摘要
本文对快速培养性能稳定的好氧颗粒污泥(AGS)进行研究,记录接种活性絮状污泥(AS)培养成AGS的外观形貌变化过程,并从微观层面揭示AGS机械强度高、稳定性强的原因。另外,从力学层面研究AGS的胞外聚合物(EPS)对Cd^(2+)的吸附机理,对AGS-EPS能否成为具有潜力的生物吸附剂进行验证,以揭示AGS在水处理领域的优势作用。培养过程中,第85 d反应器内污泥形态稳定,污泥粒径由31.59μm增至442.72μm,污泥磷含量增长232.70%,从25.93 mg/g增长至86.27 mg/g。16s rRNA基因高通量测序结果表明,Chloroflexi可能是颗粒污泥的初始颗粒框架,而Proteobacteria是污泥颗粒化的核心菌门;聚糖菌Candidatus_Competibacter和聚磷菌Candidatus Accumulibacter是污泥颗粒化的核心菌属。从AS到AGS的培养,EPS含量从79.18 mg/g VSS增至133.63 mg/g VSS,3维荧光光谱(3D-EEM)证实AGS-EPS含有更高水平的蛋白质,驯化过程中细胞分泌的蛋白质分解溶解性降低,更加有利于生物膜中微生物细胞凝聚;傅里叶红外光谱(FTIR)和蛋白质2级结构研究表明,两类EPS均含有醇酚、糖类中的—OH、—CH、C—O、C—C,糖醛酸中的羧酸盐基团,蛋白质中的N—H及烷烃类有机物,而AGS-EPS具有更丰富的多糖种类,稳定的细胞结构。颗粒化培养使AGS对Cd^(2+)的吸附机理发生了变化,吸附动力学研究表明ASEPS对于Cd^(2+)的吸附,同时存在物理、化学吸附;AGS-EPS对于Cd^(2+)的吸附适合用拟2级动力学模型来拟合,具有更强的生物化学属性。吸附热力学研究表明,两类EPS对于Cd^(2+)的吸附实验适合用Langmuir模型来拟合,该吸附过程属于均相单分子层吸附,而AGS-EPS的理论最大吸附容量大于AS-EPS,分别为617.09 mg/g、542.90 mg/g。实验过程证明:在高磷环境中增加COD含量能够提升污泥的除磷性能,对于污泥颗粒化的培养具有积极作用;颗粒化的培养使得污泥的物理、化学性质均得到了强化;颗粒污泥培养的副产物AGS-EPS具有更强的Cd^(2+)吸附效果,其对Cd^(2+)的吸收主要为生物化学作用,也说明了AGS在污废水处理领域具有更大的潜力。
Objective Due to the advancement of industry and the improvement of residents’living standards,the urban sewage treatment load continues to increase,making it urgent to develop cost-effective water treatment technologies.In recent years,aerobic granular sludge(AGS)has been increasingly applied in practical projects because of its high stability and good pollutant removal efficiency.This study examines the rapid cultivation of stable AGS,records the changes in appearance and morphology of inoculated activated sludge floc(AS)and AGS,and reveals,at the microscopic level,the reasons why the structure and stability of AGS are superior to those of AS.In addition,this study investigates the adsorption mechanism of Cd^(2+)by the extracellular polymeric substances(EPS)of AGS from a mechanical perspective and verifies whether AGS-EPS exhibits a higher pollutant removal capacity.Methods The sludge was collected from the secondary sedimentation tank of a wastewater treatment plant in Hefei and was pretreated to obtain cleaner inoculating sludge.It was divided into two portions:one was used for research,and the other was concentrated and placed into the SBR reactor.The process of granular sludge cultivation was documented,including morphological transformations and variations in key indicators.The microbial community structure was analyzed through high-throughput sequencing of 16 s rRNA genes.Changes in EPS content before and after sludge granulation were determined,and the EPS was characterized using Three-Dimensional Excitation Emission Matrix Fluorescence Spectroscopy(3D-EEM)and Fourier Transform Infrared Spectroscopy(FTIR)to analyze the structural differences between AS and AGS.At the mechanical level,kinetic and thermodynamic models were employed to fit the adsorption experiments of AS-EPS and AGS-EPS for Cd^(2+).Results and Discussions During the domestication of AS into AGS,on the 85th day,the sludge morphology stabilized,and the sludge particle size increased from 31.59 to 442.72μm.This experiment successfully produced phosphorus-rich granular sludge,with the phosphorus content of the sludge increasing from 25.93 to 