Reclamation of Treated Domestic Wastewater Using Biological Membrane Assisted Carbon Filtration (Biomac)

Abstract

Membrane processes are increasingly used as an advanced treatment technique for the reclamation of treated domestic wastewater. Despite their inherent advantages, fouling remains an operational problem, while the removal of dissolved organic components such as volatile organic compounds is negligible. In the present work, the addition of a partially non-submerged biological granular activated carbon filtration to a microfiltration lab-scale reactor was investigated. It was observed that the reactor could be operated under stable flux conditions although regular hydraulic backwashing was necessary. Preferential attached growth of nitrifiers on the activated carbon particles allowed for a complete and very stable nitrification, with permeate total ammonium nitrogen and nitrite levels below 0.2 mg l−1 regardless of influent concentrations. Chemical oxygen demand of the permeate averaged 5.26 mg O2 l−1 which is below the Environmental Protection Agency guideline for wastewater reuse. Using an electronic nose, elimination of volatile compounds was assessed. The combined process resulted in complete odour removal, with the permeate odour levels equalling the reference samples (tap water), even during periods of increased reactor load (shock load experiment). A 4.2 log10CFU and 3.7 log10CFU removal were observed for total coliforms and E. coli, respectively.