Copper biosorption on Lyngbya putealis: Application of response surface methodology (RSM)

The potential use of biosorbent prepared from an indigenously isolated cyanobacterium, Lyngbya putealis, for the removal of copper from aqueous solution has been investigated under optimized conditions in this study. Batch mode experiments were performed to determine the adsorption equilibrium and kinetic behavior of copper in aqueous solution allowing the computation of kinetic parameters and maximum metal adsorption capacity. Influences of other parameters like initial metal ion concentration (10-100 mg l⁻¹), pH (2-8) and biosorbent dose (0.1-1.0 g/100 ml) on copper adsorption were also examined, using Box-Behnken design matrix. Very high regression coefficient between the variables and the response (R² = 0.9533) indicates excellent evaluation of experimental data by second order polynomial regression model. The response surface method indicated that 40-50 mg l⁻¹ initial copper concentration, 6.0-6.5 pH and biosorbent dose of 0.6-0.8 g/100 ml were optimal for biosorption of copper by biosorbent prepared from L. putealis. On the basis of experimental results and model parameters, it can be inferred that the biosorbent which has quite high biosorption capacity can be utilized for the removal of copper from aqueous solution.     

Biosorption of cadmium by biomass of marine algae

Biomass of nonliving, dried brown marine algae Sargassum natans, Fucus vesiculosus, and Ascophyllum nodosum demonstrated high equilibrium uptake of cadmium from aqueous solutions. The metal uptake of cadmium from aqueous solutions. The metal uptake by these materials was quantitatively evaluated using sorption isotherms. Biomass of A. nodosum accumulated the highest amount of cadmium exceeding 100 mg Cd(2+)/g (at the residual concentration of 100 mg Cd/L and pH 3.5), outperforming a commercial ion exchange resin DUOLITE GT-73. A new biosorbent material based on A. nodosum biomass was obtained by reinforcing the algal biomass by formaldehyde cross-linking. The prepared sorbent possessed good mechanical properties, chemical stability of the cell wall polysaccharides and low swelling volume. Desorption of deposited cadmium with 0.1-0.5M HCI resulted in no changes of the biosorbent metal uptake capacity through five subsequent adsorption/desorption cycles. There was no damage to the biosorbent which retained its macroscopic appearance and performance in repeated metal uptake/elution cycles. (c) 1993 Wiley & Sons, Inc.     

Effect of the presence of lead on the biosorption of copper,cadmium and nickel by anaerobic biomass

Heavy metals are toxic pollutants released into the environment as a result of industrial, mining and agricultural activities. The biosorption of Pb, Cu, Cd, and Ni from single and binary metal systems were studied in equilibrium systems and in a flow-through column packed with a calcium-saturated anaerobic sludge biosorbent, respectively. The single-metal sorption uptake capacity of the biomass for Pb was slightly inhibited by the presence of Cu and Cd cations (by 6%) and by the presence of nickel (by 11%). The affinity order of anaerobic biomass for the four metals was established as: Pb > Cu > Ni > Cd. Factors such as hydration effects, hydrolysis effects and covalent binding of the metal ions may contribute to this result. By studying the breakthrough curves obtained from a fixed bed column fed with an equimolar mixture of Pb, Cd, Cu, and Ni, it was determined that lead was the last metal to break through the column at the 150 bed volume mark compared to 4, 15, 30 bed volume marks for Ni, Cd, and Cu, respectively.     

