An overview of our research
Why investigate activated sludge?
Almost all modern wastewater treatment systems rely on microbial processes for the removal of contaminants. For this reason, wastewater treatment is often regarded as one of the largest biotechnology industries in the world, with a global market estimated at several hundred billion dollars.
The activated sludge process, which was developed over 80 years ago, is one of the most widely used forms of wastewater treatment in industrialised nations. The underlying principle of this process is the conversion of organic matter and nutrients to microbial biomass which is then able to be separated from the waste stream, leaving a clarified effluent.
Despite the comparative sophistication of modern wastewater treatment plants, suboptimal treatment or complete system collapse are still very common problems in the waste treatment industry. The main reason for this is that our understanding of the factors controlling the structure and function of the key microbial communities is still rudimentary.
Our integrated ecological and genomic research programme is attempting to address this knowledge gap.
Our research programme
Our research is focused upon three levels of biological organisation:
1. The individual organism
Central to our research is the bacterium Acidovorax, which is commonly found in activated sludge. We have isolated a strain of Acidovorax with two different morphotypes which differ in their ability to form flocs and biofilms—processes which are important in wastewater treatment systems.
We are in the final stages of completing the genome sequence of this Acidovorax strain. This has been carried out using a whole-genome shotgun sequencing approach.
The genome has enabled prediction of metabolic capabilities of Acidovorax and has also supported the development of functional genomic tools such as genetic systems and gene expression microarrays, which we are using to investigate genes and metabolic processes involved in biofilm formation and aggregation.
We are also undertaking proteome analyses to identify differentially expressed surface and cytoplasmic proteins. In addition, we have developed a protocol for transformation of Acidovorax and genetic tools for construction of gene knock-outs by homologous recombination.
2. The microbial community
We are using molecular and microbiological methods to investigate bacterial community dynamics in activated sludge, and the role of Acidovorax within this community.
We are also conducting a long-term study of bacterial community dynamics in three municipal treatment plants employing activated sludge processes.
3. The wastewater treatment ecosystem
By combining biological information from Acidovorax and microbial community studies with physical treatment process data, we can investigate linkages between microbial community dynamics and treatment system operation and performance.
Learn more about Acidovorax >>>
Learn more about the role of activated sludge in wastewater treatment >>>
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Research applications
Our research is providing improved understanding of the nature and function of microbial communities in wastewater treatment systems. This offers the potential for improved effectiveness and reliability of treatment processes, and for development of leading edge technology for the wastewater treatment industry.
The long term studies of microbial community dynamics provide a valuable resource for diagnosis of problems in wastewater treatment processes, and a basis for development of tools for control of treatment processes.