Featured Research

from universities, journals, and other organizations

Water purification on the cheap: System cleans 'produced water' from natural gas wells

Date:
February 5, 2013
Source:
Massachusetts Institute of Technology
Summary:
A new system cleans 'produced water' from natural gas wells, and could lead to improved desalination plants for developing countries.

This 12-foot-high system in a lab at MIT has demonstrated the principles of the new humidification-dehumidification system.
Credit: David Castro-Olmedo/MIT Creative Commons License http://creativecommons.org/licenses/by-nc-nd/3.0/

A new system cleans 'produced water' from natural gas wells, and could lead to improved desalination plants for developing countries.

Increased natural gas production is seen as a crucial step away from the greenhouse gas emissions of coal plants and toward U.S. energy independence. But natural gas wells have problems: Large volumes of deep water, often heavily laden with salts and minerals, flow out along with the gas. That so-called "produced water" must be disposed of, or cleaned.

Now, a process developed by engineers at MIT could solve the problem and produce clean water at relatively low cost. After further development, the process could also lead to inexpensive, efficient desalination plants for communities in the developing world, the researchers say.

The new technology is described in a series of papers recently published in three journals: the International Journal of Heat and Mass Transfer, Applied Energy and the American Institute of Chemical Engineers' AIChE Journal. The research is the work of a team including MIT postdoc Prakash Narayan, mechanical engineering professor John H. Lienhard V, and collaborators at King Fahd University of Petroleum and Minerals (KFUPM) in Saudi Arabia.

The method is a variation of the standard distillation process, in which salty water is vaporized and then condenses on a cold surface; the salt separates out during evaporation. But this process is energy-intensive -- and therefore costly -- because all the water must be heated to the boiling point, while the condensing surfaces must be kept cold.

In the new process, water well below the boiling point is vaporized by direct contact with a carrier gas; the moist air is subsequently bubbled through cooler water where the purified vapor condenses. But the temperature difference between the warm and cool water is much less than in conventional dehumidifiers, and the surface area provided by the small bubbles is much greater than that of a flat condenser surface, leading to a more efficient process.

Less energy needed

The traditional version of this process is called a humidification dehumidification (HDH) desalination system. While other groups have designed HDH systems, this new version requires far less energy than previous systems, the team says.

Lienhard says, "We became interested in the HDH process at the start of our collaboration with KFUPM as a means of providing water to off-grid regions of the developing world. Both the MIT and the KFUPM faculty wanted to develop a technology that might benefit people all over the world."

At the beginning of his doctoral thesis research, Narayan was focused, he says, on ways "to increase energy efficiency and thermal efficiency, and to reduce size and cost" for desalination plants. Such facilities are a critical need in parts of the developing world -- such as in southern India -- that have limited fresh water but abundant seawater.

Conventional distillation plants have efficiencies of scale -- the bigger they are, the more cost-effective -- but for the HDH system, the optimum size is a plant that produces about 1,200 to 2,400 liters of clean water a day, about the capacity needed for a rural village. Such plants can easily be made larger simply by adding more modules, he says.

Lienhard notes that the HDH technology had not previously been the target of systematic analysis: "Over a period of years, our group developed new thermodynamic methods for assessment of these cycles, followed by a deep understanding of the causes of energy inefficiency in them. Eventually, this led us to the new configurations and components that are described in these latest publications."

Cleaning up gas-well water

The researchers have already filed for patents on the system, and the team has set up a company to commercialize the process in collaboration with another MIT group that has been pursuing a related system for desalination. While Narayan says the team's ultimate goal is desalination in developing countries, it turns out that the system is especially well suited for treating the produced water that comes from natural gas wells.

The water and other fluids used to open wells through hydraulic fracturing -- also known as fracking -- are a somewhat different matter, requiring other kinds of treatment and disposal. But a much bigger issue for the operators of these wells is the ongoing treatment of produced water, which represents a significant expense. This water is typically several times saltier than seawater, which makes it a particularly good candidate for treatment with the HDH process, Narayan says: Unlike membrane-based desalination systems, this system's efficiency is unaffected by saltier water. In fact, he adds, "The biggest advantage is when you deal with high salinity."

