Heavy Industry Plant Wastewater Treatment, Recovery and Recycle Using Three Membrane Configurations in Combination with Aerobic Treatment – A Case Study

In the late 1990's a major diesel engine manufacturing plant began evaluation of wastewater treatment technologies that would improve the quality of wastewater discharge, would produce treated effluent of reduced oil and grease, BOD and COD load suitable as feed to their sanitary waste biological treatment plant, and eliminate the costs and risks associated with the use of hazardous chemical/physical treatment chemicals used to traditionally treat industrial waste. Several waste management options were examined, including waste reduction via production modification within the plant, point-source, and end-of-pipe membrane separations technology. This study led to the commissioning of a UF (Ultrafiltration) pilot study using full scale membrane modules with the objective of economically specifying the correct membrane type and configuration to reduce oil and grease, suspended solids, and total solids contaminants. It was found, based on cost, technical, and operating (labor, chemical cost, variability in effluent quality) considerations, that UF met those objectives.The commercial scale membrane system specified was an open-channel tubular UF system. Permeate off the UF contains less than 30 mg/l oil and grease, less than 0.5 mg/l Cu and Zn, and less than 10 mg/l suspended solids.In 2005, with increased water demand in the plant, and pressure from the authorities to reduce water usage, additional membrane systems (UF and RO) were designed and installed as post treatment to the activated sludge process for recovery and recycle of wastewater back into the plant. The UF system is a hollow fiber configuration. The RO design is spiral wound membrane. This paper describes the performance of membrane systems of three configurations. Productivity, filtrate quality, and operating costs on this installation are presented and show that membrane filtration, in combination with biological treatment, is an economically viable and accepted technology for closing the loop and recovering water for reuse in heavy industry facilities.