) Excess-sludge discharge rate
(12) Sludge viscosity
(13) Sludge filterability
Preferable recording frequencies are;
Every five (5) minutes for on-line instruments
Every day for off-line instruments and sludge properties
Every week for water quality analysis
3. Basic Control Philosophy
Presented below is the point of the generic MBR control philosophy. The actual MBR system
control philosophy will be based on the specific site operating conditions.
(1)
Suction Pump
: The filtrate suction pump should be controlled to operate for intervals of
nine (9) minutes on and one (1) minute off. The filtrate suction pump motor should be
fitted with a VFD drive. A filtrate flow transmitter should be installed to provide a control
signal to the suction pump VFD. The suction pump should be stopped if the liquid level in
the membrane tank drops to a predetermined low liquid level. If, at any time, the air
supply to the membrane module or RAS (return activated sludge) is interrupted, the
suction pump should be stopped. Do not operate the filtrate suction pump on low
membrane tank level or high TMP. Once the air supply has been restored the membrane
tank and good RAS circulation is observed, delay the activation of the suction pump for
one minute to make certain sufficient sludge mixing has taken place prior to restarting the
filtration process. The suction pump should always be off when performing air diffuser
cleaning.
