Method and apparatus for treating production water

Apparatus comprising

• a trailer frame having a front end and a back end, said trailer having a fifth wheel coupler at its front end and at least one axle with at least two wheels at the back end;
• said trailer frame having at least one jack to raise and lower the coupler;
• a first upright tank, a second upright tank, and a third upright tank mounted serially in a line on a top side of the trailer frame, said line extending from the back end toward the front end of the trailer, the third tank being positioned at the back end of the trailer frame,
• a stirrer extending into the first tank from the upper end of the first tank, said stirrer having a fan-shaped screw impeller,
• a variable speed driver for the stirrer, for rotating the stirrer to pull fluid from the bottom of the first tank, said variable speed driver being mounted to the trailer frame by a support bracket,
• a set of three parallel weir walls positioned in the first tank, to divide the first tank into a first and a second downcomer section and a first and a second riser section, the first downcomer section being positioned nearest the front end of the trailer, the second riser section being positioned nearest the back end of the trailer, the first riser section being positioned adjacent to the first downcomer section and containing the fan-shaped impeller, and the second downcomer section being positioned between the first riser section and the second riser section,
• wherein a middle weir wall has an upper end surface that is lower than a peripheral lip defining the top of the first tank and a lower end surface that is spaced above the bottom of the first tank, so that fluid upwells centrally in the first riser section, spills over the upper end of the middle weir wall and flows through the second downcomer to the bottom of the first tank,
• wherein each tank has an inlet and an outlet at the upper end of each tank, the inlet facing the front end of the trailer frame, the outlet facing the back end of the trailer frame, the outlet of the first tank being in flow communication with the inlet of the second tank, and the outlet of the second tank being in flow communication with the inlet of the third tank,
• wherein the outlet of the first tank is positioned higher than the inlet to the second tank, and the outlet of the second tank is positioned higher than the inlet to the third tank, so that fluid will flow by gravity from the first tank to the second tank to the third tank,
• a fourth tank positioned at the front end of the trailer, said fourth tank containing an oil skimmer,
• a control room positioned between the fourth tank and the first tank,
• an electrocoagulation unit in the control room, said electrocoagulation unit positioned to draw from the fourth tank and to discharge though a flow path to the first tank, and
• an inline mixer positioned in the control room in the flow path between the electrocoagulation unit and the first tank.