Desorption of cobalt-laden algal biosorbent

Following an effective accumulation of cobalt by nonliving algal biomass of Ascophyllum nodosum, the desorption release of the metal from the biosorbent was examined using H(2)SO(4), HCl, NH(4)OH, KHCO(3), EDTA, KSCN, KCl, and CaCl(2) solutions. The solution of CaCl(2) (0.05M) in HCl appeared to be the best eluant capable of desorbing more than 96% of the sequestered cobalt at the optimum pH 2-3. The optimum solid-to-liquid ratio was more than 10 with the cobalt reuptake capacity of the biosorbent undiminished. The effect of temperature on the elution process and the elution rate was not significant up to 60 degrees C. The infrared (IR) spectra of the native and the eluted biomass did not show significant differences. The electron micrographs of the algal biomass taken after washing it with the CaCl(2) (0.1M) eluant solution indicated no damage to the cells and cell walls, while strong acid, alkaline, and KSCN treatment resulted in some changes in the cellular structure. The kinetics of the cobalt stripping process was quite rapid. The required contact time for the complete metal removal from the biomass was shorter than 2 h, even for the highest levels of cobalt initially deposited on the biomass.     

Loss of cell components during rehydration of dried Rhodotorula glutinis and its implications for lead uptake

Microbial cells are routinely dried and ground before they are used in metal biosorption studies. In this work, a metal biosorbent was prepared by drying biomass of the yeast Rhodotorula glutinis in an oven at 70°C for 24 h followed by grinding. Two forms of the prepared biosorbent particles, washed and unwashed, were examined for their ability to remove lead from solution. It was found that the unwashed biosorbent exhibited higher lead uptake than the washed biosorbent. Analysis of the supernatant of washed cells incubated in water and that of unwashed cells incubated in lead solution revealed the presence of protein, carbohydrates, organic acids and inorganic phosphate. Overall, the washed and unwashed cells leached, respectively, 14.5 and 13.4% of their initial dry weight (100 mg). Acid‐base titration data revealed that the leached components contained several potential binding sites for metal cations with carboxyl and phosphoryl groups being particularly important. The higher level of lead uptake exhibited by the unwashed biomass was attributed to the fact that it leached smaller amounts of cell constituents with proton binding sites relative to the washed cells.     

Cloning of the <Emphasis Type="Italic">cnr</Emphasis> operon into a strain of <Emphasis Type="Italic">Bacillaceae</Emphasis> bacterium for the development of a suitable biosorbent

In this study, a potential microbial biosorbent was engineered to improve its capacity to remediate heavy metal contaminated water resources. A Bacillaceae bacterium isolated from a mining area was transformed with a plasmid carrying the (pECD312)-based cnr operon that encodes nickel and cobalt resistance. The bioadsorption ability of the transformed strain was evaluated for removal of nickel from metallurgical water relative to the wildtype strain. Results showed that transformation improved the adsorption capacity of the bacterium by 37 % at nickel concentrations equivalent to 150 mg/L. Furthermore it was possible to apply prediction modelling to study the bioadsorption behaviour of the transformed strain. As such, this work may be extended to the design of a nickel bioremediation plant utilising the newly developed Bacillaceae bacterium as a biosorbent.     

Potential utilisation of sewage sludge and paper mill waste for biosorption of metals from polluted waterways

The adsorption of cadmium, copper(II), lead and zinc ions from aqueous solution by sewage sludge, paper mill waste (PMW) and composted PMW was investigated along with the influence of pre-treatment on composted PMW. Langmuir adsorption isotherms were fitted where appropriate. Sewage sludge was the most effective biosorbent of the waste products for all metal ions examined, adsorbing, for example, up to 39.3 mg/g of Pb at an initial concentration of 77.8 mg/l. PMW was a less effective biosorbent than sewage sludge. However, it was found that composting the PMW resulted in an increase in metal uptake capacity and both sewage sludge and composted PMW have potential for low-cost remediation of high leachate wastewaters. The desorption of metal ions from PMW compost was most effective using 0.1 N H2SO4 and 1 mM nitrilotriacetic acid (NTA).     

