微生物淋滤技术在去除城市污泥重金属中的应用

重金属是目前污泥土地利用的最大障碍,有效去除污泥中的重金属成为污泥再次利用的关键。微生物淋滤法作为一种高效、低成本、绿色的污泥重金属的处理方法,展现出广阔的应用前景。综述了污泥重金属去除技术的优缺点,分析了微生物淋滤技术的优越性及去除效果,展望了微生物淋滤技术的前景与方向。     

Influence of solid content on bioleaching of heavy metals from contaminated sediment by Thiobacillus spp

The bioleaching process is one of the promising methods for removing heavy metals from contaminated sediments. In this study the effects of sediment solid content on the performance of the bioleaching process using a mixed culture of two sulfur‐oxidizing bacteria were investigated. The results showed that the rate of pH reduction decreased with increasing sediment solid content because of the buffering capacity of sediment solids. It was found that there was a linear relationship between buffering capacity and sediment solid content. For different solid contents (10–100 gdm⁻³), 82–95% (w/w) of Cu; 58–70% (w/w) of Zn; 55–73% (w/w) of Mn; 33–72% (w/w) of Pb; 35–65% (w/w) of Ni and 9–20% (w/w) of Cr were leached from sediments in this bioleaching process. The rate of metal leaching was found to decrease with an increase in sediment solid content. The solubilization of heavy metal from sediments was well described by a solid content‐related kinetic equation. © 2000 Society of Chemical Industry     

Effect of solid loading on thermophilic bioleaching of sulfide minerals

The effect of solid loading (mineral pulp density) on thermophilic bioleaching of pyrite by Sulfolobus metallicus (BC) was investigated in a batch reactor. Different mineral pulp densities in the range 3–18% (w/v) were tested. With mineral pulp densities ranging from 3 to 9% the bioleaching proceeded in a single stage with a relatively constant rate. The bioleaching rates calculated for pulp densities of 3, 6 and 9% were 0.10, 0.11 and 0.09 kg iron m⁻³ h⁻¹ respectively. By contrast the bioleaching of pyrite at pulp densities of 12 and 15% proceeded in two distinct stages. During the exponential phase of microbial growth a sharp and linear increase in concentration of released iron was achieved. This increasing trend levelled off in the presence of non‐growing cells and the second stage of bioleaching continued with a slower rate. For the pulp density of 12% the bioleaching rates of the first and the second stages were 0.09 and 0.02 kg iron m⁻³ h⁻¹ respectively, whereas the calculated rates in the presence of 15% mineral were 0.07 and 0.017 kg iron m⁻³ h⁻¹ for the first and the second stages. Application of 18% mineral adversely influenced the activity of the cells and the extent of bioleaching in this case was insignificant. © 2000 Society of Chemical Industry     

生物浸提在含重金属废物资源化中的应用研究

含重金属的各种工业废物或副产物、消费品和城市垃圾若处理不当会成为潜在的污染物;若以环境友好的方式去处理与回收它们,则可成为重要的二次资源。生物浸提含重金属废物恰好能实现资源循环利用与环境污染治理的目的。文章综述生物浸提技术在冶金与制造、化工和石化、电镀和制革,电子行业等产生的废物资源化应用研究。     

Bioleaching of heavy metals from dewatered sludge by Acidithiobacillus ferrooxidans

The feasibility of bioleaching for removal of heavy metals from dewatered sewage sludge using an iron‐oxidizing bacterium Acidithiobacillus ferrooxidans was investigated. The influence of seven process parameters including cell adaptation, total amount and particle size of the sludge, initial concentrations of Fe²⁺ and At ferrooxidans, and addition of inorganic nutrients and sulfur were evaluated in terms of the solubilization of Zn, Cu and Cr. When sludge‐adapted cells, addition of inorganic nutrients and lower sludge content were involved, higher yields of metal extraction were obtained. However, higher initial concentrations of At ferrooxidans and Fe²⁺, fine particle size of the sludge and S addition did not improve the metals' solubilization during an experimental period of 7 days. As a result of a long‐term (40 days) bioleaching experiment, 42% of Zn (1300–1648 mg kg^?1), 39% of Cu (613–774 mg kg^?1) and 10% of Cr (37–44 mg kg^?1) in the sludge were leached into the solution. The results indicate that a bioleaching process conducted under operationally optimal conditions can be effectively employed for the removal of heavy metals from sewage sludge before land application. Copyright © 2005 Society of Chemical Industry     

