Assembly of Low-Dose Nonionic Surfactant Hydrophobic Functional Groups with Extracellular Polymeric Substances to Destabilize Waste-Activated Sludge and Improve Biomass Energy Recovery

To destabilize the microstructure resulting from microorganism physiology and substance combination in waste-activated sludge (WAS), this study proposes a novel approach by employing nonionic surfactants for pretreatment with a specific focus on alkyl polyglucosides (APG). Inspired by the enhanced dispersibility and targeted hydrophobic interactions of surfactants at low doses, this approach strategically applies APG pretreatment at 0.05 and 0.10 g/g TS, which boosted biogas production by 49.7 and 62.9%, respectively, compared to the control group. The analysis showed that the assembly of APG hydrophobic functional groups with hydrophobic functional groups in EPS enhanced the surface free energy of sludge particles and led to the evacuation of TB-EPS. Microbial diversity analysis reveals shifts in bacteria and archaea in response to APG pretreatment, significant as bacteria <i>Azonexus</i>, <i>Syntrophomonas</i>, <i>Lutispora</i>, and archaea <i>Methanosarcina</i> emerge as new dominant genera. When adding a low dose of APG (<0.10 g/g TS), the destabilization of sludge microstructure (weakening nonfunctional binding between sludge particles and biological enzymes) led to a significant increase in the freedom and activity of enzymes involved in methane metabolism pathways. This study can provide valuable insights for surface interface regulation and efficient biomass energy recovery of complex organic waste.