NIRE-170-1-6
12
IV.
MEMBRANE FILTRATION PROCESS DESIGN FOR
“NHP210 SERIES”
This section will address the
following for the Toray “NHP210 Series”: Standard sequence of
operation/time chart, illustrated piping and flow schematic, and module(s) layout in the
membrane tank.
1. Standard Time Chart
Usually intermittent filtration (filtration with relaxation) is recommended.
The most common
mode of filtration operation is nine (9) minutes of filtration followed by one (1) minute
of suspended membrane filtration (membrane relaxation) with continued air scour,
as
shown in Fig.IV-1. This period of relaxation, with no filtration, allows the continued air scour
to be more effective at removing solids that may have accumulated on the surface of the
membrane. Intermittent filtration followed by a relaxation period is recommended for stable
and efficient membrane filtration.
The air scour should be suspended when the filtration process is stopped except for the
following conditions:
1) During normal membrane relaxation periods.
2) During suspended filtration operation unless aeration is required for mixing or biological
demand requirements. For the latter the air flow should be reduced to minimum flow
rates to prevent membrane damage.
* During low wastewater supply period, basically all modules should be in operation at lower
flux rate, considering maintaining viable activated sludge. In case operation of some or all
modules will be shut down, the air scour for those modules should be suspended or applied
intermittently following above description. For long-term shutdown please refer to the
following chapter 8 “Storage Products after Use”.
Fig.IV-1 Recommended Time Chart for Intermittent Filtration
Filtration
Air diffusion
Continuous
Filtration: 9 min.
Relaxation: 1 min.
Cycle of 10 minutes
F1: Average flow rate for treatment capacity
and membrane area calculation
F2: Filtration flow rate for suction pump
capacity calculation
F1
F2
