One of the most direct public impacts of algal blooms was seen in August 2014, when a harmful algal bloom in Toledo caused a “Do Not Drink” order to be issued for more than two days, an impact felt by residents and businesses alike. With direct guidance from state agencies at the front lines of algal drinking water crises like this one, HABRI researchers are developing new treatment methods that will give public health and water treatment professionals the tools they need to make informed decisions when water supplies are threatened by algal blooms.
Treatment of Cyanotoxins by Advanced Oxidation Technologies
Dionysios Dionysiou, University of Cincinnati
Research from the University of Cincinnati is looking into finding new and cost-effective ways to remove and destroy cyanotoxins from drinking water by combining traditional chlorine-based treatment with new approaches to destroying algal toxins.
Using various technologies to treat different stages of water from surface water treatment plants, the research team explored different doses and types of degradation processes to see which will destroy the algal toxin microcystin-LR the fastest. The processes tested in the lab include combinations of chlorination and ultraviolet (UV) rays. A related project at the University of Toledo expanded the range of methods tested with ozonation and filtration.
The researchers found that adding UV light treatments to the chlorination step reduced the amount of chlorine needed by two-thirds. As water treatment plants are updating their technology, these findings can provide guidance on how to produce high-quality drinking water at a lower cost. A partnership with a surface water treatment plant is already putting the research into practice, and managers have expressed interest in further details on using UV light to make their processes more efficient.
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Development of Microcystin-Detoxifying Water Biofilters; Discovery of Enzymes in Pathways Responsible for Microcystin Degradation
Jason Huntley, University of Toledo
Some bacteria have the ability to degrade the microcystin toxin MC-LR into non-toxic component parts, including bacteria naturally found in Lake Erie. The researchers involved in this project have isolated and identified groups of these bacteria, which are now being examined at the genetic level to potentially produce enzymes that can be used in water treatment plants. And of course, those toxin-degrading enzymes can’t be ones that cause disease in humans or animals.
The research group had hoped to find already known MC-LR degradation genes, based on studies from Australia, Japan and China. However, those genes were nowhere to be found in Lake Erie bacteria, so new genetic pathways have to be identified.
Current work focuses on using next generation genomic sequencing technology to examine the genetic information from these bacteria in the presence and absence of MC-LR. The toxin triggers an increase in the production of enzymes that attack it, so a gene that is observed in a higher number of copies when MC-LR is present is a likely candidate for further use.
So far, the researchers haven’t been able to identify the degradation pathway in a single type of Lake Erie bacteria, but they recently narrowed down the list to groups of five bacteria. They’re now working on confirming and replicating these results, as well as quantifying just how much microcystin the groups can break down, before digging deeper into the smaller list of options to find candidates for production of enzymes that can be used in water treatment.
In addition, they’ve started to grow these groups of bacteria on silica-based substrates, in preparation for larger-scale studies on the sand filters commonly used in water treatment plants. The eventual goal is to add microcystin-degrading bacteria to already existing filtration systems to improve and enhance water treatment in a safe and cost-effective manner.
The team has partnered with investigators at a number of Ohio universities to achieve these results, including the University of Toledo, Bowling Green State University, The Ohio State University and Kent State University.
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Investigation of ELISA and interferences for the detection of cyanotoxins
Dragan Isailovic, University of Toledo
A research partnership partnership among The University of Toledo, The Ohio State University and the University of Cincinnati aims to investigate potential problems with a standard test for harmful algal toxins.
During the 2014 water quality crisis in western Lake Erie caused by harmful algal blooms, there was one test that all public health agencies turned to: ELISA. Standing for Enzyme-Linked ImmunoSorbent Assay, ELISA is the most widely used way to test water for harmful algal toxins. However, there may be some conditions—for instance, when certain other chemicals like calcium are present in water—under which ELISA may give inaccurate answers.
This research team tested ELISA’s performance detecting algal toxins in many possible mixtures that simulate lake and reservoir water as well as the stages that water goes through in a water treatment plant.
In order to know for sure, the research team checked ELISA’s answers against results from a much more timeconsuming but reliable method, liquid chromatography mass spectrometry (LC-MS), which focuses on the most common types of microcystins. They found that the two methods showed generally similar trends for total microcystin levels in lake water, while in some cases the LC-MS results showed higher toxin levels than ELISA, which looks at overall toxin levels.
