Removal efficacy was influenced by the cyanobacterial biomass and at higher biomass more ballast was needed to achieve good removal. When those low dose coagulants were combined with ballast, effective settling in a dose-dependent way up to 99.7% removal of the flocks could be achieved without any effect on the zeta potential and thus without potential membrane damage. Addition of low doses of PAC and chitosan (1–8 mg Al L⁻¹) to the cyanobacterial suspensions caused flock formation, but did not settle the cyanobacteria.
We also examined if zeta potential was altered by treatments. We tested the effect of different cyanobacterial biomass concentrations on removal efficiency. Here, we studied the efficacy of combinations of a low dose coagulant (poly-aluminium chloride-PAC-or chitosan) with different ballast compounds (red soil, bauxite, gravel, aluminium modified zeolite and lanthanum modified bentonite) to remove cyanobacterial biomass from water collected in Funil Reservoir (Brazil). These nuisance organisms can be removed from water bodies by biomass flocculation and sedimentation. Cyanobacteria blooms are a risk to environmental health and public safety due to the potent toxins certain cyanobacteria can produce.
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