Iranian Journal of Environmental Health, Science and Engineering Iranian Association of Environmental Health (IAEH) ISSN: 1735-1979 Vol. 6, Num. 2, 2009, pp. 107-114

Iranian Journal of Environmental Health, Science and Engineering, Vol. 6, No. 2, 2009, pp. 107-114

BIOSORPTION OF IRON FROM AQUEOUS SOLUTION BY DRIED BIOMASS OF ACTIVATED SLUDGE

R. Shokoohi,* M. H. Saghi, H. R. Ghafari , M. Hadi

Department of Environmental Health Engineering, School of Public Health and Center For Health Research, Hamadan University of Medical Sciences, Hamadan, Iran

*Corresponding author: saghi@umsha.ac.ir Tel: +98 915 320 80 83, Fax: +98 811 823 53 01107108

Received 3 December 2008; revised 11 May 2009; accepted 20 May 2009

Code Number: se09017

ABSTRACT

This study was conducted to investigate the removal of iron by dried biomass of activated sludge. Dried activated sludge, prepared as a powder, was tested as a sorbent for the removal of iron from aqueous solutions. The effects of various experimental parameters including initial iron concentration, mass of biomass and contact time were examined and optimal experimental conditions were obtained. The equilibrium time for iron adsorption onto biomass was determined as 150 min. The rate of iron removal was directly correlated to biomass amount and contact time. Increasing contact time from 0.5h to 2.5h resulted in 25% improvement in iron removal efficiency. When the weight of the biomass increased from 0.1g to 0.9 g, the iron removal efficiency increased from 62% to 95%. High initial iron concentration had an adverse effect on iron removal efficiency. Increasing initial iron concentration from 2 to 10 (mg/L) caused declining the iron removal efficiency from 70% to 56%. Freundlich, Langmuir, Dubinin-Radushkevich and Temkin isotherm models could describe the adsorption equilibrium of the iron onto the activated sludge. Meanwhile, Freundlich isotherm represented a better correlation compared to other isotherms (R² > 0.999). Also Elovich kinetic models fits well with experimental data (R²>0.997).

Key words: Biosorption, Dried Activated Sludge, Iron, Adsorption

INTRODUCTION

The production of metals has rapidly increased since the industrial revolution. Some metals usually form compounds that can be toxic, carcinogenic or mutagenic, even in very low concentrations (Manriquez et al., 1977; Kazemian and Mallah, 2008 ; Picardo et al., 2009). Iron is commonly found in rocks and soil. Under proper conditions, iron will leach into the water resources from rock and soil formations. Exceeding iron concentration greater than 0.3 mg/L causes water staining that adversely affect plumbing fixtures, dishware and clothes and produce a yellow to reddish appearance in water. These levels may also impart taste and odor of drinking water. The US Environmental Protection Agency (USEPA) has established a secondary drinking water regulation of 0.3 mg/L for iron (EPA, 2000; Ncibi et al., 2007).

Conventional techniques for metal removal from aqueous solutions include chemical precipitation, ion exchange, adsorption process, membrane process, crystallization and electrochemical treatment. Considering the cost, technical complexity and limitations of the conventional methods make the alternative biological methods more appealing (Volesky, 1990; Schiewer and Volesky, 1995). Biological process for metal ions removal from aqueous solutions can be divided into three general categories: (a) sorption of metal ions onto the surfaces of a microorganism, (b) intracellular uptake of metal ions, and (c) chemical transformation of metal ions by microorganisms. The latter two processes require live organisms to proceed (Veglio and Beolchini, 1994; Mamisahebei et al., 2007).