The team concluded that each method can provide valuable answers to water treatment plant managers and public health officials, as long as the limitations of each are taken into account.
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Guidance for Powdered Activated Carbon Use to Remove Cyanotoxins
John Lenhart, The Ohio State University
Harmful algal blooms can produce a family of toxins called microcystins that have to be scrubbed from water before it is safe to drink. Most water treatment plants use powdered activated carbon (also called activated charcoal) to adsorb and remove the toxins, but knowing the specific dosage of carbon to use can be a complicated matter, as it depends on varying levels of toxin and environmental conditions.
A research team at The Ohio State University has developed guidelines for water treatment plant operators to help them know exactly which dosage of powdered activated carbon to use under which conditions. These guidelines take into account the types and concentrations of toxins present and the composition of the water—for instance, the presence of decaying organic matter from plants and animals, which is known to affect how the carbon adsorbs toxins.
Highlights from the study results, which have been passed along to the Ohio Environmental Protection Agency, suggest that wood-based activated charcoal is the best choice for removing algal toxins, especially because it interacts with the toxin and any organic matter in the water more quickly than coal-based activated carbon. Coconut-based activated carbon, a common choice in water pitcher filters, was found to be a poor option for removing microcystin.
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Prevention of Cyanobacterial Bloom Formation Using Cyanophages
Jiyoung Lee, The Ohio State University
Environmental health scientists at The Ohio State University are searching for a more environmentally friendly way to reduce microcystins in both lake water and water treatment plants. Ingesting water contaminated with microsystins can cause everything from stomach cramps to liver failure. In August 2014, microcystins shut down Toledo’s water supply for more than two days. Microcystins are toxins produced by the cyanobacteria, also known as blue-green algae, that cause harmful algal blooms.
Scientists believe there may be a solution in cyanophages, which are viruses prevalent in water that infect only their host, cyanobacteria. Cyanophages can add or delete genes from their host, but haven’t been studied much in lake water yet.
The research team discovered a cyanophage, now named Cyanophage LEP, that infects toxic Microcystis algae and interferes with growth and pigment production. This interference not only turns the algae from bright green to yellowish green, but also disrupts photosynthesis and structurally ruins cyanobacteria cells, based on electron microscope observations.
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Identifying Bacterial Isolates for Bioremediation of Microcystin-Contaminated Waters
Xiaozhen Mou, Kent State University
Because of their unusual shape, microcystins do not break down easily in the conditions found in most water treatment plants. However, bacteria naturally present in lake water and sediments have evolved to use microcystins and related chemicals as a food source—a fact that water treatment plants would like to take advantage of.
A team of microbiologists at Kent State University has been collecting water and sediment samples since 2013 to find bacteria that thrive when exposed to microcystins, the toxins produced by many harmful algal blooms. Now they are purifying cultures of the bacteria to see if they can be used as part of bioremediation systems in water treatment plants.
Results show that of the nearly 500 bacteria strains isolated from Lake Erie water and sediments, 40 are able to degrade microcystins. The researchers also collected data on the shape, size and genetic make-up of those bacteria and tested their ability to break down microcystins under various temperatures and pH levels.
This information is informing separately funded projects from the Ohio Department of Higher Education and the National Science Foundation that aim to use some of these bacteria in the development of biofilters for eventual use in drinking water treatment.
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Investigation of Water Treatment Alternatives in the Removal of Microcystin-LR
Researchers are developing new methods to remove the algal toxin microcystin from drinking water using various filtration methods as well as ozone gas. The laboratory models can eventually be scaled up for use at water treatment plants that deal with harmful algal blooms in their water supply so they can better ensure their customers’ drinking water is safe to use.
Lab results so far have shown that bubbling ozone into a solution of microcystin-LR, one of the most common forms of the toxin, can lead to 100 percent toxin destruction. Further experiments are in progress to achieve similar results at ozone concentrations and treatment times that work with treatment plant procedures. Several kinds of filter membranes are also showing promising results, removing up to 96.9 percent of microcystin from tested solutions in the lab experiments.
Once these separate experiments are completed, combinations of ozone and filter membranes will be examined to determine the best pairing for toxin removal and cost effectiveness. The ultimate goal is to provide water treatment plant managers with a series of strategies to remove toxins.
