Abstract: In accordance with the present invention, the chromium content of an aqueous waste containing significant amounts of at least one soluble chromium compound, such as blowdown waters from cooling towers utilizing chromium-containing materials as corrosion inhibitors is reduced, by contacting the chromium-containing waste water with an aqueous waste containing sodium sulfides, particularly spent caustic utilized in a desulfurization of petroleum fractions, to precipitate a substantial amount of the chromium and, thereafter, separating the precipitated chromium from the mixture as a sludge, to produce a waste water which can be safely disposed of to the earth's surface in a sewer or the like.

Abstract: Normally gaseous feed materials, having a pressure significantly above ambient pressure, are cooled by passing the gaseous feed through an indirect heat exchange means, such as a plate-fin heat exchanger, passing a normally gaseous refrigerant, having a pressure substantially above ambient pressure, through the heat exchange means as a first stream in a concurrent direction with the feed stream, reducing the pressure of at least one second stream of refrigerant, preferably a plurality of second streams, as it exits the heat exchange means and passing the second stream of refrigerant, which has thus been reduced in pressure, through the heat exchange means in a countercurrent direction to the feed stream. This method can be employed for each cooling cycle of a method for cooling a natural gas stream to remove components therefrom and/or liquify the same.

Abstract: A method to restore the activity of a cracking catalyst which has been deactivated at least partially by metals contamination which involves contacting the cracking catalyst with an aluminum containing treating agent.