The adsorption of metals onto various types of biomass has been introduced as a cost-effective method in multiple studies. In this method, in addition to direct use of microbial biomass, their by-products including biosorbent may be applied as a low cost method of metal-removal process. In addition to fermentation processes, production of biosorbent can be considered by employing simple and inexpensive culture propagation techniques (Kuyucak, 1990; Gupta and Rastogi, 2008; Mata et al., 2008; Pejic et al., 2008; Vitor and Corso, 2008; Yurtsever and Sengil, 2008; Dang et al., 2009; Quintelas et al., 2009). Sorption of heavy metals by various biological materials has been proposed as an efficient and potentially cost effective tool for metal enriched industrial effluents. Biosorption is a property of certain types of inactive, dead microbial biomass to bind and concentrate heavy metals from very dilute aqueous solutions (Gaur and Dhankhar,  2009).

Capability of microorganisms to bind heavy metals in aqueous solutions has long been of scientific interest (Aksus and Gulen, 2002; Sen and Ghosh Dastidar, 2007). Mapolelo et al. (2005) showed that yeast is a viable trace metal enrichment agent that can be used freely by suspending in solution to enrich metal ions at a relatively low concentration (Mapolelo et al., 2005). Bisorption of uranium by filamentous fungus ucor has been documented in another study (Guibal et al., 1999). Activated sludge from wastewater treatment processes is probably the most abundant source of mixed biomass. The ability of activated sludge biomass to remove and accumulate heavy metals and organics has been recognized in different studies (Al-Asheh and Duvnjak, 1995).

The use of biomass or its derived products has carried the advantages of reducing dissolved metals related toxicity, improving operating conditions, and cost-benefit utility maintenance including nutrient supply (Hua-Jun et al., 2008). The aim of this study was to investigate the adsorption rate and kinetics of removing iron by using dried activated sludge (DAS) biomass.

MATERIALS AND METHODS

Preparation of dried activated sludge

Activated sludge was obtained from a food industrial wastewater treatment plant in Hamedan city of Iran. The activated sludge was dried at 105°C for 12 h to a constant weight and sieved through a 205 µm diameter mesh. All glass and other instruments were washed with detergent and distilled water to be free from any precontaminations.

Preparation of iron solution

Solution of 500 mg/L of iron was prepared as stock solution and diluted to 2, 3,4,5, and 10 mg/L for the experiments.

Batch adsorption experiments

Erlenmeyer flasks were filled with 10 mg/L of iron solution and different amount of biomass (measured as 0.1, 0.3, 0.5, 0.7 and 0.9 g) mixed to 100mL volume. Five Erlenmeyer flasks filled with dried activated sludge and deionized water and a control flask containing only iron with no adsorbent were used to determine the sludge initial iron and extent of iron removal via non-adsorptive mechanisms. The control flasks contained similar solutions, but no activated sludge. The flasks were charged with different concentrations of DAS and allowed to shake for 1– 4 h. Upon completion of shaking, (HANA-HI 190 model), the samples were withdrawn at 30, 60, 90, 120 and 150 minutes and their iron concentration was analyzed. The effect of different retention times (30, 60, 90, 120 and 150 min) with variation of initial concentration (2, 3, 4, 5 and 10mg/L) at constant pH and temperature on removal of iron by dried mass was considered in batch system. All experiments were carried out at pH= 7±0.2 and temperature =20±0.2°C.

Analytical methods

For seperation of activate sludge from the solution, samples were centrifuged (Model-301 Sigma) at 3800 rpm for 15 min. The iron concentration in the supernatant was measured using a spectrometer( UV-1700 Pharma Spect Shimadzo) at a 510 nm wavelength and computing from the calibration curves(Lenore et al., 1998). The amount of iron adsorbed by biomasses was calculated using the following equation.

Where: q_e (mg/g) is the amount of iron adsorbed by biomass; C₀ and C (mg/L) are the initial and equilibrium liquid-phase concentrations of iron, respectively; V(L) represent the initial volume of iron solution, and M(g) the mass of the biomass. The performance of DAS adsorption was evaluated in terms of its removal efficiency as RE(%), estimated by the following equation:

Where C_t is the iron concentration at time t (Xing et al., 2008).

