Control process for wastewater treatment system

A method of treating wastewater with a wastewater treatment system,

• the wastewater treatment system comprising:
• a wastewater source,
• a pressurization pump for pressurizing and pumping wastewater from the wastewater source,
• an ultrafiltration unit downstream of the pressurization pump having a feed side and a permeate side,
• a first pass reverse osmosis unit downstream of the ultrafiltration unit having a feed side, a permeate side, and a first pass recovery loop having a first recirculation pump that recirculates a first portion of concentrate to the feed side of the first pass reverse osmosis unit, and discharges a second portion of concentrate through a first pass bleed valve,
• a second pass reverse osmosis unit downstream of the first pass reverse osmosis unit having a feed side, a permeate side, and a second pass recovery loop having a second recirculation pump that recirculates a first portion of concentrate to the feed side of the second pass reverse osmosis unit, and discharges a second portion of concentrate through a second pass bleed valve;
• wherein the wastewater treatment system is configured such that the pressurization pump can feed through the ultrafiltration unit, the first pass reverse osmosis unit, and the second pass reverse osmosis unit without secondary pressurization pumps arranged downstream of the pressurization pump and upstream of the ultrafiltration unit, the first pass reverse osmosis unit, or the second pass reverse osmosis unit;
• the method comprising:
• operating the pressurization pump to feed wastewater to the feed side of the ultrafiltration unit, though the ultrafiltration unit to the permeate side of the ultrafiltration unit, to the feed side of the first pass reverse osmosis unit, through the first pass reverse osmosis unit to the permeate side of the first pass reverse osmosis unit, to the feed side of the second pass reverse osmosis unit, through the second pass reverse osmosis unit to the permeate side of the second pass reverse osmosis unit to produce treated wastewater without secondary pressurization pumps arranged downstream of the pressurization pump and upstream of the ultrafiltration unit, the first pass reverse osmosis unit, and the second pass reverse osmosis unit,
• inputting a desired flow rate for wastewater on a permeate side of the second pass reverse osmosis unit, the pressurization pump operating to pump the wastewater through the wastewater treatment system such that the desired flow rate for wastewater on the permeate side of the second pass reverse osmosis unit is achieved,
• continuously determining a normalized transmembrane pressure through the ultrafiltration unit, a normalized transmembrane pressure through the first pass reverse osmosis unit, and a normalized transmembrane pressure through the second pass reverse osmosis unit while the pressurization pump is operated,
• continuously comparing the normalized transmembrane pressure through the ultrafiltration unit to an upper and lower limit for normalized transmembrane pressure through the ultrafiltration unit, the normalized transmembrane pressure through the first pass reverse osmosis unit to an upper and lower limit for normalized transmembrane pressure through the first pass reverse osmosis unit, and the normalized transmembrane pressure through the second pass reverse osmosis unit to an upper and lower limit for normalized transmembrane pressure through the second pass reverse osmosis unit while the pressurization pump is being operated,
• continuing the operation of the pressurization pump if the normalized transmembrane pressure through the ultrafiltration unit is within the upper and lower limit for normalized transmembrane pressure through the ultrafiltration unit, if the normalized transmembrane pressure through the first pass reverse osmosis unit is within the upper and lower limit for normalized transmembrane pressure through the first pass reverse osmosis unit, and if the normalized transmembrane pressure through the second pass reverse osmosis unit is within the upper and lower limit for normalized transmembrane pressure through the second pass reverse osmosis unit,
• ceasing the operation of the pressurization pump if the normalized transmembrane pressure through the ultrafiltration unit is outside the upper and lower limit for normalized transmembrane pressure through the ultrafiltration unit, if the normalized transmembrane pressure through the first pass reverse osmosis unit is outside the upper and lower limit for normalized transmembrane pressure through the first pass reverse osmosis unit, or if the normalized transmembrane pressure through the second pass reverse osmosis unit is outside the upper and lower limit for normalized transmembrane pressure through the second pass reverse osmosis unit.