Proceedings

This paper reports the main findings of a research project undertaken by the authors to identify the fundamental biophysical factors determining the behaviour of activated sludge in municipal wastewater treatment. The biophysical and biochemical factors determining how
flocs form and how the system microbial ecology is shaped were found to originate with how Arden and Lockett carried out their experiments in 1914. This paper describes how biophysical factors relate to microbial ecology and the key role of heterotrophic prokaryotes within it, how floc-forming and filamentous bacteria actually compete and how floc forming bacteria evolved the ability to produce EPS. The core hypothesis is then also applied to operational problems in activated sludge plants and to biofilm reactors, to provide designers and operators with risk analysis parameters for municipal wastewater biotreatment.

Keywords: Biotreatment system biophysics, activated sludge bulking, EPS, biofilm risks.