Membrane batch filtration process
First Claim
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1. A batch membrane filtration process comprising the steps, performed in repeated cycles, of:
- a) filling a tank to immerse membranes in the tank;
b) after step (a), withdrawing permeate through the membranes while adding feed to keep the membranes immersed;
c) after step (b), withdrawing permeate while the flow of feed is reduced or stopped to lower the water level in the tank;
d) backwashing the membranes; and
, e) after steps (a), (b) and (c), draining the tank.
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Abstract
A membrane batch filtration process has a step of reducing the water level in the tank by permeation prior to emptying the tank to reduce the volume of water drained after each batch. Permeation may continue even after a portion of the membranes is exposed to air to further lower the water level. The membranes may be backwashed after the water level has been lowered. The water level may be lowered again after the backwash. The tank drain may begin with a portion of the membranes exposed to air.
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Citations
14 Claims
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1. A batch membrane filtration process comprising the steps, performed in repeated cycles, of:
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a) filling a tank to immerse membranes in the tank;
b) after step (a), withdrawing permeate through the membranes while adding feed to keep the membranes immersed;
c) after step (b), withdrawing permeate while the flow of feed is reduced or stopped to lower the water level in the tank;
d) backwashing the membranes; and
,e) after steps (a), (b) and (c), draining the tank. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A batch membrane filtration process wherein the tank is drained starting at a time when the water level has been lowered by permeation to expose a portion of the membranes to air.
- 13. A reactor having a membrane tank with a membrane module and an overflow area, the overflow area being fluidly connected to the tank through a valved passageway from the bottom of the overflow area to the tank such that the overflow area can drain into the tank, the passageway located below the top of the membrane module.
Specification