Extracellular polymeric substances in relation to nutrient removal from a sequencing batch biofilm reactor

Abstract

Experimental investigations were performed to determine the possibility of simultaneous biological nitrogen and phosphorus removal during various biofilm processes in conjunction with biofilm characterisation, especially extracellular polymeric substance (EPS). Since biologial nitrogen removal requires an alternating exposure of anaerobic-anoxic-oxic conditions in the bulk liquid that surrounds the biofilm growth media, a sequencing batch reactor (SBR)-type operation was used. Various materials including expanded clay, polystyrene, polyurethane, and acrylic materials were used as the biofilm growth support medium. Simultaneous nitrogen and phosphorus removal was possible with SBR, but it was postulated that nutrient removal efficiencies varied with film thickness. Thinner biofilm promoted nitrification and phosphorus removal, but thicker biofilm enhanced denitrification and reduced phosphorus removal. EPS contents were similar regardless of support media types or biofilm configuration, but EPS contents gradually increased as the film growth continued after backwashing. EPS contents were increased with increased nitrogen removal, but it was difficult to define its relation with phosphorus removal. In addition, suspended solids removal was correlated well with the EPS content in the biofilms.

A comparative study of fatty acid profile and formation of biofilm inGeobacillus gargensisexposed to variable abiotic stress

“…2c-2e). Increased incubation periods result in nutrient removal, creating cell starvation, oxidative stress, consequently resulting in increased formation of EPS (Choi et al 2001). The influence of temperature, time, and salinity on the formation of biofilm with the modulation of physiological parameters has been reported for the fish pathogen Flavobacterium columnare (Cai et al 2013).…”

Characterization of the biofilm matrix composition of psychrotrophic, meat spoilage pseudomonads

“…Previous studies have found that bio-flocculation of microbes increased with increasing protein content of the matrix 39 . Some studies have also reported an increase in EPS in biofilms due to increased biomass 37 . In our study the increase in EPS secretion under low temperature was not correlated to an increase in the biomass as the biofilms were extracted at approximately similar maturity and cell count levels.…”

“…According to past research done on EPS, soluble and bound forms are distributed in different layers. Soluble EPS are distributed in outside layers in aqueous phase are weakly adhered to cells and easily dissolved in solutions 37 . Bound EPS closely accumulate on the outside of cells.…”

Development of microbial granules under alternating aerobic-anaerobic conditions for carbon and nitrogen removal

“…5.9. In fact, the thickness of biofilm has been postulated to be an important factor for nutrient removal in alternating biofilm systems (Pochana et al, 1999;Choi et al, 2001). Thin biofilm or small size granules would be advantageous for nitrification to provide sufficient oxygen flux into the deep layer of biofilm or granules, whereas a better denitrification can be expected in a thicker biofilm or a bigger granule.…”

“…5.9 shows that the mean diameter of microbial granules increased after the supply of external carbon source at all tested NLRs. In study of biofilms, Choi et al (2001) found that a thicker biofilm would benefit denitrification. This is consistent with Fig.…”