Kinetic analysis of metal uptake by dry and gel alginate particles

The kinetics of metal uptake by gel and dry calcium alginate beads was analysed using solutions of copper or lead ions. Gel beads sorbed metal ions faster than the dry ones and larger diffusivities of metal ions were calculated for gel beads: approximately 10⁻⁴ cm²/min vs. 10⁻⁶ cm²/min for dry beads. In accordance, scanning electron microscopy and nitrogen adsorption data revealed a low porosity of dry alginate particles. However, dry beads showed higher sorption capacities and a mechanical stability more suitable for large-scale use. Two sorption models were fitted to the kinetic results: the Lagergren pseudo-first order and the Ho and McKay pseudo-second order equations. The former was found to be the most adequate to model metal uptake by dry alginate beads and kinetic constants in the orders of 10⁻³ and 10⁻² min⁻¹ were obtained for lead solutions with concentrations up to 100 g/m³. The pseudo-first order model was also found to be valid to describe biosorbent operation with a real wastewater indicating that it can be used to design processes of metal sorption with alginate-based materials.     

Nickel(II) biosorption by <Emphasis Type="Italic">Rhodotorula glutinis</Emphasis>

The present study reports the feasibility of using Rhodotorula glutinis biomass as an alternative low-cost biosorbent to remove Ni(II) ions from aqueous solutions. Acetone-pretreated R. glutinis cells showed higher Ni(II) biosorption capacity than untreated cells at pH values ranging from 3 to 7.5, with an optimum pH of 7.5. The effects of other relevant environmental parameters, such as initial Ni(II) concentration, shaking contact time and temperature, on Ni(II) biosorption onto acetone-pretreated R. glutinis were evaluated. Significant enhancement of Ni(II) biosorption capacity was observed by increasing initial metal concentration and temperature. Kinetic studies showed that the kinetic data were best described by a pseudo-second-order kinetic model. Among the two-, three-, and four-parameter isotherm models tested, the Fritz-Schluender model exhibited the best fit to experimental data. Thermodynamic parameters (activation energy, and changes in activation enthalpy, activation entropy, and free energy of activation) revealed that the biosorption of Ni(II) ions onto acetone-pretreated R. glutinis biomass is an endothermic and non-spontaneous process, involving chemical sorption with weak interactions between the biosorbent and Ni(II) ions. The high sorption capacity (44.45 mg g⁻¹ at 25°C, and 63.53 mg g⁻¹ at 70°C) exhibited by acetone-pretreated R. glutinis biomass places this biosorbent among the best adsorbents currently available for removal of Ni(II) ions from aqueous effluents.     

Biosorption and Desorption of Lead(II) by Hydrilla verticillata

The potential of nonliving biomass of Hydrilla verticillata to adsorb Pb(II) from an aqueous solution containing very low concentrations of Pb(II) was determined in this study. Effects of shaking time, contact time, biosorbent dosage, pH of the medium, and initial Pb(II) concentration on metal-biosorbent interactions were studied through batch adsorption experiments. Maximum Pb(II) removal was obtained after 2 h of shaking. Adsorption capacity at the equilibrium increased with increasing initial Pb(II) concentration, whereas it decreased with increasing biosorbent dosage. The optimum pH of the biosorption was 4.0. Surface titrations showed that the surface of the biosorbent was positively charged at low pH and negatively charged at pH higher than 3.6. Fourier transform infrared (FT-IR) spectra of the biosorbent confirmed the involvement of hydroxyl and C?O of acylamide functional groups on the biosorbent surface in the Pb(II) binding process. Kinetic and equilibrium data showed that the adsorption process followed the pseudo-second-order kinetic model and both Langmuir and Freundlich isothermal models. The mean adsorption energy showed that the adsorption of Pb(II) was physical in nature. The monolayer adsorption capacity of Pb(II) was 125 mg g^?1. The desorption of Pb(II) from the biosorbent by selected desorbing solutions were HNO₃ > Na₂CO₃ > NaOH > NaNO₃.     

