Bioflocculants from wastewater: Insights into adsorption affinity, flocculation mechanisms and mixed particle flocculation based on biopolymer size-fractionation.

Hypothesis: Microbial extracellular polymeric substances (EPS) produced from wastewater are generally heterodispersed, which is expected to influence their flocculation performances and mechanism, particularly in mixed particle systems. The different molecular weight (MW) fractions should contribute to the overall adsorption affinity and flocculation mechanism of EPS in single and dual clay systems.

Experiments: EPS harvested from bioreactors were size-fractionated into high, medium and low MW fractions (HMW, MMW, LMW, respectively).

Regeneration and reuse of microbial extracellular polymers immobilised on a bed column for heavy metal recovery.

Microbial extracellular polymeric substances (EPS) have gained increasing attention for various water treatment applications. In this study, EPS produced from nitrogen-limited glycerol/ethanol-rich wastewater were used to recover Cu and Pb from aqueous solutions. Continuous flow-through tests were conducted on a column packed with silica gel coated with polyethyleneimine, to which EPS were irreversibly attached as shown by optical reflectometry.

Valorization of glycerol/ethanol-rich wastewater to bioflocculants: recovery, properties, and performance.

Microbial extracellular polymeric substances (EPS) were produced in two membrane bioreactors, each separately treating fresh and saline synthetic wastewater (consisting of glycerol and ethanol), with the purpose of applying them as sustainable bioflocculants. The reactors were operated under nitrogen-rich (COD/N ratios of 5 and 20) and limited (COD/N ratios of 60 and 100) conditions. Under both conditions, high COD removal efficiencies of 87-96% were achieved.