Patent ID: 8491788

Claim:
A membrane filtration system, comprising: a first treatment stage, comprising: a first mixing tank for holding a volume of water; a first pH probe for measuring a pH level of said water in said first mixing tank; a mechanism for dispersing a coagulant into said water in said first mixing tank; a first mechanical mixing device configured to rapidly agitate water in a first zone of said first mixing tank; a second mechanical mixing device configured to slowly agitate water in a second zone of said first mixing tank; and a liquid-solid separator device in fluid communication downstream of said first mixing tank for receiving water from said first mixing tank; a second treatment stage, comprising: a second mixing tank for holding water, said second mixing tank in fluid communication downstream of said liquid-solid separator device for receiving water that has passed through said liquid-solid separator device; a second pH probe for measuring a pH level of said water in said second mixing tank; a third mechanical mixing device configured to rapidly agitate water in a first zone of said second mixing tank; a fourth mechanical mixing device configured to slowly agitate water in a second zone of said second mixing tank; and a membrane filter in fluid communication downstream of said second mixing tank for receiving water from said second mixing tank; and a dual pH control system comprising: a first pH set point controller in communication with the first pH probe and configured to adjust the pH level of said water in said first mixing tank to a first pH set point selected for optimum TOC removal in response to a signal from said first pH probe prior to said water being directed through said liquid-solid separator device; and a second pH set point controller in communication with the second pH probe and configured to adjust the pH level of said water in said second mixing tank to a second pH set point selected for optimum performance of said membrane filter in response to a signal from said second pH probe prior to said water being directed through said membrane filter.