December 2013, Vol. 25, No.12

Research Notes

New adsorbent shows promise for removing select contaminants from wastewater

new adsorbent made from cyclodextrins can remove emerging contaminants from wastewater, according to Temple University (Philadelphia) Water and Environmental Technology Center researchers. 

Cyclodextrins, a family of compounds made of bound glucose molecules, attract organic compounds and an adsorbent area with a cavity-like area traps them, according to a Temple University news release. Researchers were able to increase or reduce the size of cavity by changing the functional groups on the glucose molecule. This presents the possibility for manipulating the adsorbent to target and remove select contaminants, said Rominder Suri, professor of civil and environmental engineering and director of the Temple University center, in the release.  

Cyclodextrins are soluble but the researchers were able to make the adsorbent insoluble. They also made the material easy to attach as a thin coating to surfaces such as sand, glass, silica, and filter paper, the news release says.  

Even though the adsorbent has less surface area than the commonly used activated carbon treatment, especially if coated on sand, researchers found that both have comparable capacity for contaminant removal. They also found the new adsorbent has the potential to be more efficient by coating it on porous, high-surface materials, the new release says.  

Researchers tested the adsorbent material on several batches of contaminants — such as steroid hormones, detergent compounds, and bisphenol A, both in labs and discharged wastewater — to find it removed more than 90% of contaminants.  

The adsorbent material also can be regenerated and reused. Solvents, such as methanol, can remove contaminants or ozone can destroy trapped contaminants to enable reuse of the material, the news release says. Researchers noted the need for more extensive pilot testing of the material. 

 



United Nations joint study finds insufficient wastewater data worldwide   

Information on three key aspects of wastewater — generation, treatment, and reuse — is insufficient, outdated, or absent in most countries worldwide, according to a study led by Tottori (Japan) University and the United Nations University Institute for Water, Environment, and Health (UNU-INWEH; Hamilton, Ontario). 
The study found that effluent often is unused and unquantified. Out of 181 countries studied, only 55 have information on all three aspects of wastewater, 69 have information on one or two aspects, and 57 have no information. And data are 5 or more years-old in 63% of the countries that have collected information, according to a UNU-INWEH news release.  
In developing countries — especially those in water-scarce regions — wastewater volumes are thought to have increased as populations migrate to urban areas. Reusing water offers potential benefits for farmers in these regions, including accessing a consistent source of water and reducing the need for fertilizer, the news release says. 
“It is a vast resource if we reclaim it properly, which includes the separation of municipal from industrial wastewater,” said Zafar Adeel, director of UNU-INWEH, in the release. 
The study, published in the journal Agricultural Water Management, predicts a rapid increase in the use of treated wastewater for farming and other purposes as competition for freshwater grows and shortages of nutrients expand. The study found that water demands exceed supply in regions where more than 40% of the world’s population lives; this statistic may increase to 60% of the world’s population in 12 years, the news release says. 
 
The study explains that information needs to be collected to fill the data gap, develop effective solutions for water scarcity, and assess the potential for wastewater to produce food and improve health of people and economies, the news release says.  

 


   

Real-world test of effluent for irrigation shows promise 

Crops irrigated with treated wastewater showed only low levels of pharmaceuticals and personal care products (PPCPs), according to a University of California–Riverside study. 

The research, presented at a meeting of the American Chemical Society (ACS; Washington, D.C.), determined that these substances do not tend to accumulate in vegetables at concentrations likely to pose health concerns, according to an ACS news release.  

Other studies on this topic have been conducted at a small-scale in laboratories or greenhouses. For this study, farms irrigated with treated wastewater, which often contains traces of prescription drugs and remnants of soaps, cosmetics, and other personal care products, were tested. This effluent otherwise would have been discharged into local waterways, the news release says.  

This study focused on 20 PPCPs in multiple crops in realistic field conditions. The researchers chose eight vegetables people often eat raw, including carrots, bell peppers, tomatoes, cucumbers, lettuce, spinach, celery, and cabbage, to determine the maximum concentrations  delivered through ingestion. Cooking can destroy PPCPs. 

While the overall concentration of PPCPs were low, researchers found that all the crops did absorb PPCPs. Leafy vegetables took up the greatest amount. But the substances did not tend to accumulate in vegetables to concentrations that would cause health concerns, the news release says. The findings add to a full understanding of potential human health effects from using effluent for irrigation, the news release says.  

The researchers note that reclaimed water can contain substances other than the PPCPs included in this study. They also noted that young children, older individuals, and people with chronic diseases could be more susceptible to the low levels of PPCPs, the news release says.