低成本生物材料去除废水中铅的研究探讨

水体中的铅是环境的危险污染物之一,寻找经济、高效的废水中铅的去除方法是水处理研究的热点问题.低成本生物吸附剂具有操作简单、去除重金属离子效果好的特点,对当前低成本生物吸附材料在含铅废水处理中的应用情况进行了总结探讨,分析了低成本生物吸附剂处理含铅废水的影响因素及机理,探析了吸附剂再生的可行性,并指出了目前研究中存在的问...     

Thermal plasma vitrification process as an effective technology for fly ash and chromium‐rich sewage sludge utilization

The main goal of the vitrification process for environmental research is the destruction of hazardous waste. This study proposes the use of a thermal plasma treatment process to transform fly ash and chromium‐rich sewage sludge into glassy products called vitrificates that can be stored on the land without harmful environmental effects. This is achieved by: (i) decreasing the temperature and energy used to adjust process cost minimization; and (ii) stabilization of vitrificates for different compositions of waste mixture. The chemical stabilization of final products was examined by heavy metals leachability tests. Hardness tests were done to verify the physical stabilization of vitrificates. The most stable vitrificates were obtained from a sample consisting of 90 wt% fly ash and 10 wt% chromium sludge. The thermal plasma treatment is an effective method which can be used to convert hazardous waste mixtures into less toxic or inert glassy products. The chemical composition of raw materials influenced the chemical and physical properties of the vitrificates and determined their internal structures. Mixtures of two different hazardous wastes reduces the process cost without negative environmental impact, which is an innovation in thermal plasma treatment technology. © 2013 Society of Chemical Industry     

Investigations on twenty Australian sewage sludges — their evaluation by means of chemical analysis

To evaluate twenty sludges from different places in Australia for disposal on arable land, these sludges were extracted with (a) HNO₃ to determine the ‘total’ contents of some heavy metals and other elements; (b) a solution containing DTPA to determine contents of ‘available’ heavy metals; and (c) with a CaCl₂-solution to determine contents of water-soluble heavy metals and some other elements. Measurements of the pH of the sludges, their electrolytic conductivity, NaHCO₃-extractable P, water-extractable Cl, and contents of ash and organic carbon were also made. The HNO₃-extractable Cd, Cu, Mn, Ni, Pb, and Zn in the sludges were compared with those in sludges from three other countries. High correlations between HNO₃-extractable and DTPA-extractable metals were found in the Australian sludges; therefore, the HNO₃ is equally good as the DTPA as an extractant of heavy metals in sewage sludges. The correlations between HNO₃- and CaCl₂-extractable Cd, Cu, Mn, and Zn were not significant. ‘Young’ and ‘aged’ sludges from the same treatment plants consistently differed in their Na and Cl contents, which were lower in the ‘aged’ sludges. A wheat experiment treated with high application rates of a saline and metalliferous sludge showed that the balance of nutrients and the amount of soluble salts in a sewage sludge are of greater direct importance to the growth of plants than the heavy metal content of that sludge.     

Heavy Metals Precipitation in Sewage Sludge

Abstract

There is a great need for heavy metal removal from strongly metal‐polluted sewage sludges. One of the advantages of heavy metal removal from this type of sludge is the possibility of the sludge disposal to landfill with reduced risk of metals being leached to the surface and groundwater. Another advantage is the application of the sludge as soil improver. The use of chemical precipitation to remove dissolved heavy metals from sewage sludge implies a high cost for chemicals. This work shows, for real sewage sludge for the first time that the addition of NaOH as first precipitating agent considerably saves the addition of Na₂S, that is one of the most effective metal precipitating agents and also expensive. After solubilization of heavy metals by chemical leaching with previous aeration, the next step was the separation of the sludge solids from the metal‐rich acidic liquid (leachate) by centrifugation and filtration. Afterwards, the filtered leachate was submitted to the application of NaOH and Na₂S, separately and in combination, followed by filtration. The results showed that when iron and aluminium are present in the leachate, adsorption and/or coprecipitation of Cr, Pb, and Zn with Fe(OH)₃ and Al(OH)₃ might occur at increasing pH conditions. The combination of hydroxide and sulfide precipitation was able to promote an effective removal of heavy metals from leachate. Applying NaOH at a pH of 4–5 as a first precipitation step, followed by filtration and further addition of Na₂S to the filtered liquid at pH of 7–8 as a second precipitation step, decreased considerably the dosage of the second precipitant (almost 200 times), compared to when it was solely applied. This has practical applications, as the claimed costs drawbacks of H₂S addition is considerably reduced by the addition of the less expensive NaOH. The best removal efficiencies obtained were: Pb: ～100%, Cr: 99.9%, Cu: 99.7%, and Zn: 99.9%.     

