Petroleum refineries, selenium

Selenium 0.05 0.05 Hair or fingernail loss numbness in fingers or toes circulatory problems Discharge from petroleum refineries erosion of natural deposits discharge from mines... 

Nurdogan, Y. Schroeder, R.P. Meyer, C.L. Selenium removal from petroleum refinery wastewater. Proceedings, 49th Purdue Industrial Waste Conference, West Lafayette, IN, 1994. 

Roehl, R., Recent Advances in the Speciation of Selenium in Petroleum Refinery and Municipal Waste Waters Using ICP-MS and ICP-MS Coupled with Liquid Chromatography, Transcript of Oral Presentation, 1996 Winter Conference on Plasma Spectrochemistry, Ft. Lauderdale, FL, January 8-13,1996. 

The extent of the selenium problem in petroleum refineries depends on the types of crude oil processed. For example, crude oil from the San Joaquin Valley contains higher levels of selenium while other sources of crude are essentially selenium free. Because San Joaquin crude is processed in several reBneries along the western coast of the US, several of these refineries have problems with selenium contamination of their process waters. Depending on the process waters (stripped sour water or final biotreated effluent) the volumetric flowrates range from 10... 

To develop an effective, optimized ELM process for selenium removal, it is necessary to understand the forms of the selenium ions present in contaminated aqueous streams. Selenium can exist in several oxidation states -II, 0, IV, and VI (13). In naturally occurring ground or surface waters, inorganic selenium is found in the IV (selenite) and VI (selenate) states (14). In petroleum refinery wastewater effluents, the form of selenium depends on the process stream. In stripped sour water the selenium exists primarily in the Se(-II) oxidation state as either organoselenium compounds or selenocyanate. In the final biotreated effluent, selenium exists primarily as selenite [Se(IV)] and selenate [Se(VI)] oxyanions (1). 

The emulsion liquid membrane (ELM) process was shown to be an effective method for pre-concentrating dilute selenium streams, such as those found in the wastewaters from petroleum refineries. By concentrating the selenium, the ELM process can greatly reduce the operating costs and capital costs of the coagulation/coprecipitation processes presently used to remove selenium. 

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