Comparative analysis between the biologi

The elimination of 4-nitrophenol (4NPh) from aqueous solutions by electrooxidation and biodegradation methods was investigated. Electrochemically, the process was studied in alkaline media on Pb/PbO anodes at a current density of 20 mA cm² and 60 °C. The biological process was carried out in mineral medium of pH 7 with 4NPh as the only carbon and nitrogen source. The strains chosen for the study were isolated from soils close to contaminated industrial aqueous streams, identified, and characterized as Neisseria sp. and Acinetobacter sp. The removal of aqueous 4NPh by electrooxidation and biodegradation was monitored by UV spectroscopy and high performance liquid chromatography (HPLC). All kinetic studies showed that in the biological process, the 4NPh concentration began to diminish in the early stages of the log phase and stabilized at the end of the stationary phase. HPLC results have demonstrated that the 4NPh concentration was reduced from 50 to 8.5 mg L⁻¹ in 10.5 h and to 4.9 mg L⁻¹ after 31 h. By electrooxidation, the best 4NPh elimination (97%) was obtained in 7 h of electrolysis, suggesting a high level of 4NPh mineralization (> 80%) and a scarce formation of aliphatic acids.