(Webinar video available to watch here)
The new EBNet Webinar series is designed to replace our annual Research Colloquium with top-quality, specialist webinars on a range of EB topics. Leading the series, with a look at “Aerobic Granules in Wastewater Treatment – Combining Novel Molecular Techniques and Technologies for Environmental Biotech” were Dr Zhiwu (Drew) Wang, of Virginia Polytechnic Institute and State University, USA and Prof. Jeremy Webb, of the National Biofilms Innovation Centre, University of Southampton. Dr Wang’s extensive experience in the field of large-scale engineering of these granules in a waste water context was combined with Prof Jeremy Webb’s insights into the underlying biofilm biology to provide a top-down, bottom-up view of these useful microbial communities. This exploration of the biology and engineering of aerobic granules was chaired by Dr Yongqiang Liu, University of Southampton.
From an engineering perspective, identifying the key parameters that enable granule formation and their continuous operation is critical to putting them to work. In waste water situations the benefits of granules over older methods include significantly reduced capital cost, a more stable process and increased dewaterability. Dr Wang has mapped the interplay of parameters which determine successful operation in plug flow reactors. Manipulation of the feast/famine regime stimulates granule formation whilst exerting a selection pressure on them via settling velocity selection helps to wash out flocs in favour of granules. In real situations, knowing the process Damköhler number and making changes to the number of bioreactor chambers (via lamella plates or hydrocyclones) provides optimal conditions for this to occur at large scale.
At NBIC, microbial aggregates (or biofilms) are studied – generally in a medical context – using techniques currently seldom deployed in EB. Insights from Prof. Webb’s talk included the growing power and role of ‘Omics and RAMAN spectroscopy for real time monitoring of the microbial composition, activity and structure. Combining this with newest developments in bioinformatics is a prerequisite for understanding more about biofilm abilities. The role of signalling molecules like Nitric Oxide or Quorum Sensing Inhibitors can have applications where biofilm manipulation is important – such as membrane cleaning. And the role that Bacteriophages play in biofilm/granule biogeography is still providing surprises – they may have key roles in the underlying architecture of microbial communities which have not been fully explored.
Exploitation of the microbial communities within granules for the purpose of water treatment and pollutant removal requires a holistic understanding of their underlying properties and the essential engineering parameters that affect large-scale implementation. Gaps in our understanding of the fundamental microbial mechanisms remain to be addressed and as Dr Liu noted, researchers in EB would benefit if the somewhat expensive techniques currently employed in medical applications were to become more accessible. Future cross-discipline collaboration will be an essential next step to bridging those gaps.