Desarrollo de un bioadsorbente laminar con Phanerochaete chrysosporium hipertolerante al cadmio,al níquel y al plomo para el tratamiento de aguas

BackgroundThe use of basidiomycetes for metal removal is an alternative to traditional methods. In this, the biomass acts as a natural ionic exchanger removing metals from solution.ObjectiveTo develop a laminar biosorbent using a basidiomycete fungus resistant to high Cd, Ni and Pb concentrations.MethodsThe tolerance of Trametes versicolor, Pleurotus ostreatus and Phanerochaete chrysosporium was evaluated using increasing concentrations of the heavy metal salts, cadmium sulphate, lead acetate and nickel chloride. A biosorbent system was developed based on polyethylene sheets with a fungal biomass. It was evaluated in bubble columns using synthetic wastewater with the 3 metal salts at a rate of 300 mg/l. Finally, in a complementary experiment using shake flasks, the effect of a higher amount of biomass related to the metal removal efficiency was evaluated.ResultsP. chrysosporium strain was more tolerant to C₄H₆O₄Pb (10,000 mg/l), Cl₂Ni (300 mg/l) and CdSO₄·8H₂O (1,500 mg/l). In a reactor, under non-ligninolytic conditions, the fungus removed 69% of the chemical oxygen demand and produced enzymes such as LiP (0.01 U/l) and MnP (0.6 U/l.). An accumulation of metals in the wall was observed. By increasing the biomass to 1.6 (w/v), the metal biosorption was favored in the mixture (57% Pb, 74% Cd, and 98% Ni) and separately (95% Pb, 60% Cd, and 56% Ni). Competition between Ni and Pb by ligands of the wall was observed.ConclusionA novel laminar system based on P. chrysosporium viable biomass was developed. It has a large surface area and tolerance to high concentrations of Cd, Ni and Pb. It seems to be an alternative for the removal of metals from water.     

Preliminary investigation on multi metal tolerance of Bacillus thuringiensis isolated from industrial effluent soil

Bacteria are considered as foremost bioremediating agents among microorganisms, encompassing simple biological mechanism to tolerate higher concentration of heavy metal and favoring conservative strategies to substitute the usage of chemicals. Relating this implication, the present study is designed to identify, screen and characterize bacteria from industrial site soil to tolerate multimetals. Almost 108 colonies were obtained at various concentrations (0.5–2.0 mM) of heavy metals (cadmium, nickel and lead) and were thrived in the reformed minimal media. Bacterial isolates that grown in the higher concentration of heavy metals (2.0 mM) were taken for further studies. Among ten bacterial colonies, one isolate was selected for each heavy metal and further screened for their multi metal tolerance. Isolate, C20 alone survived in heavy metal mixture fortified medium with high recovery rate and increased colony forming units. Molecular level characterization and phylogenetic tree analysis revealed that the isolate is identical to Bacillus thuringiensis. The study highlights that the multi metal tolerant B. thuringiensis could be used as an effective bioremediating agent to manage heavy metals particularly cadmium, nickel and lead in industrial area. Further, attributed to be a plant growth promoting rhizobacteria, this organism can promote dual stratagems as a bio remediating agent and fertility enhancer in agricultural field due to its dual functions.     

A new approach to study the decolorization of complex reactive dye bath effluent by biosorption technique

This work focused on the development of a practical biosorbent for the decolorization of textile effluents. The fermentation waste, Corynebacterium glutamicum biomass, when decarboxylated and immobilized in polysulfone matrix performed well in decolorization of simulated reactive dye bath effluent comprised of four different reactive dyes and other auxiliary chemicals. The regeneration of polysulfone-immobilized C. glutamicum was successful with the aid of 0.01 M NaOH as the eluant, which enabled the biosorbent to maintain consistent decolorization efficiency for up to 25 cycles. An up-flow packed column loaded with polysulfone-immobilized biomass performed well in the continuous treatment of Remazol effluent. Samples collected after 14 h of column operation revealed almost zero color and TOC. The column was also able to decrease the TDS level from 55,840 to 33,480 mg/L. Column regeneration experiments revealed that the biosorbent was able to continuously treat Remazol effluent over ten cycles, with more than 90.6% decolorization efficiency.     

