Biosorption of copper by fungal melanin

Summary Melanin obtained from Aureobasidium pullulans and Cladosporium resinae was an efficient biosorbent for copper. Copper uptake could be expressed using various adsorption isotherms; melanin from A. pullulans obeyed Freundlich and Langmuir isotherms whereas C. resinae melanin followed the BET isotherm indicating a more complex type of adsorption than in A. pullulans. In general, uptake capacities of melanin were greater than for intact biomass and the higher uptake by pigmented rather than albino biomass could be correlated with the presence of melanin. Cu²⁺ was less readily desorbed from melanin by dilute mineral acids than from intact biomass and again, the relative ease of Cu²⁺ desorption from pre-loaded pigmented or albino biomass was correlated with the presence or absence of melanin. Mg²⁺ and Zn²⁺ appeared to be the most effective cations for desorption with Na⁺ and K⁺ the least effective. The addition of melanin to a coppercontaining culture of the albino strain of A. pullulans resulted in some reduction of toxicity.     

Biosorption of americium using biomasses of various Rhizopus species

Biomasses from eight different Rhizopus species were tested for the sorption of americium from nitric acid medium. Rhizopus arrhizus NCIM 997 showed maximum sorption at pH 2. Laboratory scale experiments were carried out using this biomass in packed columns for the sorption of -activity from an americium spiked low level waste stream of PUREX process. The biomass was found to be an excellent sorbent for remediation of low level waste streams on once through basis.     

Biosorption of zinc by fungal mycelial wastes

Summary Waste mycelia from several industrial fermentation plants (Aspergillus niger, Penicillium chrysogenum, Claviceps paspali) were used as a biosorbent for zinc ions from aqueous environments, both batchwise as well as in a column mode. With all mycelia testes, biosorption per biomass dry weight was a function of pH (increasing with increasing pH between 1.0 and 9.0), biomass concentration (decreasing at high biomass concentrations) and the zinc concentration. Under optimized conditions, A. niger and C. paspali were superior to P. chrysogenum. Treatment of A. niger biomass with NaOH further increased its biosorbent capacity. Desorption of biosorbed zinc was achieved by elution with 0.1 m HCl, best results being obtained with NaOH-treated A. niger. Such treatment did not affect the capacity for biosorption in repeated experiments. NaOH-treated A. niger mycelia were also successfully used in removal of zinc from polluted waters in Austria, thereby showing that the simultaneous presence of other naturally occurring ions does not affect biosorption. Offprint requests to: C. P. Kubicek     

Biosorption of gold by immobilized fungal biomass

The characteristics of polyvinyl alcohol (PVA) and calcium alginate as immobilization matrices were examined and compared for the uptake of gold by a fungal biomass. PVA-immobilized biomass showed superior mechanical strength and chemical stability. In addition, PVA beads were also stable under a wider range of pH (1-13). The lower mass transfer resistance in PVA beads was evident from kinetic studies which showed a significantly shorter period of time for the immobilized PVA beads to achieve 80% gold removal as compared with immobilized alginate beads. Calculated rate constants and maximum rates for the uptake of gold by both immobilized PVA and immobilized alginate biosorbent revealed a much more rapid uptake phenomenon by the former. BET analyses also indicated a larger surface area and larger pore size distribution in PVA beads, further indicating a lower resistance to mass transfer. Gold biosorption in the immobilized PVA bead could be modeled by both the Langmuir and Freundlich adsorption isotherms.     

Biosorption of pentachlorophenol from aqueous solutions by a fungal biomass

This study focuses on the use of non-viable Aspergillus niger biomass, for the biosorption of pentachlorophenol (PCP) from aqueous solutions. Various forms of the biomass-autoclaved and chemically conditioned, were tested for their potential in the removal of PCP from aqueous solutions. It was found that PCP removal was pH dependent; PCP removal decreased with the increase in pH for all type of biomass, except for cetyltrimethylammonium bromide (CTAB) biomass. For CTAB biomass, a near complete removal of PCP was observed at all pHs. Therefore, CTAB biomass was used in further studies. PCP removal was rapid, with an equilibrium time of 2h. The rate of adsorption kinetics was well described by a pseudo-second order model. Isotherm models of the type one and two parameter models were found to fit the isotherm data. PCP biosorption was found to be exothermic in nature; the amount of PCP sorbed decreased with an increase in temperature. Desorption was carried out using deionized water, dilute HCl and dilute NaOH, and it was found that most of the PCP was irreversibly bound to the biomass. The addition of inorganic salts did not affect the removal of PCP from aqueous solutions. Among the surface functional groups present on the biomass, carboxyl, amide and hydroxyl groups seem to have played a role in PCP biosorption. It was concluded that CTAB treated biomass was an excellent adsorbent for the removal of PCP from aqueous solutions.     

