钛盐混凝剂调理对活性污泥絮体理化性质的影响作用机制

研究了预制的不同形态钛盐混凝剂对污泥的调理效果,结果表明不同碱化度[B值,即n(OH)/n(Ti)]聚合氯化钛(PTC)单一调理污泥时,在相同投加量时,PTC_(0.5)调理后污泥比阻、可压缩性以及EPS中有机物含量均低于其他形态钛盐,其最佳投加量以TSS计,为0.005 g·g~(-1),该投加量远低于传统的铁盐和铝盐混凝剂.不同B值PTC调理污泥脱水能力的强弱顺序为:PTC_(0.5)PTC_(1.5)Ti Cl_4PTC_(2.5).同时分析了调理过程中污泥絮体粒径(d_(0.5))和分形维数(D_F)的变化特征.采用三维荧光光谱和高效体积排阻色谱,解析了钛盐混凝剂对污泥胞外聚合物(EPS)分布和组成的影响,EPS蛋白峰的荧光强度和有机物相对分子质量峰分布变化规律与污泥比阻、可压缩性和脱水能力变化规律有一定相关性.     

高铁酸钾调理改善活性污泥脱水性能的反应机制研究

研究了高铁酸钾(K_2FeO_4)对处理活性污泥脱水性的效果,重点考察了不同pH和剂量条件下,K_2FeO_4调理对污泥过滤脱水特性和胞外聚合物(EPS)分布和组成的影响,以深入认识K_2FeO_4调理污泥的反应机制.研究表明,K_2FeO_4调理效果随pH值的降低而改善,其不仅有氧化裂解作用导致结合型EPS(BEPS)释放,同时其还原产物三价铁离子兼具混凝功效,能够通过电中和与界面吸附去除部分溶解性EPS(SEPS),同时压缩EPS结构,增强污泥絮体结构.此外,当pH值为3,K_2FeO_4投加量为0.1 g·g~(-1)(以TSS计)时,污泥过滤脱水速率和程度均达到最佳.过量投加K_2FeO_4(0.2 g·g~(-1),以TSS计)后,BEPS大量释放,污泥过滤阻力增加,脱水性能恶化.     

不同铝聚合形态对聚合铝混凝效果的影响

通过氯化铝(铝单体或初聚物形态Ala)、高Alb含量聚合铝(中等聚合形态Alb)、高Alc含量聚合铝(铝溶胶等高聚合形态Alc)和工业PACl(不同聚合度铝的混合形态Alabc)对某水厂沉后水实际水样进行烧杯混凝实验,依据絮体生长状况、浊度、UV254、颗粒数和过滤指数等参数综合评价不同铝形态的混凝作用效果,从而得出铝的最佳混凝形态.结果表明,高Alb含量聚合铝对浊度去除较好;而高Alc含量聚合铝对于颗粒物和UV254的去除效果较佳.     

缺氧酸化联合零价铁-过氧化氢改善污泥脱水性能的研究

为探讨缺氧酸化联合零价铁(ZVI)-过氧化氢(H_2O_2)调理对污泥脱水性能的影响,本文通过单因素试验,以污泥比阻(SRF)作为参考指标,系统考察了调理条件对污泥脱水性能的影响.同时,在试验的最佳调理条件下,分析了污泥各层胞外聚合物(EPS)有机物质量浓度及荧光光谱强度以阐明该联合作用机理.结果表明,当初始pH为2,ZVI投加量为280 mg·g~(-1)(以干污泥量(DS)计,下同),缺氧时间为4 h,H_2O_2投加量为30 mg·g~(-1)(以DS计,下同),类芬顿反应时间为10 min时,SRF降低了90.39%,处理效果较单独类芬顿处理提升了1倍.机理探究试验表明,在缺氧条件下,酸化处理可加速污泥的水解,溶解得到更多的二价铁离子,促使EPS结构发生改变;ZVI-H_2O_2调理可有效地氧化部分EPS,使得紧密结合胞外聚合物(TB-EPS)破解转化至松散结合胞外聚合物(LB-EPS)和上清液胞外聚合物(SB-EPS).EPS分析结果表明,蛋白质的减少能有效提高污泥脱水性能,腐殖酸和富里酸类有机物的产生能提高污泥疏水性能.此外,ZVI的再次利用效率高,重复利用仍能使SRF降低率达到82.04%.因此,缺氧酸化联合ZVI-H_2O_2处理能实现污泥的水解、氧化和絮凝过程,达到改善污泥脱水性能的目的.     