Adsorption isotherm

Adsorption isotherm is the basic requirement for designing any adsorption system. Isotherm express the relation between the amounts of adsorbate removed from liquid phase by unit mass of adsorbent at constant temperature. Since adsorption is one of the fundamental surface phenomena, it is important to have a satisfactory description of an equilibrium state in order to successfully represent the kinetic adsorption behavior of any species from the fluid to the solid phase (Passos et al., 2008). Langmuir, Freundlich, Dubinin-Radushkevich and Temkin adsorption isotherms were used to analyze the biosorption isotherms of iron.

Adsorption kinetics

In order to determine the potential rate-controlling steps involved in the adsorption process, kinetic models should be established (Zhi-Yan et al., 2008). Therefore, the first order, pseudo-second-order kinetics and Elovich were used to analyze the biosorption kinetics of iron.

RESULTS

Influence of initial iron concentration

The influence of initial iron concentration on the biosorption of iron is shown in Table.1. Considering steady values of other parameters, the initial iron concentration was increased from 2 to 10 (mg/L) which caused a removal efficiency decline from 70% to 56%. Adsorption capacity of dried activated sludge increased with increasing the initial iron concentration.

This was due to an increase in the driving force of the concentration gradient, as an increase in the initial iron concentration.

Influence of contact time

The influence of contact time on the biosorption of iron is shown in Table. 2. Increasing contact time from 0.5h to 2.5h caused a removal efficiency improvement from 56% to 89%. The association between contact time and iron removal efficiency was statistically significant (p<0.05).

Influence of the mass of biomass

The influence of mass of the biomass on the iron biosorption is shown in Fig 1. When the weight of the biomass was increased from 0.1g to 0.9 g, the iron removal efficiency increased from 62% to 95%. Nearly 150 min was required for the equilibrium adsorption for iron. Therefore, the equilibrium time was set conservatively at 150 min for further experiments. The variations of iron removal with initial DAS mass for 10 mg/L iron at the end of 150 min incubation period are shown in Fig.1. Iron removal by adsorption improved by increasing DAS concentrations for all samples with different iron concentrations and reached a maximum level at 0.9 g DAS mass.

Adsorption isotherm

Langmuir, Freundlich, Dubinin-Radushkevich and Temkin adsorption isotherms were employed to determine the preference of one to another. Plot for the nonlinear Langmuir Freundlich, Dubinin-Radushkevich and Temkin equation are shown in Fig.2. Table 3 gives the values of the isotherm constants.

The essential characteristics of the Langmuir isotherm can be expressed in terms of dimensionless constant separation factor or equilibrium parameter, R_L, which is defined by Eq. (3) (Hall, 1996):

Where: C₀ (mg/L) is the highest initial iron concentration. According to the value of R_L the isotherm shape can be interpreted as presented in Table 4 (Langmuir, 1918):

The Freundlich constant, n, should have values lying in the range of 1 to 10 for classification as favorable adsorption.

Adsorption kinetics

To find the potential rate-controlling steps involved in the process of biosorption of iron onto DAS, first order, Elovich and pseudo second-order kinetic models were tested to fit the experimental data at various DAS. Adsorption kinetics of iron first- order model, pseudo second-order model and Elovich models shown in Fig 3, and Table 5 shows the comparison of first-order, pseudo second-order and Elovich kinetics constants.

The isotherm and kinetic models parameters were determined using the trial-and-error nonlinear method by MATLAB software.

DISCUSSION

A high correlation was represented for four Freundlich, Langmuir, Dubinin-Radushkevich and Temkin isotherms. However regarding the correlation coefficient (R²), the Freundlich adsorption isotherm (R² >0.999) was found to represent the equilibrium adsorption data with much better fitting compared to Langmuir isotherm ( R² >0.994) , Dubinin-Radushkevich( R² >0.927) and Temkin( R² >0.954). Calculated R_L for Langmuir isotherm was 0.16; so, Langmuir isotherm was favorable. Calculated n for Freundlich isotherm was 1.4454; hence, Freundlich isotherm was favorable for experimental data. The correlation coefficients for the second-order kinetic model were close to (R²>0.995) for all cases. The correlation coefficients for the Elovich kinetics was (R²>0.997) and for first-order model was (R²>0.987). The theoretical values of q_e also agreed well with the experimental data. The theoretical q_e values calculated from the first-order kinetic model did not give reasonable values with obvious deviation from the experimental ones. This may imply that the biosorption of iron on DAS concentration follows Elovich rather than pseudo second-order kinetics.

