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Algal Bloom Mitigation: Innovative Strategies and Industry Pioneers


In the world of water management, the serenity of pristine lakes and rivers occasionally faces a disruptive presence: harmful algal blooms (HABs). These blooms not only create a visually unappealing body of water, but can also cause harm to the ecosystems within and around the bloom. Fortunately, there are a variety of tools across chemical, mechanical, and biological means, dedicated to both mitigating and preventing these blooms from occurring. 


The spectrum of algal bloom mitigation strategies is diverse, offering a range of tools and techniques. Chemical algaecides, for instance, work by targeting algal cells, disabling their reproduction or overwhelming their metabolic pathways. Copper sulfate, arguably the most common of this category, limits cell division with copper ions, which are toxic to most varieties of algae. This works rapidly and locally, albeit with a non-selective nature that demands careful application to avoid collateral harm to non-target species, such as local fish, which can also be affected by copper ions. 


Innovative compounds, such as encapsulated peroxides, are on the forefront of chemical treatments for algal bloom mitigation and prevention. BlueGreen Water Technologies, for instance, has harnessed the power of peroxides to trigger programmable cell death (‘PCD’). Sodium percarbonate, which degrades into hydrogen peroxide (an industry standard algaecide), is used to overwhelm the biological systems of algae cells, causing cell-death cascades that eliminate algal blooms. This technology offers a controlled approach to targeting harmful algae while preserving other aquatic life.



BlueGreen Water Technologies’ Lake Guard OXY, the treatment described above.


While not strictly an algaecide, shading dyes are colored substances that are added to the water to alter its optical properties, primarily by reducing the penetration of sunlight into the water column. They work by absorbing and scattering light, creating shading effects that limit the depth at which photosynthesis can occur. As a result, existing algae deeper in the water column dies off, and new algae struggles to grow. 


Mechanical technologies are also used to mitigate HABs. By manually altering the flow of nutrients through a body of water, or adding oxygen to water to rejuvenate eutrophic ecosystems, companies can prevent algal blooms from growing out of control. Manual water column mixing, for instance, breaks down stratification between the different layers of a body of water, ensuring even nutrient distribution and stifling algal growth. 


Companies also offer a range of mechanical aeration solutions. Of particular note are Alarivean’s nanobubblers, which introduce oxygen, ozone, or hybrid gasses into bodies of water affected by HABs in situation specific mixtures. This ozone gas not only disrupts algal cells in much the same way as peroxide, but can both restore oxygen to hypoxic environments and sequester nutrients such as phosphorus and nitrogen through oxidation reactions.



ART takes off onboard Alarivean’s Sea Breather, a vessel used to apply nanobubbles.


Existing mechanical technologies have also been innovatively repurposed to mitigate HABs. Surface skimmers generally used to clean oil spills, for example, are a direct way to remove algal blooms from the surface of a water body, especially in the later stages of a bloom. This type of treatment is often coupled with the application of coagulants, which cause groups of algal cells to sink to the low-oxygen depths of a water body, and/or flocculants, which cause bloom-feeding nutrients to do the same. AECOM’s Hydronucleation Flotation Technology (HFT), takes this process a step further, removing algae from water and processing it into usable aviation fuel, returning clean water as a by-product.


Removing algae via mechanical or chemical means has historically proven to be effective. Directly targeting the nutrients that allow algal blooms to exist in the first place, though, is also a productive means of preventing algal blooms. Total prevention of harmful blooms, although difficult, is the ultimate goal of HAB-fighting tech.


As phosphorus is frequently the limiting nutrient that drives algal growth in water, there are several commercial solutions available for nullifying or removing phosphorus from bodies of water that are or could be affected by a harmful bloom. PET Water Technologies’ Phoslock, for example, uses bentonite clay to bind with phosphorus, creating inert molecules of a naturally-occurring mineral. Eutrosorb, from SePRO, functions similarly, but comes in several varieties that can target phosphorus in sediment or in the water column. 


Ecosystem-based solutions, which use biological principles against algae, have seen both long-term use and recent innovation as an alternative to artificially-derived means of bloom mitigation and prevention. They focus on limiting nutrient runoff into bodies of water. Features like riparian wetlands and bioswales utilize plants and microorganisms that absorb nutrients from runoff, removing them as a source of algal bloom growth. These are especially useful when non-target species are of concern. Barley straw bales, beginning in England in the 1990s, have also been found to be effective preventative measures when placed into bodies of water that could be affected by a bloom. As they decay, though, they have the potential to deoxygenate the water they’re placed into, limiting their usage. 



The world’s first floating water treatment wetland, in Australia’s Sunshine Coast. Image obtained from news.com.au


There are dozens of additional solutions to harmful algal bloom growth, ranging across the types of treatment discussed here. The battle against algal blooms is a testament to human ingenuity, scientific innovation and ecological stewardship, but also to the scale of the growing problem. With a focus on cleaner waters, healthier ecosystems, and a brighter aquatic future, the power of innovation drives us toward a future free of harmful algal blooms. 


SOURCES:

  1. Resources for Mitigating HABs (California Water Quality): https://mywaterquality.ca.gov/habs/resources/mitigating_habs.html

  2. Mitigating the Expansion of Harmful Algal Blooms Across the Freshwater-to-Marine Continuum. Hans W. Paerl, Timothy G. Otten, and Raphael Kudel. Environmental Science & Technology 2018 52 (10), 5519-5529. DOI: 10.1021/acs.est.7b05950

  3. HABSlayer AOPs (Alarivean): https://alarivean.com/system/aop/

  4. Water Formulations (BlueGreen Technologies) : https://bluegreenwatertech.com/water-formulations

  5. Eutrosorb (Eutrosorb): https://eutrosorb.com/

  6. Control Measures for Cyanobacterial HABs in Surface Water (Environmental Protection Agency): https://www.epa.gov/cyanohabs/control-measures-cyanobacterial-habs-surface-water

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