Biosorption of heavy metals by Saccharomyces cerevisiae

Abundant and common yeast biomass has been examined for its capacity to sequester heavy metals from dilute aqueous solutions. Live and non-living biomass of Saccharomyces cerevisiae differs in the uptake of uranium, zinc and copper at the optimum pH 4–5. Culture growth conditions can influence the biosorbent metal uptake capacity which normally was: living and non-living brewer's yeast: U > Zn > Cd > Cu; non-living baker's yeast: Zn > (Cd) > U > Cu; living baker's yeast: Zn > Cu (Cd) > U. Non-living brewer's yeast biomass accumulated 0.58 mmol U/g. The best biosorbent of zinc was non-living baker's yeast ( 0.56 mmol Zn/g). Dead cells of S. cerevisiae removed approximately 40% more uranium or zinc than the corresponding live cultures. Biosorption of uranium by S. cerevisiae was a rapid process reaching 60% of the final uptake value within the first 15 min of contact. Its deposition differing from that of other heavy metals more associated with the cell wall, uranium was deposited as fine-needle-like crystals both on the inside and outside of the S. cerevisiae cells.     

Biosorption of heavy metals by distillery-derived biomass

Biomass derived from the Old Bushmill's Distillery Co. Ltd., Northern Ireland was harvested and examined for its ability to function as a biosorbent for metals such as Cu, Zn, Fe, Pb and Ag. Binding studies were carried out using biosorption isotherm analysis. Although the material had previously been shown to be capable of efficient U biosorption, its affinity for Cu, Zn, Fe was lower. However, binding studies with Pb demonstrated that it had a maximum biosorption capacity for that metal of 189?mg/g dry weight of the biomass. In addition, the biomass exhibited a maximum biosorption capacity of 59?mg/g dry weight for Ag and this compared very favourably with previously quoted values for other industrial sources of Saccharomyces cerevisiae. On the basis of the biosorption isotherm analyses carried out in this study, preference for this series of metals by the biomass was found to be Pb?>?U?>?Ag?>?Zn?≥?Fe?>?Cu.     

Biosorption of heavy metals by Fucus spiralis

The sorption uptake of cadmium, nickel, zinc, copper and lead by marine brown alga Fucus spiralis was investigated in bimetallic, trimetallic and multimetallic solutions. The experimental data fitted very well to Langmuir model. In bimetallic systems, the affinity of biomass for lead and copper increased and the sorption uptake of these metals was not affected by increasing concentrations of cadmium, nickel or zinc. However, in solutions with both metals there was a significant mutual decrease of their sorption levels at high concentrations of the other metal. The sorption uptake of cadmium, nickel and copper was investigated in trimetallic aqueous systems. Based on the kinetic parameter b, the affinity of F. spiralis for copper was considerably higher than for cadmium or nickel: bCd=6.39, bNi=1.82 and bCu=17.89. In all tests, the maximum sorption uptake remained practically constant around 1 mmol/g, indicating that the number of active sites on the biomass was limited. Tests with four and five metals showed that copper was preferentially adsorbed. The differences between the experimental sorption data and those given by the chemical speciation program PHREEQCI were negligible. In general, the software used provided satisfactory estimated data for each metal and hence can be a useful tool to predict or simulate the real process.     

解脂假丝酵母对重金属工业废水的吸附特性

利用解脂假丝酵母对Cr(Ⅵ)、Ni(Ⅱ)和Cu(Ⅱ)共存的模拟重金属废水及3种实际重金属废水进行了微生物吸附,结果表明,pH、吸附时间和菌浓度等均是显著的影响因素.Cr(Ⅵ)、Ni(Ⅱ)和Cu(Ⅱ)的去除均符合准一级和准二级动力学模型,其中准二级模型的拟合效果最理想,证明该菌种对重金属的吸附包括了多个步骤,其中化学吸附是限速步骤.解脂假丝酵母对共存重金属的生物吸附效果理想,1g·L^-1菌体在120min时,对18.7～37.86mg·L^-1Cr、2.39～9.21mg·L^-1Cu、2.27～9.87mg·L^-1Ni和0.43～1.32mg·L^-1Zn的去除率分别为81.6%～84.6%、84.0%～100%、84.1%～100%和93.9%～100%.菌体的蛋白质、脂质和多糖均参与了重金属吸附,起作用的主要功能团是-OH、-NH₂、-CH₂、-CH₃、-COOH、-CHO、C=C、-PO₄^3-和-SO₃H.     

