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.firstname.lastname@example.org).
C. A. Aragon-Cruz is with Foundation Center for New Water Technologies, CENTA, Seville, Spain (e-mail: email@example.com).
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.