# US 11,440,819 B2 · Dosing control method and system for micro-flocculation in ultrafiltration

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- Number: US 11,440,819 B2
- Document ID: US11440819B2
- Status: Granted
- Kind: B2
- Application number: 17/703,953
- Filed: 2022-03-24
- Published: 2022-07-07
- Granted: 2022-09-13
- Earliest claimed: 2021-05-31
- Assignees: Greentech Environment Co., Ltd.
- Applicants: Greentech Environment Co., Ltd.
- Inventors: Mu Liu; Yingqiang Su; Zehua Li; Kai Sun; Xiaofeng Lin; Huiming Han; Mengyuan Duan; Liyan Zhang
- Web page: https://patentgrep.com/patent/US11440819B2

## CPC

- C02F 1/444: {by ultrafiltration or microfiltration}
- B01D 61/145: {Ultrafiltration}
- B01D 61/16: Feed pretreatment
- B01D 61/22: Controlling or regulating
- B01D 65/06: with special washing compositions
- C02F 1/008: {Control or steering systems not provided for elsewhere in subclass C02F}
- C02F 1/5209: {Regulation methods for flocculation or precipitation}
- C02F 9/00: Multistage treatment of water, waste water or sewage
- B01D 65/02: Membrane cleaning or sterilisation {; Membrane regeneration}
- B01D 2311/14: Pressure control
- B01D 2311/2642: Aggregation, sedimentation, flocculation, precipitation or coagulation
- B01D 2321/04: Backflushing
- C02F 1/52: by flocculation or precipitation of suspended impurities {(C02F1/463 takes precedence)}
- C02F 2209/005: Processes using a programmable logic controller [PLC]
- C02F 2209/006: comprising a software program or a logic diagram
- C02F 2209/03: Pressure
- C02F 2209/40: Liquid flow rate
- C02F 2209/44: Time
- C02F 2303/16: Regeneration of sorbents, filters
- C02F 2303/22: Eliminating or preventing deposits, scale removal, scale prevention (C02F1/042, C02F1/4602, C02F5/00 take precedence)
- C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes)
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)

## Abstract

A dosing control method for micro-flocculation in ultrafiltration, including: calculating a preset value of a first differential pressure before an initial backwash and a preset value of a second differential pressure before a final backwash in each chemically enhanced backwash cycle; calculating a preset value of a third differential pressure between the first differential pressure and the second differential pressure according to the preset value of the first differential pressure and the preset value of the second differential pressure; obtaining a predicted value of the third differential pressure according to a differential pressure curve plotted based on online filtration differential pressure data; and comparing the preset value of the third differential pressure and the predicted value of the third differential pressure to determine whether to dose. A dosing control system is also provided.

## Claims

### Claim 1

A dosing control method for micro-flocculation in ultrafiltration, comprising the following steps:
1) calculating a preset value of a first differential pressure before an initial backwash and a preset value of a second differential pressure before a final backwash in each chemically enhanced backwash cycle according to a work condition and quality of raw water;
2) calculating a preset value of a third differential pressure between the first differential pressure and the second differential pressure according to the preset value of the first differential pressure and the preset value of the second differential pressure;
3) starting a filtration system;
4) obtaining a predicted value of the third differential pressure according to a differential pressure curve plotted based on online filtration differential pressure data;
5) comparing the predicted value of the third differential pressure with the preset value of the third differential pressure to obtain a first judgement result, and recording a duration that the first judgement result remains unchanged;
6) if the first judgement result indicates that the predicted value of the third differential pressure is greater than the preset value of the third differential pressure, and the duration that the first judgement result remains unchanged is less than a first preset duration, performing a dosing operation at a preset dosage;
7) if the first judgement result indicates that the predicted value of the third differential pressure is greater than the preset value of the third differential pressure and the duration that the first judgement result remains unchanged is no less than the first preset duration, performing a dosing operation at an increased dosage; and
8) if the first judgement result indicates that the predicted value of the third differential pressure is smaller than or equal to the preset value of the third differential pressure, and the duration is no less than a second preset duration, stopping the dosing operation, wherein the first, second, and third differential pressures are transmembrane differential pressures, and wherein the dosing operation is a flocculant dosing operation.

### Claim 2 (depends on 1)

The dosing control method of claim 1, wherein the step (3) is performed through steps of:
operating the filtration system; and
performing the dosing operation at the preset dosage continuously dosing for a dosing duration.

### Claim 3 (depends on 1)

The dosing control method of claim 1, wherein the step (7) further comprises:
starting a timing operation with a preset dosing duration as a timing cycle;
continuously performing the dosing operation in each timing cycle;
monitoring the predicted value of the third differential pressure in real time comparing the predicted value of the third differential pressure with the preset value of the third differential pressure in real time to obtain a second judgement result; and
recording a duration that the second judgement result keeps unchanged;
if the second judgement result indicates that the predicted value of the third differential pressure is less than or equal to the preset value of the third differential pressure within one timing cycle, and the duration that the second judgement result keeps unchanged is not less than the second preset duration, stopping the dosing operation;
if the second judgement result indicates that the predicted value of the third differential pressure is greater than the preset value of the third differential pressure at an end of one timing cycle, performing the dosing operation at an increased dosage; and
if the second judgement result indicates that the predicted value of the third differential pressure is less than or equal to the preset value of the third differential pressure within one timing cycle, the judgement result is kept until an end of one timing cycle, and the duration that the second judgement result remains unchanged is less than the second preset duration, performing the dosing operation at an increased dosage and continuing performing the timing operation; and when the duration that the second judgement result remains unchanged is no less than the second preset duration, stopping the dosing operation.

### Claim 4 (depends on 3)

The dosing control method of claim 3, wherein the preset dosing duration is greater than the first preset duration.

### Claim 5 (depends on 4)

The dosing control method of claim 4, further comprising:
if a cumulative duration that the predicted value of the third differential pressure is less than or equal to the preset value of the third differential pressure is no less than the second preset duration within the preset dosing duration, and then a cumulative duration that the predicted value of the third differential pressure is greater than the preset value of the third differential pressure is no less than the first preset duration, dosing time is extended, and a dosage is no longer controlled according to a differential pressure until an end of a filtration.

### Claim 6 (depends on 5)

The dosing control method of claim 5, further comprising:
if a cumulative duration that the predicted value of the third differential pressure is less than or equal to the preset value of the third differential pressure is no less than the second preset duration within the preset dosing duration, and then a cumulative duration that the predicted value of the third differential pressure is greater than the preset value of the third differential pressure is no less than the first preset duration, a dosing failure is determined, and an alarm is generated to allow an operator to check a dosing condition.