Enhancing anaerobically digested sludge dewaterability through peroxydisulfate activation by zero-valent iron loaded on nitrogen-doped biochar
Although anaerobic digestion offers potential for valorizing waste activated sludge,it often results in a significant deterioration of the sludge's dewaterability.In this study,we developed a Zero-Valent Iron Loaded on Nitrogen-Doped Biochar(ZVI/N-BC)through a simple co-pyrolysis process involving medium density fiberboard wastes and mill scale.These materials served dual roles as a Peroxydisulfate(PDS)activator and skeleton builder to enhance the dewaterability of Anaerobically Digested Sludge(ADS).Following treatment with ZVI/N-BC+PDS,the capillary suction time(tCST)and water content(WC)of the ADS substantially decreased to 47.93 s and 67.44％,respectively,under specific conditions including an initial pH of 6.0,PDS dose of 6.8 g/L,ZVI/N-BC dose of 19.2 g/L,and reaction time of 35 minutes.Mechanistic analysis identified heterogeneous oxidation as the primary driver of enhanced ADS dewaterability in the ZVI/N-BC+PDS system.·SO4-and·OH were identified as Reactive Oxygen Species(ROS)during the catalytic reaction,with·SO4-generated primarily through the interaction of sp2 carbon,pyridinic N,and Fe0 on ZVI/N-BC,playing a pivotal role in the ZVI/N-BC+PDS treatment.Extracellular Polymeric Substances(EPS)and sludge cells were effectively decomposed by the ROS,leading to a significant release of intracellular and bound water.Simultaneously,ZVI/N-BC+PDS induced a noteworthy increase in hydrophobic groups by modifying the secondary structure of extracellular proteins,thereby augmenting the hydrophobic nature of ADS.Additionally,ZVI/N-BC facilitated the creation of rigid and permeable pathways for water outflow,acting as a skeleton builder and substantially enhancing ADS dewaterability alongside its robust oxidative capability.A feasibility study demonstrated that ZVI/N-BC+PDS exhibited remarkable ADS dewatering performance,offering higher environmental benefits and holding significant potential for further pilot-scale promotion.This research presents an innovative and sustainable technique aimed at highly efficient enhancement of ADS dewaterability,contributing to a new horizon in anaerobically digested sludge management with a sustainable perspective of treating waste with waste.
NETL
NSTL
万方数据