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Investigation of Water Treatment Alternatives in the Removal of cyanotoxins
Youngwoo (Young) Seo, University of Toledo
Research under development at the University of Toledo and The Ohio State University is designed to create alternative treatments for algal toxins often found in drinking water drawn from Lake Erie.
While activated carbon is an effective way to remove algal toxins such as microcystins from drinking water, high toxin levels can lead to extensive and potentially unsustainable use of activated carbon, which can add as much as $10,000 to water treatment costs per day. An effective alternative is needed to expand treatment options during harmful algal blooms.
A research team at the University of Toledo has examined biological filter systems as well as treatment with potassium permanganate. Biofilters use microcystin-degrading bacteria to remove toxins from drinking water. Potassium permanganate neutralizes algal toxin, but also destroys algal cells. That destruction can potentially lead to additional toxin release.
Using water samples from Ohio reservoirs as well as lab samples with pure toxin strains, the researchers were able to determine an optimal dose of permanganate that neutralized toxin while keeping algal cell destruction to a minimum. Two bacterial strains also showed promise for use in biofilters, and evaluation of those biofilters at the Toledo water treatment plant is showing promise.
Information and results have been shared with the city of Toledo as well as statewide water managers, and collaborations with water treatment plants will continue after the project concludes.
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Transport and Fate of Cyanotoxins in Drinking Water Distribution Systems
Youngwoo (Young) Seo, University of Toledo
Research at the University of Toledo examined whether toxins from harmful algal blooms “stick” to water infrastructure like pipes and storage tanks, and how that potential stickiness could impact toxin concentrations in drinking water. The team is partnering with the city of Toledo, whose water supply was heavily affected by an August 2014 harmful algal bloom in western Lake Erie.
While reducing harmful algal bloom toxins at water treatment plants is a well-studied process, how toxins travel through and potentially remain in other parts of the system between plant and consumer is not well understood. “Flushing pipes” after a toxin event can remove any dissolved toxins in the water itself, but particles could adhere to pipes and be released later, potentially raising toxin levels after checks are performed at the water treatment plant.
The research team determined how cyanotoxins interact with various pipe and storage tank materials in laboratory experiments. They found that chlorine doses already used to disinfect drinking water can also be effective in ensuring microcystins do not stick to water pipes, and created a chlorine dose table to detail this information for water treatment plants in an easily applied way. They also found that high-density polyethylene pipes absorb the highest amount of microcystin, suggesting that updates to municipal water systems in areas commonly affected by harmful algal blooms may want to avoid that particular material. Experimental results were used to model the spread of microcystin within a drinking water system to identify potential “hot spots” for decontamination.
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Optimization of Carbon Barriers for Effective Removal of Dissolved Cyanotoxins from Ohio’s Fresh Water
Water treatment plants use activated carbon to remove microcystins, the toxins produced by most harmful algal blooms, from the drinking water they provide to their residents. Currently, most Ohio utilities use activated carbon made from bituminous coal, according to local utility managers who are providing information on their current water treatment processes to the scientists. However, guidelines on how much carbon is needed to remove a certain amount of toxin are scarce, so many operators err on the side of caution, leading to the potential for unnecessarily high treatment costs.
Researchers at the University of Cincinnati and The Ohio State University are now working on guidelines for optimal use of activated carbon in drinking water treatment, and on designing new carbon nanofilters that may be more effective than activated carbon in removing various cyanotoxins.
Preliminary results indicate that coconut-based activated carbon is the least effective in removing microcystins from water, probably because the pores in the carbon that would capture the toxin molecules are too small for the molecules to fit into. Better results came from wood-based activated carbon and lignite coal.
Currently, the team is using synthetic water, which represents a kind of “average” of surface waters in Ohio, to determine how well their techniques remove dissolved cyanotoxins. The plan for next year is to then add natural organic matter to the synthetic water to better mimic natural water conditions. Once they better understand the influence of that organic matter on toxin removal, they’ll begin testing on water samples drawn from Lake Erie and its tributaries. The scientists have also created some of the carbon nanofilters they will be testing for toxin removal efficiency during the project’s second year.
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Evaluation of Optimal Algaecide Sources and Dosages for Ohio Drinking Water Sources
Like any standing body of water, reservoirs that collect water to be used as drinking water tend to grow algae. In addition to clogging pipes and interfering with various water treatment steps, algal masses in reservoirs could be composed of cyanobacteria capable of producing toxins — Microcystis or Aphanizomenon, for example. As a result, water treatment plants use algaecides to control their growth.
