Method for controlling fouling of a membrane filter

A method for controlling fouling of a membrane filter in a biological wastewater treatment process, comprising:

• directing wastewater influent into one or more reactors and treating the wastewater;
• directing the wastewater into and through one or more membrane tanks having one or more membrane filters therein;
• filtering the wastewater by directing the wastewater through the membrane filters and producing a permeate;
• cleaning the membrane filters with air scouring;
• measuring a liquid level in a membrane tank;
• executing one or more control cycles to control one or more control variables;
• and
• in at least one control cycle, adjusting one control variable selected from the group including scouring air flow rate, flux, permeation phase duration, and relaxation phase duration as a function of the measured liquid level.

A method for controlling fouling of a membrane filter in a biological wastewater treatment process, comprising:

• directing wastewater influent into one or more reactors and treating the wastewater;
• directing the wastewater into and through one or more membrane tanks having one or more membrane filters therein;
• filtering the wastewater by directing the wastewater through the membrane filters and producing a permeate;
• cleaning the membrane filters with air scouring;
• measuring a first change in trans-membrane pressure during a permeation phase, measuring a second change in trans-membrane pressure from the start of a first permeation phase to the start of a second permeation phase, and measuring liquid level in the membrane tank;
• executing a hierarchy of control cycles to control one or more control variables;
• in a first control cycle, adjusting a control variable selected from the group including scouring air flow rate and flux as a function of the measured first change in trans-membrane pressure and of the measured liquid level;
• in a second control cycle, adjusting a control variable selected from the group including relaxation phase duration and flux as a function of the second measured change in trans-membrane pressure and of measured the liquid level;
• and
• in a third control cycle, adjusting a control variable selected from the group including permeation phase duration and flux as a function of the measured liquid level.

A method for controlling fouling of a membrane filter in a biological wastewater treatment process, comprising:

• directing wastewater influent into one or more reactors and treating the wastewater;
• directing the wastewater into and through one or more membrane tanks having one or more membrane filters therein;
• filtering the wastewater by directing the wastewater through the membrane filters and producing a permeate;
• cleaning the membrane filters with air scouring;
• executing a series of filtration cycles, each filtration cycle including a permeation phase and a relaxation phase wherein a membrane filter undergoes permeation during the permeation phase followed by relaxation during the relaxation phase;
• measuring a first trans-membrane pressure at a first point in the permeation phase of a first filtration cycle;
• measuring a second trans-membrane pressure at a second point in the permeation phase of a second filtration cycle;
• measuring a third trans-membrane pressure at a third point in the permeation phase of the second filtration cycle;
• measuring a liquid level in a membrane tank;
• executing control logic that includes a hierarchy of control levels to optionally adjust scouring air flow rate, flux, permeation phase duration, and relaxation phase duration for a third filtration cycle;
• in a first control level, optionally adjusting each of scouring air flow rate and flux as a function of the first measured trans-membrane pressure, the second measured trans-membrane pressure, and the measured liquid level in the membrane tank;
• in a second control level, optionally adjusting each of relaxation phase duration and flux as a function of the second measured trans-membrane pressure, the third measured trans-membrane pressure, and the measured liquid level in the membrane tank;
• and
• in a third control level, optionally adjusting each of flux and permeation phase duration as a function of the measured liquid level in the membrane tank.