Kinetic study on biodegradation of glyphosate with unacclimated activated sludge

This article is concerned with the study of biodegradation of an organophosphorus herbicide (glyphosate) using unacclimated activated sludge. Glyphosate at different concentrations (0.1, 0.5, 1, 2 and 5 g/L) was tested for cellular growth. On the other hand, the effect of glyphosate on its own biodegradation was studied by evaluating the fittings of different kinetic models (Andrews, Aiba et al., Han and Levenspiel, Luong, Tessier, Webb, Tseng and Wayman, Yano and Koga). According to the obtained results, the activated sludge was able to use glyphosate as the sole carbon source; however, 2 and 5 g/L glyphosate seemed to inhibit cellular growth. Moreover, glyphosate at initial concentrations of 0.1, 0.5 and 1 g/L was completely degraded within 4, 13 and 18 h of incubation, respectively. Yano and Koga model was the best-fit model (R² = 0.999, F = 173,106 and P = 0.000006).