生物沥滤-焚烧法处理制革污泥中铬迁移转化研究

采用生物沥滤-焚烧方法,先将制革污泥中大部分难溶的有毒重金属——铬从固相溶出转移至液相,之后将沥滤后制革污泥进行有效的固液两相分离,并对分离后的固相污泥进行焚烧处理实验,研究生物沥滤-焚烧处理法对制革污泥中的总Cr在不同介质中的浓度影响。结果表明,生物沥滤法处理制革污泥后,以金属离子交换形态存在的总Cr含量增加,其中68.56%的总Cr6+和87.70%的总Cr得以去除,去除效果十分明显;将沥滤脱水后的污泥进行焚烧处理,以残渣态形式存在的总Cr相对含量变大,迁移能力减弱;铬在高温下与其他重金属元素形成复杂的金属化合物及络合物:Cr1.3Fe0.7O0.5、Na4(CrO4)(SO4)、Ca5(CrO4)3O0.5,有助于今后进一步对整个生物沥滤-焚烧处理过程进行反应机理研究。     

堆肥污泥重金属在黄土中的淋滤特征

堆肥污泥中所含重金属是污泥堆肥土地利用最大的障碍,实验选用北方贫瘠的黄土作为供试样品,通过室内土柱淋滤实验,对堆肥污泥重金属在黄土中的淋滤特征进行了研究。结果显示,在0～40 cm的浅层淋滤层,各种重金属在黄土中的纵向迁移能力为:Pb>Zn>Ni>Cu,而在50～55 cm的深层淋滤层,Cd在黄土中的迁移能力相对其他4种重金属是比较强的;各种重金属在50～60 cm深层淋滤层中会出现二次富集,出现明显富集层。研究揭示了堆肥污泥重金属在黄土中的迁移特征,为有效控制和消除堆肥污泥土地利用中重金属的污染研究提供了理论依据。     

污泥果肥利用中重金属迁移特征研究

为了厦门城市污泥的安全利用，将石渭头污水处理厂污泥经过好氧堆肥后施用于柚子树，对重金属元素在土壤、树叶及果肉中的迁移特征进行了研究。结果表明：Cd在土壤中的富集能力强；重金属元素从土壤向树叶迁移累积能力比向果肉的大得多，污泥肥料不能用于叶类食用植物的施用；Cr向树叶、Ni向果肉的迁移累积能力强；泥肥的施用加重了土壤中Cd的污染，提高了Cr向树叶、Ni向果肉的迁移能力；污泥果肥利用需降低Ni的浓度，对污泥中含量较高的Cu、Zn、Ni、Cr和Cd需进行跟踪检测。     

利用芦竹修复重金属污染湿地的研究

研究了芦竹(Arundodonaxlinn)对Cu2+、Ni2+、Cr6+重金属污染湿地的响应和对该污染湿地的影响。实验结果表明,芦竹对这3种重金属离子有一定的耐受性,并有不同程度的吸收,Cu2+、Ni2+和Cr6+去除率分别为63.8%,42.3%和34.4%。芦竹在100mg/kg浓度的Cu2+、Ni2+污染湿地中生长正常,在低浓度(55mg/kg)Cr6+污染中能存活,但生长速度较慢。在100mg/kg浓度Cr6+污染湿地中,出现急性中毒现象,半月后致死。在重金属污染环境中,芦竹普遍出现失绿现象,但除高浓度Cr6+(100mg/kg)以外,都能正常存活,表现出较强的适应性。     

以城市污泥为掺料制备烧结砖

以城市污泥为部分原料制备烧结砖,对不同烧成温度下不同污泥掺量的烧结砖的物理、力学性能进行了详细分析。结果表明,污泥可用于制备烧结砖,当污泥掺量≤12%,烧成温度为1 100℃时,烧结砖物理力学性能均符合烧结砖标准要求。此外,实验以污泥掺量为12%的烧结砖,烧成温度为1 100℃为例,进行了重金属毒性浸出实验,以考察烧制污泥砖对重金属的固化作用,进而评定污泥制砖的安全性。结果表明,经过高温焙烧,大多数重金属浸出毒性都显著降低,且符合规范要求,不会对环境造成危害。其中,重金属固化效果最好的为Zn,最差的为Cr。     

