The transformation and removal of selenium species in refinery biological treatment systems
- Shell Oil Co., Houston, TX (United States); and others
Refinery activated sludge systems usually achieve 20 to 30% removal of the influent selenium. The selenium species in the raw refinery wastewater and effluent have recently been identified as selenocyanate (SeCN{sup -}) and selenite/selenate (SeO{sub 3}{sup =}/SeO{sub 4}{sup =}), respectively. Little information is available on the mechanisms(s) involved in this transformation. In addition, enhanced biological selenium uptake was considered promising based on previous research on biological selenium transformation and removal in agricultural drainage water in California`s San Joaquin Valley. It is desirable for the petroleum refineries to better understand the selenium removal in the existing biological treatment systems and the potential for further enhancement of selenium uptake by manipulation of the operating conditions and configuration of these treatment units. A pilot-scale field testing program was carried out at the Martinez Manufacturing Complex of Shell Oil Company to evaluate various aspects of biological selenium removal mechanisms in petroleum refinery wastewater treatment plant settings. This study employed variations of aerobic activated sludge, anoxic/aerobic systems, in-situ ferric precipitation as well as an anoxic fixed film (sand filter)system. A comprehensive report is being prepared to submit to the co-sponsors - Shell Oil Company and the Western States Petroleum Association (WSPA). The current paper presents a portion of the results of this 8-month study. This portion is considered pertinent in understanding the selenium fate and removal mechanisms in existing refinery biological treatment systems.
- OSTI ID:
- 96697
- Report Number(s):
- CONF-9504134--
- Country of Publication:
- United States
- Language:
- English
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