Modelling of chlorophyll-a and Microcystis aeruginosa decay under the effect of different oxidants in culture mediae toxin

ARANDA, OSWALDO; ANDRINOLO, DARÍO; GIANNUZZI, LEDA; JUÁREZ, IVAN; SEDAN, DANIELA; BLANCO, GUILLERMO; GOÑI, SANDRO; LOMBARDO, TOMÁS

Murcia

Congreso; 2° Congreso Iberoamericano y 6° Ibérico de Cianotoxinas; 2019

Universidad de Murcia

Blooms of the cyanobacterium Microcystis aeruginosa are common in many eutrophiclakes and pose a serious threat to water quality, potentially giving rise to high turbidity, food web alterations, increased production of toxic Microcystin (MC) and odorous compounds. The comparative effectiveness of oxidant treatment of M. aeruginosa cells in culture media was evaluated by applying a mathematical model of chlorophyll-a (Chl-a), cell and MC removal. The oxidants were chlorine (1-5 mgL-1), hydrogen peroxide (HP: 50- 150 mgL-1), percitric acid (PCA: 10- 50 mgL-1), and peracetic acid (PAA: 1.5-7.5 mgL-1). The Weibull distribution model was applied to assess the degree of inactivation of M. aeruginosa viability under different oxidant treatments. First-order kinetics was successfully applied to the experimental data for Chl-a decay. Using the Weibull model, it was possible to predict the required exposure time for oxidants to achieve a 99.9% reduction in viable M. aeruginosa cells with respect to the initial value (Tr). Five milligram per litre (5 mgL-1) chlorine produced a 77% degradation of MC after 72 h, with an exposure time (Tr) of 141 h. Among the peroxide treatments (HP, PCA and PAA), PCA (10-50 mgL-1) produced the highest level of MC degradation (66-69%), with low exposure times (Tr=119-125 h). This is the first modelling report of M.aeruginosa decay by oxidant treatment.