March 2014, Vol. 26, No.3

How to slow down the tide

news

Researchers say water rates will continue to increase, but there are things utilities can do to reduce operational costs and rates in the future 

Though other organizations have released studies documenting the rise of water rates nationally, in October 2013, researchers at Columbia University’s (New York) Columbia Water Center took this work one step further with the release of “America’s Water: An Exploratory Analysis of Municipal Water Survey Data.” 

The study was conducted in conjunction with Veolia Environnement (Paris) and Growing Blue, a consortium of private water companies, associations, and nongovernmental organizations. Researchers analyzed data from various sources, including the 2010 American Water Works Association (Denver) survey, the U.S. Census demographic data, and climate data from the National Oceanic and Atmospheric Administration (NOAA). All these data were brought together to fulfill a major objective: to explain why water rates are increasing. 

“The purpose of this study was to see if we could find correlations between various factors and the rates,” said Edwin Piñero, chief sustainability officer at Veolia North America (Chicago). “So, yes, rates are typically published, but we were trying to drill a bit deeper into why they are what they are.”  

Piñero said to be able to do this, Columbia Water Center decided prior to conducting the study which other variables besides water rates it would consider, such as the U.S. Census and NOAA data.  

“We do realize that there may be other variables in play as well,” Piñero said. 

In addition to sharing what major factors contribute to water utilities’ rising operational costs and the subsequent increase in water rates, researchers also shared ways in which utilities can help stop these increases because ultimately, there are limits to how high rates can go. 

“Achieving sustainability in our water systems requires a transparent understanding of the factors that influence rates,” said Upmanu Lall, director of the Columbia Water Center in an Oct. 14 news release. “In the last 30 years, federal funding for water infrastructure has almost dried up, and it will be difficult for many utilities to raise rates high enough to pay down existing levels of debt. But although debt is increasing, the age of our water infrastructure continues to pose a challenge. We need to rethink what the water utility of the future should look like and how we will pay for water services and stimulate sustainable use,” he said.

 

Mining the data
 

The researchers at Columbia Water Center made several key findings in the course of their study, such as the fact that debt and water rates increased from 2000 to 2010 by 33% and 23%, respectively, and utility water rates will continue to increase in the near future. They also discovered that out of all rates, groundwater seems to be the least expensive. The median groundwater rate for 42 m3 (1500 ft3) is $30 compared to $37, $44, and $42 rates for surface, split, and purchase/other, respectively, according to the study. 

“On average, the infrastructure and operations complexity necessary to collect and prepare groundwater is less than for surface water,” Piñero explained. “In part, this has to with the conveyance from source to plant, as well as the treatment,” he said. 

The researchers also found that smaller utilities have the highest operating expenses and some smaller utilities have the highest debt ratios, which leaves these entities with a unique challenge. 

“It is difficult to generalize on this point, other than to say they will have to be more creative and focused on financial matters,” Piñero said. “The rest of the report does address some possible solutions. But one conclusion of the study is that simply raising rates continuously is not a viable solution.” 

In contrast to many smaller utilities, the study found that larger utilities are more likely to recover the full cost of service through rates.   

“Again, this is very case by case, but in general, more total revenue comes in due to greater numbers of users, plus the higher operational efficiencies noted for larger utilities,” Piñero said.
 

Finding the takeaway
 

In addition to their findings, the researchers also came to several conclusions. They determined that to curtail rate increases, water utilities would have to make several changes. These changes include the following: 

 

  • Improve operational efficiency at water utilities. “Inefficient utilities cost ratepayers more money and typically use relatively more energy, chemicals, resource and manpower,” according to the Oct. 14 news release.   
  • The source of a utility’s water directly affects its rates. “Utilities tend to use the least expensive source to its limit, and then look at other resources,” according to the release. To reduce costs, utilities with less-expensive water sources, such as groundwater, should try to ensure its long-term viability.   
  • Utilities should explore alternatives to the existing rate structure. “The municipal solid waste sector developed a sliding scale fee system to encourage waste reduction by charging a premium rate to those that exceed preset limits. A similar system could apply to water, encouraging conservation and reducing wastage,” according to the news release.   
  • Utilities should consider all revenue sources. “Other revenue sources include connection fees, green infrastructure incentives, or [energy] savings performance contracting. In some cases, the investment community can be recruited to provide options for transferring liabilities from municipalities to the private sector,” according to the release.   
  • Piñero acknowledged that utilities may be limited in what they can do to reduce operational costs and subsequently rates, but some are trying.     