Biosorption of heavy metals from aqueous solutions with tobacco dust

A typical lignocellulosic agricultural residue, namely tobacco dust, was investigated for its heavy metal binding efficiency. The tobacco dust exhibited a strong capacity for heavy metals, such as Pb(II), Cu(II), Cd(II), Zn(II) and Ni(II), with respective equilibrium loadings of 39.6, 36.0, 29.6, 25.1 and 24.5 mg of metal per g of sorbent. Moreover, the heavy metals loaded onto the biosorbent could be released easily with a dilute HCl solution. Zeta potential and surface acidity measurements showed that the tobacco dust was negatively charged over a wide pH range (pH > 2), with a strong surface acidity and a high OH⁻ adsorption capacity. Changes in the surface morphology of the tobacco dust as visualized by atomic force microscopy suggested that the sorption of heavy metal ions on the tobacco could be associated with changes in the surface properties of the dust particles. These surface changes appeared to have resulted from a loss of some of the structures on the surface of the particles, owing to leaching in the acid metal ion solution. However, Fourier transform infrared spectroscopy (FTIR) showed no substantial change in the chemical structure of the tobacco dust subjected to biosorption. The heavy metal uptake by the tobacco dust may be interpreted as metal–H ion exchange or metal ion surface complexation adsorption or both.     

Biosorption of heavy metals by Saccharomyces cerevisiae: a review

Heavy metal pollution has become one of the most serious environmental problems today. Biosorption, using biomaterials such as bacteria, fungi, yeast and algae, is regarded as a cost-effective biotechnology for the treatment of high volume and low concentration complex wastewaters containing heavy metal(s) in the order of 1 to 100 mg/L. Among the promising biosorbents for heavy metal removal which have been researched during the past decades, Saccharomyces cerevisiae has received increasing attention due to the unique nature in spite of its mediocre capacity for metal uptake compared with other fungi. S. cerevisiae is widely used in food and beverage production, is easily cultivated using cheap media, is also a by-product in large quantity as a waste of the fermentation industry, and is easily manipulated at molecular level. The state of the art in the field of biosorption of heavy metals by S. cerevisiae not only in China, but also worldwide, is reviewed in this paper, based on a substantial number of relevant references published recently on the background of biosorption achievements and development. Characteristics of S. cerevisiae in heavy metal biosorption are extensively discussed. The yeast can be studied in various forms for different purposes. Metal-binding capacity for various heavy metals by S. cerevisiae under different conditions is compared. Lead and uranium, for instances, could be removed from dilute solutions more effectively in comparison with other metals. The yeast biosorption largely depends on parameters such as pH, the ratio of the initial metal ion and initial biomass concentration, culture conditions, presence of various ligands and competitive metal ions in solution and to a limited extent on temperature. An assessment of the isotherm equilibrium model, as well as kinetics was performed. The mechanisms of biosorption are understood only to a limited extent. Elucidation of the mechanism of metal uptake is a real challenge in the field of biosorption. Various mechanism assumptions of metal uptake by S. cerevisiae are summarized.     

