Low temperature nutrient removal from municipal wastewater by purple phototrophic bacteria (PPB)

This study evaluated the performance of purple phototrophic bacteria (PPB) at temperatures of 22 °C and 11 °C in a membrane photobioreactor. PPB performance and Monod parameters were evaluated at 11 °C and were compared to PPB performance at 22 °C. At 22 °C, the optimum HRT with respect to meeting target limits of TCOD < 50 mg/L, TN < 10 mg/L, and TP < 1 mg/L was 9 h with ethanol supplementation at 300 mgCODL^-1 noting that ethanol was only needed to meet the TN limit. However, at 11 °C, the photobioreactor achieved effluent TCOD, TN, and TP concentrations of 70 mg/L, 10 mg/L, and 1.2 mg/L respectively at 9 h HRT and 300 mgCOD/L ethanol addition. Monod kinetic parameters K_s, K, Y, and K_d were determined to be 20 mgCOD/L, 1.8 mgCOD/(mgVSS.d), 0.54 mgVSS/mgCOD, and 0.09 d^-1 at 22 °C and 31 mgCOD/L, 1.2 mgCOD/(mgVSS.d), 0.51 mgVSS/mgCOD, and 0.07 d^-1 at 11 °C respectively.