含重金属污泥制砖毒性的浸出

污泥中的重金属是影响污泥处置利用的重要因素,污泥制砖可以有效固结重金属。采用污水厂污泥与页岩按一定配比混合制备烧结砖,通过毒性浸出实验,研究烧结砖对重金属的固化程度以及重金属浸出稳定性,从而评定烧结制砖的安全性。结果表明,在浸出液为中性和酸性条件下,Cu、Cr、As和Pb的浸出浓度基本保持稳定,浸出时间的影响不大,而Zn的初始浸出浓度相对较大,最终逐渐降低;碱性条件下,Cr、Cu和Pb的浸出浓度随时间变化不大,而Zn和As的浸出浓度则在浸提时间内无明显变化规律;但不同p H浸出液下的重金属浸出浓度均远低于国家限值,污泥制砖重金属固化效果好,安全可靠。     

污水污泥中重金属污染物的溶出过程研究

污水污泥中污染物尤其是重金属的水体浸出作为重要的二次污染途径备受关注。为了探讨污水污泥中重金属的溶出规律,对上海7个污水处理厂的污水污泥进行了重金属总量分析,并采用水平振荡法对上述污水污泥中重金属进行了溶出动力学研究。结果表明,污水污泥中Cu、Cr和Zn的含量均较高,之后依次是Pb、As、Cd和Hg;污水污泥中重金属溶出动力学过程分为快速反应和慢速反应两个过程,可以用Elovich方程进行模拟;污水污泥中各重金属的溶出负荷差异较大,Cu、Cr和Zn的溶出负荷较大,其他较小,但各重金属相对于污水污泥中重金属总量的溶出百分比差异不大,基本处于10%以下。     

土壤胶体对重金属迁移及生物有效性影响的研究进展

土壤中重金属能够通过土壤孔隙迁移至地下水中,对生态环境造成污染,对人体健康构成威胁。土壤胶体因其巨大的比表面积和特殊的双电层结构能够对土壤中重金属的迁移和生物有效性产生影响。总结归纳了pH、离子强度、水动力作用、胶体粒径和孔隙尺寸等因素对重金属迁移行为的阻滞和促进作用。探讨了土壤胶体对重金属生物有效性的影响机制,并对今后的研究方向进行了展望。     

造纸污泥固化/稳定化处理技术研究

为了能更好地无害化处理造纸污泥,对造纸污泥的固化/稳定化处理技术进行了研究。以水泥、粉煤灰和煤渣作为固化剂对造纸污泥进行固化/稳定化处理。通过抗压强度评价污泥固化块的力学性质;并对固化块浸出液的COD浓度与重金属质量浓度进行了检测。当水泥、粉煤灰和煤渣的掺量分别为0.12、0.02和0.10 kg/kg,养护时间为6 d时,固化块抗压强度达到360 kPa。结果表明,水泥和煤渣对提高造纸污泥固化块的抗压强度具有促进作用,而它们与粉煤灰对造纸污泥中的有机质和重金属均具有一定的固化作用。在以上条件下,固化块浸出液中COD浓度约为115.7 mg/L,重金属浓度符合国家标准。经养护后的固化块含水率均保持在35%~40%,符合填埋场的进场标准。     

山西省城市污泥农用潜力与安全施用

城市污泥中重金属的含量是限制污泥农用的主要泥质因素,本研究对山西省不同地区城市污泥采样分析结果表明,污泥pH为6.76~7.78、N+P2O5+K2O含量为3.03%~21.39%、有机质含量为18.5%~68.8%、重金属Cu、Zn、As、Hg、Pb、Cd和Cr含量分别为61.1~225.4、76.2~1 557.1、11.5~29.1、0.2~1.7、13.5~89、0.5~8.6和108.9~328.1mg/kg,均符合农用泥质标准(CJ/T309-2009)中限定的泥质要求。依据山西省不同地区农田土壤重金属含量以及土壤环境质量二级标准,山西省不同地区土壤重金属环境容量大小顺序依次均为PbZnCrCuAsHgCd。以年施入污泥量7 500 kg/(hm2·a)计算,山西省晋北地区污泥连续施用年限为大同市约为117年,朔州市约为217年,忻州市约为133年,晋中地区太谷县约为6年,晋东南地区晋城市约为163年,长治市约为29年。     

金属铁去除水中Cr6+的影响因素研究

研究Fe/Cr6+比值和不同浓度的NO3-、Cl-和SO42-对金属铁去除Cr6+效果的影响.结果表明,金属铁对水中Cr6+有很好的还原去除效果;当金属铁的使用量为Cr6+量的1/2000时,铁对Cr6+的去除效果较差且易失去活性,而当金属铁的使用量为Cr6+量的8 000倍时,铁对Cr6+的去除效果较好且其活性的持续...     