生物淋滤技术处理城市垃圾堆肥中重金属的研究进展

阐述了生物淋滤技术的研究现状,着重介绍了生物淋滤技术用于堆肥中重金属去除的研究进展,包括微生物种群、环境条件以及堆肥产品营养组成等。优化运行条件、运用分子生物学技术对机理进行深入探讨以及建立完善的数学模型将是生物淋滤技术的发展方向。     

生物反应器的研究及其相关问题思考

分析了生物反应器工程的研究现状，探讨了研究中存在的一些问题并提出了解决这些问题的研究思路。     

不同底物浓度下生物淋滤垃圾焚烧飞灰中重金属的动力学研究

通过氧化硫硫杆菌生物淋滤处理城市垃圾焚烧飞灰中的重金属。采用分批摇床培养,研究了生物淋滤过程中,底物浓度(S)对飞灰中重金属去除速率的影响。采用经验方程研究了S浓度对飞灰中重金属去除速率的影响,得到不同S浓度下4种重金属(Cu、Zn、Cd、Pb)的去除速率常数km,其大小顺序为ZnCuCdPb。综合各个动力学参数推知S浓度为5 g/L是本生物淋滤体系的最佳底物浓度。     

Mathematical Modelling for Removal of Mixture of Heavy Metal Ions from Waste-Water Using Micellar Enhanced Ultrafiltration (MEUF) Process

The micellar enhanced ultrafiltration (MEUF) was studied for the removal of heavy metals using a mixture of non-ionic surfactant TWEEN-80 and anionic surfactant sodium dodecyl sulphate (SDS). The gel polarization model and resistance-in-series model were used to estimate the mass transfer coefficient (3 x 10-6 m/s) and the permeate flux. The total metal ion concentration was varied from 1 mM-4 mM and the corresponding effect of the trans-membrane pressure and limiting fluxes were studied. The modified resistance-in-series model was applied to these experimental data to correlate the flux with the feed concentration and applied pressure.     

Electrochemical reduction of chromate ions from dilute artificial solutions in a GBC-reactor

Reduction of chromate in very low concentration (20 ppm) has been carried out in a GBC reactor. Final concentrations below 0.5 ppm have been achieved at reasonable reaction rates. Spontaneous reduction of chromate by hydrogen in a GBC reactor without an external power source requires careful selection of cathode material. Chemically stable materials such as titanium and RVC tend to passivate when in contact with chromate solution and are unsuitable for use as cathode materials. Graphite, active carbon and graphite felt show no obvious passivation. Reduction of oxidized groups and oxygen are the major side reactions. These occur significantly, especially when using an activated carbon bed as a cathode.     

生物淋滤去除污泥中重金属铬的试验研究

比较研究了皮革废水处理厂的剩余污泥在生物淋滤除铬过程中,由于添加辅助基质的种类、浓度及反应温度不同,重金属铬溶出效果的差异。结果表明:与对照相比,添加单质硫或硫酸亚铁作辅助基质可明显提高重金属铬的溶出效果;添加七水硫酸亚铁比添加单质硫的效果更好;其它反应条件相同,中温(35℃)条件下重金属铬的溶出效果比常温(25℃)和高温(45℃)都要好。控制反应温度可明显提高铬的溶出效果。     

Interaction of transport resistances with biochemical reaction in packed bed solid state fermenters: The effect of gaseous concentration gradients

Mass transfer plays an important role in solid state fermentation (SSF) systems. Earlier work on SSF in tray bioreactors⁷ indicated that steep gaseous concentration gradients developed within the substrate bed, owing to mass transfer resistances, which may adversely affect the bioreactor performance. For all practical purposes these gradients have been eliminated using a packed bed column bioreactor with forced aeration. Gaseous concentrations (oxygen and carbon dioxide) and enzyme activities were measured at various bed heights for various air flow rates during the course of fermentation. The results indicated that concentration gradients were decreased effectively by increasing air flow rate. For example, the actual oxygen and carbon dioxide concentration gradients reduced from 0.07% (v/v) cm^?1 and 0.023% (v/v) cm^?1 to 0.007% (v/v) cm^?1 and 0.0032% (v/v) cm^?1 respectively when the air flow rate was increased from 5 dm³ min^?1 to 25 dm³ min^?1. This resulted in an overall improvement in the performance of the bioreactor in terms of enzyme production.     

