Polyhydroxyalkanoate production in a biofilm by mixed culture phototrophic bacteria

Anoxygenic purple phototrophic bacteria (PPB) were utilised in an 80 L biofilm flat plate photobioreactor to generate polyhydroxyalkanoate (PHA) over 44 cycles, with acetate as feed. Over the cycles, net PHA yield (growth + accumulation) averaged 21% while accumulation yield averaged 55%. Average PHA content was 35 wt% volatile solids (VS),...

Biotransformation of micropollutants in moving bed biofilm reactors under heterotrophic and autotrophic conditions

We investigated the transformation of four pharmaceuticals (Diclofenac, Naproxen, Ibuprofen and Carbamazepine) in a moving bed biofilm reactor subjected to different COD/N ratios in four experimental phases. The shift from medium to high range COD/N ratio (i.e., 5:1 to 100:1) intensified the competition between heterotrophs and nitrifying...

Turnover of the extracellular polymeric matrix of granules performing biological phosphate removal

Polyphosphate accumulating organisms (PAOs) are responsible for enhanced biological phosphate removal (EBPR) from wastewater, where they grow embedded in a matrix of extracellular polymeric substances (EPS). EPSs comprise a mixture of biopolymers like polysaccharides or (glyco)proteins. Despite previous studies, little is known about the...

Formation and ripening of alginate-like exopolymer gel layers during and after membrane filtration

The properties of biofilm EPS are determined by the multiple interactions between its constituents and the surrounding environment. Because of the high complexity of biofilm EPS, its constituents' characterisation is still far from thorough, and identification of these interactions cannot be done yet. Therefore, we use gels of bacterial...

Impact of metal ions on structural EPS hydrogels from aerobic granular sludge

Structural extracellular polymeric substances (structural EPS) can form stable hydrogels and are considered to be responsible for the stability of biofilms and aerobic granular sludge. Structural EPS were extracted from aerobic granular sludge and characterized for their gel-forming capacity with different alkaline earth and transition metal...

Aerobic granular sludge contains Hyaluronic acid-like and sulfated glycosaminoglycans-like polymers

Glycosaminoglycans (GAGs) are linear heteropolysaccharides containing a derivative of an amino sugar. The possibility of the presence of GAGs in aerobic granular sludge was studied by combining SDS-PAGE with Alcian Blue staining (at pH 2.5 and 1), FTIR, mammalian Hyaluronic acid and sulfated GAG analysis kits, enzymatic digestion and specific...

Bacterial community dynamics and disinfection impact in cooling water systems

Understanding the bacterial dynamics in cooling towers is imperative for the assessment of disinfection efficiency and management of microbial risks linked to aerosol formation. The objective of this study was to evaluate the impact of feed water on the cooling water bacterial microbiome and investigate the survival ability of its members...

Stratification of nitrifier guilds in granular sludge in relation to nitritation

A lab-scale partial nitritation granular sludge air-lift reactor was operated in continuous mode treating low strength synthetic medium (influent ca. 50 mg-N-NH₄ ⁺/L). Granules were initially stratified with AOB in the external shell and NOB in the inner core at 20 °C. Once temperature was decreased progressively from 20...

Chemical characterization methods for the analysis of structural extracellular polymeric substances (EPS)

Biofilm structure and functionality depend on extracellular polymeric substances (EPS), but analytical methods for EPS often lack specificity which limits progress of biofilm research. EPS were extracted from aerobic granular sludge and analyzed with frequently applied colorimetric methods. The colorimetric methods were evaluated based on...

The acid soluble extracellular polymeric substance of aerobic granular sludge dominated by Defluviicoccus sp.

A new acid soluble extracellular polymeric substance (acid soluble EPS) was extracted from an acetate fed aerobic granular sludge reactor operated at 35 °C. Acid soluble EPS dominated granules exhibited a remarkable and distinctive tangled tubular morphology. These granules are dominated by Defluviicoccus Cluster II organisms. Acetic acid...

Extraction of structural extracellular polymeric substances from aerobic granular sludge

To evaluate and develop methodologies for the extraction of gel-forming extracellular polymeric substances (EPS), EPS from aerobic granular sludge (AGS) was extracted using six different methods (centrifugation, sonication, ethylenediaminetetraacetic acid (EDTA), formamide with sodium hydroxide (NaOH), formaldehyde with NaOH and sodium...