In another study the kinetics of heavy metals biosorption by inactive biomass of the marine algae Sargassum were fast, reaching 60% of the total biosorption capacity in ten minutes. All charts were linear (their regression line was acceptable) and all of the data obtained for isotherm constants in different experiments were in a same range and on echelon type after equilibrium time (Barkhordar and Ghiasseddin, 2004). The rate constants of the pseudo second-order equation for Pb²⁺ biosorption were obtained as 1.86, 0.83 and 0.52gm/mol/min at initial Pb concentrations of 5, 1 and 0.5mM, respectively (Nabizadeh et al., 2005). Both Freundlich and Langmuir isotherm models could describe the adsorption equilibrium of the reactive dye onto the activated sludge with the Langmuir isotherm showing better agreement. Second-order kinetic models confirmed the agreement (Ju et al., 2008). In another study the pseudo second-order and first-order models described the biosorption kinetics of As (V) with good correlation coefficient (R²>0.93) and better than the other equations. The data obtained from the experiment of biosorption isotherm were analyzed using the Freundlich and Langmuir isotherm models. The equation described the isotherm of As (V) biosorption with relatively high correlation coefficient (R²>0.93) (Mamisahebei et al., 2007).

Considering constant values of other parameters, an increase in initial iron concentration resulted in declining iron removal efficiency but improving dried activated sludge adsorption capacities. This may be due to an increase in the driving force of the concentration gradient, as an increase in the initial iron concentration. This study showed that DAS has an equilibrium adsorption capacity for iron. The iron removal rate at the end of the 2.5 h incubation period increased and the effluent iron concentrations decreased with increasing DAS concentrations and decreasing initial iron concentration.

ACKNOWLEDGEMENTS

The authors are most grateful to the laboratory staff of the Department of Environmental Health Engineering, School of Public Health, Hamedan University of Medical Sciences, Iran, for financial support and their collaboration in this research.

