Patent ID: 7972518

Claim:
A method for recovering water from aqueous fluids containing suspended solid matter, said method comprising the steps of: (a) providing a settling tank; a primary mixing tank; a secondary mixing tank; and fluid transfer means whereby fluids can flow from a lower region of the primary mixing tank into a lower region of the secondary mixing tank; said secondary mixing tank having overflow means whereby fluids can flow from an upper region of the secondary mixing tank into the settling tank; (b) providing primary and secondary agitation means in association with the primary and secondary mixing tanks, respectively; (c) providing a generally horizontal spillway adjacent to an upper region of the settling tank, said spillway having: c.1 a first gate operable to allow fluid flow from the settling tank into the spillway or from the spillway into the settling tank; and c.2 a second gate operable to allow fluid flow from the spillway into a selected one of the primary and secondary mixing tanks; (d) introducing a flow of solids-laden aqueous fluid into the primary mixing tank; (e) introducing selected amounts of precipitation enhancement agents into the primary mixing tank, said precipitation enhancement agents being selected from the group consisting of coagulants and flocculants; (f) actuating the primary agitation means to mix the precipitation enhancement agents with the solids-laden aqueous fluid within the primary mixing tank, and to induce flow of the fluid mixture downward within the primary mixing tank and thence into the secondary mixing tank via the fluid transfer means; (g) actuating the secondary agitation means to induce flow of the fluid mixture upward within the secondary mixing tank and thence into the settling tank via the overflow means; (h) allowing solids to precipitate out of the fluid mixture in the settling tank; and (i) collecting clean water from an upper region of the settling tank; wherein the method comprises the further steps of operating the first gate to allow clean water to flow from the settling tank into the spillway, and operating the second gate to allow clean water to flow from the spillway into the selected mixing tank.