Water treatment process and plant using ballasted flocculation and settling

A method of treating wastewater using a ballasted flocculation process comprising:

• a. measuring at least one property of the wastewater and determining a concentration of one or more pollutants in the wastewater;
• b. calculating, based on the concentration of one or more pollutants in a wastewater, a required ballast concentration level in a flocculation tank to obtain a predetermined quality of the treated water;
• c. directing the wastewater into the flocculation tank and injecting a ballast and a flocculating reagent into the wastewater;
• d. forming a water-floc mixture in the flocculation tank, the water-floc mixture comprising ballasted flocs;
• e. directing the water-floc mixture into a settling tank, settling at least some of the ballasted flocs, and forming a sludge-ballast mixture in the settling tank;
• f. directing at least a portion of the sludge-ballast mixture from the settling tank into an intermediate tank and therein agitating the sludge-ballast mixture;
• g. directing the sludge-ballast mixture from the intermediate tank to an inlet of a hydrocyclone;
• h. using the hydrocyclone to separate ballast from the sludge-ballast mixture and recirculating the separated ballast by directing the separated ballast into the flocculation tank;
• i. determining a ballast concentration level in the flocculation tank and determining whether the ballast concentration level in the flocculation tank is sufficient to obtain the predetermined quality of the treated water;
• j. if needed, calculating an additional amount of ballast required to be injected to increase the ballast concentration level in the flocculation tank to a level sufficient to obtain the predetermined quality of treated water;
• and,
• k. if needed, injecting the amount of additional ballast into the flocculation tank with the recirculated ballast.