International Journal of Environmental Science and Development

Abstract—The reduction of sewage sludge generated in wastewater treatment plants is one topic of interest due to the high cost related to the management of this waste and the rising amount of volume at which sludge is produced worldwide. Within the techniques to reduce sludge, the Oxic-Settling-Anaerobic (OSA) process is one of the most promising due to its simplicity and to the absence of negative consequences for system. In the OSA process the recycled sludge is submitted to an anaerobic stage prior to flow again into the biological reactor. In this study, OSA process is run in a lab scale pilot plant together with a lysis step by ultrasound treatment, applied daily to a certain fraction of the total sludge of the system previously to the anaerobic holding tank. Results point to an enhancement of sludge reduction rate for the two sonication applied regimes (45.72% and 78.56%). Also the TN removal rate increases from 21.95% during control stage to 47.28% during the first of the two ultrasound regimes applied (US1). A too intense sonication treatment during the second synergic stage (US2) is reported to lead to a serious damage of system. Increases of dehydrogenase activity were described during both stages.

Index Terms—Activated sludge process, excess sludge reduction, OSA process, ultrasound.

P. M. Romero-Pareja, J. M. Quiroga-Alonso, and D. Coello-Oviedo are with Environmental Technologies Department, University of Cadiz, Spain (e-mail: Pablo.romero@uca.es).
C. A. Aragon-Cruz is with Foundation Center for New Water Technologies, CENTA, Seville, Spain (e-mail: caragon@centa.es).

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Cite: P. M. Romero-Pareja, C. A. Aragon-Cruz, J. M. Quiroga-Alonso, and D. Coello-Oviedo, "Sludge Reduction and General Performance in a Combined US+OSA System," International Journal of Environmental Science and Development vol. 8, no. 6, pp. 404-407, 2017.