The problem with killing off cyanobacteria in this way is that quite often, the algaecide may kill non-target organisms like diatoms and green algae, and the dead cyanobacteria release toxin from their cells into the water. So the optimal dosage for a given algaecide addressing a certain type of algae is a delicate balance between what kills a reasonable amount of algae and what keeps toxin release to a minimum.
Researchers at the University of Akron are now working to better understand that balance in four Ohio reservoirs: two near Akron, one near Willard, and one near Norwalk. The team is working with the associated water treatment plants to obtain samples and information on algaecide use to integrate all information from the study into a set of best practices for improving water treatment effectiveness and reducing costs where possible.
The goal is to create tailored solutions to various treatment goals for each reservoir, with the primary goal of minimizing the impact of algae removal while limiting toxin release from dead algal cells. So far, experiments have shown that factors like reservoir volume and shape, the types of algae present, the types of algaecide and concentration used, and overall water chemistry all affect treatment outcomes.
During the first year of the study, optimal dose experiments with all three algaecides have been completed for the city of Akron and city of Willard reservoirs, and one set of laboratory experiments for the city of Norwalk was recently finished as well. Additional dosage experiments, flow-through studies for a more real-world picture of water treatment, and final discussions with utilities managers are on track for the second project year.
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Evaluating home point-of-use reverse osmosis membrane systems for cyanotoxin removal
Glenn Lipscomb, University of Toledo
There’s already a lot of activity going on in the aftermath of the 2014 harmful algal bloom (HAB) in Lake Erie, which left residents in the city of Toledo without drinking water. Water treatment plants have added additional testing for the algal toxin microcystin that caused Toledo’s water shutdown, scientists are monitoring HABs as they develop, and backup intakes let larger plants avoid pulling in potentially contaminated water altogether.
A team at the University of Toledo is taking that activity one step further by showing that reverse osmosis (RO) membranes, an essential component of drinking water purification systems installed under kitchen sinks in many homes, can remove algal toxins from drinking water.
Reverse osmosis occurs when water is pushed through a semipermeable membrane with “holes” that are too small for anything but the water molecules themselves. The process removes minerals and particles that can cause undesirable flavors, but to the scientists, the removal of algal toxins was an obvious additional benefit that needed to be explored further.
Partnering with NSF International (formerly the National Sanitation Foundation), the research focuses on the reverse osmosis systems commonly sold at home improvement stores at a relatively low cost of $250-300. The goal is to develop a certification process for these home membrane systems that shows that they remove microcystin from drinking water, with the final certification protocol complete in early 2018.
One of the challenges the researchers face is the chlorine that’s added to drinking water to help disinfect it: The chemical attacks the filter membrane and can reduce its ability to filter out toxins. So they’re developing some “accelerated aging” protocols based on previous research that shows that higher chlorine concentrations over a short time age filters the same as low concentrations over a longer time.
The chlorine trials are first completed on just the filter system components, to see in detail how the different membrane and support layers are affected. Once those characterizations are completed, the researchers will move on to drinking water that includes known levels of toxin to assess the filter system’s effectiveness and complete the certification protocol.
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Kinetic models for oxidative degradation of cyanotoxins in raw drinking water
Allison MacKay, The Ohio State University
Water treatment plants in Ohio use chlorine as part of their arsenal to fight drinking water contamination, including the presence of toxins like microcystin. Researchers are now working to make that treatment technique more effective by adding UV light and a permanganate oxidant into the equation.
The laboratory experiments so far have shown that rates of toxin degradation and destruction are higher in the presence of UV light at chlorine doses comparable to typical water disinfection procedures. It also looks like the combination of UV and chlorine is effective in pH ranges that occur during algal blooms, bringing the researchers another step closer to eventually using this method at water treatment plants.
Applying permanganate to speed the degradation process along also shows promise, without requiring additional or longer treatment to be most effective. Researchers are working to understand how permanganate can be applied so that organic matter such as plant debris, mud and other things often suspended in lakes and streams doesn’t affect the treatment protocols in a negative way.
Collaborations with local water utilities and Ohio’s harmful algal bloom monitoring program have allowed the scientists to confirm whether the water samples used in the laboratory experiments were correlated with an active algal bloom, based on information provided by the Ohio Environmental Protection Agency.