Biosorption of organochlorine pesticides using fungal biomass

Cladosporium strain AJR³18,501 was tested for its ability to sorb the organochlorine pesticide (OCP) p,p′-DDT from aqueous media. When p,p′-DDT was added to distilled water, ethanol or 1-propanol solutions in excess of its solubility, p,p′-DDT was sorbed onto the fungal biomass. Increasing the amount of p,p′-DDT in solution by changing the medium composition increased sorbent uptake: p,p′-DDT uptake by the fungal biomass was 2.5 times greater in 25% 1-propanol (17 mg of p,p′-DDT g⁻¹ dry weight fungal biomass) than in distilled water. When p,p′-DDT was dissolved in 25% 1-propanol (12 mg l⁻¹), rapid p,p′-DDT sorption occurred during the first 60 min of incubation. p,p′-DDT in solution was reduced to 2.5 mg l⁻¹ with the remaining p,p′-DDT recovered from the fungal biomass. A number of environmental parameters were tested to determine their effect on p,p′-DDT biosorption. As arsenic (As) is prevalent at DDT-contaminated cattle dip sites, its effect on p,p′-DDT uptake was determined. The presence of As [As(III) or As(V) up to 50 mg l⁻¹] did not inhibit p,p′-DDT uptake and neither As species could be sorbed by the fungal biomass. Changing the pH of the medium from pH 3 to 10 had a small effect on p,p′-DDT sorption at low pH indicating that an ion exchange process is not the major mechanism for p,p′-DDT sorption. Other mechanisms such as Van der Waals forces, chemical binding, hydrogen bonding or ligand exchange may be involved in p,p′-DDT uptake by Cladosporium strain AJR³18,501. Journal of Industrial Microbiology & Biotechnology (2002) 29, 163–169 doi:10.1038/sj.jim.7000280 Received 15 January 2002/ Accepted in revised form 18 May 2002     

Biosorption of mercury by the inactivated cells of pseudomonas aeruginosa PU21 (Rip64)

Biomass of a mercury-resistant strain Pseudomonas aeruginosa PU21 (Rip64) and hydrogen-form cation exchange resin (AG 50W-X8) were investigated for their ability to adsorb mercury. The maximum adsorption capacity was approximately 180 mg Hg/g dry cell in deionized water and 400 mg Hg/g dry cell in sodium phosphate solution at pH 7.4, higher than the maximum mercury uptake capacity in the cation exchange resin (100 mg Hg/g dry resin in deionized water). The mercury selectivity of the biomass over sodium ions was evaluated when 50 mM and 150 mM of Na(+) were present. Biosorption of mercury was also examined in sodium phosphate solution andphosphate-buffered saline solution (pH 7.0), containing 50mM and 150 mM of Na(+), respectively. It was found that the presence of Na(+) did not severely affect the biosorption of Hg(2+), indicating a high mercury selectivity ofthe biomass over sodium ions. In contrast, the mercury uptake by the ion exchange resin was strongly inhibited by high sodium concentrations. The mercury biosorption was most favorable in sodium phosphate solution (pH 7.4), with a more than twofold increase in the maximum mercury uptake capacity. The pH was found to affect the adsorption of Hg(2+)bythe biomass and the optimal pH value was approximately 7.4. The adsorption of mercury on the biomass and the ion exchange resin appeared to follow theLangmuir or Freundlich adsorption isotherms. (c) 1994 John Wiley & Sons, Inc.     

Removal of thorium from simulated acid process streams by fungal biomass

Biomass from several fungal species removed thorium from solution in 1M HNO(3), pH 0-1. Thorium uptake was saturable with increasing thorium concentration, although the equilibria did not correspond to a simple ad sorption isotherm. Thorium uptake was altered by the biomass concentration, the uptake per unit biomass being reduced at high biomass concentrations. The presence of Al(3+) and Fe(3+) only slightly inhibited uptake of thorium while Ca(2+), Mg(2+), and Na(+) had no effect. Thus fungal biomass appears capable of removing thorium from solution under chemical conditions existing in acid waste liquors. Thorium uptake was increased by pretreatment using detergent and also, in the case of filamentous fungi, varied with the culture conditions, which implies that the thorium uptake characteristics of fungal biomass are able to be manipulated by these or similar means for optimum performance.     

Lateral fungal spore movement inside a simulated wall

Moisture inside walls can facilitate mold growth if left untreated. Once spores become airborne they may interact with pressures inside walls. Two laboratory experiments were conducted to determine if airborne spores have the potential to migrate laterally inside walls with and without wiring installations. A simulated wall was fabricated, and Penicillium chrysogenum spores were aerosolized into a distant stud bay and an adjacent stud bay. The wall was subjected to a typical indoor pressure. Spore levels inside the bays were sampled, and a total of 36 trials (n = 36) were conducted. Results of Kruskal–Wallis tests revealed that spore levels inside the sampling bay and the distant bay with wiring installations were not significantly different. Spore levels inside the sampling bay were significantly lower than the adjacent bay without wiring installations (P < 0.05). The findings of the study suggest airborne fungal spores have the potential to move laterally inside walls.     

