Right now it's summer in the Northern Hemisphere, which means that if you go to Google News and type in "algae" you'll see news stories from the last day or two of locations around the world where toxic algae warnings are taking effect and people are urged to refrain from swimming, allowing pets to swim, and even to be cautious about standing on shore, as they can potentially be exposed to air around the algae bloom.
Algae isn't all bad. A type of microalgae called diatoms that live in oceans are responsible for 50% of the planet's oxygen. Phytoplankton, another type of algae, account for half of the photosynthetic activity on Earth. Algae can be used as biofuels, or in wastewater treatment to remove bacteria, reduce biological and chemical oxygen demand, remove heavy metals, and remove nitrogen and phosphorous. Even types of cyanobacteria like spirulina can be used as nutritional supplements or as feed in the aquaculture and poultry industry.
Ironically, nitrogen and phosphorous, elements which algae can remove from wastewater, are also some of the causes. These 'nutrients' are present in agricultural runoff and storm water, spilling into surface water bodies and causing the algae blooms.
Algae of the worrisome variety are called harmful algae blooms or HABs which seem to be becoming more common. People and animals can be affected through skin contact, inhalation or by drinking contaminated water, and in fact, the EPA estimates that HAB contamination of drinking water is poised to increase.
One of the most startling facts from the CDC is study that HAB toxins from the sea were detected almost 4 miles inland from the source algae-contaminated water, transported in the air. The study centered around the red tide bloom off the coast of West Florida which occurs annually and kills fish and marine animals. Just standing on the beach during the bloom can reduce lung function in asthmatics.
Worse than inhalation and skin exposure is undoubtedly ingestion. According to the CDC, people can inadvertently swallow between 16–200 mL of contaminated water while swimming. For humans, some of the effects can include abdominal pain, headaches, neurological symptoms, vomiting, and diarrhea and even liver and kidney damage.
For animals it is seemingly far more serious. Just in the last few weeks, dogs have died in Texas, North Carolina, and Georgia. Massachusetts and New York are warning pet owners of toxic algae in ponds and lakes around the the states. Some are even positing that the recent stumbling of Florida panthers and bobcats is a result of algae exposure.
And authorities are worried about human exposure as well. Mississippi closed its beaches last month. New Jersey had to close its largest lake, dealing a major blow to the tourism and workers the lake supports. Shellfish harvesting was just stopped off the coast of Washington State due to toxins from algae.
It's clear that the blooms are getting worse, sustained for longer, and occurring in more places. Bluefield Research, an advisory firm for the water sector, estimates that over half of US lakes and reservoirs will be affected with harmful cyanobacteria by 2022. With 140 million people served by surface water in the US that figure is quite startling. They're advocating for utilities to be regularly testing for cyanobacteria. To discover that they aren't already doing that is even more jarring.
For smaller lakes and ponds it is possible to use algaecide to kill algae but this has to be done repetitively, sometimes weekly and these chemicals are often made of copper sulfate which induces cellular breakdown in the algae - not the best for plants, animals and humans either. Fish aquaculture as well has some benefits - for instance stocking fish like tilapia that feed off of algae. But they only function in waters above 65 degrees and only feed on benign types of algae.
For ponds and larger bodies of water it is possible to use flocculants and clarifiers. Clarifiers are basically settling tanks that use mechanical processes to constantly input water. The particles settle to the bottom and this 'sludge' of condensed particles is removed. Clarifiers are costly and take up quite a lot of space and it's laborious to remove the sludge. Lamella clairfiers are clarifiers at an incline, reducing the space required and making it a bit easier to collect and remove sludge but it's still cumbersome and they're even more expensive than traditional clarifiers.
DAFs, or Dissolved Air Flotation is another technology that is gaining popularity for dealing with algae. It works by dissolving air into the algae-infested water under pressure. The air is then released into another tank, forming small bubbles which fuse with the algae particles, causing the particles to float to the surface where it can then be skimmed off. DAFs are effective but they're complicated to deploy, they take up a lot of space and use quite a bit of electricity to make the air bubbles.
There are also newer filtration technologies and techniques on the market. For instance, we work with a company called AquaHD that has a hydrodynamic separator they call the Natica. It uses centrifugal forces to create laminar flow of the liquid inside of it, thereby separating particles from the clean water stream. What's cool about this technology is the significant price reduction compared to clarifiers, and even more importantly the footprint of it is significantly smaller so it's a great solution for smaller lakes and ponds that you might find in Central Park, NYC or on golf courses and the like.
Separation methods can remove between 90-90% of algae but for drinking water this is still far from perfect. For more acute instances of HAB with cyanobacteria that can negatively impact health, water utilities have to use still other techniques like activated carbon filtration and oxidation in order to remove toxins that have been released from algal cells as the algae begins to die. Unfortunately these treatment methods are not always part of a water utility's service offering.
The Safe Drinking Water Act at present does not regulate algae toxins. Coupling that with the fact that 68 percent of Americans get their drinking water from lakes and rivers, and it's evident that something needs to be done. Unfortunately, a lack of regulation leads to this issue being a political hot potato. We need innovative technological solutions to treat algae blooms, storm water, and municipal and agricultural wastewater. It's critical to preventing this crisis from becoming a permanent epidemic.
In the meantime, keep your dogs safe.