Operation of Full-Scale Oily Wastewater Treatment System

Abstract

An aluminum company that produces an oily wastewater upgraded their wastewater treatment facilities to prevent ground and surface water contamination. Applying pilot-scale data collected over a 2.5 year period, the following treatment train was proposed: gravity separation → tubular ultrafiltration (TUF) → unlined hybrid wetlands. TUF residual was to be concentrated using a high-shear rotary ultrafiltration (HSRUF) system. Full-scale operation differed from what was initially proposed due to several phenomena unforeseen in the pilot-study/design phase. TUF permeate produced during full-scale operation was of much higher quality than that observed during the pilot-scale study (<10 mg/L compared with 66 mg/L O/G). Therefore, the hybrid wetlands were not constructed. A significant amount of free-oil formed in the TUF feed tanks (average: 1,420 L/day), resulting in the oil concentration of the TUF feed streams remaining at <20%, greatly prolonging run lengths and reducing the volume of TUF residual that required treatment. Thus, the HSRUF system was not required to concentrate the residual. The following modified full-scale treatment train is currently operating: gravity separation → TUF → lined permeate holding pond → direct discharge to receiving water.