Living the Granular Life! Microbial ecology of biological phosphorus removal in granular sludge systems.

Aerobic granular sludge (AGS) represents a true revolution in the field of biological wastewater treatment with significant advantages in comparison to conventional activated sludge, such as low energy use, small footprint, process efficiency, recovery of biopolymers & phosphorus...).The granulation process relies on the specific metabolism of carbon-storing bacteria, such as polyphosphate accumulating organisms (PAO). The most intensively studied PAOs in AGS are Accumulibacter species, but these bacteria have a very narrow substrate range (i.c. the volatile fatty acids VFA acetate and propionate). Other abundant putative PAOs using broader substrate ranges have been identified in (conventional) biological wastewater treatment systems, but their role in granulation and biopolymer formation remains unexplored.The main objective of the current proposal is to investigate (1) the formation of AGS, and (2) the production of the valuable gel-forming alginate-like extracellular polysaccharides (ALE), in well-defined enrichments of putative PAOs, other than Accumulibacter, by applying carbon substrates other than the VFAs acetate and propionate. Advanced microbial analyses, i.e. quantitative PCR (qPCR) and 16S rRNA gene amplicon sequencing analysis, will be used to monitor taxonomic composition of the microbial community in the sludge during the enrichments.The results of the project will have a significant impact on the development of the aerobic granular sludge technology. The results will help define the application potential of the technology, by pointing out the type of wastewaters that can be treated. Increased knowledge of the key PAOs involved in granulation is also very useful in view of the optimization of the treatment process as it allows tuning the reactor operation in favor of the desired PAO.

Keywords:ACTIVATED SLUDGE, MICROBIAL ECOLOGY, PHOSPHORUS

Disciplines:(Waste)water treatment processes