Potential utilization of oil sludge incineration bottom ash for glass-ceramics: Crystallization kinetics,properties and toxicological evaluation

The bottom ash (OIBA) generated from the incineration of hazardous oil sludge is classified as a hazardous waste. In this work, the OIBA was applied as raw material to prepare SiO₂-Al₂O₃-CaO system glass-ceramics by melt-sintering with the addition of waste glass wool (GW). The effects of basicity (CaO/SiO₂ ratio, 0.52-1.05) and sintering temperature (900–1050 °C) on the crystallization kinetics, properties, microstructure, leaching concentrations of heavy metals and potential toxicity of glass-ceramics were investigated. The results showed that the crystallization pattern was two-dimensional crystallization, and with the decrease of basicity, the main crystalline phase evolved from gehlenite to diopside. And the glass-ceramics with basicity of 0.88 and sintering temperature of 950 °C exhibited the best comprehensive properties, including density (2.72 g/cm³), water absorption (0.06%), compressive strength (452.45 MPa) and chemical corrosion resistance. In addition, the reduction of heavy metal leaching concentration indicates that produced glass-ceramics showed excellent solidification effect on heavy metals, the low toxicity of glass-ceramics leaching solution to the wheat seeds and Artemia suggests the environmental protection characteristics of OIBA-based glass-ceramics. These findings proved that the glass-ceramics produced by OIBA and GW could be a promising method to dispose hazardous waste with preparing high value-added construction materials.     

Environmental impact of fertilizing soils by using sewage and animal wastes

The European Community is producing annually about 300 × 10⁶ tons of sewage sludges as well as about 150, 950,160 and 200 tons of domestic, agricultural, industrial and other wastes (street litter, dead leaves etc.). About 20–25% of the German sewage sludges, which contain in average about 3.8,1.6, 0.4, 0.6, 5.3% DM^–1 N, P, K, Mg and Ca, 202, 5, 131, 349, 53, 3 and 1446 mg kg^–1 DM Pb, Cd, Cr, Cu, Ni, Hg, Zn as well as ca. 37 and 5 mg kg^–1 Dm polychlorinated hydrocarbons and biphenyls, are recycled annually as fertilizer. In addition environmental impacts on the arable land of Germany may derive from 76,19.2, 64.7, 33.6, 7.8 and 0.1 kg ha^–1 a^–1 of N, P, K, Ca, Mg and Cu added as animal manures. Besides heavy metals and hazardous organics pathogens are disseminated with organic wastes.Crop production and soil fertility generally profit from the considerable amounts of plant nutrients and carbon in sewage sludges, animal slurries and manures, but the physicochemical soil properties, the composition of microbial, faunal and plant communities as well as the metabolic processes in the soil-, rhizo- and phyllosphere are changed by organic manuring. Consequences for the soil carbon-, nitrogen-and phosphorus-cycle are discussed. Impacts of heavy metals and hazardous organics on the soil biomass and its habitat as well as on transport mechanisms and surival times of disseminated pathogens in soils are reviewed with emphasis on the German situation. A proposal for future strategies (landscape recycling) is made.     

染料残渣焚烧过程中微量元素的形态转化及其迁移分配的预测

The release of heavy metals from the combustion of hazardous wastes is an environmental issue of increasing concern. The species transformation characteristics of toxic heavy metals and their distribution are considered to be a complex problem of mechanism. The behavior of hazardous dyestuff residue is investigated in a tubular furnace under the general condition of hazardous waste pyrolysis and gasfication. Data interpretation has been aided by parallel theoretical study based on a thermodynamic equilibrium model based on the principle of Gibbs free energy minimization. The results show that Ni, Zn, Mn, and Cr are more enriched in dyestuff residue incineration than other heavy metals （Hg, As, and Se） subjected to volatilization. The thermodynamic model calculation is used for explaining the experiment data at 800℃ and analyzing species transformation of heavy metals. These results of species transformation are used to predict the distribution and emission characteristics of trace elements. Although most trace element predictions are validated by the measurements, cautions are in order due to the complexity of incineration systems.     

