By Doug Conley
In August 2014, more than 400,000 residents in Toledo, Ohio, lost access to drinking water when the Toledo drinking water treatment system shut down because of algal blooms on Lake Erie. Interestingly, downriver from Toledo, the 30,000 residents of the city of Bowling Green using the same source water remained unaffected.
The difference was the use of granular activated carbon (GAC) at the Bowling Green Drinking Water Treatment Plant. GAC is used by hundreds of drinking water treatment plants across the U.S. to remove undesirable chemicals -- including disinfection byproducts, pharmaceuticals, unpleasant tastes and odors, and more. In addition to Bowling Green, the use of GAC also protects communities in Celina, Clermont County and others from potentially harmful algal toxins.
When a treatment plant shuts down, a community not only suffers a major inconvenience but also experiences significant economic damage as retail stores, malls, restaurants, schools, public facilities, and other businesses are forced to close.
The use of GAC for the treatment of drinking water is a well-established practice among municipal water utilities in the U.S. Since the 1960s, GAC has been used to remove dissolved organic compounds from water, including those emanating from algal blooms, chemical spills and oil spills. GAC has also proven effective in removing microcystins and anatoxins as well as cylindrotoxins and saxitoxins.
The ability of GAC to protect against algal toxins while simultaneously addressing other critical challenges, such as carcinogenic disinfection byproducts, volatile organic compounds, endocrine disrupting compounds, and others, makes it a uniquely effective and affordable solution for municipal water providers.
Legislative Activity
The outbreaks of harmful algae blooms and the occurrence of harmful algal toxins have been detected across the nation. Recognizing the need to address this national challenge, the U.S. House of Representatives voted in February 2015 to approve H.R. 212, which directs the EPA to develop a strategic plan to assess and manage the risks associated with algal toxins in drinking water. The U.S. Senate has taken up a similar bill (S. 460).
About Algal Toxins
Algae occur naturally in both marine and fresh water. Nurtured by sunlight, warm water temperatures and a food source (typically phosphorus), algae can bloom on water surfaces. Harmful algal blooms can cause a variety of problems to the environment, as well as pose a threat to human health. Contact with water contaminated with algal toxins can cause flu-like symptoms and/or skin rashes.
Of particular interest to water and health experts is blue-green algae, or cyanobacteria. There are over 3,000 known species of cyanobacteria, which can tolerate a wide range of environmental conditions. While not all of these species produce toxins, those that do can produce a variety of harmful substances, including hepatotoxin, neurotoxin, dermatotoxin, cytotoxin, and endotoxin -- all of which impact the human body and its organs in a harmful and sometimes fatal way.
Of these toxins, the three most widely recognized as being linked to human health issues are Microcystin-LR (hepatotoxin), Cylindrospermopsin (hepatotoxin) and Anatoxin-A (neurotoxin). All three have been widely found in the 48 continental states.
EPA Health Advisory
On May 6, 2015, the EPA issued health advisories to protect Americans from algal toxins in drinking water. The advisories recommend 0.3 micrograms per liter (µg/L) for microcystin and 0.7 µg/L for cylindrospermopsin as levels not to be exceeded in drinking water for children younger than school age. For all other ages, the values for drinking water are 1.6 µg/L for microcystin and 3.0 µg/L for cylindrospermopsin.
Potential health effects from longer exposure to higher levels of algal toxins in drinking water include gastroenteritis and liver and kidney damage. The health advisory values are based on exposure for 10 days. While briefly exceeding these advisory levels may not indicate an immediate emergency, EPA recommends that utilities use treatment techniques to reduce levels as quickly as possible. Additional steps that can protect the public include:
- Watching for harmful algal blooms in waterbodies used as a source of drinking water
- Monitoring source water and drinking water for detection of algal toxins
- Treating drinking water as necessary to reduce/remove algal toxins
- Notifying the public if levels exceed the values outlined in EPA's health advisory
About the Author: Doug Conley is marketing manager of the Municipal Business Unit for Calgon Carbon Corporation. Calgon is a member of the Water and Wastewater Equipment Manufacturers Association (WWEMA).
