An apparatus for filtering and dialyzing a suspension and increasing the concentration of retainable matter, comprising:
- (a) a suspension holding means;
- (b) a suspension including particulate matter retained within said suspension holding means;
- (c) a dialysis buffer holding means;
- (d) a dialysis buffer retained within said dialysis buffer holding means;
- (e) means for capturing filtrate;
- (f) a filter means further comprising a housing having an inlet port, an exit port, a pair of sidewall openings, and a filter membrane within the housing;
- (g) a first pump means;
- (h) a second pump means;
- (i) a third pump means;
- (j) an interchangeable valve means;
- (k) means for interconnecting said first pump means, said second pump means, said third pump means and said interchangeable valve means to said filter means, to said suspension holding means, to said dialysis buffer holding means and to said means for capturing filtrate;
- (l) said first pump means, said second pump means and said third pump each functionally located downstream from said filter means when used for re-circulating suspension or extraction of filtrate from the fluid phase of the suspension;
- (m) said interchangeable valve means having a first setting wherein said first pump means causes said suspension to be drawn out of said suspension holding means and run through said filter means and recirculated back into the suspension holding means while said second pump means causes filtrate from the fluid phase of the suspension which has passed through said filter membrane to be drawn through one of said pair of sidewall openings in the filter housing and directed to said means for capturing filtrate;
- (n) when said interchangeable valve means is set at the first setting, said first pump means set to cause suspension flow at a rate sufficiently greater than the filtrate flow from the second pump means so that negative pressure away from the filter membrane generated on the recirculating suspension by said first pump means is greater than the positive pressure applied onto the filter membrane generated by the second pump means on said filtrate;
- (o) said interchangeable valve means having a second setting wherein said second pump means causes said suspension to be drawn out of said suspension holding means and run through said filter means and recirculated back into the suspension holding means while said first pump means causes dialysis buffer to be drawn out of said dialysis buffer means and run through one of said pair of openings in the sidewall of the filter housing and through the filter membrane while said third pump means causes dialysis buffer which has passed through the filter membrane and the dialysis buffer in the filter housing to be removed from the filter means through the other of said pair of openings in the sidewall of the filter housing and directed to said filtrate capturing means;
- (p) when said interchangeable valve means is set at said second setting, said third pump means is set to extract filtrate from the fluid phase of the suspension at a rate equal to the rate at which the first pump means delivers dialysis fluid to the filter means;
- (q) when said second pump means is set at said second setting, said second pump means is set to cause suspension flow sufficiently greater than the flow of dialysis buffer from said first pump and extraction rate of filtrates by the third pump so that negative pressure away from the filter membrane generated on the recirculating suspension by said second pump means is greater than the positive pressure against the filter membrane generated by the third pump means;
- (r) said interchangeable valve means having a third setting identical to the setting set forth in element (o);
- (s) when said interchangeable valve means is set at said third setting, said third pump means is set to extract filtrate from the fluid phase of the suspension at a rate greater than the rate at which the first pump means delivers dialysis fluid to the filter means;
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- (t) when said interchangeable valve means is set at said third setting, said second pump means is set to cause suspension flow sufficiently greater than the difference between the flow of dialysis buffer from said first pump and extraction rate of filtrates by the third pump so that negative pressure away from the filter membrane generated on the recirculating suspension by said second pump means is greater than the positive pressure against the filter membrane generated by the third pump means;
- (u) whereby the greater negative pressure generated by the downstream pump means on the suspension causes the particulate matter in the suspension to be drawn away from the filter membrane and thereby prevents clogging of the filter membrane.