AE2S - Blue Green Algae Mitigation

Cyanobacteria

By: Deon Stockert, PE; Grant Meyer, PE; David Brown, PE; Mary Anderson; Colleen Anderson

Cyanobacteria, also known as blue-green algae, is a phylum of bacteria that obtains energy through photosynthesis and is often present in surface waters in the late Summer to early Fall. The presence of cyanobacteria in surface water bodies used as drinking water sources or recreational waters is a particular concern to utilities across the Midwest, as research has shown a correlation between cyanobacteria exposure and several potential human health effects.

Certain cyanobacteria produce cyanotoxins such as Anabaena, Aphanizomenon, Cylindrospermopsis, Microcystis, or Oscillatoria, among others. Cyanobacteria can also produce microcystin, a harmful cyanotoxin, and geosmin, a problematic, taste and odor causing constituent. At times, rapid and abundant reproduction of cyanobacteria results in blue-green algae blooms. Such algae blooms not only cause undesirable taste and odor events, but can result in elevated levels of cyanotoxins and microcystin, which can be dangerous to animals and humans.

According to the Center for Disease Control (CDC), exposure to high concentrations of cyanotoxins can cause damaging health effects to humans. Some of the potential effects include:
- stomach and intestinal illness
- trouble breathing
- allergic responses
- skin irritation
- liver damage
- neurotoxic reactions, such as
tingling fingers and toes

Scientists are exploring the human effects associated with long-term exposure to low levels of cyanotoxins. Some studies have suggested that such exposure could be associated with chronic illnesses, such as liver cancer and digestive-system cancer.

For more information visit: http://www.cdc.gov/hab/cyanobacteria/about.htm

Other types of toxins produced as a result of blue-green algae blooms include dermatoxins, gastrointestinal toxins, hepatotoxins, cytotoxins, and neurotoxins. These toxins can have effects ranging from rashes to asthma, and under extreme conditions can cause paralysis, cancer, or death.

In addition to posing a potential hazard to animals and humans that may encounter cyanobacteria present in blue-green algae blooms at the surface of fresh water bodies, the algae blooms can also have a negative effect on fish and aquatic life. As blue-green algae blooms (cyanobacterial cells) begin to die off, the cells are broken down by microbial organisms, which in turn create a biological oxygen demand in the water. This oxygen demand can result in decreasing concentrations of dissolved oxygen in the water body, thus causing strain on fish and other aquatic life forms in the water body, or even resulting in fish kills.

Unfortunately, there is no quick and easy remedy for the control of blue-green algae blooms within a lake or pond. Reducing the amount of nutrients that wash into lakes and ponds could eventually reduce the frequency and intensity of blue-green algae blooms, but it may take a long time and a lot of public involvement to effectively change the nutrient concentrations in a water body. Regulatory agencies are working with communities around the region to reduce stormwater runoff, and to encourage agricultural practices that don’t enhance algal blooms.

Most municipal drinking water treatment plants with surface water supplies do not regularly monitor for the presence of cyanobacteria and associated algal toxins in their raw water supplies. However, it is likely that most plants have treatment processes in place that will at least partially remove algal toxins, such as flocculation and sedimentation processes that use chemicals to bind together and settle out colloidal particles, or conventional filtration. Technologies are available for partial mitigation of algae blooms in surface water bodies, as well treatment processes for the removal of algae once it enters treatment facilities. Additional physical and chemical treatment processes are available for the removal and/or inactivation of algal toxins, such as powder activated carbon addition or granular activated carbon adsorption.

AE2S has the qualified staff and experience to ensure the best solution to your blue-green algae problems and concerns. AE2S is currently designing a water treatment plant for the City of Fairmont, Minnesota which will incorporate advanced algae and cyanotoxin removal technologies in conjunction with the City’s raw water source, Budd Lake. Budd Lake experiences significant blue-green algae blooms on an annual basis. For more information on this topic, please contact AE2S, or visit: http://dnr.wi.gov/lakes/bluegreenalgae/