改性污泥活性炭对水中镉离子的吸附性能

以城市污水处理厂的剩余污泥为原料,氯化锌为活化剂制备污泥活性炭,对一部分污泥活性炭用6.0 mol/L的硝酸进行改性,并研究了未改性和改性的污泥活性炭对Cd2＋的吸附行为的影响。结果表明,在pH为5.0、Cd2＋初始浓度为100 mg/L、吸附剂投加量为2.0 g/L、反应温度为25℃时,未改性的污泥活性炭吸附容量为8.45 mg/g,硝酸改性的污泥活性炭吸附容量达到了23.35 mg/g。改性和未改性的污泥活性炭对Cd2＋都有较好的吸附容量,硝酸改性大幅度提高了污泥活性炭对Cd2＋的吸附性能。常温下改性污泥活性炭对Cd2＋的吸附符合Langmuir吸附等温式。     

活性污泥法处理高钙废水中污泥特性的变化

通过单级SBR法处理模拟高钙废水,研究了活性污泥法处理高钙废水的过程中钙离子对COD,MLVSS,MLSS,SVI,污泥增长速率,污泥形态结构及生物相的影响,揭示活性污泥法处理高钙废水的过程中污泥量巨大的原因。采用逐步增加钙离子浓度的方法,检测到在污泥培养期([Ca2+]=0 mg/L),COD去除率为98.1%,MLVSS和MLSS稳定在4 900~5 500mg/L,污泥增长速率为67 mg/(L·d),SVI为55~60 mL/g;在驯化处理期([Ca2+]=120~2 400 mg/L),COD去除率降至87.37%,MLVSS降至2 500 mg/L,MLSS增加至19 300 mg/L,污泥增长速率为212.31 mg/(L·d),SVI降至25 mL/g;在冲击期([Ca2+]=4 000 mg/L),COD去除率降至69.23%,MLVSS降至1 600 mg/L,MLSS迅速增加至24 200 mg/L,污泥增长速率为816.67 mg/(L·d),SVI降至14 mL/g。经显微镜观察发现,污泥絮体由松散变得密实,生物相由钟虫等指示性微生物变为不适应环境的胞囊结构。结果表明,随Ca2+浓度的增加,COD去除率下降,MLSS迅速增加,MLVSS和SVI急剧缩小,说明活性污泥中的活性微生物逐渐减少,而无机物组分逐渐增多;钙离子的加入促使系统碳酸平衡向右移动,使离子状态的钙大部分转化为难降解的碳酸盐,并附着于污泥絮体上,污泥绒粒被压缩,使污泥颗粒密实度及MLSS迅速增加,导致污泥排放量巨大。     

Pentachlorophenol dechlorination and simultaneous Cr6+ reduction by Pseudomonas putida SKG-1 MTCC (10510): characterization of PCP dechlorination products, bacterial structure, and functional groups

