Optimization of Xhhh strain biodegradation with metal ions for pharmaceautical wastewater treatment.

Effects of three ions, Mn2+, Cu2+ and Zn2+ on biological treatment of pharmaceutical wastewater by a functional strain Xhhh were investigated. Through orthogonal tests, Cu2+ was determined to be the most important factor influencing Xhhh biodegradation performance. Biodegradation kinetic experiments demonstrated that with Cu2+concentration at about 2.00 mg l-1, the maximum of specific growth rate and specific degradation rate were obtained to be 0.033 and 0.075 d-1, respectively. The optimal levels of Mn2+ (5.00 mg l-1), Cu2+ (2.00 mg l-1) and Zn2+ (5.00 mgl -1) were achieved based on experimental results of their effects on the activities of manganese peroxidase and lignin peroxidase, and biodegradation kinetic parameters. Among three types of biodegradation kinetic models (Monod, Tessier and Contois), Tessier model was found most reasonable for kinetics description of Xhhh growth (R2 = 0.995) and pollutants degradation (R2 = 0.970) in the case of metals optimization. Both kinetics evaluation and experimental results demonstrated that optimization with the three metals made a great contribution to Xhhh growth and COD removal for pharmaceutical wastewater treatment.