A kinetic study of combined aerobic biological phenol and nitrate removal in batch suspended growth cultures

Abstract

The progress of biological phenol and nitrate removal in batch assays of mixed bacteria culture was examined. The aim was to study the performance of the culture for biological phenol and nitrate removal in synthetic wastewater containing phenol and nitrates at various concentrations, under aerobic conditions. The maximum removal rates achieved were 1.07 mg NO 3 −-N l −1 h −1 and 27.8 mg phenol l −1 h −1, for feed concentrations 20 mg NO 3 −-N l −1 and 600 mg phenol l −1 in a draw-fill experiment. The kinetics of the process was studied in batch cultures of suspended bacteria acclimatized in phenol and originated from olive pulp. The rates of phenol and nitrate biological removal were found to be inhibited beyond 40 mg NO 3 −-N l −1 and 300 mg phenol l −1, respectively. A kinetic model was developed and its kinetic parameters were determined. The growth kinetics could be very well described by using expressions for triple nutrient limitation (nitrate, nitrite, phenol) with inhibition from nitrate and phenol. The proposed model is capable of describing accurately enough, cellular growth, nitrate, nitrite and phenol utilization, in the presence of various concentrations of nitrate (20–100 mg NO 3 −-N l −1) and phenol (300–950 mg phenol l −1).