Electrical impedance for bacterial metabolic activity screening-evaluation of single and mixed bacterial consortia for wastewater biodegradation

The use of an electrical impedance measurement method for selection of bacteria with high metabolic activity, specific for treatment of high loaded potato industry wastewaters was investigated. The dynamic and effectiveness of wastewater biodegradation were evaluated in two ways: by the analysis of electrical impedance changes caused by bacterial metabolism during bioremediation process as well as by the reduction of chemical oxygen demand (COD). The course of impedance signals were described with Gompertz mathematical model and a parameter of maximal impedance changes rate (Imax), expressed as % of impedance changes h^-¹, was proposed for bacterial metabolic activity screening tests. A significantly higher (p 0.05) metabolic activity of bacteria occurring in the mixed cultures in comparison with single isolates coming from them was determined. A linear correlation (r=0.89), found between the wastewater COD reduction and the values of the maximal impedance changes rate (Imax) allowed the use of electrical impedance method and the proposed parameter for easier and quicker, in comparison with classic COD measurement, evaluation of the microbial wastewater treatment capability.