Influence of Photoperiod on Membrane Fouling Reported in a Membrane Photobioreactor for Reclamation of Anaerobic Effluent

The combination of anaerobic and membrane photobioreactor (MPBR) technologies has generated interest as a sustainable strategy for domestic wastewater treatment. The former allows lower sludge production than aerobic technologies and energy recovery through biogas production, while MPBRs act as an advanced secondary effluent treatment. This study shows the effects of the light photoperiod on the suspension characteristics and overall performance of bench-scale MPBRs applied to an advanced secondary effluent treatment of a pilot upflow anaerobic sludge blanket (UASB). The results of the experimental runs showed the key role played by light incidence on the organisms developed and consequently on wastewater recovery performance and membrane fouling. The two light/dark photoperiods tested (9/15 h and 12/12 h) resulted in similar values for regeneration performance and membrane fouling. However, the longer photoperiod promoted a more sustainable process of nitrogen conversion associated with photosynthetic activity. In addition, longer daylight hours contributed to membrane performance characterized by more easily removable fouling using physical cleaning methods and with less residual character. Consequently, the tested technology can further improve performance in terms of long-term membrane operation and contributes to the design of an overall sustainable process.