It is the first report in which a novel psychrotrophic Pseudomonas putida SKG-1 strain was evaluated for simultaneous bioremediation of pentachlorophenol and Cr⁶⁺ under various cultural and nutritional conditions. Pentachlorophenol (PCP) dechlorination products, bacterial structure, and functional groups were characterized by gas chromatography and mass spectrometry (GC–MS), scanning electron microscope and energy dispersive X-ray spectroscopy (SEM–EDS), and Fourier-transform infrared (FTIR) techniques. The strain was extremely tolerant to excessively higher individual concentration of PCP (1,400 mg l^?1) and Cr⁶⁺ (4,300 mg l^?1). Increasing concentration of PCP and Cr⁶⁺ exerted inhibitory effect on bacterial growth and toxicants’ removal. The strain exhibited growth, and concomitantly remediated both the pollutants simultaneously over a broad pH (7.0–9.0) and temperature (28–32 °C) range; maximum growth, PCP dechlorination (87.5 %), and Cr⁶⁺ removal (80.0 %) occurred at optimum pH 8.0 and 30 °C (from initial PCP 100 mg l^?1 and Cr⁶⁺ 500 mg l^?1) under shaking (150 rpm) within 72 h incubation. Optimization of agitation (125 rpm) and aeration (0.4 vvm) in bioreactor further enhanced PCP dechlorination by ~10 % and Cr⁶⁺ removal by 2 %. A direct correlation existed between growth and bioremediation of both the toxicants. Among other heavy metals, mercury exerted maximum and cobalt minimum inhibitory effect on PCP dechlorination and Cr⁶⁺ removal. Chromate reductase activity was mainly associated with the supernatant and cytosolic fraction of bacterial cells. GC–MS analysis revealed the formation of tetrachloro-p-hydroquinone, 2,4,6-trichlorophenol, and 2,6-dichlorophenol as PCP dechlorination products. FTIR spectrometry indicated likely involvement of carbonyl and amide groups in Cr³⁺ adsorption, and SEM–EDS showed the presence of chromium on P. putida surface. Thus, our promising isolate can be ecofriendly employed for biotreatment of various industrial wastes contaminated with high PCP and Cr⁶⁺ concentrations.     

Response surface modelling of Cr6+ adsorption from aqueous solution by neem bark powder: Box–Behnken experimental approach

The main aim of this study is to investigate the combined effect of different operating parameters like adsorbent dose, initial Cr⁶⁺ concentration and pH on the removal of Cr⁶⁺ from aqueous solution using neem bark powder (NBP). A series of batch experiments were performed to find out the adsorption isotherms and kinetic behaviour of Cr⁶⁺ in the aqueous solution. The adsorption process was examined with three independent variables viz. NBP dosage, initial Cr⁶⁺ concentrations and pH. Seventeen batch experiments designed by Box–Behnken using response surface methodology were carried out, and the adsorption efficiency was modelled using polynomial equation as the function of the independent variables. Based on the uptake capacity and economic use of adsorbent, the independent variables were optimized by two procedures. The desirability of first and second optimization procedures were found to be 1.00 and 0.84, respectively, which shows that the estimated function may well represent the experimental model. The kinetic study indicated that the rate of adsorption confirms to the pseudo-second-order rate equation. Thermodynamics study indicated that the adsorption process was spontaneous and endothermic in nature. The surface texture changes in NBP were obtained from FT-IR analysis. The optimized result obtained from RAMP plots revealed that the NBP was supposed to be an effective and economically feasible adsorbent for the removal of Cr⁶⁺ from an aqueous system.     

磷酸活化-微波热解改性污泥对镉的吸附性能

以城市污水处理厂剩余污泥为原料,利用磷酸活化-微波热解制取改性污泥。以此污泥作为吸附剂,对含Cd2+废水进行了吸附实验研究。考察了溶液反应时间、Cd2+浓度、pH值和吸附剂用量对镉吸附去除效果的影响;利用等温吸附实验作出吸附等温线,并考察了改性污泥吸附剂吸附Cd2+的动力学方程。实验结果表明,改性污泥对Cd2+有良好的吸附性能,吸附最佳pH值为6.0,吸附较好地符合一级动力学吸附模型和Langmuir-Freundlich等温吸附方程,吸附为物理吸附,吸附反应发生12 h后达到吸附平衡。     

钙对李氏禾富集和耐受铬的调控作用

通过水培实验，研究钙对铬胁迫下李氏禾幼苗生理生化、草酸分泌及铬吸收量的影响，考察钙对李氏禾体内草酸合成的调控，进而促进李氏禾的铬耐性富集能力的作用。结果显示，不同浓度Cr³⁺胁迫下缺钙处理，李氏禾生长受抑制及质膜过氧化作用加剧，体内总草酸含量为对照处理的113%~169%，且主要表现为水溶性草酸含量显著高于对照，水溶性草酸含量为对照处理的135%~197%；高钙处理，李氏禾细胞膜透性、丙二醛（MDA）含量低于对照，李氏禾叶部总草酸含量为对照处理的125%~155%，且主要表现为不溶性草酸含量显著高于对照，其含量为对照处理的181%~270%。低浓度（0.2、0.4 mmol/L）铬胁迫下，高钙处理总铬含量分别为对照处理的175%和215%，高浓度（0.8、1.0 mmol/L）铬胁迫下，总铬含量与对照处理无显著差异（P>0.05）。可见，添加Ca²⁺能在一定Cr³⁺浓度胁迫下，有效缓解铬对李氏禾的毒害，且能通过提高植物体内不溶性草酸含量达到促进植物富集和耐受铬的能力。     

