US 6,656,356 B2 · Aerated immersed membrane system

Abstract

An element of immersed, suction driven, filtering membranes has a plurality of hollow fiber membranes suspended between upper and lower headers. The lower header is movable between a first position in which the fibers are substantially elongated and second position in which the two headers are closer to each other by between 1 and 4% of the un-potted length of the membranes. The weight of the lower header is sufficient to keep the lower header in the first position in substantially quiescent water while allowing the lower header to rise to the second position in upwardly flowing water. Aerators are mounted generally below the elements and supply scouring bubbles to each element at a higher rate and then at a rate less than one half of the higher rate in repeated cycles. The cycles are preferably between 10 seconds and 60 seconds in duration. The lower header rises to the second position when bubbles are supplied at the higher rate and falls to the first position when bubbles are supplied at the lower rate.

Claims17

Dependent claims

An element of filtering hollow fibre membranes comprising:

(a) a fixed upper header;
(b) a lower header;
(c) a plurality of hollow fibre membranes attached to and suspended between the headers, the hollow fibre membranes having each at least one open end and having each an outer surface, the outer surface of the open ends of the membranes connected to at least one header with a water impermeable connection;
and
(d) one or more permeate channels in at least one of the headers in fluid communication with the interior of the hollow fibre membranes for collecting permeate, wherein,
(e) the lower header is movable between a first position in which the fibres are substantially elongated and second position in which the headers are a selected distance closer together;
and
(f) the weight of the lower header is sufficient to keep the lower header in the first position in substantially quiescent water while allowing the lower header to rise to the second position in upwardly flowing water or water and bubbles.

5 more elements

A process for treating water with filtering hollow fibre membranes comprising:

(a) providing a plurality of elements of filtering hollow fibre membranes each having,
(i) an upper header;
(ii) a lower header;
(iii) a plurality of hollow fibre membranes attached to and suspended between the headers, the hollow fibre membranes having each at least one open end and having each an outer surface, the outer surface of the open ends of the membranes connected to at least one header with a water impermeable connection, the headers capable of movement relative to each other;
and
(iv) one or more permeate channels in at least one of the headers in fluid communication with the interior of the hollow fibre membranes for collecting permeate;
and
(v) a frame which fixedly secures said upper header and restrains said lower header within a range of movement including a first position and a second position, the second position being above the first position, the weight of the lower header sufficient to keep the lower header in the first position in substantially quiescent water while allowing the lower header to rise to the second position in upwardly flowing bubbles;
(b) applying suction to the interior of the hollow fibre membranes to withdraw a filtered permeate;
(c) providing a supply of scouring bubbles from below the elements;
and
(d) varying the supply of scouring bubbles from a higher rate to a rate less than one half of the higher rate in repeated cycles, said lower header moving upwards when the bubbles are supplied at said higher rate and moving downwards when said bubbles are supplied at said lower rate.

9 more elements

Dependencies are inferred from the claim text.

Aerated immersed membrane system

Life of this patent

Aerated immersed membrane system

Life of this patent

Abstract

Claims17