Biosorption and biodegradation of pentachlorophenol (PCP) in an upflow anaerobic sludge blanket (UASB) reactor

In order to understand the fate of PCP in upflow anaerobic sludge blanket reactor (UASB) more completely, the sorption and biodegradation of pentachlorophenol (PCP) by anaerobic sludge granules were investigated. The anaerobic granular sludge degrading PCP was formed in UASB reactor, which was seeded with anaerobic sludge acclimated by chlorophenols. At the hydraulic retention time (HRT) of 20–22 h, and PCP loading rate of 200–220 mg l⁻¹ d⁻¹, UASB reactor exhibited good performance in treating wastewater which containing 170–180 mg l⁻¹ PCP and the PCP removal rate of 99.5% was achieved. Sequential appearance of tetra-, tri-, di-, and mono-chlorophenol was observed in the reactor effluent after 20 mg l⁻¹ PCP introduction. Sorption and desorption of PCP on the anaerobic sludge granules were all fitted to the Freundlich isotherm equation. Sorption of PCP was partly irreversible. The Freundlich equation could describe the behavior of PCP amount sorbed by granular sludge in anaerobic reactor reasonably well. The results demonstrated that the main mechanism leading to removal of PCP on anaerobic granular sludge was biodegradation, not sorption or volatization.     

Biosorption of heavy metals using whole mold mycelia and parts thereof.

Biosorption of heavy metals was carried out using whole mycelia and selected components of Aspergillus niger, Rhizopus oryzae and Mucor rouxii. Binding of copper, cadmium, nickel and zinc was considerably improved by treating the cell wall fraction with 4 M NaOH at 121 degrees C. Chitosan contributed most to the biosorptive capacity. 0.96 mmol copper was bound by 1 g of the treated mycelium of M. rouxii DSM 1191.     

茶废弃物对溶液中重金属的生物吸附研究进展

茶废弃物是农业固体废弃物的一个重要组成部分,来源广泛,数量庞大.由于其具有吸附特性,利用茶废弃物作吸附剂去除废水中的重金属受到了国内外学者的广泛关注.本文从影响因素、吸附机理、吸附剂制备和脱附再生等方面综述了茶废弃物吸附去除溶液中重金属的最新研究进展,认为吸附机理、制备、脱附再生、工艺参数和后处理等是今后实现茶废弃物吸附剂工业化应用的主要研究方向.     

Biosorption of precious metals

Biosorption has emerged as a low-cost and often low-tech option for removal or recovery of base metals from aqueous wastes. The conditions under which precious metals such as gold, platinum and palladium are sorbed by biomass are often very different to those under which base metals are sorbed. This, coupled with the increasingly high demand for precious metals, drives the increase in research into efficient recovery of precious metal ions from all waste material, especially refining wastewaters. Common biosorbents for precious metal ions include various derivatives of chitosan, as well as other compounds with relatively high surface amine functional group content. This is generally due to the ability of the positively charged amine groups to attract anionic precious metal ions at low pH. Recent research regarding the biosorption of some precious metals is reviewed here, with emphasis on the effects of the biosorption environment and the biosorption mechanisms identified.     

Immobilization of selected heavy metals in sewage sludge by natural zeolites

This contribution presents the possibility of application of natural sorbent (Transcarpathian clinoptylolite (KL)) for immobilization of selected heavy metals in the sewage sludge. The influence of ion-exchange parameters (e.g. time, amount of zeolite) were discussed. Process of immobilization was performed using a static method (Batch). It was found that best possible conditions for immobilization of heavy metal ions were as follows: zeolite fraction 0.7–1.0 mm, 5 h of shaking, zeolite/sewage sludge ratio 2/98.     

Leaching of iron and toxic heavy metals from anaerobically-digested sewage sludge