“I do not have a handle on how many, but anecdotal input through the study as well as other inputs tell us that more and more utilities are looking at such approaches,” Piñero said. “And true, traditionally some of these things would be out of the scope or control of the utility. [But] participating in raising awareness among their ratepayers and stakeholders, plus exploring ways of collaborating with such partners, will increase opportunities to influence what occurs elsewhere within their jurisdictions,” he said.


 

                                                                                           — LaShell Stratton-Childers, WE&T  


 

Getting the lead out

Scientists develop new ways to remove heavy metals, recycle rare earth elements in industrial wastewater 

 

Industrial wastewater isn’t what it used to be. And it’s becoming more challenging to treat all the time.

At one end of the spectrum is the increasing amount of heavy metal-laden effluent being produced at mining, fracking, remediation, and other industrial sites throughout the world. Left untreated, these difficult-to-remove metals, including selenium, mercury, and zinc, can infiltrate groundwater and pose a threat to drinking water supplies.

On the other end is a surge in industrial wastewater that contains trace amounts of valuable rare earth elements. Essential to the production of everything from hybrid cars and flat-panel TVs, to cell phones and hundreds of other “cleantech” gadgets, these expensive, difficult-to-mine elements are going up in price as demand soars and the global supply grows more constrained.

The cost to remove and, in some cases, recycle both kinds of substances from wastewater historically has been high and often impractical. But researchers say that may be about to change.

 

A new approach to heavy metal removal 
 

A new chemical-based technology is expected to come on the market this summer that its creators say will remove heavy metals from industrial wastewater more efficiently and economically than current biological methods.   

Texas A&M AgriLife Research (College Station, Texas) and Evoqua Water Technologies (formerly Siemens Water Technologies, Alpharetta, Ga.) are working together to develop and commercialize the technology, which is based on an activated iron process pioneered by Yongheng Huang, a Texas A&M AgriLife Research scientist. Huang received the Water Environment Federation’s 2013 Rudolfs Industrial Waste Management Medal in October.     

The technology, which is being designed to meet National Pollutant Discharge Elimination System limits, differs from the biological solutions now in use in several key ways, according to Joe Gifford, director of Industrial and Electrochemical R&D at Evoqua.

 “Biological solutions typically require extensive pretreatment [with] other physical and chemical treatment methods that add significant capital and operating expenses,” Gifford said.   

The new Texas A&M/Evoqua alternative is a stand-alone system that requires no pretreatment. Instead, chemical reduction is used to remove metals in a single process that is unaffected by temperature or pH, Gifford said.   

The new system is being designed to occupy a smaller footprint than current remediation treatment systems. It will be more economical to operate as well, he said.  

Just how much time and space it might save is still to be determined. “The footprint and cost reduction depend on the market and particular application,” he said.   

For now, the technology is being developed with an eye to applications in environmental remediation, power, oil and gas, and mining — all markets where heavy metal presence is significant. According to U.S. Environmental Protection Agency estimates, the U.S. power industry alone faces annual costs of $185 million to $954 million to comply with upcoming effluent limitation guidelines. Refinery and mining wastewater streams face similar challenges.   

“From flue gas desulfurization water treatment for power utilities to heavy metals removal from [hydrocarbon processing industry/chemical processing industry] and mining wastewater, there is a clear need for a cost-effective solution unaffected by temperature or pH levels,” Gifford said.  

With bench-top and pilot-scale activities now complete, researchers currently are testing the technology in large-scale demonstration plants, with plans to make it available commercially this summer.   

 

Finding needles in haystacks  
 

The toxic heavy metals removed by the Texas A&M/Evoqua technology will, in most cases, eventually be disposed of as solid waste, Gifford said.     

But there are 17 highly valuable elements of the periodic table that manufacturers would love to recover from wastewater and then reuse. With names like dysprosium and europium, these valuable rare earth elements are essential to, but comprise just a tiny fraction of, many of today’s electronic products. The rare earth magnets used in cell phones, for example, make up less than 0.1% of the device by weight. They’re even more highly diluted in wastewater and, therefore, extremely difficult to reclaim.   

But a team of scientists at the Chinese Academy of Sciences (Beijing) may have found a novel way to do just that using a nanomaterial known as nano-magnesium hydroxide.    

“The raw material adopted in our technology is an [inexpensive] and environmental material, and the process is very simple,” said Dr. Yangping Hong, a scientist with the State Key Laboratory of Structural Chemistry (Fuzhou, Fujian, China).  

A paper on the research recently was published in ACS Applied Materials and Interfaces. It describes how the scientists produced particles of nano-magnesium hydroxide, which was already known for its ability to remove some metals and dyes from wastewater. To test its ability to remove rare earth elements, they conducted an experiment during which the flower-shaped particles captured 99% of the rare earth elements diluted in wastewater.   

