Kinetics of Phenol Biodegradation by an Indigenous Pseudomonas citronellolis NS1 Isolated from Coke Oven Wastewater

Coke oven wastewater from the iron and steel plant industry is composed of highly refractory and recalcitrant phenolic pollutants. To overcome the process instability, inhibition, and poor performance of coke oven wastewater treatment plants an efficient phenol degrading bacterial culture was isolated from the coke oven wastewater of a local steel plant industry in Odisha, India. In this study, the kinetics of phenol biodegradation by a newly isolated Pseudomonas citronellolis NS1 was carried out using batch shake flasks. The results revealed that the culture could degrade 1,500 mg/L⁻¹ of phenol almost completely within 90 h as the sole source of carbon and energy. In addition, under these conditions, approximately 95.5% of the chemical oxygen demand (COD) and 98.5% of toxicity removal were achieved by the indigenous P. citronellolis NS1. The growth and biodegradation kinetics of the isolated Pseudomonas species were evaluated at phenol concentrations pf 50–1,500 mg/L⁻¹. The specific growth rate of the culture followed the substrate inhibition kinetic pattern and the estimated biokinetic parameters were; μ = 0.246 h⁻¹, K_si = 890 mg/L⁻¹, and K_s = 14.85 mg/L⁻¹. Further, the effects of temperature on the biodegradation of phenol were carried out. The estimated values of maximum phenol biodegradation rate and the activation energy (E_a) of the enzyme-catalyzed reactions were 0.0152 h⁻¹ and 47.21 kJ · mol⁻¹ respectively at 36°C.