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waste and wastewater treatment

  • TriSep Introduces New Membrane Concepts

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    The field of membrane technology is constantly changing and growing with new technologies to tackle new problems and introduce new capabilities.  TriSep Corporation is one the companies that is leading the way with its innovations, which they discuss in the December issue of International Filtration News Magazine.

    In TriSep's article, they introduce three new technologies:

    • A line of high-temperature elements that are capable of continuous operation and periodic sanitation.
    • TurboClean® sanitary hard shell elements, which provides higher flow velocity and efficiency than traditional sanitary elements.
    • The iSepTM ultrafiltration membrane, the first UF membrane that is specifically designed to the handle high-fouling water and wastewater feeds.

    The full article can be found in PDF form here.

    This post was posted in bench scale, cross-flow filtration, waste and wastewater treatment, TriSep, Flat sheet membrane, reverse osmosis, ultrafiltration

  • UNICEF Uses Membrane Distillation to Make Sweat Drinkable

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    People do strange things for attention. Children throw tantrums, celebrities shave their heads and UNICEF builds a machine to take the sweat from your clothes and turn it into drinking water. UNICEF, at least, is trying to raise awareness of the lack of clean water for children with its unusual machine. Unveiled during the Gothia Cup, and built by Swedish engineer Andreas Hammar, the aptly named Sweat Machine works by using membrane distillation to separate water from other components of sweat.

    Unlike other membrane-based processes of water purification, such as reverse osmosis, membrane distillation is a thermally-driven process that employs a hydrophobic, microporous membrane. The water (or sweat) to be processed is heated, while the water on the permeate side of the membrane is kept cool. The temperature difference across the membrane creates a corresponding difference in pressure which pulls water, in the form of vapor, over to the permeate side of the membrane. Water’s naturally high surface tension keeps the liquid phase of the water out of the membrane’s pores.

    Membrane distillation is good choice for compact desalination and water purification units because the process doesn’t require the energy and equipment to create the extreme pressures needed for reverse osmosis. Heating the feed water can be done with the waste heat of a power plant or factory or with renewable energy sources like solar power. While membrane distillation has been used at the laboratory scale since the 1960s, its potential to provide easy access to drinking water for remote or rural areas is only now being recognized.

    During the Gothia Cup, UNICEF encouraged everyone to hand in their sweaty clothes and take in a glass of their recycled fluid. The Sweat Machine managed to wring out about 10 mL of water out every sweaty shirt.

    You can read UNICEF’s original press release and learn more about their clean water campaign here.

    This post was posted in Did you know, waste and wastewater treatment

  • A Winter of Discontent at the Arizona Snowbowl

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    After nearly ten years of legal wrangling, the Arizona Snowbowl Ski Resort was given the green light to use reclaimed wastewater to make artificial snow for the first time this winter. It is also the first ski resort in the world to do so, taking its water from treatment facilities in nearby Flagstaff, AZ. It’s definitely a novel use for wastewater and, if it proves successful, it may help combat the stigma against the use of reclaimed wastewater in other applications where human contact may occur.

    Unfortunately, the first run of snow sprayed onto the slopes was yellow.

    Face-planting into a pile of yellow snow made from reclaimed wastewater is an icky proposition. Joking aside, the discolored snow raises serious questions about the potential health and environmental impact of spraying wastewater effluent onto the slopes. Some studies have shown that the effluent contains traces of pharmaceuticals, hormones and other chemicals which are not regulated by current water quality laws. The controversy is also complicated by the fact that the resort sits on a mountain that is considered sacred by 13 Native American tribes.

    The managers of the Arizona Snowbowl assert that their artificial snow does not pose a risk to skiers’ health. They claim that the discoloration snow was a result of rusty residue from the actual snow-making equipment. The snow guns have since been cleaned to prevent further discoloration of the snow.

    Ski resorts have been making artificial snow for decades. In the face of a changing climate and increasing demand for fresh water, using reclaimed wastewater to powder the slopes may just become a standard practice at resorts around the world. Let’s hope they keep it white.

    Contributing Sources:

    Chappell, Bill. "Ski Resort Makes Snow With Treated Wastewater, After A Long Dispute." NPR. NPR, n.d. Web. 28 Feb. 2013.