废弃农林生物质在废水处理中环境友好利用的研究进展

综述近年来国内外利用废弃农林生物质环境友好处理各种废水的现状,重点阐述了废弃农林生物质作为吸附剂对印染、重金属等工业废水的处理以及通过改性手段来提高农林生物质处理效果的研究进展。     

Carbon dioxide sequestration through novel use of ion exchange fibers (IX-fibers)

Electrical power generation and metal removal processes are practiced globally and share two common attributes that make them ideal candidates to be incorporated in a novel carbon dioxide sequestration scheme using ion exchange fibers (IX-fibers). First, the softening of boiler feed water used in power generation and the removal of metals from finishing wastewaters often employs the use of ion exchange for the purpose of selective separation. Second, both processes represent significant point source CO₂ emissions. This investigation demonstrated that using IX-fibers it is possible to sequester a portion of the CO₂ produced in these practices as carbonate alkalinity during the regeneration step of both the water softening and the trace heavy metal removal processes. Weak acid IX-fibers were used for hardness removal while hybrid cation exchange fibers (HCIX-F) loaded with hydrated Zr(IV) oxide (HZO) were used to remove toxic heavy metals such as zinc, cadmium and copper. IX-fibers offer the unique capability to use and consume CO₂ during the efficient regeneration of IX-fibers, whereas commercial ion exchange resins are not amenable to regeneration with CO₂. A much shorter intraparticle diffusion path length in cylindrical IX-fibers as compared to resin beads is the underlying reason for a highly efficient regeneration of the fibers. In addition to sequestering carbon dioxide, no hazardous or aggressive chemicals/brine solutions are present in the regenerant wastes as compared with traditional ion exchange processes.     

Recovery of uranium and other valuable metals from substrates and waste from copper and phosphate industries

ABSTRACT

Recovery of heavy metals and other useful materials from industrial waste is crucial because it reduces the environmental impact of the production facilities. The selective separation of uranium from such waste might be very important in the context of future energy production and the still essential role of nuclear power in the energy mix. The copper ores, waste from the copper industry, phosphate rocks and phosphogypsum were considered as sources of uranium in these studies. Apart from uranium, these materials also contain other valuable metals, e.g. rare earth elements. In the present work the procedures of extraction of uranium and accompanying metals designed for specific materials – the potential sources of metals, were reported.     

Supercritical fluid extraction of hazardous metals from CCA wood

Contamination of the environment by waste CCA (Cu, Cr, As) wood, containing the toxic heavy metals, copper, chromium, and arsenic that are hazardous to human health, can be significantly reduced by supercritical fluid extraction (SFE) technology. An environmentally benign solution for the detoxification of these CCA woods is the use of SFE technology for the treatment because no extra pollutant is added. In this work, we studied SFE of Cu, Cr, and As from CCA wood by using supercritical CO₂ modified with chelating agents. Effects of pressure and temperature on the extraction efficiency for the heavy metals were studied with organophosphorous chelating agent, Cyanex 302. Some other chelating agents were also compared. Cyanex 302 was the best ligand in our experiments at pressure of 24 MPa and temperature of 333 K. The extraction efficiencies for Cu, Cr, and As were up to 63.5, 28.6, and 31.3%, respectively.     

城市污泥重金属电动修复技术与应用研究进展

重金属污染是目前城市污水处理厂污泥农用的主要障碍之一。电动修复作为一门新兴的污染环境介质绿色修复技术,具有投资少、去除效率高和处理时间短等优点。特别是对于水力渗透性差的污泥,电动修复技术具有良好的应用前景。论文介绍了城市污泥重金属电动去除技术原理,并综述了近几年国内外在修复效果及其影响因素等方面的研究现状。同时,对该技术应用过程中存在的问题和未来研究方向进行了讨论和展望。     

Removal of heavy metal ions from aqueous solutions by radiation‐induced chitosan/(acrylamidoglycolic acid‐co‐acrylic acid) magnetic nanopolymer

An effective method was developed to isolate toxic heavy metal ions from the aqueous solution by the magnetic nanopolymers. The magnetic sorbent was prepared with radiation‐induced crosslinking polymerization of chitosan (CS), 2‐acrylamido‐glycolic acid (AMGA), and acrylic acid (AAc), which stabilized by magnetite (Fe₃O₄) as nanoparticles. The formation of magnetic nanoparticles (MNPs) into the hydrogel networks was confirmed by Fourier transform infrared spectroscopy, X‐ray diffraction, transmission electron microscopy, and Scanning electron microscopy, which revealed the formation of MNPs throughout the hydrogel networks. The swelling behavior of the hydrogels and magnetic ones was evaluated at different pH values. The adsorption activity for heavy metals such as Cu²⁺ and Co²⁺ by nonmagnetic and magnetic hydrogels, Fe₃O₄/CS/(AMGA‐co‐AAc), in terms of adsorption amount was studied. It was revealed that hydrogel networks with magnetic properties can effectively be used in the removal of heavy metal ions pollutants and provide advantageous over conventional ones. POLYM. ENG. SCI., 55:1441–1449, 2015. © 2015 Society of Plastics Engineers     

