How effective aerated continuous electrocoagulation can be for tetracycline removal from river water using aluminium electrodes?

The study assessed the effects of aeration on continuous electrocoagulation (EC) for tetracycline (TCL) removal from river water. Influence of hydraulic retention time (HRT) and initial drug concentration on treatment efficiency was tested. Best conditions for continuous EC operation were 12 min HRT, electrode spacing 2 cm, 9 V, and Al-Al electrode combination. Highest COD removal with non-aerated EC was 59.4% at 1 mg L initial TCL concentration and further increasing TCL concentration decreased COD removal efficiency. Maximum TCL removal was 66.6% at 10 mg L initial TCL concentration with non-aerated EC. Aerated EC enhanced COD and TCL removal to 61.4% and 71.5%, respectively. In XRD and FTIR spectra no new peaks were detected following EC treatment. XRD, FTIR and FESEM-EDS data supported that significant removal of TCL occurred by charge neutralization, entrapment, adsorption and precipitation driven by Al (OH) flocs. Pseudo-second order reaction rate constants explained the kinetics of TCL removal from river water. Sludge volume produced with continuous mode EC non-aerated and aerated EC was 31 cm and 39 cm, respectively. Operating cost was estimated to 0.018 US$/m for non-aerated EC and 0.025 US$/m for aerated EC. EC can be augmented by aeration for enhanced removal of TCL from river water.