Removal of Heavy Metals by Waste Tea Leaves from Aqueous Solution

In this paper, tea leaves were shown to be an effective, low‐cost biosorbent. Removal of lead, iron, zinc and nickel from 20 mg/L metal solution by dried biomass of waste tea leaves amounted to 96, 91, 72 and 58 %, respectively, at equilibrium, which followed Langmuir and Freundlich adsorption isotherms. Adsorption of metal was in the order of Pb > Fe > Zn > Ni from 5–100 mg/L of metal solution. From a multi‐metallic mixture, 92.5, 84 and 73.2 % of lead, iron and zinc, respectively, were removed. Fourier transform infrared (FTIR) studies indicated that the carboxyl group was involved in the binding of lead and iron, whereas the amine group was involved in the binding of nickel and zinc. A flow through sorption column packed with dried biomass demonstrated a sorption capacity of 73 mg Pb/g of biomass, indicating its potential in cleaning metal containing wastewater. The metal laden biomass obtained could be disposed off by incineration.     

Biosorption of nickel(II) ions by using chemically pre-treated Sargassum filipendula biomass in a fixed bed column

The application of fixed bed adsorption is an important separation technique used for heavy metals in environmental pollution control. To design a fixed bed column, it is necessary to find dynamics data in the breakthrough curve form. The objective of this study was to model the biosorption process of nickel by using biomass of Sargassum filipendula in a fixed bed column. Experimental data were generated at 30°C, pH 3, flow rate of 6 ml/min and feed concentrations of 1, 1.5, 2, 3, 5 and 6 mequiv/l. Langmuir isotherm was used to represent the equilibrium data in the column (q _max = 2.496 mequiv/g, b = 0.456 l/mequiv) and in a batch operation of the system (q _max = 1.577 mequiv/g, b = 0.269 l/mequiv). These Langmuir parameters were used to simulate the continuous adsorption process of nickel. The partial differential equations model has taken into consideration the mass transfer resistance in the biosorbent as the key controlling phenomenon, which adequately represented the dynamic biosorption process of nickel.     

Application of seaweeds for the removal of lead from aqueous solution

Ten different seaweed species were compared on the basis of lead uptake at different pH conditions. The brown seaweed, Turbinaria conoides, exhibited maximum lead uptake (at pH 4.5) and hence was selected for further studies. Sorption isotherms, obtained at different pH (4–5) and temperature (25–35 °C) conditions were fitted using Langmuir and Sips models. According to the Langmuir model, the maximum lead uptake of 439.4 mg/g was obtained at optimum pH (4.5) and temperature (30 °C). The Sips model better described the sorption isotherms with high correlation coefficients at all conditions examined. Various thermodynamic parameters such as ΔG°, ΔH° and ΔS° were calculated indicating that the present system was a spontaneous and endothermic process. Through potentiometric titrations, number of binding sites (carboxyl groups) and pK₁ were determined as 4.1 mmol/g and 4.4, respectively. The influence of co-ions (Na⁺, K⁺, Mg²⁺ and Ca²⁺) on lead uptake was well pronounced in the case of divalent ions compared to monovalent ions. The solution of 0.1 M HCl successfully eluted all lead ions from lead-loaded T. conoides biomass. The regeneration experiments revealed that the alga could be successfully reused for five cycles without any loss in lead biosorption capacity. A glass column (2 cm i.d. and 35 cm height) was used to study the continuous lead biosorption performance of T. conoides. At 25 cm (bed height), 5 ml/min (flow rate) and 100 mg/l (initial lead concentration), T. conoides exhibited lead uptake of 220.1 mg/g. The column was successfully eluted using 0.1 M HCl, with elution efficiency of 99.7%.     

