A Review of the Role of Extracellular Polymeric Substances (EPS) in Wastewater Treatment Systems

Abstract

A review of the characterization and functions of extracellular polymeric substances (EPS) of microbial aggregates in biological wastewater treatment systems is presented in this paper. EPS represent the complex high-molecular-weight mixture of polymers excreted by microorganisms generated from cell lysis as well as adsorbed inorganic and organic matter from wastewater. EPS exhibit a three-dimensional, gel-like, highly hydrated matrix that facilitates microbial attachment, embedding, and immobilization. EPS play multiple roles in containments removal, and the main components of EPS crucially influence the properties of microbial aggregates, such as adsorption ability, stability, and formation capacity. Moreover, EPS are important to sludge bioflocculation, settleability, and dewatering properties and could be used as carbon and energy sources in wastewater treatment. However, due to the complex structure of EPS, related knowledge is incomplete, and further research is necessary to understand fully the precise roles in biological treatment processes.

Methane Oxidation Coupled to Selenate Reduction in a Membrane Bioreactor under Oxygen-Limiting Conditions

“…EPS are metabolic products accumulating on the bacterial cell surface, forming a protective layer against harsh external environments such as oxygen stress and also serving as carbon and energy reserves during starvation. − Considering the biodegradable and reductive capability of EPS, it is assumed that EPS might participate in selenate reduction in batches B and C. Our speculation was further supported by the observed decreasing trend of EPS contents during batches B and C along with the reduction of selenate, in contrast to the almost steady EPS contents in batch A (Figure E). This implies that EPS accumulated might be degraded into available electron donors to support selenate reduction in batches B and C. It should be noted that EPS contents could be influenced by multiple other factors; thus further research is required to confirm whether EPS was indeed utilized for selenate reduction under methane-absent or oxygen-absent conditions.…”

Deciphering the Interplay of Sludge Age and Aeration on Reactor Performance and Microbial Dynamics in High-Rate Contact Stabilization

“…EPS is important for the biosorption of organics from wastewater contributing to carbon capture. 41 The protein and polysaccharide contents in TB-EPS were always the highest among all types of EPS (Figure 3). The protein concentrations in all EPS fractions were three to six times higher than the polysaccharide concentrations, which is similar to previous research on activated sludge.…”

An Overview of the Impact of Pharmaceuticals on Aquatic Microbial Communities

“…Their polymeric matrix is composed of extracellular polymeric substances (EPS) secreted by the cells [ 70 ], consisting of polysaccharides and other biomolecules such as proteins, lipids, and nucleic acids [ 71 ]. EPS are the main ones responsible for ECs sorption processes on biofilms [ 72 ] as well as the interactions between pollutants and bacterial cell surface, for example, through the production of vesicles and other compounds that capture and/or solubilize ECs [ 5 ].…”