Over the past decade, cyanobacteria blooms have emerged as an important issue in the water and wastewater industry. Tory Colling, Scientist, explains what water professionals ought to know about cyanobacteria and cyanotoxins in water:
1. What are cyanotoxins?
Cyanotoxins are produced by some species of cyanobacteria or as commonly known as blue-green algae. These toxins are typically stored inside the cells, but when cyanobacteria cells degrade, the toxins are released.
Cyanobacteria are microscopic bacteria that have some plant-like characteristics. They are commonly called “algae blooms” in the media.
2. Where are they found?
Cyanobacteria naturally occur in freshwater. In fact, they contribute oxygen in our atmosphere. When conditions are favourable, such as warm temperatures and nutrient-rich, shallow and stagnant waters, cyanobacteria can form blooms. Cyanobacteria blooms are made up of densely-populated cells that form discoloured water, which is often described as pea soup or spilt paint with an oily appearance.
Certain cyanobacteria can produce by-products, known as cyanotoxins. When these cyanobacteria cells form a bloom, large amounts of cyanotoxins can be detected.
3. What are the health concerns?
Health concerns can range from liver toxins, neurotoxins, tumor-promoting effects or skin irritation. There are different types of cyanotoxins and each type has different health concerns. The most common cyanotoxin is called microcystin. Microcystin is a liver toxin and can cause tumor-promoting effects.
4. What are some strategies to control cyanotoxins?
Reducing nutrient inputs to source water or effective reservoir/watershed management are long-term strategies to control cyanobacteria and cyanotoxins.
5. How can cyanotoxins be removed from drinking water?
For larger municipal systems, combining effectively operated drinking water treatment processes can provide a multiple barrier to remove intact cells or released cyanotoxins. Some drinking water treatment processes, such as coagulation, flocculation and sedimentation or flotation, are capable of removing intact cyanobacteria cells. While other drinking water treatment processes, such as chlorination or ozonation, are capable of degrading released cyanotoxins, provided there is enough disinfectant concentration and contact time with the disinfectant.
Some very small or private drinking water systems may only rely on point-of-entry (POE) drinking water treatment units. If these private drinking water systems suspect a bloom in the water supply, it is recommended to contact the local health unit and use an alternative water source. Very limited POE treatment units are certified to specifically remove cyanotoxins. However, in 2019, the National Sanitation Foundation (NSF)/American National Standards Institute (ANSI) updated NSF/ANSI Standard 53 to include a protocol to test activated carbons filters to reduce microcystins.Read More
The Walkerton Clean Water Centre (WCWC) recently completed a pilot testing project with Wauzhushk Onigum Nation, helping the community address a long-term boil water advisory that has been in place since 2012.
Wauzhushk Onigum Nation is located on Lake of the Woods in Northwestern Ontario. The lake water has high organics and colour making it a challenging water source for satisfying the requirements of UV disinfection. Before implementing decentralized point-of-entry (POE) systems for a portion of the community, Wauzhushk Onigum Nation worked with WCWC on a pilot testing project. WCWC tested POE technologies for effectiveness in removing turbidity and organics in order to improve UV disinfection. The test results were shared with consultants in the design of the decentralized water systems.
WCWC conducts pilot tests for clients to enhance their understanding of source water characteristics and the performance of treatment processes and alternative treatment options. Bench or pilot scale projects can be undertaken at a client’s location or at the Technology Demonstration Facility in Walkerton.
WCWC has years of pilot testing experience in areas such as natural organic matter, disinfection by-products, iron and manganese treatment, arsenic, and coagulation. Completed pilot testing reports are available on WCWC’s Drinking Water Resource Library, which is a free online portal that assists drinking water professionals in finding information on various topics.
To learn more about WCWC’s pilot testing services, please visit https://wcwc.ca/services/pilot-testing/ or contact us at 866-515-0550.
The spread of COVID-19 is an evolving situation that the Walkerton Clean Water Centre (WCWC) is acting upon. WCWC will continue to serve its clients and is making new resources available to the water sector daily through the Drinking Water Resource Library and the Helpline.
WCWC has added a dedicated section to the Drinking Water Resources Library containing links to guidance documents, fact sheets and free webinars related to COVID-19 for water professionals. This online system provides access to a variety of trusted resources and features multiple search functions to assist our clients in their search for information.
As well, WCWC staff will continue to respond to technical calls and provide information related to drinking water treatment processes, equipment, operational requirements and environmental factors through the Helpline. Staff will respond to inquiries during business hours, Monday to Friday, as we always have.
Visit www.wcwc.ca/drinking-water-resource-library/ and scroll down to view the folder of resources on the COVID-19 pandemic and the water sector or contact the Helpline at 1-855-306-1155 or firstname.lastname@example.org.Read More