Sludge formation in the activated sludge process with a sludge disintegration unit


  • Asma Alharbi University of Wollongong
  • Mark Ian Nelson University of Wollongong
  • Annette Worthy University of Wollongong
  • Harvinder Sidhu University of New South Wales at Canberra



activated sludge, CSTR, sludge disintegration unit, wastetreatment


The activated sludge process is one of the major aerobic processes used in the biological treatment of wastewater. A significant drawback of this process is the production of excess `sludge', the disposal of which can account for 50--60% of the running costs of a plant. We investigate how the volume and mass of excess sludge produced is reduced by coupling the bioreactor to a sludge disintegration unit. References
  • A. O. M. Alharbi, M. I. Nelson, A. L. Worthy, and H. S. Sidhu. Sludge formation in the activated sludge process: Mathematical analysis. In Proc. Australasian Chem. Eng. Conf., Chemeca 2013. Chemical College, Engineers Australia, 2013.
  • Y.-C. Chung and J. B. Neethling. Viability of anaerobic digester sludge. J. Environ. Eng., 116(2):330–342, 1990. doi:10.1061/(ASCE)0733-9372(1990)116:2(330)
  • M. I. Nelson, T. Kerr, and X. D. Chen. A fundamental analysis of continuous flow bioreactor and membrane reactor models with death and maintenance included. Asia-Pac. J. Chem. Eng., 3:70–80, 2008. doi:10.1002/apj.106
  • S.-H. Yoon. Important operational parameters of membrane bioreactor-sludge disintegration (MBR-SD) system for zero excess sludge production. Water Res., 37(8):1921–1931, 2003. doi:10.1016/S0043-1354(02)00578-X

Author Biographies

Asma Alharbi, University of Wollongong

PhD student, School of Mathematics and Applied Statistics

Mark Ian Nelson, University of Wollongong

Associate Professor, School of Mathematics and Applied Statistics

Annette Worthy, University of Wollongong

Associate Professor School of Mathematics and Applied Statistics

Harvinder Sidhu, University of New South Wales at Canberra

Associate Professor School of Physical, Environmental and Mathematical Science





Proceedings Engineering Mathematics and Applications Conference