Dosing control method and system for micro-flocculation in ultrafiltration

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.