Study on a novel reactor of sludge process reduction for domestic sewage treatment

A laboratory-scale novel Sludge Reduction Reactor with Arc Guide Plate (SRR) for sludge process reduction was developed in this study. Pollutant removal efficiency and biomass yield for domestic sewage treatment in the Anaerobic/Anoxic/Oxic-SRR (A2/O-SRR) process were compared with performances in a control A2/O process. One of the competitive advantages in the SRR was that part of the inert suspended solids (ISS) could be separated and discharged out of system with flux at the bottom of the SRR. Mixed liquid volatile suspended solids (MLVSS) in the A2/O-SRR system also could be steadily kept at a good level under a relatively long solid retention time. The average MLVSS/mixed liquor suspended solids (MLSS) ratio of 77.5% in the A2/O-SRR was higher than that in the A2/O process. Average removal rates of chemical oxygen demand (COD), total nitrogen (TN) and NH4(+) showed little difference, while total phosphorous (TP) removal efficiency in the A2/O-SRR decreased slightly (81.89% in the A2/O-SRR and 86.50% in the A2/O process) due to the reduction of sludge discharge. The A2/O-SRR system demonstrated a considerable sludge reduction effect, with the sludge reduction ratio of 43.8%, lower solid volume index and higher dehydrogenase activity (DHA) value in comparison to the control A2/O system. The mainly mechanisms of sludge reduction in the SRR have been proved to be the uncoupling effect under the condition of anaerobic/oxic circulation and the sludge lysis with the lack of substrate.