September 2013, Vol. 25, No.9

Research Notes

Loofah sponge plant shows promise for cleaning water

The luffa cylindrica plant, source of the loofah sponge, may have yet another use: purifying water to prevent the spread of waterborne diseases. This finding comes from research by Adewale Adewuyi, a lecturer at Redeemer’s University (Lagos, Nigeria). 

Luffa cylindrica , known as a sponge gourd, produces spongelike fruits that, when dried, are used as loofah sponges. The plant’s seeds, which are considered a waste, can help clean wastewater, according to an American Chemical Society (ACS; Washington, D.C.) news release.  

In laboratory tests, Adewuyi isolated oil from the seeds and used it to produce surfactants that serve as absorbents. The oils absorb heavy metals and other potentially harmful organic compounds, the news release says. 

Other absorbents, such as activated carbon, also clean pollutants from water, but many are expensive, work slowly, and only are effective within a limited acidity range, Adewuyi said in the news release. He found the sponge seeds to be cheaper and more effective than other absorbents, the release says.  

Adewuyi now is examining other underutilized seeds and oils to see if they could have the same effect. Developing countries may find this type of solution particularly useful, because drinking water often comes directly from rainwater, rivers, and streams, which often are polluted by factories and agricultural runoff, the news release says.  

“It’s a win–win process,” Adewuyi said. “It’s cost-effective, green, reproducible, and, of course, applicable in developing countries, because it is very easy to start up and maintain.” 

Adewuyi presented his research at the 17th Annual Green Chemistry and Engineering Conference, which is sponsored by the ACS Green Chemistry Institute®. 

 

Wastewater shows potential for use in cellulosic ethanol production  

Using wastewater to produce cellulosic ethanol is a distinct possibility, according to a study conducted by researchers at the University of Illinois at Urbana–Champaign. Findings from this study, funded in part by the Illinois Sustainable Technology Center (Champaign), were published in the report Use of Treated Effluent Water in Cellulosic Ethanol Production.   

Ethanol production requires large amounts of water. To produce about 4 L (1 gal) of ethanol, corn-dry-grind ethanol plants use 11 to 15 L (3 to 4 gal) of water, while cellulosic ethanol plants use 23 to 38 L (6 to 10 gal), the report says. 

To conserve potable water while producing ethanol, researchers evaluated the ability to use effluent from either residential wastewater or mixed residential and industrial wastewater. The study was conducted using different proportions of the effluents and deionized water. Researchers examined the effect of each type of effluent on the fermentation rate and final ethanol yield from pure cellulosic substrate, the report says. 

Researchers found that after coarse filtration, both effluents produced similar final ethanol concentrations. “Findingssuggest that with proper characterization studies and under appropriate conditions, the use of treated effluentwater in cellulosic ethanol production is feasible,” according to the report. But because limited effluent water samples were used for the study, more research on the topic is required, the report says. 

  

Overcoming roadblocks to graywater reuse  

Reusing “graywater” (domestic wastewater that does not originate from toilets or urinals) could reduce demand for potable water and reduce the load of wastewater delivered to water resource recovery facilities. So, University of California–Los Angeles researchers set out to determine the incentives and impediments for graywater reuse. Their findings are presented in the July issue of Water Environment Research.  

Regulations and plumbing codes in states are both impediments and potential incentives for graywater reuse, the article says. Regulations in 29 states promote safe graywater reuse, but there are inconsistencies in plumbing codes and other regulations among the states, according to the article.  

After examining U.S. regulations and guidelines for graywater reuse, the researchers found problems with the acceptance of graywater segregation as a separate wastewater stream, allowable graywater storage, onsite treatment requirements, and permitted graywater use applications. “The acceptance of graywater as a separate wastewater source is a first step toward allowing its segregation, collection, treatment, and reuse,” the article says. 

Graywater often is not allowed to be collected separately from other wastewater, and reuse is restricted to subsurface irrigation with limited indoor use, the article notes. Easing restrictions and guidelines to promote development of low-cost, proven treatment technologies are needed to promote graywater reuse, the article says.  

“Graywater policies are essential to propelling the acceptance, economic viability, and adoption of graywater reuse as a key element of water sustainability and moving toward a paradigm shift in water reuse,” the article says. 

“Critical Review: Regulatory Incentives and Impediments for Onsite Graywater Reuse in the United States” is available as an open-access document and can be downloaded free at http://bit.ly/1cKpaZS. 

 

  
Water Environment Research allows open access to one article per issue on a range of important technical topics such as nutrient removal, stormwater, and biosolids recycling