Water companies in the United Kingdom have been dealing with seasonal algal blooms for many decades, with escalating costs as bloom occurrences have increased markedly with elevated demand on water supply. Environmentally friendly water treatment solutions, such as ultrasound and barley straw, are defined as those that use less energy and chemicals. Barley straw has been used quite extensively by certain UK water companies, and results are generally positive. Ultrasound has only recently been used as a treatment for algal removal, with limited results from several successful trials finding cyanobacteria to be the most susceptible algal group at field scale, with results also indicating susceptibility in other algal groups; however, energy costs are higher than barley straw. Ultrasound has been extremely successful at removing bacteria in wastewater treatment; therefore, ultrasound should be considered as an in-works solution where its effectiveness would be enhanced while reducing energy requirements.
Purcell, D., Parsons, S., Jefferson, B., Holden, S., Campbell, A., Wallen, A., Chipps, M., Holden, B., & Ellingham, A. (2013). Experiences of algal bloom control using green solutions barley straw and ultrasound, an industry perspective. Water and Environment Journal, 27(2), 148-156. https://doi.org/10.1111/j.1747-6593.2012.00338.x