Optimizing sludge dewatering with a combined conditioner of Fenton's reagent and cationic surfactant

Enhancing sludge dewatering is of importance in reducing environmental burden and disposal costs. In this work, a cationic surfactant, cetyl trimethyl ammonium bromide (CTAB), was combined with Fenton's reagent for sludge dewatering. Results show that the Fenton-CTAB conditioning significantly promotes the sludge dewatering. Using combined techniques of response surface methodology and uniform design, dosages of Fe²⁺, H₂O₂, and CTAB for water content response were optimized to be 89, 276, and 233?mg/g dry solids (DS), respectively. The water content of sludge decreased from 79.0% to 66.8% under the optimal conditions. Compared with cationic polyacrylamide, the Fenton-CTAB system exhibited superior sludge dewatering performance. To gain insights into the mechanisms involved in sludge dewatering, the effects of Fenton-CTAB conditioning on the composition of extracellular polymeric substances (EPS) and the morphology of the sludge flocs were investigated. The decomposition of EPS into some dissolved organics and the release of proteins in tightly bound EPS facilitated the conversion of bound water to free water and further reduced the water content of sludge cake. After conditioning, morphology of sludge showed aggregation. Overall, the enhanced sludge dewatering by Fenton-CTAB treatment provides an efficient way for management of sewage sludge.     

铝、铁、钛3种金属盐基混凝剂调理污泥的性能比较

以铝盐、铁盐和钛盐混凝剂为研究对象,重点比较了3种混凝剂的污泥调理性能.通过测定调理前后污泥比阻、胞外聚合物中蛋白质和多糖的含量变化,结合三维荧光光谱与分子量变化分析及调理前后污泥尺寸大小与颗粒表面形貌变化,系统比较了它们对污泥的调理性能,并揭示了调理机制.3种无机混凝剂的污泥调理能力依次为:聚合氯化铝(PAC)、钛凝胶混凝剂(TXC)、聚合硫酸铁(PFS);调理后,污泥胞外聚合物中蛋白质和多糖含量明显降低;PFS和TXC对有机物的结合能力要强于PAC,疏松结合的胞外聚合物中多糖含量是影响污泥脱水性能的关键因素;调理过程中3种混凝剂所形成污泥颗粒的大小顺序为:TXCPFSPAC,所形成污泥颗粒的大小并非影响污泥脱水性能的关键因素,无机混凝剂电中和能力和与有机物的络合能力共同影响无机混凝剂的污泥调理性能.本研究为污泥调理混凝剂的选取提供了实验和理论依据.     

芬顿试剂氧化对污泥脱水性能的影响

利用芬顿试剂调理污泥,以W_C(污泥滤饼含水率)和CST(毛细吸水时间)作为评价污泥脱水性能的指标,通过分析污泥中各层ρ(EPS)(EPS为胞外聚合物)和上清液中小分子有机物质量浓度来阐明污泥脱水性能的变化. 结果表明:芬顿试剂调理可促进EPS氧化分解,TB-EPS(紧密结合的胞外聚合物)破解转化为LB-EPS(松散结合的胞外聚合物)和S-EPS(上清液层胞外聚合物),大幅降低W_C和CST. 试验中当pH为4,w(H₂O₂)和 w(Fe2+)均为40 mg/g时,ρ(EPS)降低了33.04%,W_C和CST分别降至63.36%和28.7 s. Pearson相关性分析表明,ρ(TB-EPS)与W_C和CST均存在显著的正相关性(P＜0.01),是影响污泥脱水性能的重要因素,而ρ(LB-EPS)和ρ(S-EPS)与污泥脱水性能的相关性较低. 液相色谱分析表明,随着芬顿试剂投加量的增大,EPS等有机物分解程度增大,污泥上清液中小分子有机物种类明显增多,其质量浓度显著升高,ρ(甲酸)和ρ(乙酸)分别由原污泥的52.72、15.99 mg/L升至446.05、522.36 mg/L.      

铁负载污泥炭的表征及其促进PAM调理高级厌氧消化污泥的效能研究

本研究首先分析了铁负载污泥炭的物理化学性质,评估了铁负载污泥炭与有机高分子（聚丙烯酰胺,PAM）联合调理改善高级厌氧消化污泥脱水性的效能,研究了联合调理过程中污泥絮体特性与胞外聚合物（EPS）的变化特征.结果表明,单独投加污泥炭可以通过铁的电中和作用降低污泥颗粒间的静电排斥力,同时充当骨架材料改善污泥的脱水性能.此外,铁负载污泥炭可以有效去除污泥体系中大分子溶解性有机物,从而改善污泥的过滤性能.污泥炭和有机絮凝剂在污泥调理过程中表现出明显的协同作用,污泥碳和PAM的最佳投加量分别为250 mg·g^-1（以TSS计）和8 mg·g^-1（以TSS计）.激光共聚焦显微镜分析表明,PAM主要与污泥絮体中的蛋白质分子作用,从而促使污泥颗粒凝聚.     

聚硅酸对不同形态铝沉积行为的影响

针对给水管网中残余铝沉积和再溶解现象可能引起的水质问题,研究了聚硅酸对不同水解聚合形态铝沉积、再溶解的影响,并以石英微晶天平为表征手段,初步探讨了聚硅酸对不同形态铝沉积、再溶解过程影响的机理.结果表明,聚硅酸能显著改变不同水解聚合形态铝的沉积、再溶解行为.聚硅酸可与3种水解聚合形态的铝迅速结合而生成可沉积产物,但产物性质不同.以单体形态为主的Al_0与聚硅酸的反应产物性质较稳定,部分以溶解态存在,部分以非溶解态(可沉积态)存在;尽管铝的两种聚合形态Al_(13)和Al_(30)与聚硅酸反应也生成了部分可沉积产物,但随着时间的推移,这些产物又逐渐向溶解态转化.铝硅比对Al_0体系中铝的沉积溶解行为影响较小,而对Al_(13)和Al_(30)影响较大,且在0.2∶20(以Al和SiO_2计的质量比)时,沉积态铝的溶解速率最快.     

水力空化-酸化调理增强污泥脱水性能分析

研究了水力空化-酸化调理作用于污泥脱水的机理。以污泥比阻（specific resistance to filtration,SRF）、污泥含水率和污泥毛细吸水时间（capillary sunction time,CST）作为主要的评价指标,测定污泥胞外聚合物（extracellular polymeric substances,EPS）中多糖、蛋白含量并进行了污泥酸化程度、污泥电子显微图像分析。结果表明:经水力空化-酸化调理污泥,污泥含水率和SRF分别从83.1%和5.12×1011 m/kg下降到69.8%和2.41×1011 m/kg,CST由50 s下降至20.8 s,各EPS组分含量下降明显,酸化作用通过影响污泥的溶解型胞外聚合物（S-EPS）和松散结合型胞外聚合物（LB-EPS）中的多糖及蛋白含量改变污泥的脱水性,pH=3时污泥脱水效果最好。综上所述,水力空化-酸化调理能大大增强污泥的脱水性能,在实际工程中具有很大的应用价值。     

Functions and behaviors of activated sludge extracellular polymeric substances (EPS): a promising environmental interest

Extracellular polymeric substances （EPS） are the predominant constituents of activated sludge and represent up to 80% of the mass of activated sludge. They play a crucial role in the flocculation, settling and dewatering of activated sludge. Furthermore, EPS also show great efficiency in binding heavy metals. So EPS are key factors influencing reduction in sludge volume and mass, as well as activity and utilization of sludge. EPS are of considerable environmental interest and hundreds of articles on EPS have been published abroad, while information on EPS in China is limited. In this paper, results of over 60 publications related to constituents and characteristics of EPS and their influences on flocculation, settling and dewatering of sludge are compiled and analyzed. Metal-binding ability of EPS is also discussed, together with a brief consideration of possible research interests in the future.     

Effects of acid,acid-ZVI/PMS,Fe(Ⅱ)/PMS and ZVI/PMS conditioning on the wastewater activated sludge(WAS)dewaterability and extracellular polymeric substances(EPS)

The effects of four conditioning approaches:Acid,Acid-zero-valent iron(ZVI)/peroxydisulfate(PMS),Fe(Ⅱ)/PMS and ZVI/PMS,on wastewater activated sludge(WAS) dewatering and organics distribution in supernatant and extracellular polymeric substances(EPS) layers were investigated.The highest reduction in bound water and the most WAS destruction was achieved by Acid-ZVI/PMS,and the optimum conditions were pH 3,ZVI dosage 0.15 g/g dry solid(DS),oxone dosage 0.07 g/g DS and reaction time 10.6 min with the reductions in capillary suction time(CST) and water content(Wc) as 19.67% and 8.49%,respectively.Four conditioning approaches could result in TOC increase in EPS layers and supernatant,and protein(PN) content in tightly bound EPS(TB-EPS).After conditioning,organics in EPS layers could migrate to supernatant.Polysaccharide(PS) was easier to migrate to supernatant than PN.In addition,Acid,Acid-ZVI/PMS or Fe(Ⅱ)/PMS conditioning promoted the release of some polysaccharides containing ring vibrations v P=O,v C-O-C,v C-O-P functional groups from TB-EPS.ESR spectra proved that both radicals of SO_4~-· and·OH contributed to dewatering and organics transformation and migration.CST value of WAS positively correlated with the ratios of PN/PS in LB-EPS and total EPS,while it negatively correlated with TOC,PN content and PS content in TB-EPS,as well as PS content in supernatant and LB-EPS.BWC negatively correlated to zeta potential and TOC value,PN content,and HA content in supernatant.     

Flocculating characteristic of activated sludge flocs: Interaction between Al3+ and extracellular polymeric substances

Aluminum flocculant can enhance the flocculating performance of activated sludge.However,the binding mechanism of aluminum ion(Al 3+) and extracellular polymeric substances(EPS) in activated sludge is unclear due to the complexity of EPS.In this work,threedimensional excitation emission matrix fluorescence spectroscopy(3DEEM),fluorescence quenching titration and Fourier transform infrared spectroscopy(FT-IR) were used to explore the binding behavior and mechanism between Al 3+ and EPS.The results showed that two fluorescence peaks of tyrosineand tryptophan-like substances were identified in the loosely bound-extracellular polymeric substances(LB-EPS),and three peaks of tyrosine-,tryptophanand humic-like substances were identified in the tightly boundextracellular polymeric substances(TB-EPS).It was found that these fluorescence peaks could be quenched with Al 3+ at the dosage of 3.0 mg/L,which demonstrated that strong interactions took place between the EPS and Al 3+.The conditional stability constants for Al 3+ and EPS were determined by the Stern-Volmer equation.As to the binding mechanism,the-OH,N-H,C=O,C-N groups and the sulfurand phosphorus-containing groups showed complexation action,although the groups in the LB-EPS and TB-EPS showed different behavior.The TB-EPS have stronger binding ability to Al 3+ than the LB-EPS,and TB-EPS play an important role in the interaction with Al 3+.     

次氯酸钠与亚铁对污泥破解及脱水效果的影响

采用次氯酸钠（NaClO）与亚铁（Fe（II））结合处理污泥以提高污泥破解和脱水效能,考察了NaClO和Fe（II）投加量的影响,并通过定量和定性分析污泥中胞外聚合物质（EPS）的迁移转化,确定NaClO和Fe（II）对污泥脱水和破解的机制.试验结果表明,NaClO和Fe（II）投加量（以干泥固体计）分别为44 mg·g^-1和66 mg·g^-1时,污泥毛细吸吮时间（CST）从原泥的112 s下降到66.3 s.同时,NaClO/Fe（II）处理污泥能够使上清液中化学需氧量（COD）显著升高,并使污泥中紧密束缚型EPS（TB-EPS）和松散束缚型EPS（LB-EPS）转化成溶解性EPS（S-EPS）,导致S-EPS的溶解性有机碳（DOC）含量升高,而LB-EPS和TB-EPS的DOC含量降低.此外,NaClO/Fe（II）还能使污泥中有机物质矿化,使3种EPS中蛋白质类和腐殖酸类物质减少.NaClO和Fe（II）能够改善污泥脱水性能,强化污泥破解效果,利于污泥后续的处理处置.     

Deposition behavior of residual aluminum in drinking water distribution system: Effect of aluminum speciation

Finished drinking water usually contains some residual aluminum.The deposition of residual aluminum in distribution systems and potential release back to the drinking water could significantly influence the water quality at consumer taps.A preliminary analysis of aluminum content in cast iron pipe corrosion scales and loose deposits demonstrated that aluminum deposition on distribution pipe surfaces could be excessive for water treated by aluminum coagulants including polyaluminum chloride（PACl）.In this work,the deposition features of different aluminum species in PACl were investigated by simulated coil-pipe test,batch reactor test and quartz crystal microbalance with dissipation monitoring.The deposition amount of non-polymeric aluminum species was the least,and its deposition layer was soft and hydrated,which indicated the possible formation of amorphous Al（OH）₃.Al₁₃ had the highest deposition tendency,and the deposition layer was rigid and much less hydrated,which indicated that the deposited aluminum might possess regular structure and self-aggregation of Al₁₃could be the main deposition mechanism.While for Al₃₀,its deposition was relatively slower and deposited aluminum amount was relatively less compared with Al₁₃.However,the total deposited mass of Al₃₀ was much higher than that of Al₁₃,which was attributed to the deposition of particulate aluminum matters with much higher hydration state.Compared with stationary condition,stirring could significantly enhance the deposition process,while the effect of pH on deposition was relatively weak in the near neutral range of 6.7 to 8.7.     

Effects of Al3+ on the microstructure and bioflocculation of anoxic sludge

The aluminum ions generated from mining aluminum,electrolytic aluminum and the industrial production of aluminum-based coagulants(such as AlCl_3 and Al_2(SO_4)_3) enter sewage treatment plants and interact with activated sludges.An anaerobic/anoxic/oxic(A~2 O) process was used to reveal the effects of Al~(3+) on the pollutant removal efficiencies,bioflocculation and the micro structure of sludge.The results showed that a low concentration of Al~(3+) improved the pollutant removal efficiencies and increased the sludge particle size.However,a high concentration of Al~(3+) hindered microbial flocculation and reduced the pollutant removal efficiencies.With a 10 mg/L Al~(3+) addition,the chemical oxygen demand(COD),total nitrogen(TN) and NH_4~+-N increased by 3%,16% and 27%,and reached as high as 68%,60% and 87%,respectively.At the same time,the dehydrogenase activity,flocculation ability(FA) and contact angle of the sludge reached their maximum levels at 41.3 mg/L/hr,45% and 79.63°,respectively.The specific surface area of the sludge decreased to 7.084 m2/g and the sludge pore size distribution shifted to concentrate in the me soporous range.Most of Al~(3+) was adsorbed on the surface of sludge,changing the physicochemical properties and physical structure of the sludge.     

基于酸化与Fenton试剂处理的焦化污泥脱水过程及其重金属迁移研究

焦化废水污泥作为典型的危险废物,含有氰类、酚类、稠环芳烃与多环芳烃等有毒成分,严重影响人类健康与生态环境安全,焦化污泥减量化是其处理处置中重要一环.针对焦化废水污泥高有机物、高油含量特点,采用酸化+Fenton试剂进行复合调理改性,改性后污泥毛细吸水时间(Capillary Suction Time,CST)、比阻(Specific Resistance to Filtration,SRF)分别达到51.2 s和0.043×10¹³ m·kg^-1,药剂投加量通过响应表面法(Response Surface Method,RSM)进行优化,在实验室板框脱水实验中得到30%硫酸投加量为37.8 mL·L^-1,FeSO₄、H₂O₂和生石灰投加量分别为47.93、34.29和143.21 mg·g^-1DS时,脱水后泥饼含水率为55.82%,滤液pH为6.66,达到污泥深度脱水目标.采用酸化+Fenton试剂复合处理可使焦化废水污泥有效减量化,其良好的深度脱水效果能为后续的无害化处置奠定基础,并有效降低处置费用.     

