Method for mixing coagulating agents into a contaminated water flow, and for removing contaminants therefrom

A method of mixing a stream of liquid to be treated with a stream of a treatment gas or liquid, comprising the steps of:

• admitting said stream of liquid to be treated to a vertically elongated vessel comprising a first lower mixing chamber, an intermediate elongated tubular portion, and a second upper mixing chamber, a first one of said first lower and second upper mixing chambers having an inlet for receiving said stream of said liquid to be treated,
• admitting said stream of a treatment gas or liquid to said first one of said mixing chambers so as to become entrained with said stream of liquid to be treated near said inlet,
• wherein said inlet at which said stream of said liquid to be treated is admitted to said first one of said mixing chambers is located such that said stream of said liquid to be treated having had said stream of treatment liquid or gas entrained therein flows tangentially around the said first mixing chamber and thence in a generally spiral pattern along said intermediate elongated tubular portion, reaching the second of said mixing chambers,
• a fluid exit tube extending vertically through said vertically elongated vessel from an open end disposed in the second of said mixing chambers to a discharge end, such that liquid from said second mixing chamber flows through said fluid exit tube, said fluid exit tube being located generally concentrically within said intermediate elongated tubular portion of said vessel such that said generally spiral flow pattern of said stream of said liquid to be treated having had said stream of treatment liquid or gas entrained therein continues around said fluid exit tube, and
• applying an electromagnetic field to said stream of said liquid to be treated having had said stream of treatment liquid or gas entrained therein, at least during flow of said stream in said intermediate elongated tubular portion of said vessel,
• whereby said treatment fluid or gas is intimately mixed with said stream of liquid to be treated during flow through said vessel, said treatment fluid or gas being selected to coagulate materials in said stream to be treated.