The impacts of different types of commercial algaecide products on cyanobacteria control and intracellular organic matter releases

Cyanobacterial harmful algal blooms (cHABs) pose great challenges to public water systems when producing safe drinking water. Applying algaecide is one of the most common methods to control the cHABs in source waters, however, it can cause cell lyses and release the intracellular organic matter (IOM) and the toxins, which are difficult to remove in public drinking water systems with conventional drinking water treatment processes. In this study, we evaluated four commercial algaecide products (two copper-based and two peroxide-based) and assessed the impact of algaecide treatment on cyanobacteria cell removal and the release of IOM and toxins. The optimal dose and the treatment time of each product were determined using both granular (Microcystis aeruginosa) and filamentous (Planktotrix agardhii) cyanobacteria. A Parallel Factor Analysis (PARAFAC) model was built using collected Excitation-Emission Matrix (EEM) spectra from collected samples under different algaecide treatment time and doses to characterize and quantify the release of IOM during the treatment. The obtained results may help public water systems better control HABs without causing adverse impacts on finished water quality.