    MacMillan, Leslie. "Discolored Slopes Mar Debut of Snow-Making Effort." The New York Times. N.p., 11 Jan. 2013. Web. 28 Feb. 2013.

    Macmillan, Leslie. "Resort's Snow Won't Be Pure This Year; It'll Be Sewage." The New York Times. The New York Times, 27 Sept. 2012. Web. 28 Feb. 2013.


    This post was posted in Water Sterilization, waste and wastewater treatment, pollution, water treatment

  • Biomineralizing Pay Dirt

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    Bacteria is something of a dirty word. They’re everywhere, invisible and insidious, waiting for their chance to climb into your body and wreak havoc. But before you reach for your hand sanitizer and start counting your sick days, take a moment to consider the many uses that people have found for bacteria. Bacteria are essential in making yogurt and cheese, fixing nitrogen for our crops, and they help us digest our food. In the near future, Damian Palin would like to add mining the ocean to the list of things bacteria do for us.

    Damian Palin, a geomicrobiologist working in Singapore, has been developing bacteria strains that can be used to precipitate useful minerals out of the briny effluent produced by desalination plants. If he is successful, he would be killing two birds with one stone: useful minerals that would otherwise go to waste could be extracted, and the highly concentrated brine could be treated before it is pumped back into the ocean.

    Biomining is already used to extract gold, copper, iron and uranium from low grade ores that were once thought to be worthless. Using bacteria to mine for useful metals is less destructive and less energy intensive than traditional mining methods. As the global demand for metals increases, bacteria’s ability to mine metals from unusual sources will become increasingly important.

    To watch Damian Palin’s TED presentation, click here.

    Contributing Sources

    Palin, Damian. "Damian Palin: Mining Minerals from Seawater." TED: Ideas worth Spreading. N.p., June 2012. Web. 20 Aug. 2012 <>.

    Siddiqui, Mohd. H., Ashish Kumar, Kavindra Kumar Kesari, and Jamal M. Arif. "Biomining- A Useful Approach Toward Metal Extraction." American-Eurasian Journal of Agronomy (2009): 84-88. Print.

    Wassenar, T. M. "Applied Bacteriology: Use of Bacteria in Industry." The Virtual Museum of Bacteria. N.p., 06 Jan. 2009. Web. 20 Aug. 2012 <>.

    This post was posted in waste and wastewater treatment, Biotechnology, Microbiology and Life Sciences

  • EPA to Create Standards for Natural Gas Wastewater

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    The Environmental Protection Agency announced last week that they are planning to develop standards for wastewater discharges produced by natural gas extraction from underground coalbed and shale formations (a process commonly referred to as “Fracking”). This method of extraction involves fracturing rock formations by injecting them with a pressurized fluid consisting mostly of water, a little bit of sand, and some chemical additives as well. The debate over the possible environmental consequences of fracking is a hot button issue right now, and since its popularity has grown to the point where it now accounts for about 15% of all natural gas production in the US, it is understandable that the EPA wants to look into setting some uniform regulations.

    Any potential EPA standards in this area can be broken down into two areas: shale gas standards and coalbed methane standards. In shale gas extraction, wastewater is prohibited from being discharged into waterways. Instead, it is either recycled back into use or sent to a treatment plant. Unfortunately, many of these treatment plants are not properly equipped to handle shale gas wastewater so the EPA will look into standards that could be implemented on wastewater before it reaches the treatment plant.

    Creating a coalbed methane standard for wastewater treatment is a little bit trickier, since there aren’t any national standards for it yet. Currently it is up to individual states to regulate where the wastewater is discharged and what pre-treatment standards to follow. The EPA is hoping to address the matter by creating a uniform standard for the whole nation.

    Based on the current EPA schedule, a proposed rule should come in 2013 for coalbed methane and 2014 for shale gas. This is to allow the EPA time to consult with stakeholders and allow for public comment.

    You can read the full announcement from the EPA here.

    This post was posted in waste and wastewater treatment, environmental lab, EPA, water and wastewater treatment, water treatment

  • Are Our Clothes Polluting the Ocean?

