Experiences of algal bloom control using green solutions barley straw and ultrasound, an industry perspective

Abstract

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.Algal bloom control using barley straw and ultrasound D. Purcell et al.

Effects of Commercially Available Ultrasound on the Zooplankton Grazer Daphnia and Consequent Water Greening in Laboratory Experiments

“…However, despite several studies suggest ultrasound might be applicable in situ (e.g., [8,9]), field trials are far from conclusive. Three field trials with ultrasound in the UK were reviewed [27]; no effect on total algal concentration in all three were reported, a significant lower chlorophyll-a concentration in one experiment, but no selective inhibition of cyanobacteria [27]. In contrast, a strong decrease of cyanobacteria by ultrasound as supportive for the selective effect of ultrasound on cyanobacteria was claimed [28].…”

Evaluation of several end-of-pipe measures proposed to control cyanobacteria

“…The latter authors mentioned a case of two ponds where a combination of barley straw and aerators reduced phytoplankton biomass (Boylan and Morris 2003). Positive effects of barley straw on controlling Microcystis and cyanobacteria for some reservoirs in the UK were reported (Purcell et al 2013), but these find no strong support in the underlying data.…”

“…Although widely accepted that barley straw can be an ''effective control method'' (Purcell et al 2013), an ''effective and environmentally-sound option for the control of cyanobacterial and microalgal blooms '' (Iredale et al 2012) and ''very useful for controlling of M. aeruginosa based blooms'' (Shao et al 2013), the lag phase, the different sensitivity of organisms, the contrasting field results and the proposed underlying mechanism of oxidative stress imply that use of rotting barley straw should be met with care.…”

Ultrasonic Treatment of Algae in a New Jersey Reservoir

“…Recent work by Purcell et al (2013b) indicates that, for four cyanobacteria genera (two unicellular and two filamentous), the ultrasonic frequency used has a large impact on the removal of the different genera. This would seem to suggest that algae (or cyanobacteria) with different morphological features may have different optimum frequencies for cell removal and that increasing the power input to the water may not overcome an “incorrect” frequency for a specific genus.…”

“…Rajasekhar et al (2012) provide an excellent discussion on the impact of ultrasonic frequency on bubble resonance and the subsequent destruction of gas vesicles in cyanobacteria. Three peer‐reviewed field studies on ultrasonic treatment of water were reviewed by LaLiberte and Haber in 2014: Nakano et al (2001), Ahn et al (2007), and Purcell et al (2013b).…”