The role and significance of extracellular polymers in activated sludge. Part I: Literature review

Abstract

In biological wastewater treatment, bacteria tend to aggregate by forming flocs, biofilms and even granules. A large part of the floc structure in activated sludge is composed of extracellular polymers. The extracellular polymeric substances (EPS) are mainly responsible for the structural and functional integrity of biofilms/flocs and they are considered to be important for the physico‐chemical properties of activated sludge. This review considers the composition of EPS and proportion between the constituents. Moreover it includes the relationship between the EPS constituents and sludge properties such as sludge retention time, hydrophobicity and surface charge.

Degradation properties of protein and carbohydrate during sludge anaerobic digestion

“…In addition, some carbohydrate compounds act as extracellular polymeric substances for sludge flocs and were degraded during the first 3 days, which reduced the restriction effect of sludge flocs to protein (Raszka et al, 2006). This also contributed to the rapid degradation of protein from 3 to 21 days.…”

A review of practical tools for rapid monitoring of membrane bioreactors

“…ECPs also serve as a protective barrier; providing resistance to toxins, temperature shocks and osmotic pressure changes and prevent desiccation. Thirdly ECPs assist in nutrient acquisition by sorption of organic compounds and metal ions, as well as assisting to retain enzymes involved in the digestion of exogenous macromolecules or those used for quorum communications (Raszka et al, 2006). Lastly it has been noted by numerous authors that the production of ECPs increases when nutrient limitations occur, with most finding that the carbohydrate portion is particularly elevated (Janga et al, 2007;Sheng et al, 2010).…”

Effects of Temperature, Polymer Dose, and Solid Concentration on the Rheological Characteristics and Dewaterability of Digested Sludge of Wastewater Treatment Plant (WWTP)

“…Bands of carbonyl groups and hydroxyl groups around 2920-2950 and 3600-3200 cm −1 , respectively, represent proteins, carboxylic acids, phenols, and water (Show et al 2007;Lay et al 1999;Yeneneh 2014). The polysaccharides and proteins shown by these bands are the biopolymers which play key role in the floccu- (Neyens et al 2004;Yin et al 2004;Raszka et al 2006). …”