Biosorption of Basic Blue 7 by fungal cells immobilized on the green-type biomatrix of Phragmites australis spongy tissue

Biosorption is an effective alternative method for the control of water pollution caused by different pollutants such as synthetic dyes and metals. A new and efficient biomass system was developed from the passively immobilized fungal cells. The spongy tissue of Phragmites australis was considered as the carrier for the immobilization of Neurospora sitophila cells employed for the biosorption of Basic Blue 7. This plant tissue was used for the first time as a carrier for fungal cells. The biosorption was examined through batch- and continuous-mode operations. The biosorption process conformed well to the Langmuir model. Maximum monolayer biosorption capacity of the biosorbent was recorded as 154.756 mg g^?1. Kinetic findings showed a very good compliance with the pseudo-second-order model. The negative values of ΔG° indicated a spontaneous nature of the biosorption process and a positive value of ΔH° (14.69 kJ mol^?1) concluded favorable decolorization at high temperature. The scanning electron microscopy analysis showed that a porous, rippled, and rough surface of biomass system was covered with BB7 molecular cloud. IR results revealed that functional groups like –OH, –NH, and C?O participated to the decolorization. Breakthrough and exhausted points were found as 360 and 570 minutes, respectively. The biomass system was successfully applied to the treatment of real wastewater.     

Biosorption of copper by yeasts

Summary The ability to accumulate copper from aqueous solutions was determined with different yeast species. Yeast cells did not show any significant differences in process kinetics. The uptake was very fast and was influenced by environmental factors. The metal-accumulating capacity differed among the tested strains. The yeastsCandida tropicalis andPichia guilliermondii were chosen for extensive research. Cells of the stationary growth phase were able to adsorb a high amount of copper. The uptake capacity decreased with increasing biomass concentration. Copper adsorption obeyed the Freundlich isotherm. Optimal pH range was between 5 and 7. The biomass could be used repeatedly for biosorption after desorption by mineral acids.     

Biosorption of mercury by microorganisms

Biomasses are able to sorb great amounts of mercury ions from water solutions. Sorbed concentrations are dependent on the pH-value, the strain of microorganisms and the substrate used for cultivation. The uptake of mercury takes place at a high reaction rate and is completed after few minutes. A comparison between maximum amounts of uptake concentration and theoretical maximum amounts with a total sataration of the surface leads to the assumption that mercury is bound to definite sites.     

Biosorption of radionuclides by Rhizopus arrhizus

The sorption of various radionuclides viz. 233U, 239Pu, 241Am, 144Ce, 147Pm, 152+154Eu and 95Zr from aqueous nitrate medium has been studied using biomass Rhizopus arrhizus. The biosorption of 233U and 239Pu was found to be maximum at pH 6-7 whereas for other trivalent actinides and fission products viz. 241Am, 144Ce, 147Pm, 152+154Eu and tetravalent 95Zr, it was more effective at pH 2. This biomass is a promising sorbant for the treatment of radioactive effluents from nuclear industry. © Rapid Science Ltd. 1998     

Biosorption of Cu by Thiobacillus ferrooxidans

Current technologies for removal and recovery of both toxic and industrial interest metals usually produce wastes with high concentrations of those substances. They are an important source of environmental pollution, specially when they contain heavy metals. This is one of the most important environmental problems, and of the most difficult to solve. So far, there have been a number of studies considering the possibility of removing and recovering heavy metals from diluted solutions. These are due, principally, because of the commercial value of some metals as well as the environmental impact caused by them. The traditional methods for removing have several disadvantages when metals are present in concentrations lower than 100?mg/l. Biosorption, which uses biological materials as adsorbents, has been considered as an alternative method. In this work, several variables that affect the capacity for copper biosorption by T. ferrooxidans have been studied. Particularly, the effect of pH, chemical pretreatment, biomass concentration and temperature have been considered. Results indicate that a capacity as high as 119?mg of Cu/g of dry biomass can be obtained at a temperature of 25?°C.     

Bench-scale development and evaluation of a fungal bioreactor for color removal from bleach effluents

Summary A recently developed color removal method uses a ligninolytic fungus,Phanerochaete chrysosporium, and a rotating biological contactor to decolorize pulp and paper bleach effluents. Bench-scale studies were undertaken with the objective of developing an aeration reactor to remove color. Culture conditions and biomass characteristics of the process were established. Experiments determined that the aeration process had a maximum color removal rate of 1300 color units per liter per day.     

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.