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    The simple act of machine washing our clothes may be causing serious environmental damage, according to a new study from University College Dublin. A research team led by Dr. Mark Browne has traced a path from washing machine wastewater to abnormally high concentrations of microplastic debris found all over the world. The problem arises because the synthetic fibers that many of today’s clothes are made of, polyester and acrylic, get rinsed by the machine. While we may not notice it, one cycle can strip as much 1,900 fibers off each piece of synthetic clothing! These dangerous fibers eventually make their way to the ocean and wash up on our beaches. Research also shows that the pollutants are eaten by mussels and locusts, which can then work their way up the food chain to humans.

    As a part of this study Dr. Browne’s team investigated 18 sites on six continents and through forensic analysis was able to match the proportions of polyester and acrylic fiber present in these sites with their proportions in clothing. They also found a correlation between sites with greater-than-average concentrations of microplastics and their exposure to washing machine wastewater.

    Microplastic debris doesn’t get a lot of attention now in the environmental community, but as the human population grows and synthetic fibers become more commonplace, they have the potential to be a major concern in the future. Since it is likely that any solution to the problem will include standard or experimental methods of wastewater treatment, including filtration (see Flat Sheet Membranes), we’ll continue to look out for possible cures.

    Read the full study from the ACS Journal of Environmental Science & Technology
    Learn more about the work of Dr. Browne

    This post was posted in waste and wastewater treatment, environmental lab, water and wastewater treatment

  • Wastewater Mistreatment

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    Western Biodiesel Inc. was fined $160,000 (Canadian dollars) yesterday by the Provincial Court of Alberta for releasing wastewater that contained methanol into the environment and for providing false or misleading statements to investigators. The fine is the outcome of an incident in October 2008 in which Western Biodiesel dumped around 16,000 liters of methanol-laced water onto its property.

    Problems arose for Western Biodiesel the day after this release occurred when an unsuspecting welder accidentally ignited the wastewater with his torch, causing a fire that luckily yielded no injuries. In what had to be an incredibly gutsy and foolish move, the (now former) plant manager denied the release occurred when investigators showed up. He was later sentenced to four months house arrest.

    So besides dumping it in a river and hoping nobody lights a match, what are the actual proper methods of methanol disposal? Methods for extracting methanol from biodiesel include: Vacuum stripping, flash evaporation, distillation, and water washing. Methanol and especially glycerol are high-value byproducts of biodiesel production, so facilities try to reclaim as much as possible for resale. Membrane separation is also used as an effective biodiesel purification method, particularly for removing glycerol particles.

    Methanol is routinely used in biodiesel production during the transesterification reaction to turn plant or animal fats into fatty acids and glycerol. (Fun fact: Methanol is also a by product in liquor distillation and can cause blindness if ingested in large enough quantities!). European Standard 14214 specifies that biodiesel should contain no more than 0.2% methanol.

    For more information you can check out the official statement from the Government of Alberta and this publication on biodiesel production from the University of Idaho.

    This post was posted in waste and wastewater treatment, News, water treatment

  • What the Crap?

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    Biogas, a form of renewable energy this is produced through, among other things, animal and human waste (hey, it’s not like you were using it) is one of several developing energy sources whose proponents are exploring membrane separation techniques to improve their purification process. A recent study published in the “Applied Chemistry – A Journal of the Society of German Chemists” experimented with a new method of membrane separation called the “condensing-liquid membrane” (or CLM) in an effort to enrich raw biogas, which typically contains between 50-80% methane, to natural gas quality (at least 95% methane content), with favorable results.

    Common membrane materials like Cellulose Acetate and Polyimide have been tried for this application with some success, but the problem is that they can be ruined by the aggressive gases that are present in raw biogas, such as carbon dioxide and hydrogen sulfide. The CLM is a liquid (water in this case) layer that condenses on a porous hydrophilic membrane which then gets regenerated to allow for continuous operation. This support, made from PTFE, gathers water vapor from the biogas on the feed side of the membrane and is partially removed from the permeate side by nitrogen gas, thus allowing for separation to occur in one step as the water is constantly refreshed. One of the more brilliant aspects of the CLM method is that the presence of water in biogas, usually regarded as a disadvantage, suddenly becomes a key component in the process.