Summary Heavy metal-loaded sewage sludge was leached abiotically using FeCl₂ and FeCl₃ which are applied in waste water treatment plants to eliminate phosphate and for coagulation. Due to the hydrolyzing nature of ferric iron, ferric chloride (100 mmll L^–1) was able to solubilize more than 90% of copper and zinc and more than 80% of cadmium, with an optimal pulp density of 3% (w/v), after 10 h of exposition at 25°C. Chromium, lead and nickel were solubilized to an extent of 40–70%. With the exception of copper (redoxolysis), all heavy metals monitored were leached following the principle of acidolysis. Chemical leaching with iron resulted in a secondary contamination of sewage sludge (96 g iron per kg dry weight). The insoluble iron compounds which were precipitated for adsorbed to sludge flocks could be resolubilized with oxalic acid (100 mM, pH<3.3) up to an extent of 90%. Iron was leached by acidolysis and held in solution by complexation with oxalic acid. The pH optimum for the treatment of sewage sludge with 100 mmol L^–1 oxalic acid was pH 3.3. At this pH an excessive solubilization of nutrient elements and compounds (phosphorus, nitrogen, alkali and alkali earth elements) could be avoided concomitantly leaching 75% iron. Furthermore the hydrophobicity of the sewage sludge was significantly reduced as a result of treatment with iron chloride.Thiobacillus ferrooxidans (isolated from arsenopyrite and adapted on sewage sludge) utilized ferrous iron as an energy source in the presence of chloride ions (FeCl₂) as efficiently as ferrous sulphate. No toxic effects of oxalic acid onT. ferrooxidans were observed at the prevailing concentration.     

Granular sludge formation in upflow anaerobic sludge blanket (UASB) reactors

The state of the art for upflow anaerobic sludge blanket (UASB) reactors is discussed, focusing on the microbiology of immobilized anaerobic bacteria and the mechanism of granule formation. The development of granular sludge is the key factor for successful operation of the UASB reactors. Criteria for determining if granular sludge has developed in a UASB reactor is given based on the densities and diameters of the granular sludge. The shape and composition of granular sludge can vary significantly. Granules typically have a spherical form with a diameter from 0.14 to 5 mm. The inorganic mineral content varies from 10 to 90% of the dry weight of the granules, depending on the wastewater composition etc. The main components of the ash are calcium, potassium, and iron. The extracellular polymers in the granular sludge are important for the structure and maintenance of granules, while the inorganic composition seems to be of less importance. The extracellular polymer content varies between 0.6 and 20% of the volatile suspended solids and consists mainly of protein and polysaccharides. Both Methanosaeta spp. (formerly Methanothrix) and Methanosarcina spp. have been identified as important aceticlastic methanogens for the initial granulation and development of granular sludge. Immunological methods have been used to identify other methanogens in the granules. The results have showed that, besides the aceticlastic methanogens Methanosaeta spp. and Methanosarcina spp., hydrogen and formate utilizing bacteria are also present, e.g., Methanobacterium formicicum, Methanobacterium thermoautotrophicum, and Methanobrevibacter spp. Microcolonies of syntrophic bacteria are often observed in the granules, and the significant electron transfer in these microcolonies occurs through interspecies hydrogen transfer. The internal organization of the various groups of bacteria in the granules depends on the wastewater composition and the dominating metabolic pathways in the granules. Internal organization is observed in granules where such an arrangement is beneficial for an optimal degradation of the wastewater. A four-step model is given for the initial development of granular sludge. (c) 1996 John Wiley & Sons, Inc.     

Biotransformation of nitrophenols in upflow anaerobic sludge blanket reactors

Four identical bench-scale upflow anaerobic sludge blanket (UASB) reactors, R1, R2, R3 and R4, were used to assess nitrophenols degradation at four different hydraulic retention times (HRT). Reactor R1 was used as control, whereas R2, R3, and R4 were fed with 2-nitrophenol (2-NP), 4-nitrophenol (4-NP), and 2,4-dinitrophenol (2,4-DNP), respectively. The concentration of each nitrophenol was gradually varied from 2 to 30 mg/l during acclimation. After acclimation reactors were operated under steady-state conditions at four different HRTs – 30, 24, 18, and 12 h, to study its effect on the removal of nitrophenols. Overall removal of 2-NP and 4-NP was always more than 99% but 2,4-DNP removal decreased from 96% to 89.7% as HRT was lowered from 30 to 12 h. 2-Aminophenol (2-AP), 4-aminophenol (4-AP) and 2-amino,4-nitrophenol (2-A,4-NP) were found to be the major intermediates during the degradation of 2-NP, 4-NP and 2,4-DNP, respectively. Out of the total input of nitrophenolic concentration (30 mg/l), on molar basis, about 41.2–48.4% of 2-NP, 59.4–68% of 4-NP, 30–26.6% of 2,4-DNP was recovered in the form of their respective amino derivatives at 30–12 h HRT. COD removal was 98–89%, 97–56%, 97–52%, and 94–46% at 30–12 h HRT for R1, R2, R3 and R4, respectively. Average cell growth was observed to be 0.15 g volatile suspended solid (VSS) per g COD consumed. Methanogenic inhibition was observed at lower HRTs (18 and 12 h), however denitrification was always more than 99% with non-detectable level of nitrite. The granules developed inside the reactors were black in color and their average size varied between 1.9 and 2.1 mm.     