Biosorption of lead and nickel by biomass of marine algae

Screening tests of different marine algae biomas types revealed a high passive biosorptive uptake of lead up to 270 mg Pb/g of biomass in some brown marine algae. Members of the order Fucales perfomed particularly well in this descending sequence: Fucus > Ascophyllum > Sargassum. Although decreasing the swelling of wetted biomass particles, their reinforcement by crosslinking may significantly affect the biosorption performance. Lead uptakes up to 370 mg Pb/g were observed in crosslinked Fucus vesiculosus and Ascophyllum nodosum. At low equilibrium residual concentrations of lead in solution, however, ion exchange resin Amberlite IR-120 had a higher lead uptake than the biosorbent materials. An order-of-magnitude lower uptake of nickel was observed in all of the sorbent materials examined. (c) 1994 John Wiley & Sons, Inc.     

Effect of nickel on regeneration in <Emphasis Type="Italic">Jatropha curcas</Emphasis> L. and assessment of genotoxicity using RAPD markers

The aim of the present study was to determine the effect of nickel on shoot regeneration in tissue culture as well as to identify polymorphisms induced in leaf explants exposed to nickel through random amplified polymorphic DNA (RAPD). In vitro leaf explants of Jatropha curcas were grown in nickel amended Murashige and Skoog (MS) medium at four different concentrations (0, 0.01, 0.1, 1 mM) for 3 weeks. Percent regeneration, number of shoots produced and genotoxic effects were evaluated by RAPD using leaf explants obtained from the first three treatments following 5 weeks of their subsequent subculture in metal free MS medium. Percent regeneration decreased with increase in addition of nickel to the medium up to 14 days from 42.31% in control to zero in 1.0 mM. The number of shoot buds scored after 5 weeks was higher in control as compared to all other treatments except in one of the metal free subculture medium wherein the shoot number was higher in 0.01 mM treatment (mean = 7.80) than control (mean = 7.60). RAPD analysis produced only 5 polymorphic bands (3.225%) out of a total of 155 bands from 18 selected primers. Only three primers OPK-19, OPP-2, OPN-08 produced polymorphic bands. The dendrogram showed three groups A, B, and C. Group A samples showed 100% genetic similarity within them. Samples between groups B and C were more genetically distant from each other as compared to samples between groups A and B as well as groups A and C. Cluster analysis based on RAPD data correlated with treatments.     

Biosorption of lead, cadmium, and zinc by Citrobacter strain MCM B-181: characterization studies

The biosorption process for removal of lead, cadmium, and zinc by Citrobacter strain MCM B-181, a laboratory isolate, was characterized. Effects of environmental factors and growth conditions on metal uptake capacity were studied. Pretreatment of biomass with chemical agents increased cadmium sorption efficiency; however, there was no significant enhancement in lead and zinc sorption capacity. Metal sorption by Citrobacter strain MCM B-181 was found to be influenced by the pH of the solution, initial metal concentration, biomass concentration, and type of growth medium. The metal sorption process was not affected by the age of the culture or change in temperature. Equilibrium metal sorption was found to fit the Langmuir adsorption model. Kinetic studies showed that metal uptake by Citrobacter strain MCM B-181 was a fast process, requiring <20 min to achieve >90% adsorption efficiency. The presence of cations reduced lead, zinc, and cadmium sorption to the extent of 11. 8%, 84.3%, and 33.4%, respectively. When biomass was exposed to multimetal solutions, metals were adsorbed in the order Co2+ < Ni2+ < Cd2+ < Cu2+ < Zn2+ < Pb2+. Among various anions tested, only phosphate and citrate were found to hamper metal sorption capacity of cells. Biosorbent beads prepared by immobilizing the Citrobacter biomass in polysulfone matrix exhibited high metal loading capacities. A new mathematical model used for batch kinetic studies was found to be highly useful in prediction of experimentally obtained metal concentration profiles as a function of time. Metal desorption studies indicated that Citrobacter beads could, in principle, be regenerated and reused in adsorption-desorption cycles. In an expanded scale trial, biosorbent beads were found to be useful in removal/recovery of metals such as lead from industrial wastewaters.