Electro ultrafiltration process and apparatus

A process for separating particulate material from a fluid medium in which it is disposed, comprising,

• establishing a bath volume isolated from a main bath volume by an anisotropic microporous ultrafiltration membrane,
• maintaining a differential pressure across said membrane capable of supporting a predetermined first flow rate of said fluid medium through said membrane into said isolated bath volume,
• locating a first electrode in the main bath volume and a second electrode in said isolated bath volume,
• passing a current through said anisotropic membrane to effect deposition of said particulate material at said first electrode,
• said current being independently capable of supporting a second predetermined flow rate of said fluid medium through said anisotropic membrane into said isolated bath volume, and
• the total flow of fluid medium through said membrane into said isolated bath volume exceeding the sum of the flows individually attributable to the pressure and current applied.

A bath control method for anodic electrophoretic deposition on anodic surface areas wherein current is passed through the bath to deposit electrophoretic material on one or more recipient anodes which move into, through and out of the bath, comprising,

• locating at least one cathode in contact with an enclosed pressure-tight bath volume isolated from the main bath volume by an anisotropic ultrafiltration membrane,
• establishing a pressure differential of at least about 5 psi across the membrane to initiate a first flow component of ultrafiltrate through the membrane,
• passing a current between said cathode and said recipient anodes to effect electrodeposition upon said recipient anodes and to initiate a second flow component of ultrafiltrate through the membrane which is directly proportional to the current density on the membrane,
• maintaining a constant voltage between said electrodes thereby assuring a constant deposition rate per unit area and a second flow component of ultrafiltrate which varies in direct relation to the depletion of solids from the bath and proportionally to the changes in surface area of the anode,
• the total flow of ultrafiltrate through said membrane substantially exceeding the sum of the flows individually attributable to the pressure and current applied.

An ultrafiltration system for treating a filterable fluid medium which is capable of attaining accelerated transport of filtrate through an anisotropic ulrafiltration membrane, comprising,

• a vessel having two chambers separated by said anisotropic ultrafiltration membrane, one of said chambers being open to the atmosphere and the other closed to the atmosphere,
• said anisotropic ultrafiltration membrane comprising a thin skin of from about 0.1 to 5 microns in thickness having an average pore diameter of from about 1 to 1,000 millimicrons on a coarsely porous support layer,
• means for establishing a pressure differential between said chambers across said anisotropic membrane wherein the fluid at higher pressure bears on the skin surface of said membrane and is capable of forcing filtrate through said membrane at a first flow rate,
• an electrode in each of said chambers adapted to be immersed in the fluid therein,
• means for establishing an electrical potential between said electrodes to thereby initiate a flow of electrical current between said electrodes across said membrane,
• said current flow being capable of initiating a flow of fluid at a second flow rate through said membrane which is supplementary to said fluid flow generated by said pressure differential,
• the total fluid flow rate through said anisotropic membrane when both pressure and current are applied being substantialy in excess of the sum of the fluid flow rates individually attributable to said pressure differential and said current.