86.27 mg/g.The results of 16 s rRNA gene high-throughput sequencing indicated that Chloroflexi served as the initial particle framework of the granular sludge,while Proteobacteria represented the core bacterial phylum responsible for sludge granulation.In addition,Candidatus_Competibacter and Candidatus_Accumulibacter were identified as the dominant bacterial genera involved in the sludge granulation process.Throughout the cultivation period,the EPS content increased from 79.18 mg/g VSS to 133.63 mg/g VSS.The 3DEEM analysis confirmed that AGS-EPS contained a higher level of proteins,and the reduction in protein decomposition and solubilization by cells during the domestication process facilitated microbial cell aggregation within the biofilm.FTIR and protein secondary structure analyses revealed that both types of EPS contained alcohol phenols,—OH,—CH,C—O,C—C from sugars,carboxylate groups from uronic acids,N—H from proteins,and alkane-like organic compounds.However,AGS-EPS exhibited a more diverse composition of polysaccharides and a more stable cell structure.The granulation process altered the adsorption mechanism of AGS toward Cd^(2+).Adsorption kinetic studies demonstrated that the adsorption of Cd^(2+)by AS-EPS involved both physical and chemical adsorption,whereas the adsorption of Cd^(2+)by AGS-EPS was better described by the pseudo-second-order kinetic model,indicating stronger biochemical adsorption properties.Adsorption thermodynamic analyses indicated that the adsorption of Cd^(2+)by both types of EPS was best fitted by the Langmuir model,indicating a homogeneous monolayer adsorption process.The theoretical maximum adsorption capacity of AGS-EPS was higher than that of AS-EPS,at 617.09 and 542.90 mg/g,respectively.Conclusions The experimental process demonstrated that increasing the COD content in a high-phosphorus environment enhanced the phosphorus removal performance of sludge and positively influenced the cultivation of granular sludge.In the comparison between AGS and AS,3DEEM analysis revealed that AGS exhibited a higher protein level,while FTIR indicated that both had similar functional groups;however,AGS contained more abundant polysaccharides.The secondary protein structure confirmed that AGS possessed stronger cell aggregation,greater mechanical strength,and higher protein compactness.The by-product of granular sludge cultivation,AGS-EPS,exhibited a stronger Cd^(2+)adsorption capacity,primarily through biochemical interactions,indicating that AGS holds greater potential in wastewater treatment applications.
作者
郑逸涵
杨英
李卫华
冯青原
朱曼丽
陈卉静
杨婷婷
ZHENG Yihan;YANG Ying;LI Weihua;FENG Qingyuan;ZHU Manli;CHEN Huijing;YANG Tingting(School of Environmental and Energy Engineering,Anhui Jianzhu University,Hefei 230000,China;Anhui Provincial Key Laboratory of Water Pollution Control and Wastewater Recycling,Hefei 230000,China)
出处
《工程科学与技术》
北大核心
2025年第6期274-285,共12页
Advanced Engineering Sciences
基金
国家自然科学基金项目(52370021)
安徽省住房城乡建设科学技术计划项目(2023-RK025)
安徽省教育厅研究生质量工程项目(2022jyjxggyj314)。
关键词
好氧颗粒污泥
胞外聚合物
重金属
微生物群落
生物吸附剂
aerobic granular sludge
extracellular polymers
heavy metal
microbial community
biosorbent
