Treatment of contaminated liquid is provided including an integrated ultra-filtration and clarification apparatus. Clarification of liquid occurs in a gap between a casing and a tank of the apparatus. Solids settle and aggregate in the bottom of the tank. The solids act as a secondary filter prior to contact of the liquid with the ultra-filtration filters. Clarified liquid is drawn through the ultra-filtration filters. An upstream electrocoagulation unit and a downstream reverse osmosis unit may be included in combination. Electrocoagulation can occur in the tank by reaction plates mounted within the tank. One embodiment includes dual integrated ultra-filtration and clarifier apparatuses and corresponding electrocoagulation units.