好氧颗粒污泥的应用

好氧颗粒污泥是一种新型的废水生物处理材料,它凭借其密实的结构、多样的微生物种群以及优良的沉降性能已经引起了许多学者的关注。本文对好氧颗粒污泥的形成及结构、特性加以综述。并重点关注了近年来国内外好氧颗粒污泥的应用,主要包括：有机有毒废水的处理、乳品废水的处理、氮和磷的去除、重金属和染料的去除、颗粒物的去除、核废料的去除等方面。     

Catalytic potential of cauliflower (Brassica oleracea) bud peroxidase in decolorization of synthetic recalcitrant dyes using redox mediator

We investigated the effect of cauliflower (Brassica oleracea) bud peroxidase along with redox mediators on decolorization of dyes (Reactive Red 2, Reactive Black 5, Reactive Blue 4, Disperse Orange 25 and Disperse Black 9). Results indicated that among the chosen mediators, 1-hydroxybenzotriazole (HOBT) followed by riboflavin were most effective for dye decolorization. At 0.36 EU/ml and with 0.8 mM HOBT in conjunction with 0.75 mM H₂O₂ the soluble cauliflower bud peroxidase proteins could decolorize the dyes. The enzyme worked in a broader range of pH and temperature and was adequately effective in batch processes when used with organic contaminants (dioxane and dimethylformide), detergents (Triton X-100 and sodium dodecyl sulfate), sodium chloride and heavy metals including zinc and cadmium chloride. Thus peroxidase from cauliflower bud is a better choice than other vegetable peroxidases as it is sufficiently thermostable, operates in a wide range of pH, economic and effective with low concentration of redox mediators in decolorizing recalcitrant synthetic dyes. Such peroxidases with better catalytic activity have potential of being used on a large scale.     

Solvent Extraction Behavior and Mutual Separation of Some Bivalent Metal Ions Using Thiocarbohydrazide as the Complexing Agent

Abstract

Thiocarbohydrazide (NH₂. NH. CS. NH. NH₂) was used as a complexing agent for the solvent extraction separation of some bivalent metals. Separation of Cd from Co, Cu, and Pd, and of Pb from Ni and Pd was carried out using the effect of pH on their extractability. The separation of Cu from Zn and Hg, and of Pb from Zn and Cd was also carried out using various masking agents.     

Adsorbent Derived from Pinus pinaster Tannin for Cationic Surfactant Removal

Abstract

Pinus tannin gel (PTG) has proven to be an effective adsorbent for removing various cationic pollutants including heavy metals, dyes, and surfactants. The form of obtaining these condensed tannins from Pinus pinaster bark was conventional aqueous extraction using 5.0% ethanol as additive. The present study focused on the removal of the surfactant hexadecyltrimethylammonium bromide (CTAB) from aqueous solutions using PTG. Kinetic studies showed that the Lagergren, Ho, and Elovich models all adequately explained the kinetics of CTAB adsorption onto PTG, with r² correlation coefficients of around 0.98. The influences of pH and temperature were found not to be critical, and the CTAB-PTG system was modeled theoretically according to the Langmuir hypothesis using linear, nonlinear, and multiparametric forms, obtaining the values of the activation energies and such system constants as k _l .     

“长株潭”地区湘江底泥重金属含量调查研究

通过调查分析湘江＂长株潭＂段表层底泥的锌、铜、镉、铬、铅、汞、锰等重金属含量,将底泥样品中重金属的含量分别与土壤环境质量标准、污水排入城市下水道水质标准、以及生活饮用水卫生标准中重金属含量进行比较,从而发现重金属在湘江＂长株潭＂段的污染严重程度。根据调查结果分析,对湘江＂长株潭＂段底泥重金属污染问题提出减排含重金属废水,有关部门应关注底泥重金属含量变化,和修复河床表层重金属含量高的底泥等建议。     

城市污泥中重金属去除技术研究

重金属污染是目前城市污水处理厂污泥农用的主要障碍之一。综述了城市污泥中重金属去除的常用四种技术：化学浸提、生物淋滤、动电技术和固化-稳定化,同时分析了污泥中重金属去除技术的发展方向。     

Reformulation of fire retardant coatings

Fire retardant coatings currently in use contain a number of ingredients which are either considered to be ‘toxic’ heavy metals or on the hazardous air pollutants (HAPs) list. In addition, there is concern that the use of halogenated chemicals in these coatings and other products will be banned in the future. This paper contains the details of two reformulations programs. The first is a reformulation of a low volatile organic compound (VOC) chlorinated alkyd coating and the second is a reformulation of a chlorinated emulsion system. Both programs successfully reduced the heavy metals and lowered the HAPs to an acceptable level. Preliminary results of the development of non-halogenated fire retardant coatings systems will be presented.