Development of thermophilic methanogenic sludge in compartmentalized upflow reactors

The characteristics and development of thermophilic anaerobic sludge in upflow staged sludge bed (USSB) reactors were studied. The compartmentalized reactors were inoculated with partially crushed mesophilic granular sludge and then fed with either a mixture of volatile fatty acids (VFA) or a mixture of sucrose and VFA. The staged degradation of the soluble substrate in the various compartments led to a clear segregation of specific types of biomass along the height of the reactor, particularly in reactors fed with the sucrose-VFA mixture. Both the biological as well as the physical properties of the cultivated sludge were affected by the fraction of nonacidified substrate. The sludge in the first compartment of the reactor treating the sucrose-VFA mixture was whitish and fluffy, most likely resulting from the development of acidifying bacteria. Sludge granules which developed in the top part of this reactor possessed the highest acetogenic and methanogenic activity and the highest granule strength as well. The experiments also revealed that the conversion of the sucrose-VFA mixture into methane gradually deteriorated at prolonged operation at high organic loading rates (50 to 100 g COD . L(-1) . day(-1)). Stable long-term performance of a reactor can only be achieved by preserving the sludge segregation along the height of the reactor. In the reactor fed solely with the VFA mixture little formation of granular sludge occurred. In this reactor, large differences in sludge characteristics were also observed along the reactor height. Li(+)-tracer experiments indicated that the hydraulic regime in the USSB reactor is best characterized by a series of at least five completely mixed reactors. The formation of granular sludge was found to influence the liquid flow pattern. (c) 1996 John Wiley & Sons, Inc.     

High upflow velocity and organic loading rate improve granulation in upflow anaerobic sludge blanket reactors

Five laboratory scale upflow anaerobic sludge blanket (UASB) reactors were seeded with nongranular sewage sludge. Granulation was obtained after 15–35 days when between 0.5 and 2.0m/h upflow liquid velocity was applied, with an organic loading rate (OLR) of 8g COD/l.d (COD is the chemical oxygen demand). Granules had different physical characteristics and specific activity (g COD_REMOVED/g volatile suspended solids) depending on the upflow liquid velocity applied. Granules were obtained in short startup periods (5 and 14 days) when a pilot-scale (180l) UASB reactor with a height of 4.7m was used to study hydraulic effects on the granulation process.     

Biosorption behavior of heavy metals in bioleaching process of MSWI fly ash by Aspergillus niger

In this study, it was considered that the biosorption of heavy metals by biomass might occur during the bioleaching of fly ash. This work is focused on the biosorption behavior of Al, Fe, Pb and Zn by Aspergillus niger during the bioleaching process. The fungal biomass was contacted with heavy metals solution which extracted from fly ash by using gluconic acid as leaching agent. The equilibrium time for biosorption was about 120 min. The biosorption experiment data at initial pH 6.5 was used to fit the biosorption kinetics and isotherm models. The results indicated that the biosorption of Al, Fe and Zn by A. niger biomass were well described by the pseudo-first order kinetic model. The pseudo-second order kinetic model was more suitable for that of Pb. The Langmuir isotherm model could well describe the biosorption of Fe, Pb and Zn while the Freundlich model could well describe the biosorption of Al. Furthermore, the biosorption of metal ions decreased evidently in the presence of fly ash as compared to that in the absence of fly ash. This research showed that although the biomass sorption occurred during the bioleaching process, it did not inhibit the removal of Al, Fe, Pb and Zn evidently from fly ash.     

