Appeal 2006-2898
Application 10/461,687
BRIEF STATEMENT OF THE INVENTION
Appellants’ invention is directed to a method of chemical cleaning
one or more ultrafiltration or microfiltration membranes normally immersed
in water containing solids that become dirty or fouled during normal
operation. Representative independent claims 1 and 35, as presented in the
Brief, appear below:
1. A method for cleaning one or more membranes normally immersed
in water containing solids held at ambient pressure in a tank and used to
produce a permeate on the insides of the membranes, comprising the steps
of:
(a) cleaning the membranes to increase the permeability of the
membranes,
(b) after step (a), performing one or more cleaning events per week
over a period of at least 15 days, each cleaning event further comprising the
steps of flowing a chemical cleaner through the membranes to provide a
chemical cleaner in or adjacent the membranes for a period of time; and,
(c) choosing the concentration of the chemical cleaner and the period
of time such that the cleaning events reduce the rate of a decline in
permeability of the membranes over the period of at least 15 days;
wherein steps (a) and (b) are preformed in repeated cycles.
35. A method for cleaning one or more hollow fiber membranes
normally immersed in water containing solids held at ambient pressure in a
tank and used to produce a permeate on the insides of the membranes,
comprising the steps of:
(a) performing recovery cleanings to increase the permeability of the
membranes from time to time; and
(b) between recovery cleanings, performing one or more cleaning
events per week, each cleaning event comprising the steps of flowing a
chemical cleaner through the membranes to provide a chemical cleaner in or
adjacent the membranes for a period of time.
2
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