Integrated performance and techno-economic evaluation of pilot-scale Catalytic Wet Peroxide Oxidation (CWPO) for toxic cyanobacteria and cyanotoxins removal

The increasing occurrence of toxic cyanobacteria blooms in drinking water sources poses a global health risk, underscoring the need for new, economically viable, and eco-friendly treatments. Catalytic Wet Peroxide Oxidation (CWPO), using natural magnetite, has shown strong potential for degrading cyanobacteria and cyanotoxins, though scaling it up for continuous, large-scale treatment remains challenging. This study evaluated the CWPO process at pilot scale using a continuous stirred slurry tank reactor (3 L) coupled with continuous magnetite recovery to degrade microcystin-LR (MC-LR), one of the most prevalent cyanotoxin worldwide, under ambient conditions. Key operational variables (including magnetite concentration, initial H 2 O 2 concentration, and pH) were optimized. Under optimal conditions ([Fe 3 O 4 ] = 8 g L −1 ; [H 2 O 2 ] 0 = 12.6 mg L −1 ; flow rate = 50 mL min −1 ; pH 0 = 3.5), the process achieved up to 90% MC-LR degradation. Simultaneous elimination of cyanobacteria (>99.9%) and 85% cyanotoxin reduction was achieved in the presence of Microcystis aeruginosa cells (50 μg L −1 , measured as chlorophyll- a ). A slight process intensification ([Fe 3 O 4 ] = 10 g L −1 ; [H 2 O 2 ] 0 = 15 mg L −1 ) allowed increasing to 95% the cyanotoxin degradation, resulting in a fully non-toxic effluent (Daphtoxkit-F ISO standard 6341 procedure). Finally, an industrial-scale design was proposed for a Drinking Water Treatment Plant (DWTP) designed for 10,000 population equivalent, with estimated costs of 0.19 € per treated cubic meter after economical optimization. Electricity for aeration, hydrogen peroxide consumption and pH adjustment were identified as the main contributors to the overall operating cost. This approach offers a safe and sustainable, advancing innovative water treatment technologies. • A pilot-scale CWPO system using natural magnetite effectively degraded >95% cyanotoxins and eliminated >99.9% cyanobacteria. • Continuous catalyst recovery by magnetic separation ensured high stability and reuse with minimal Fe leaching (<0.1%). • Process optimization identified an optimal H 2 O 2 /Fe 3 O 4 ratio of 1.5–2 mg g -1 for maximum efficiency and low reagent consumption. • Treated effluent was rendered non-toxic, confirmed by Daphnia magna bioassays under ISO standard procedures. • Techno-economic analysis demonstrated feasibility at 0.19 € m -3 , making CWPO competitive with conventional DWTP oxidation processes.