Feasibility of a Pulsed Sequencing Batch reactor with anaerobic aggregated biomass for the treatment of low strength wastewaters

This study concerns an assessment of a SBR operation that associates anaerobic aggregated biomass with a pulsed action during the reaction phase, a system named Pulsed Sequencing Batch Reactor (P-SBR). The system uses a diaphragm pump as a pulsator unit to increase the liquid-solid contact, in order to avoid dead zones and possible external mass transfer resistance. A preliminary study of the operation of the reactor was performed with a low strength synthetic wastewater with a COD near 1000 mg.l-1 and a sub-optimal temperature of 22°C. A removal efficiency of 60-70% was attained after 5 and 6 hours of reaction time. The respective organic loads were 5-6 kg COD.m-3.day-1, thus supporting the feasibility of the P-SBR system for wastewater treatment in such conditions. The results also indicate that a ratio of 1.8¿ between the swept volume delivered by the pump and the reactor volume was adequate to promote a flow turbulence in the sludge blanket and that a redox potential of near -400 mV was readily created by anaerobic bacteria after the reactor filling step.