Saturday, November 15, 2008

Tech to tackle oilfield water with Southern N.M. county

Thomas Guengerich New Mexico Tech

Lea County and New Mexico Tech are partnering on a ground-breaking new Department of Energy grant to clean and recycle produced water from the oilfields of southeastern New Mexico.

Scientists at the university in Socorro will develop a multi-step system to desalinate and further treat produced water.

The first year will be spent on research. By the end of the second year, mechanical engineering professor Dr. Ashok Kumar Ghosh expects to deliver a system that can process 1,000 gallons per day. The project will employ one post-doctoral student, three or four graduate students and up to 10 undergraduate students.

The grant, also referred to as a "cell membrane" grant, will be used to search for a cost-effective method of converting the solids-heavy produced water to a more usable state.

The term "cell membrane" comes from a treatment process employing forward osmosis, Ghosh said. This process uses a "draw solution" to push water through a membrane, filtering the solids from the water. Currently available membranes are made of advanced polymers.

The proposal includes two distinct processes: pre-treatment and treatment. Pre-treatment, will remove oil and grease. The treatment process will remove other elements, like salt, chloride and calcium.

To remove the petroleum products — benzene, toluene and xylene — Ghosh has two prime methods of pre-treatment that he will examine. Recent research has found biological organisms that eat petroleum. Biology professor Dr. Rebecca Reiss, through Tech's partnership with the National Genome Research Center in Santa Fe, will examine the genetic make-up of bioagents that thrive in petroleum-rich environments. Once the microbes do their job, the brackish water would then be filtered to remove the biological agents. Ghosh will also test a zeolite-filtration system developed and patented by Tech hydrology professor Dr. Rob Bowman.

The second step — the treatment process — will employ forward osmosis, a recently-developed method that uses a "draw solution" to force water through a nano-membrane, or what Ghosh calls a molecular sieve.

Yale (university) research into forward osmosis has found that the process is effective at temperatures as low as 40ºC, or 100ºF. Ghosh said he might find that the ideal temperature might be higher, which would increase the cost of forward osmosis.

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