A leading journal on desalination technology, Water Intelligence Report, gave the system the highest rating awarded to any system for dealing with produced water.

The MIT team built a 12-foot-high test unit that has run continuously for weeks, producing about 700 liters of clean water a day. They have tested it using barrels of water from natural gas wells to demonstrate that it produces water clean enough to drink.

Their next step is to scale up to a plant about two to three times the size of this initial unit, which calculations show should be an optimal size. Narayan says he expects the first commercial plants could be in operation within about two years.

The authors of these recent papers also included recent MIT graduates Steven Lam and Maximus St. John; MIT graduate students Karim Chehayeb, Ronan McGovern and Gregory Thiel; and professors Mostafa H. Sharqawy and Syed M. Zubair of KFUPM and Sarit K. Das of the Indian Institute of Technology. The work was supported by KFUPM through the Center for Clean Water and Clean Energy at MIT and KFUPM.


Story Source:

The above story is based on materials provided by Massachusetts Institute of Technology. The original article was written by David L. Chandler. Note: Materials may be edited for content and length.


Journal References:

  1. G. Prakash Narayan, Maximus G. St. John, Syed M. Zubair, John H. Lienhard. Thermal design of the humidification dehumidification desalination system: An experimental investigation. International Journal of Heat and Mass Transfer, 2013; 58 (1-2): 740 DOI: 10.1016/j.ijheatmasstransfer.2012.11.035
  2. Ronan K. McGovern, Gregory P. Thiel, G. Prakash Narayan, Syed M. Zubair, John H. Lienhard. Performance limits of zero and single extraction humidification-dehumidification desalination systems. Applied Energy, 2013; 102: 1081 DOI: 10.1016/j.apenergy.2012.06.025
  3. G. Prakash Narayan, Mostafa H. Sharqawy, Steven Lam, Sarit K. Das, John H. Lienhard V. Bubble columns for condensation at high concentrations of non condensable gas: Heat transfer model and experiments. AIChE Journal, 2012; DOI: 10.1002/aic.13944

Cite This Page:

Massachusetts Institute of Technology. "Water purification on the cheap: System cleans 'produced water' from natural gas wells." ScienceDaily. ScienceDaily, 5 February 2013. <www.sciencedaily.com/releases/2013/02/130205131754.htm>.
Massachusetts Institute of Technology. (2013, February 5). Water purification on the cheap: System cleans 'produced water' from natural gas wells. ScienceDaily. Retrieved October 1, 2014 from www.sciencedaily.com/releases/2013/02/130205131754.htm
Massachusetts Institute of Technology. "Water purification on the cheap: System cleans 'produced water' from natural gas wells." ScienceDaily. www.sciencedaily.com/releases/2013/02/130205131754.htm (accessed October 1, 2014).

Share This



More Earth & Climate News

Wednesday, October 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: 12 More Bodies Found on Japan Volcano

Raw: 12 More Bodies Found on Japan Volcano

AP (Oct. 1, 2014) — A dozen more bodies were found Wednesday as Japanese rescuers resumed efforts to find survivors and retrieve bodies of those trapped by Mount Ontake's eruption. (Oct. 1) Video provided by AP
Powered by NewsLook.com
Cultural Learning In Wild Chimps Observed For The First Time

Cultural Learning In Wild Chimps Observed For The First Time

Newsy (Oct. 1, 2014) — Cultural transmission — the passing of knowledge from one animal to another — has been caught on camera with chimps teaching other chimps. Video provided by Newsy
Powered by NewsLook.com
Raw: Trapped Scientist Rescued from Cave in Peru

Raw: Trapped Scientist Rescued from Cave in Peru

AP (Oct. 1, 2014) — A Spanish scientist, who spent 12 days trapped about 1300 feet underground in a cave in Peru's remote Amazon region, was rescued on Tuesday. (Oct. 1) Video provided by AP
Powered by NewsLook.com
Media, Industry Groups React To Calif. Plastic Bag Ban

Media, Industry Groups React To Calif. Plastic Bag Ban

Newsy (Sep. 30, 2014) — California is the first state in the country to ban single-use plastic bags in grocery, liquor and convenience stores. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins