利用柠檬酸去除污泥中镉、铅的研究

考察了利用柠檬酸去除厦门某化工厂污泥中重金属镉、铅的适宜工艺条件,包括pH、柠檬酸浓度、转速、温度、反应时间等。考察发现,在pH-3、柠檬酸摩尔浓度为0．2mol／L、转速为200r／min、温度为室温、反应时间为1d左右时,污泥中镉、铅的最大去除率分别为91．5％和96．5％。     

离子交换法选择性回收污泥厌氧消化液中的磷

为探讨高效选择性回收污泥厌氧消化液中磷的离子交换方法,采用静态实验和动态实验研究了4种阴离子交换树脂（D213、D202、D301和DSQ）的磷回收性能,筛选了适合富磷污泥厌氧消化液选择性磷回收的高交换容量树脂。实验结果表明,D213、D202、D301和DSQ 4种树脂对正磷浓度为70 mg/L的厌氧消化液进行动态处理时,其最大穿透体积分别为3、7、17和90 BV;DSQ树脂磷交换容量远高于其他3种树脂,达到6 860 mg P/L湿树脂,是目前报道的高磷交换容量树脂的3~4倍;DSQ树脂能有效地抵抗厌氧消化液中有机质和硫酸根等阴离子的干扰;用NaOH溶液再生DSQ树脂并回收磷,磷洗脱率超过96%,洗脱液是高浓度含磷液,可作为磷矿石的优质替代品。研究表明,DSQ树脂是一种高效选择性分离磷的树脂,适用于污泥厌氧消化液的磷回收。     

柠檬酸强化电动去除和回收污泥中的重金属

探讨了柠檬酸对污泥中重金属形态的影响,并以柠檬酸为络合剂、以杭州七格污水处理厂城市污泥为研究对象,在0.8 m A·cm-2恒定电流密度条件下运行120 h,在5组柠檬酸浓度分别为0.00、0.05、0.10、0.20和0.30 mol·L~(-1)的条件下,采用自行设计的双层双阳极反应器对污泥中重金属进行电动去除和回收实验。结果显示,柠檬酸能促使污泥中大量的Zn由可还原态转化为酸可提取态,但对Cu的形态影响不大。电动处理实验中,添加柠檬酸后Zn和Cu的去除率都有明显提高,当柠檬酸浓度为0.20 mol·L~(-1)时,Zn的去除率最大达58.3%,Cu的去除率为42.4%;当柠檬酸浓度为0.10 mol·L~(-1)时,Cu的去除率最大为51.7%,Zn的去除率为46.4%。柠檬酸的最佳添加浓度为0.10~0.20 mol·L~(-1),当柠檬酸添加量超过0.20 mol·L~(-1),Zn和Cu的去除率反而会因为络合物在阳极区的沉淀而降低。     

复合酸化剂对电镀污泥中铬、铜的去除效果

以电镀加工厂产生的污水污泥作为主要研究对象,研究了柠檬酸、硝酸、过氧化氢为复合酸化剂,Fe3+为增效剂对电镀污泥中铬和铜的去除效果,考察了酸化剂的浓度、反应时间、摇床转速、污泥pH、Fe3+浓度等因素对污泥中重金属去除效率的影响。结果表明:在室温下,含0.15 mol/L柠檬酸、1.5%过氧化氢、0.25 mol/L硝酸的复合酸化剂与增效剂2.0g/L Fe3+溶液共同处理污泥,固液比为1∶10,以150 r/min的转速振荡4 h,对污泥中Cr的去除效率达到80.02%,Cu的去除效率可达到92.89%,使污泥中残留Cr、Cu含量均符合国家污泥农用标准。     

混合质电镀污泥中金属分离富集与分质回收研究

对混合质电镀污泥进行了湿法分离和金属回收研究,拟采用硫化分离富集—分质回收的工艺路线实现重金属的全组元回收。结果表明,在常温下采用分段硫化可以实现电镀污泥中Cu、Ni、Zn、Cr的分离与富集,在控制pH为3.8时,浸出液中Cu、Ni、Zn的硫化沉淀率均大于98%,Cu、Ni、Zn与Fe、Cr取得了较好的分离,在pH为4.1时,Cr与Fe取得了较好的分离效果,Fe的硫化沉淀率达到了93.35%,Cr最终在铬泥中得到富集;富集了Cu、Ni、Zn的硫化渣和富集了Cr的铬泥容易实现金属的分质回收;对重金属含量较低的混合质电镀污泥,采用硫化分离富集—分质回收的工艺是可行的,可将Cu、Ni、Zn、Cr等重金属予以全组元回收,同时处理后废渣可作为一般工业固废进行处理。     

合成氨污水中镍的处理和回收

离子交换早用于水的净化,大孔型树脂出现后广泛用来处理工业废水回收重金属。近期用于处理电渡废液已经工厂化,并可建立水的回收循环利用系统和零排放处理系统。本文依据羧酸型阳离子树脂对镍有较高的选择性和酸洗脱效率,在上海化工学院DK—110树脂处理合成氨污水中镍、铵试验基础上,研究了大孔型弱酸树脂处理回收渣     

采用等电点沉淀法回收市政污泥水解液中的蛋白质

从城市污水处理厂市政污泥中回收蛋白质是一种污泥资源化的新途径,等电点沉淀法是从市政污泥水解液中回收蛋白质的有效方法。结果表明,当pH为3.5、沉淀温度为5℃、离心转速为3 000 r·min~(-1)和蛋白质浓度为6 000 mg·L~(-1)时,市政污泥水解液中的蛋白质回收率为87.46%。采用高效液相色谱仪分析所得蛋白质产品中的氨基酸含量,发现7种必需氨基酸(赖氨酸、苯丙氨酸、蛋氨酸、苏氨酸、异亮氨酸、亮氨酸和缬氨酸)占沉淀物干重的12.37%。采用电感耦合等离子体发射光谱仪(inductively coupled plasma optical emission spectrometer,ICP-OES)分析所得蛋白质的重金属含量,与原市政污泥相比,所得蛋白质中As、Pb、Cr等重金属的削减率均在90%以上,等电点沉淀法有利于市政污泥中重金属的去除,所得蛋白质产品存在重金属风险较低。     

氧化亚铁硫杆菌对电动力处理城市污泥中重金属影响研究

分析了氧化亚铁硫杆菌对污泥中重金属形态及对电动力处理污泥中重金属的去除率影响.氧化亚铁硫杆菌处理后的污泥,pH值降低,部分重金属从稳定态转化为可溶态.经氧化亚铁硫杆菌预处理后的泥样和未经预处理的泥样,在同样条件下用电动力处理,处理结果为:预处理后Cd的去除率从61.85%上升到72.54%,Cu从34.26%上升到63.51%,Zn从65.06%上升到7L 22%.预处理对Cu的影响比Cd、Zn大得多.用电动力处理Cu超标污泥中重金属时,将污泥先用氧化亚铁硫杆菌预处理,可有效地提高其去除效果,处理后的污泥有利于农用.     

中温焙烧/钠化氧化法回收电镀污泥中的铬

采用中温焙烧/钠化氧化法从电镀污泥中回收铬.结果表明,影响铬浸出率的最主要因素为焙烧温度.电镀污泥与碳酸钠质量比、焙烧时间、水浸时间对铬浸出率的影响较接近,在水浸水固比为10.0 ; 1.0(质量比)、室温、焙烧温度为650℃、焙烧时间为2.0h、电镀污泥与碳酸钠质量比为1:1、水浸时间为60 min的最佳浸出条件下,铬浸出率为99.3%;去除氢氧化铝、氢氧化锌的最佳反应温度和pH分别为90～95℃和7.5;去除硫酸钠晶体的最佳pH为4.0,在最佳试验条件下,铬回收率为90.57%.     

化学沥浸与硫化钠钝化联合处理猪粪中重金属

利用柠檬酸浸提猪粪中重金属,减少总量,再利用硫化钠钝化经柠檬酸浸提后的猪粪残渣,降低猪粪中剩余重金属的生物可利用性。柠檬酸浸提实验表明:0.2 mol·L-1柠檬酸与猪粪按固液比1:5混合,反应24 h,对猪粪中Cu、Zn、Mn的浸出率为18.10%、66.16%、43.85%;硫化钠投加量5%,钝化7 d,猪粪中离子交换态Cu、Zn、Mn的浓度由酸浸后的14.08、116、81.75 mg·kg~(-1)降为8.77、12.04、21.02 mg·kg~(-1),硫化钠对酸浸后猪粪中Cu、Zn的钝化率为52.00%、63.72%,猪粪残渣中离子交换态Mn所占全量的比例由对照组的30.22%降到7.77%;柠檬酸酸浸和硫化钠钝化对猪粪中Cu、Zn、Mn总处理效率为73.00%、61.44%、29.90%。重金属分离技术和钝化技术联合处理猪粪中重金属,可以有效减少猪粪中Cu、Zn、Mn的总量并降低其生物可利用性。     

Removal of metal ions from the complexed solutions in fixed bed using a strong-acid ion exchange resin

Fixed bed removal of equimolar metal ions (Co²⁺, Ni²⁺, Mn²⁺, Sr²⁺) from aqueous solutions using a strong-acid resin was examined. The solution contained a water-soluble complexing agent including ethylenediaminetetraacetic acid, nitrilotriacetic acid, and citric acid. Experiments were performed under different solution pH and molar concentration ratios of complexing agent to the total metals. It was shown from batch studies that the equilibrium exchange of metals and the resin mainly depended on solution pH, and partly on the type of complexing agent used. A mass transfer model was proposed to describe the breakthrough curves of the resin bed, which contained two parameters (τ and k) estimated from the observed breakthrough data. The calculated breakthrough curves agreed well with the measured ones (standard deviation <6%). In fixed bed tests at low pH (=2), the type of complexing agent had little effect on the breakthrough data. For a given complexing agent, the metal with a larger overall formation constant (K_f) showed a smaller exchange capacity. For a given metal ion, the complexing agent with a larger K_f also revealed a smaller exchange capacity.     

Metal ion removal from water by sorption on paper mill sludge

Chromatographic columns packed with paper mill sludge are employed for metal ion recovery from water. The breakthrough curves show that cadmium, copper, lead and silver are removed from acid solutions (pH 2, 4); the affinity series is Pb(II)>Cu(II)>Ag(I)>Cd(II). Both the amount of metal retained and the metal-matrix interaction are pH dependent; the sorptive capacity increases with increasing pH. When the metals are present together at the same initial concentrations a competition among the different ions occurs although the affinity order remains unchanged. In metal recovery from the paper mill sludge column, the total amount of the cadmium and copper is displaced by HCl 1.0 M, 65% of the lead by HCl 0.1 M and 75% of the silver by HNO(3) 0.1 M. More than 95% of copper and lead and less than 20% of cadmium were recovered with HCl 0.1 M when the metals were present at the same time.     

Electrokinetic enhancement removal of heavy metals from industrial wastewater sludge

An enhanced electrokinetic process for removal of metals (Cr, Cu, Fe, Ni, Pb, Zn) from an industrial wastewater sludge was performed. The electrokinetic experiments were conducted under a constant potential gradient (1.25 V cm(-1)) with processing fluids of tap water (TW), sodium dodecylsulfate (SDS) and citric acid (CA) for 5 days. Results showed that metal removal efficiency of heavy metals for EK-TW, EK-SDS and EK-CA systems are 11.2-60.0%, 37.2-76.5%, and 43.4-78.0%, respectively. A highest metal removal performance was found in EK-CA system. The removal priority of investigated metals from sludge by EK process was found as: Cu > Pb > Ni > Fe > Zn > Cr. The results of sequential extraction analysis revealed that the binding forms of heavy metals with sludge after electrokinetic process were highly depend upon the processing fluid operated. It was found that the binding forms of metals with sludge were changed from the more difficult extraction type (residual and sulfate fractions) to easier extraction types (exchangeable, sorbed, and organic fraction) after treatment by electrokinetic process. Results imply that if a proper treatment technology is followed by this EK process to remove metals more effectively, this treated sludge will be more beneficial for sludge utilization afterwards. Before it was reused, the risk associated with metals of more mobile forms to the environment need to be further investigated. The cost analysis was also evaluated for the investigated electrokinetic systems.     

电镀污泥回收重金属的新工艺

合理、经济地处理混合电镀污泥,回收其中有价值的金属具有重要意义。以不同的酸作为浸出剂对电镀污泥中的金属进行了浸出效果实验。结果表明,在相同条件下,各酸的浸出效果顺序为:硫酸>盐酸>王水>硝酸;液体水与固体电镀污泥比为3,干污泥为5 g,硫酸加入量为15 mL,时间1 h条件下,混合电镀污泥中金属铜锌的浸出率最大,达到97.38%。分别采用铁和铁锰合金还原剂常温还原低熔点重金属离子铜、锌,浸出液中99%以上含量的铜、锌沉淀,使低熔点重金属与黑色金属铁、锰、铬有效分离。低熔点混合重金属可以用来做铜合金添加剂使用,最后沉淀的混合黑色金属氢氧化物处理后可以用来做炼钢合金添加剂使用。     

Ion exchange treatment of rinse water generated in the galvanizing process.

A study was conducted of the viability of using the cationic exchange resins Amberlite IR-120 and Lewatit SP-112 to treat rinse water generated in the galvanizing process as well as acidic wastewater containing zinc (Zn) and iron (Fe). Solutions containing either 100 mg/L of Zn at pH 5.6 (rinse water) or Fe and Zn at concentrations of 320 and 200 mg/L at pH 1.5 (acidic water), respectively, were percolated through packed beds until the resins were exhausted. Breakthrough capacities obtained ranged between 1.1 and 1.5 meq metal/mL resin. The elution of metal and the regeneration of resins were performed with hydrochloric acid. The influence of the flowrate used during the loading stage was also studied, with 0.5 bed volumes/min (3.2 cm/min) found to be the optimum flowrate.     

电镀污泥的热处理特性以及对金属回收的影响

焙烧-酸浸法可有效回收电镀污泥中的有价金属,而污泥的热处理特性是决定能否采用焙烧预处理的重要因素。研究了氧化焙烧和还原焙烧对污泥成分和金属浸出性的影响,并对焙烧前后的污泥进行了金属形态分析和X射线衍射(XRD)分析。结果表明,焙烧预处理实现了污泥减量和金属富集;ES1经氧化焙烧后金属浸出率接近原泥,Cu的浸出率达99%;ES2的还原焙烧效果优于氧化焙烧,特别是Cu的浸出率超过97%,XRD分析发现,还原焙烧过程中金属Cu被还原为铁铜合金;2种焙烧均造成了ES3中目标金属Ni的浸出率的降低;金属浸出性的下降与残渣态的形成有关。     

The role of citric acid in cadmium and nickel uptake and translocation, in Halimione portulacoides

Some plants have high ability to absorb heavy metals in high concentrations. In this study, Halimione portulacoides was tested in conjunction with citric acid, in order to evaluate the possible use of this plant in phytoremediation processes in salt marshes. Two different concentrations of chelator were used combined with two heavy metal concentrations. When 25microM of citric acid was applied, Cd uptake and translocation was enhanced while for Ni these processes were almost inhibited. Increasing citric acid concentration to 50microM, Ni absorption decreased by the roots while for Cd there was still an increase in root uptake. Analysing translocation with this concentration of chelator, a decreased metal content in the upper organs for both metals was observed. While for Cd an optimal concentration of 25microM of citric acid was observed for phytoremediative processes, for nickel neither concentrations of chelator showed advantages for application in this remediative method.     

The behaviour of phosphorus and heavy metals in sewage sludge ashes

The effect of the combustion atmosphere and the additives (CaO and HCl) on the behaviour of phosphorus and heavy metals during sewage sludge combustion was investigated. The results demonstrated that the reduction combustion promoted the vapourisation of phosphorus and heavy metals during sewage sludge combustion. Moreover, the concentrations of phosphorus and heavy metals in the bottom ash decreased with increasing HCl ratio, and the addition of CaO can stabilise heavy metals and phosphorus. It was also observed that phosphorus and heavy metals increased with increasing CaO ratio. Lastly, the difference of the TG-DTA curves with and without additives is discussed.     

Enhancing aerobic digestion potential of municipal waste-activated sludge through removal of extracellular polymeric substance

A protease-secreting bacteria was used to pretreat municipal sewage sludge to enhance aerobic digestion. To enhance the accessibility of the sludge to the enzyme, extracellular polymeric substances were removed using citric acid thereby removing the flocs in the sludge. The conditions for the bacterial pretreatment were optimized using response surface methodology. The results of the bacterial pretreatment indicated that the suspended solids reduction was 18 % in sludge treated with citric acid and 10 % in sludge not treated with citric acid whereas in raw sludge, suspended solids reduction was 5.3 %. Solubilization was 10.9 % in the sludge with extracellular polymeric substances removed in contrast to that of the sludge with extracellular polymeric substances, which was 7.2 %, and that of the raw sludge, which was just 4.8 %. The suspended solids reduction in the aerobic reactor containing pretreated sludge was 52.4 % whereas that in the control reactor was 15.3 %. Thus, pretreatment with the protease-secreting bacteria after the removal of extracellular polymeric substances is a cost-effective and environmentally friendly method.