Estimation of kinetic parameters of phenol degradation by bacteria isolated from activated sludge using a genetic algorithm

Abstract

Background: the main objective of this study was to examine the growth and phenol degradation kinetic parameters for bacteria isolated from activated sludge that could register growth on phenol as high as 1410 mg L‐1. Results: phenol‐degrading bacteria of the Alcaligenes, Providencia, Acinetobacter andAeromonas genera were prevalent in the activated‐sludge tank. The degradation rate was affected by the phenol concentration; the B9‐1 and B8‐1Alcaligenes faecalis strains showed rates of 0.037 and 0.038 g L‐1 h‐1 when exposed to up to 940 mg L‐1 phenol, respectively. The B6‐2, G1, and H1‐1 A. faecalis strains showed rates of 0.036, 0.042 and 0.036 g L‐1 h‐1, respectively, when exposed to up to 1128 mg L‐1, and Acinetobacter johnsonii D1 and A. faecalis D3 strains showed rates of 0.058 and 0.049 g L‐1 h‐1, respectively, when exposed to 1410 mg L‐1 phenol. The growth kinetic parameters adjusted by genetic algorithm (GA) and the Haldane equation ranged within μm = 0.12–0.55 h‐1, μmax = 0.07–0.29 h‐1, Ks = 25–483.8 mg L‐1, and Ki = 153.7–2582.6 mg L‐1. Conclusions: the high values of μmax, Ki, and YX/S adjusted by GA showed that the studied strains are able to tolerate and degrade higher phenol concentrations compared with levels reported for single bacterial strains.