Treatment of Refinery Wastewater Containing High Concentrations of Chemical Oxygen Demand and Total Sulfides for Low Odor Processing through a Capacity-Challenged Bioreactor

ABSTRACT

Shell Puget Sound Refinery (PSR) is a fully-integrated production facility that first went on stream in September 1958, initially processing up to 45,000 barrels of crude oil per day. Currently, the plant processes up to145,000 barrels (6.1 million gallons) of crude oil per day producing many useful products — including several grades of gasoline, fuel oil, diesel fuel, propane, butane, petroleum coke.

The Effluent Plant’s Bioreactor at Shell PSR is a three channel oxidation “ditch” style biotreater (a.k.a. Racetrack) built in the early 1990’s. The Bioreactor is a concrete basin with three 14’ deep channels. While the Bioreactor has gone through several upgrades over the years, including the addition of boat-type aerators and the recent addition of steel brush-type aerators, it was limited in aeration capacity to treat peak load, non-routine wastewater while maintaining target dissolved oxygen. Bioreactor aeration capacity required processing peak load wastewater at reduced rates and led to storage issues. The lack of dissolved oxygen in the first stage of the Bioreactor led to odors and subsequent complaints from neighboring communities. In an effort to process wastewater without odors, Shell would store (divert) the peak load material and process it back to the Bioreactor slowly.

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Download Shell PSR Paper – WEFTEC 2013 (pdf)