Mass Transfer and Bioremediation of Naphthalene and Methyl Naphthalenes in Baffled and Bead Mill Bioreactors

Mass transfer and bioremediation of naphthalene, 2‐methylnaphthalene and 1,5‐dimethylnaphthalene have been studied in a rotating bioreactor modified with the addition of baffles and beads. Mass transfer rates of these low solubility organic particles dissolving in water (based on the working volume of the bioreactor) were highest in the bioreactor that combined beads and baffles, with the overall mass transfer coefficient (K_La) reaching up to 25 h^?1. Based on its capacity to hold the largest volume of polluted media, the simple baffled bioreactor was considered to be the optimum roller bioreactor design. Using Pseudomonas putida, the bioremediation rate of naphthalene reached 61 mg/l‐h in this vessel and using mixed substrates, the bioremediation rate of 2‐methylnaphthalene reached 30 mg/l‐h. The dissolution rates for hydrophobic particles into the culture media during the bioremediation process were up to four times higher compared to mass transfer rates into abiotic controls, which was likely due to the production of biosurfactants by P. putida.     

合成气生物发酵法制乙醇的研究进展

采用合成气生物发酵法制乙醇具有反应条件温和、产物选择性高、原料来源广泛、低碳可持续发展等优势,是一种具有前景的可再生能源新型生产工艺。文章综述了合成气发酵法制乙醇的微生物种类及对应的适宜操作条件,分析了合成气发酵法制乙醇的Wood-Ljungdahl代谢途径;总结了合成气的广泛来源;分析讨论了过程工艺参数如合成气组成及压力、pH、温度、培养基组分、气液传质对合成气发酵的影响;指出合成气发酵法制乙醇面临的底物传质性能差、乙醇收率低等关键问题,比较了典型反应器在传质方面的差异,归纳了传质强化方法;总结了合成气发酵法制乙醇的工业化进展, 并提出了未来的发展方向。     

合成气生物发酵法制乙醇的研究进展

采用合成气生物发酵法制乙醇具有反应条件温和、产物选择性高、原料来源广泛、低碳可持续发展等优势,是一种具有前景的可再生能源新型生产工艺。文章综述了合成气发酵法制乙醇的微生物种类及对应的适宜操作条件,分析了合成气发酵法制乙醇的Wood-Ljungdahl代谢途径;总结了合成气的广泛来源;分析讨论了过程工艺参数如合成气组成及压力、pH、温度、培养基组分、气液传质对合成气发酵的影响;指出合成气发酵法制乙醇面临的底物传质性能差、乙醇收率低等关键问题,比较了典型反应器在传质方面的差异,归纳了传质强化方法;总结了合成气发酵法制乙醇的工业化进展, 并提出了未来的发展方向。     

钠基膨润土对重金属离子的吸附特征

探讨了在不同振荡时间、不同溶液重金属离子浓度、不同矿物颗粒细度和不同pH值条件下,钠基膨润土对Cu2+、Zn2+和Cd2+的吸附效果,讨论了钠基膨润土对重金属离子吸附的影响因素。结果表明:重金属离子在钠基膨润土表面的吸附是个迅速的过程,钠基膨润土对重金属的吸附在10 min内即可达最大值。钠基膨润土不同颗粒细度对重金属离子的去除率有所不同,但并非颗粒越细吸附量越大。就试验的3种重金属离子而言,钠基膨润土对其吸附效果均很好。较高的pH值有助于钠基膨润土对溶液中重金属离子的吸附,但考虑到实际操作的其它因素,不能把pH值调得过高。     

Experimental study of O2 diffusion coefficient measurement at a planar gas–liquid interface by planar laser‐induced fluorescence with inhibition

A new method for determining the molecular diffusivity of oxygen in liquids is described. The technique was applied through a flat air–liquid interface in a Hele‐Shaw cell (5 × 5 × 0.2 cm³) and was based on planar laser‐induced fluorescence (PLIF) with inhibition. A ruthenium complex (C₇₂H₄₈N₈O₆Ru) was used as the fluorescent dye sensitive to oxygen. A mathematical analysis was developed to determine the molecular diffusivity of oxygen simply by localizing the gas diffusion front. The specificity of this mathematical analysis is that it does not require the properties of the fluids (such as the saturation concentration) to be considered, which is especially relevant for complex media that are sometimes difficult to characterize properly. This technique was applied to three different fluids (viscosities ranging from 1 to 2.4 mPa·s) corresponding to binary diffusion coefficients ranging from 9.5 × 10^?10 to 2 × 10^?9 m²/s. Experimental data were found with an uncertainty of about 5% and were in good agreement with the literature. Particle image velocimetry and numerical simulations were also carried out to determine the optimal gas flow rate (0.01 L/s) to reach purely diffusive transfer, and the corresponding hydrodynamic profiles of the two phases. © 2012 American Institute of Chemical Engineers AIChE J, 59: 325–333, 2013