By varying the solution’s pH, scientists found they could further separate the immobilized elements from the residual magnesium hydroxide. In a later pilot-scale experiment using real-world conditions, rare earth elements also were immobilized at a high flow rate, according to the published paper.   

Their new method captured many different rare earth elements, Hong said, including terbium, a soft silvery metal used in super magnets, and yttrium, an element used to produce the red color in screen monitors. But it can, in theory, capture virtually all rare earth elements, Hong said. 

Hong expects some of the best applications for the solution may be in his own backyard. 

“Our technology may be properly applied in industrial wastewater treatment, especially in rare earth refining industry,” he said. China today mines and produces as much as 97% of the world’s rare earth element supply.  

Further refinement of the technology is ongoing, with commercialization still a long way off. If it proves successful, it could be a game-changer for the rare earth element industry, which today recycles about only 1% of these elements.   

Hong believes the technology can create a new revenue stream for the companies that use it. “Companies can get higher returns by recycling these rare earth metals, and the cost input of our technology is low,” he said.    

 

Mary Bufe, WE&T  


   

An area of concern? 

A new study shows the existence of high levels of radioactive sediment near a WRRF that treats fracking wastewater    


For a few years, the state of Pennsylvania has been concerned about the level of total dissolved solids (TDS) found in hydraulic fracturing wastewater, going so far as to pose regulations mandating water resource recovery facilities (WRRFs) that treat this wastewater to meet discharge limits for both chlorides and sulfates. But a recent study by scientists at Duke University (Durham, N.C.) showed a bigger concern lies with naturally occurring radioactive materials brought to the surface by natural gas drillers. According to the study published in the October issue of Environmental Science & Technology, sediment in Blacklick Creek contained isotopic radium at concentrations 200 times above upstream and background sediment level, thus “posing potential environmental risks of radium bioaccumulation in localized areas of shale gas wastewater disposal.”
 

Avner Vengosh, professor of Earth and Ocean Sciences at Duke University and one of the authors of the study, said the data show that the state of Pennsylvania is focusing on the wrong thing with its fracking wastewater regulations. “TDS is relevant only to wastewater from domestic wastewater treatment plants,” Vengosh explained. “This is a very outdated method of monitoring when it comes to hydraulic fracturing   wastewater.”         

 

Gathering the data  


In the study, the scientists analyzed effluent discharged from the Josephine (Pa.) Brine Treatment Facility, as well as streamwater and sediments both upstream and downstream from the effluent discharge site along Blacklick Creek. They tried to determine both the short- and long-term effects of the fracking wastewater disposal on surface water quality and stream sediment. To do this, they analyzed concentrations of alkalinity and major constituents, such as chloride, bromide, sulfate, calcium, sodium, magnesium, barium, and strontium. They also analyzed isotopic ratios of radioactive elements such as radium. The wastewater data then were compared to “background concentrations collected upstream of the facility, from other streams in western Pennsylvania, and from published values for produced water and flowback from the Marcellus [Shale] and other Appalachian Basin brines,” according to the study.
 

The scientists discovered that effluent discharged from the facility increased concentrations of chloride and bromide above background levels. In contrast, barium and radium were reduced substantially (by more than 90%) in the treated effluent compared to concentrations in untreated wastewater usually produced in the Marcellus Shale. But nevertheless, some radium isotope levels in the stream sediments at the point of discharge were still very high compared to background levels.  

Vengosh said this was probably due to flowback water from shale gas. “The brine had very high levels of radiation,” he said. This is because the Marcellus Shale has high levels of uranium and that chain of decay includes radium, he said.    

“It is very mobile and can be found in the sediment, Vengosh said.


 

Combating the problem
 

Faced with these types of contaminants, what can WRRFs do to treat fracking wastewater and possibly remove or reduce these constituents? “The ultimate solution would be reverse osmosis and thermalization,” Vengosh said. He said WRRFs also should consider an ion exchanger or resin softener that can remove radium from wastewater.  

In all cases, Vengosh said the biggest issue WRRFs will face is determining the right sequence of treatment and whether they can accommodate the costs necessary to purchase these technologies.  

In the next stage of their studies on hydraulic fracturing wastewater, Vengosh said he and his fellow scientists at Duke are working on a paper about blending high sulfate water with hydraulic fracturing wastewater to reduce radiation. They also are researching other constituents found in fracking fluid in Pennsylvania, New York, and West Virginia and how these constituents effects water quality, he said.  

    

— LaShell Stratton-Childers, WE&T