The Petro MBR (membrane bioreactor) system from Siemens will consist of API oil water separators, dissolved air flotation (DAF) units, walnut shell filter units, and a Petro MBR system. Scheduled to come online in 2012, the system is designed to pre-treat 450 m3/hr of the treated water for reuse as boiler feed water.
Siemens’ integrated wastewater reuse solution includes primary, secondary and tertiary oil/water separation. During the first stage of primary oil/water separation, three trains of API separators remove up to 80% of oil from refinery process water and storm run-off. The second stage oil/water separation involves two trains of DAF units that remove additional oil from the API separator effluent, with the aid of chemicals.
Tertiary oil/water separation consists of four trains of Auto-Shell walnut shell filter units that remove additional oily contaminants from the water. Black walnut shell filters eliminate the need for flat media retention screens and can use as little as one media-scrubbing pump for up to eight filters, which simplifies the design and reduces the cost of multiple filter systems. This type of filtration removes three times the amount of oil and solids before cleaning is required.
In the final stage, tertiary treatment removes dissolved organics as pre-treatment to effluent polishing/recycle-reuse. A Petro MBR system, comprised of two biological trains and four membrane trains, forms the heart of the reuse pre-treatment system. This Petro MBR system is especially designed for refinery service and treating oily wastewater, and combines various biological treatment processes with an integrated, immersed membrane system.