Controle de biomassa Algal em águas eutróficas do semiárido: experimento em microescala com a técnica “Flock & Sink”

Abstract

Cyanobacterial bloom is the main symptom of eutrophication. The rapid growth of cyanobacteria biomass and its toxin production potential cause economic, ecological and health damages, compromising water distribution in water shortage areas, such as the Brazilian semiarid. The foreseen global climate change will induce the increase in magnitude, duration and distribution of cyanobacterial blooms. Thus, mitigating cyanobacterial nuisance is essential and urgent. Striping the water column from cyanobacteria with the combined application of coagulants and clays is a promising mitigating technique. This laboratory study examined the efficacy of coagulants polyaluminium chloride (PAC) and Tanfloc (TAN) and lanthanum modified (BML) and natural (BEN) bentonites combined application in the sedimentation of biomass from a semiarid eutrophic reservoir. Even in small doses, PAC alone was sufficient for cyanobacteria sedimentation. TAN had better results when combined with the clays. BML and BEN showed similar efficacy in cyanobacterial biomass sedimentation, although the natural clay resulted in higher turbidity in the bottom of the test tubes. The technique showed itself efficient in the algal biomass sedimentation.