Removal of Chromium from Abrasive Blast Media by Leaching and Electrochemical Precipitation

ABSTRACT

Water is effective in leaching out Cr⁶⁺ from a mixture of paint powders and abrasive blast media. However, acids such as HNO₃, HCl, and H₂SO₄ significantly enhance the leaching procedure. Cr ions in the leaching solutions are successfully removed by electrochemical precipitation. The consumable Fe electrodes generate ferrous ions to cause the reduction of Cr⁶+ to Cr³+. Cr³+ ions along with Fe²+ and Fe³+ are then removed mainly by precipitation as Cr(OH)₃, Fe(OH)₂, and Fe(OH)₃ near the cathode where OH^- ions are generated by water electrolysis. The electrochemical process is capable of discharging low levels of Cr⁶+, less than 1 mg/L, without pH adjustment.     

城市垃圾焚烧渗沥液中Ca2+对厌氧EGSB处理效果的影响简

研究了城市生活垃圾焚烧厂渗沥液中Ca²⁺对厌氧颗粒污泥膨胀床反应器（EGSB）处理效果的影响，并采用静态实验方法考察了Ca²⁺对厌氧颗粒污泥产甲烷活性的影响。实验结果表明，进水COD为17 000 mg/L的条件下，当Ca²⁺浓度低于6 000 mg/L时，EGSB对COD去除率达93%以上；当Ca²⁺浓度高于6 000 mg/L时，COD去除率随运行时间明显下降，并在污泥中形成大量沉淀。静态实验结果表明，废水中低浓度Ca²⁺促进了厌氧颗粒污泥的产甲烷活性，但高浓度Ca²⁺明显抑制了其产甲烷活性，这是导致高Ca²⁺浓度条件下EGSB对COD去除率降低的主要原因。研究表明，颗粒污泥产甲烷活性恢复程度随Ca²⁺浓度增加而减弱。     

Dechlorination of chloroorganics,decolorization, and simultaneous bioremediation of Cr6+ from real tannery effluent employing indigenous Bacillus cereus isolate

A native Bacillus cereus isolate has been employed, for the first time, for simultaneous decolorization, dechlorination of chloroorganics, and Cr⁶⁺ remediation from the real tannery effluent. Most of the physicochemical variables in 3:1 diluted effluent were well above the standard prescribed limits, which decreased substantially upon microbial treatment. The extent of bioremediation was better in diluted (3:1) as compared to undiluted effluent supplemented with nutrients and augmented with B. cereus isolate. Maximum growth, effluent decolorization (42.5 %), dechlorination (74.1 %), and Cr⁶⁺ remediation (34.2 %) were attained with 4.0 % (v/v) inoculum, 0.8 % glucose, and 0.2 % ammonium chloride in 3:1 diluted effluent at natural pH (8.1) within 72 h of incubation. The efficiency of bioremediation in a bioreactor was higher as compared to a flask trial during 72 h of incubation: decolorization (47.9 %) was enhanced by 5.4 %, dechlorination (77.4 %) by 3.3 %, and Cr⁶⁺ removal (41.7 %) by 7.5 % at an initial color of 286 Pt-Co units and initial concentration of 62 mg chloride ions and 108 mg l^?1 Cr⁶⁺. Immobilized biomass of Pseudomonas putida and B. cereus coculture enhanced the extent of Cr⁶⁺ remediation (51.9 %) by 10.2 % compared to the bioreactor trial. Chromate reductase activity and reduced Cr directly correlated and were mainly associated with soluble fraction of B. cereus plus effluent natural microflora. The GC-MS analyses revealed the formation of metabolites such as acetic acid and 2-butenoic acid in bacterially treated effluent. The supplementation of nutrients along with B. cereus augmentation is required for efficient effluent bioremediation.