Author insight: "From biofilm ecology to reactors: a focused review"

Water Science and Technology article "From biofilm ecology to reactors: a focused review" has been made Open Access for a limited time.

Glen Daigger, Distinguished IWA Fellow and professor of Civil and Environmental Engineering, is one of the paper's authors and discusses why it is valuable for the water community.

I am privileged to be a member of the author team who prepared the recently published “From biofilm ecology to reactors:  a focused review” in Water Science & Technology, 75(4), 2017.  Prepared by a diverse international team of academics and practitioners with a broad set of interests but all working with biofilms, it presents new developments that the authors, collectively, believe are relevant to many working in the water quality field.  While biofilm system have been used historically for water quality improvement within both the drinking water and wastewater fields, use of science- and model-based approaches to the development and application of biofilm technologies has tended to lag behind that for suspended growth processes, for a variety of reasons.  This situation is changing, however, due to advances in understanding biofilms and the development of fundamentally based and useful biofilm modeling approaches.  These developments are accelerating development and application of biofilm technologies, much to the benefit of the profession as a wider range of treatment technologies are becoming practically available, thereby increasing the range of options available.

In preparing this focused review the authors have elected to not comprehensively review the recent literature but rather to highlight developments in select areas where they judge that progress is advancing biofilm science and technology development the most rapidly.  The objective was to provide a useful and condensed manuscript that can be quite useful to busy water professionals.  Topics addressed include recent advances in understanding biofilm structure, function, and ecology; an update on the performance of newer types of biofilm reactors, and advancing biofilm modeling approaches.  Biofilms create unique environments which allow development of novel microbial communities.  Partial nitritation and anammox was first observed in a biofilm system.  Moving bed biofilm reactors (MBBR’s) and integrated fixed film activated sludge (IFAS) systems are increasingly well characterized and have become important reactors types in practice.  Granular sludge essentially functions as a “biofilm without support media”, and their function cannot be fully characterized without viewing them as biofilms.  Membrane Biofilm Reactors (MBfR’s) offer interesting opportunities, with the aerobic version (Membrane Aerated Biofilm Reactors – MABR’s) receiving increased commercial attention.  Microbial Fuel Cell (MFC) technology continues to advance.  While biofilms can be useful, they can also be detrimental, for example when they grow in membrane filtration systems.

While mathematical models of biofilms have existed for some time now, their application to biofilm reactors has been hampered by a number of factors, including difficulties characterizing the hydrodynamics and mass transport characteristics of many biofilm reactors used historically and a lack of supporting data.  These barriers are being overcome, especially with the newer biofilm reactor types where the hydrodynamic conditions are more well defined and where researchers and practitioners are actively developing the necessary supporting hydrodynamic and mass transport data.  As a result, biofilm reactor models are becoming available that are both useful for research purposes but also for practice.  As a result, biofilm reactor models are beginning to become standard tools for state-of-the-art biofilm practitioners who are bring biofilm reactor modeling into practice commensurate with use of International Water Association (IWA) activated sludge models.  Researchers working with any type of biological systems for water quality improvement (drinking water, wastewater) must have a contemporary understanding of biofilms, and the use of biofilm systems is becoming necessary by competent professionals.  This review is intended to provide information helpful to both the research and practice community.

This paper is Open Access for a limited time. You can access it here: http://wst.iwaponline.com/content/early/2017/02/09/wst.2017.061