基于Fe3+/EDTA-2Na的类芬顿对剩余污泥脱水性能的影响

剩余污泥的高含水率限制了对其后续处理以及资源化利用. 为了改善污泥脱水性能,利用Fe3+/EDTA-2Na类芬顿试剂作为调理剂强化污泥脱水,通过粒径分析、差示扫描量热仪(DSC)、傅里叶红外光谱(FTIR)和扫描电子显微镜(SEM)等方法对剩余污泥进行表征,探究其强化脱水机理. 结果表明:经过氧化调理后的污泥泥饼含水率降至67.8%,并有62.32%的结合水得以释放. 污泥胞外聚合物(EPS)结构被氧化破解,紧密结合的胞外聚合物(TB-EPS)中的多糖和蛋白质浓度显著减少;污泥絮体减小,但从SEM图可以看出絮体结构变得规整、平滑,且出现不规则孔洞,增加了污泥水分的输送通道,改善了污泥的脱水性能. FTIR分析表明,氧化处理后的污泥清液中水的吸收峰变小,多糖和蛋白质对应的吸收峰增强,而富里酸对应的峰消失. 研究显示,基于Fe3+/EDTA-2Na类芬顿的污泥调理可以高效氧化破解污泥,提高污泥脱水性能.      

Fenton试剂与骨架构建体复合调理剂对污泥脱水性能的影响

将Fenton试剂与骨架构建体联用作为复合调理剂开展了污泥调理及脱水试验.结果表明,赤泥与水泥作骨架构建体调理后,污泥脱水性能和脱水液pH均优于石灰与水泥调理污泥.以污泥比阻(SRF)为评价指标,开展了Fenton反应时间、初始pH及调理剂投加量对污泥脱水性能影响的单因素试验.当Fenton反应时间为90 min,初始pH为5,水泥、赤泥、Fe²⁺和H₂O₂的投加量(以污泥干固体质量计)分别为300、300、40和32 mg·g^-1时,污泥比阻降低率可达94.25%±0.21%.在此基础上,以泥饼含水率为响应指标,利用表面响应法对调理剂投加量进行优化.结果表明,水泥、赤泥、Fe²⁺和H₂O₂的投加量分别为287、287、46和37 mg·g^-1,泥饼含水率可降至47.7%±0.8%.调理后污泥的粒径减小,比表面积增大,粘度减小,Zeta电位由负变正,说明该复合调理剂能有效地破解胞外聚合物(EPS),提高污泥脱水性能.     

Optimized production of a novel bioflocculant M-C11 by Klebsiella sp. and its application in sludge dewatering

The optimized production of a novel bioflocculant M-C11 produced by Klebsiella sp. and its application in sludge dewatering were investigated. The optimal medium carbon source,nitrogen source, metal ion, initial pH and culture temperature for the bioflocculant production were glucose, NaNO3, MgSO4, and pH 7.0 and 25°C, respectively. A compositional analysis indicated that the purified M-C11 consisted of 91.2% sugar, 4.6% protein and 3.9% nucleic acids（m/m）. A Fourier transform infrared spectrum confirmed the presence of carboxyl, hydroxyl,methoxyl and amino groups. The microbial flocculant exhibited excellent pH and thermal stability in a kaolin suspension over a pH range of 4.0 to 8.0 and a temperature range of 20 to 60°C.The optimum bioflocculating activity was observed as 92.37% for 2.56 mL M-C11 and 0.37 g/L CaCl2 dosages using response surface methodology. The sludge resistance in filtration（SRF）decreased from 11.6 × 1012 to 4.7 × 1012m/kg, which indicated that the sludge dewaterability was remarkably enhanced by the bioflocculant conditioning. The sludge dewatering performance conditioned by M-C11 was more efficient than that of inorganic flocculating reagents,such as aluminum sulfate and polymeric aluminum chloride. The bioflocculant has advantages over traditional sludge conditioners due to its lower cost, benign biodegradability and negligible secondary pollution. In addition, the bioflocculant was favorably adapted to the specific sludge pH and salinity.