氮掺杂生物炭负载Fe^(0)增强厌氧消化污泥脱水性能研究

sludge dewaterability through peroxydisulfate activation by zero-valent iron loaded on nitrogen-doped biochar

研究采用中密度纤维板及氧化铁皮共热解制备了负载零价铁的氮掺杂生物炭(ZVI/N BC),并用于活化过硫酸盐(Peroxydisulfate,PDS)增强厌氧消化污泥脱水性能。结果显示,初始pH值为6,PDS投加质量浓度为6.8 g/L,生物炭投加质量浓度为19.2 g/L,反应时间为35 min时,厌氧消化污泥的毛细吸水时间及含水率降低至47.93 s和67.44%。机理分析指出消化污泥脱水性能增强主要归功于ZVI/N BC+PDS的非均相氧化作用。PDS通过sp^(2)碳、吡啶氮、Fe^(0)产生·SO_(4)^(-)和·OH,高效降解细胞外聚合物(Extracellular Polymeric Substances,EPS),释放大量结合水;ZVI/N BC+PDS能通过改变胞外蛋白质二级结构,提升EPS表面疏水官能团丰度,增强消化污泥疏水性;ZVI/N BC作为骨架材料在污泥内部形成坚固的输水通道,在活性氧物种的协同作用下,厌氧消化污泥的脱水性能得到显著增强。研究为厌氧消化污泥减量提供了“以废治废”新思路。

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(t CST)and water content(W C)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.·SO_(4)^(-) and·OH were identified as Reactive Oxygen Species(ROS)during the catalytic reaction,with·SO_(4)^(-) generated primarily through the interaction of sp^(2) carbon,pyridinic N,and Fe^(0) 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.