Total concentrations and chemical speciation of heavy metals in liquefaction residues of sewage sludge

The risk (including bioavailability and eco-toxicity) of heavy metals (Pb, Zn, Cu, Cd, Cr and Ni) in liquefaction residues (LR) of sewage sludge (SS) was estimated, according to both the speciation of heavy metals and the local environmental characteristics. The amount of organic matters in LR was lower than that in SS, resulting in a smaller calorific value, while the total content of heavy metals in LR nearly doubled. High residual rates of heavy metals (about 80%) indicated that the heavy metals in SS were concentrated into LR after liquefaction. The comparisons of sequential extraction results between SS and LR showed that after liquefaction, the mobile and easily available heavy metal fractions (acid soluble/exchangeable and reducible fractions) were mainly transformed into the relatively stable heavy metal fractions (oxidizable and residual fractions). The bioavailability and eco-toxicity of heavy metals in LR were relieved, though the total concentrations of heavy metals increased.     

Biotreatment of heavy oil wastewater by combined upflow anaerobic sludge blanket and immobilized biological aerated filter in a pilot-scale test

A field pilot study has been constructed in the Liaohe oilfield, China to treat heavy oil wastewater with large amounts of dissolved recalcitrant organic compounds and low nutrient of nitrogen and phosphorus by an upflow anaerobic sludge blanket (UASB) coupled with immobilized biological aerated filters (I-BAFs). By operating the system for 252 days (including the start-up of 128 days), the chemical oxygen demand (COD), ammonia nitrogen (NH₃-N) and suspended solid (SS) in the wastewater were removed by 74%, 94% and 98%, respectively. GC–MS analysis indicated that most of alkanes were degraded by the UASB process, while the I-BAF played important roles both in degrading organic compounds and in removing the NH₃-N and SS. The bacterial community structural analysis based on the PCR-DGGE technology reveals that the predominant bacteria in the UASB reactor belong to the Bacillales and Rhodobacterales, and that in the I-BAF was identified as uncultured soil bacterium. Our results suggest that the combined biotreatment system has immense potential in large-scale treatment of heavy oil wastewater.     

施污土壤重金属有效态分布及生物有效性

以城市污泥为研究对象,将城市污泥与土壤按照一定的质量比配成污泥混合土壤.采用6种不同性质提取剂(0.05mol/L EDTA、0.1 mol/L CH3 COOH、0.01 mol/L CaC12、1 mol/L CH3COONH4,0.05 mol/L NaHCO3和0.05 mol/L Tris-HCl)分别对污泥混合土壤中重金属(Cd、Pb、Cu和Zn)的螯合态、酸溶态、中性交换态、中性结合态、碱性交换态和蛋白质结合态进行提取,考察污泥的添加对土壤中不同形态重金属的消长规律.通过黑麦草盆栽试验,探究污泥混合土壤中不同形态重金属的植物可利用性.结果表明:污泥混合土壤中重金属螯合态比例较大,占总量的20.3％-40.0％;其次为酸溶态和中性结合态,而中性交换态、碱性交换态和蛋白质结合态的含量较低.污泥的添加促进了黑麦草对Cd、Cu和Zn的吸收,在污泥添加率为44.4％时根部对其吸收量达最大,分别较CK处理增加了0.3、2.3和6.5倍.抑制了对Pb的吸收,在污泥添加率为37.5％时,根部对Pb的吸收较CK处理下降0.4倍.Pearson相关系数分析结果表明:污泥混合土壤中以螯合态、酸溶态和中性结合态存在重金属可被黑麦草吸收利用.