    Since the membranes are being preserved and not destroyed, the potential exists for this process to be a cost-efficient method of purifying biogas in the future. Researchers will continue to investigate the CLM method in order to find the optimal conditions that will make it even more efficient.

    Visit here to read the full report “Effective Purification of Biogas by a Condensing-Liquid Membrane.”

    To learn more about biogas, try this site from Alternative Fuels and Advanced Vehicles Data Center and the U.S. Dept. of Energy.

    How does a biogas plant work? Watch this animated video to get an idea.

    This post was posted in Filtration, applications, waste and wastewater treatment, Membrane Filtration, renewable energy, hydrophilic, separation, biogas

  • Rising Salinity Cause for Concern at North Carolina Desalination Plant

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    An increase in salinity levels at the North Reverse Osmosis Water Plant in Kill Devil Hills (yes, that’s the town name) that had been creating stress for some local officials has been explained in a recent study. Researchers from nearby Duke University found that the rising salinity levels at this coastal aquifer are the result of fossil seawater and not seawater intrusion, as had been feared. Since the well’s installation in the late 1980’s salinity has more than doubled from about 1,000 mg/L to about 2,500 mg/L. There was much cause for relief however, when researchers were able to attribute the rise to fossilized seawater and not to seawater leaking in from the coast.

    According to the director of the study, Duke Professor Avner Vengosh, knowing the source of the salinity increase is important because fossil seawater raises salinity, “At a relatively slow and steady rate that is more manageable and sustainable than the rapid increase we’d see if there was modern-day seawater intrusion.” As a result of this study the community will be able to rely on this aquifer for decades to come without having to resort to more expensive seawater desalination techniques which require more energy and advanced filtration methods.

    Current treatment for groundwater desalination includes the use of reverse osmosis (RO) membranes to separate dissolved salts from potable water. Even with the rising salinity level these membranes remove around 96 to 99 percent of the dissolved salts. RO membranes also remove between 16 and 42 percent of the boron and 54 to 75 percent of the arsenic from the groundwater. Additional treatment following reverse osmosis desalination continues to remove arsenic until it is within safe drinking levels (10 parts per billion, according to the EPA).

    Because seawater consistently has more salt than groundwater it requires more energy to treat, and therefore the cost is higher. Per this report on desalination from the Pacific Institute, “Energy is the single largest variable cost for a desalination plant, varying from one-third to more than one-half the cost of produced water.” The report also states, “At these percentages, a 25% increase in energy cost would increase the cost of produced water by 11% (for RO plants).” In looking at these percentages, it’s easy to see why the plant was concerned about seawater intrusion. Thanks to this research, the local citizens can drink easier knowing they have a supply of healthy, affordable water for a long time to come.

    Click here to learn more about this case.

    This post was posted in waste and wastewater treatment, environmental lab, EPA, brakish water, water treatment, reverse osmosis

  • Performance Improvement of Cross-flow Filtration for High Level Waste Treatment

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    The Department of Energy and Savannah River National Laboratory recently published a study regarding their efforts to improve performance on cross-flow filtration for high level waste treatment. Even though the waste being treated in this case is actually radioactive material from nuclear power plants, the process they describe, along with the issues they raise and recommendations for improvement, can be applied to the more common uses for cross-flow filtration.

    The stated goal of this DOE research was to improve filter fluxes in their existing cross-flow equipment, a common request of many customers. The study examines the problem of increasing cross-flow filtration efficiency from a number of different approaches: Backpulsing, cake development, scouring, and cleaning were all taken into consideration.

    At the end of the study SRNL was able to draw some conclusions to take into consideration when evaluating your own setup.

    • Higher solids concentration presents a greater challenge to filtration.
    • The presence of a filter cake can improve the solids separation by an order of magnitude as determined by turbidity.
    • Scouring a filter without cleaning will lead to improved filter performance.
    • Filtrate flux decline is reversible when the concentration of the filtering slurry drops and the filter is scoured.

    You can read the full report here to see a detailed description of their setup and complete results.

    This post was posted in bench scale, applications, cross-flow filtration, waste and wastewater treatment, cross flow

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