REFERENCES

• AKSUS , Z., & GULEN, H., (2002). Binary biosorpyion of iron-cyanid complex ions on Rhizopus arrhizus :modlling of ynergistic interaction. proc Biochem, 38.
• AL-ASHEH, S., & DUVNJAK, Z., (1995), Adsorption of Copeer and Chromium by Aspergillu carbonarius.Biotechnol, 91: 83-87.
• BARKHORDAR, B., & GHIASSEDDIN, M., (2004). Comparision of Langmuir and Freundlich Equilibriums in Cr, Cu and Ni Adsorption by Sargassum. Iranian. J .Env. Health. Sci. Eng, 1: 58-64.
• DANG, V. B., DOAN, H. D., DANG-VU, T., & LOHI, A., (2009). Equilibrium and kinetics of biosorption of cadmium(II) and copper(II) ions by wheat straw. Bioresour Technol, 100: 211-219.
• DUBININ, M. M., & RADUSHKEVICH, L. V., (1947). Equation of the characteristic curve of activated charcoal. Chem. Zentr, 1: 875.
• EPA, U., (2000). Wastewater Technology Fact Sheet. Chemical Precipitation. US EPA Washington, DC, 832-F-00-018,.
• FREUNDLICH, H. Z. (1906) Over the adsorption in solution. J phys chem, 57: 385-470.
• GAUR, N., & DHANKHAR, R., (2009). equilibrium modelling and spectroscopic studies for the biosorption of zn+2 ions from aqueous solution using immobilized spirulina platensis. Iran. J .Environ. Health, 6: 1-6.
• GUIBAL, E., ROULPH, C., & LECLOIREC, P., (1999). Uranium biosorption by filamentous fungus Mucor miehei, pH effect on mechanisms and performances of uptake. Water Res, 26: 1139-1145.
• GUPTA, V. K., & RASTOGI, A., (2008). Biosorption of hexavalent chromium by raw and acid-treated green alga Oedogonium hatei from aqueous solutions. J Hazard Mater.
• HALL, K. R., (1996). Pore and solid-diffusion kinetics in fixed-bed adsorption under constant-pattern conditions. Ind. Eng. Chem. Fund., 5: 212-223.
• HUA-JUN, F., LI-FANG, H., QAISAR, M., YAN, L., & DONG, S., (2008). Study on biosorption of humic acid by activated sludge. Biochemical Engineering Journal 39: 478–485.
• JU, D. J., BYUN, G., PARK, J. J., LEE, C. H., AHN, G. H., & PARK, T. J., ( 2008). Biosorption of a reactive dye (Rhodamine-B) from an aqueous solution using dried biomass of activated sludge. Bioresource Technology, 99: 7971–7975.
• KAZEMIAN, H., & MALLAH, M. H., (2008 ). Removal of chromate ion from contaminated synthetic water using mcm-41/zsm-5 composite. Iran. J. Environ. Health. Sci. Eng, 5: 73-77.
• KUYUCAK, N., (1990). Feasibility of biosorbents application. In: Volesky B (ed) Biosorption of heavy metals. . CRC Press, Boca Raton, FL, pp 371-378.
• LANGMUIR, I., (1918). The adsorption of gases on plane surfaces of glass, mica, and platinum. J Am. Chem. Soc., 40: 1361-1403.
• LENORE, S., C, AMOLD, E., G., & ANDREW, D., E., (1998). Standard Methods for the Examination of Water and Wastewater american public health association 1015
• MAMISAHEBEI, S., KHANIKI, G. R. J., TORABIAN, A., NASSER, S., & NADDAFI, K., (2007). removal of arsenic from an aqueous solution by pretreated waste tea fungal biomassIran. J. Environ. Health. . Iran. J. Environ. Health. Sci. Eng., 4: 85-92.
• MANRIQUEZ, A., MAGANA, P., LOPEZ, V., & GUZMAN, R., (1977). Biosorption of Cu by Thiobacillus ferrooxidans. Bioprocess. Eng, 18: 113-118.
• MAPOLELO, M., TORTO, N., & PRIOR, B., (2005). Evaluation of yeast strains as possible agents for trace enrichment of metal ions in aquatic environments. talanta, 65: 930-937.
• MATA, Y. N., BLAZQUEZ, M. L., BALLESTER, A., GONZALEZ, F., & MUNOZ, J. A., (2008). Biosorption of cadmium, lead and copper with calcium alginate xerogels and immobilized Fucus vesiculosus. J Hazard Mater.
• NABIZADEH, R., NADDAFI, K., SAEEDI, R., MAHVI, H., VAEZI, F., YAGHMAEIAN, K., & NAZMARA, S., (2005). kinetic and equilibrium studies of lead and cadmium biosorption from aqueous solutions by sargassum spp. biomass. iran. J. Environ. Health. Sci. Eng, 2: 159-168.
• NCIBI, M. C., MAHJOUB, B., & SEFFEN, M., (2007) .Adsorptive removal of textile reactive dye using posidonia oceanica(L.) fibrous biomass. Int. J. Environ. Sci. Tech., 4: 433-440.
• PASSOS, C. G., LIMA, E. C., ARENAS, L. T., SIMON, N. M., CUNHA, B. M., BRASIL, J. L., & COSTA, T. M. H., (2008). Use of 7-amine-4 azahepthylsilica and 10-amine-4 azadecylsilica xerogels as adsorbent for Pb(II) kinetics and equilibrium study.Colloids and Surfaces A: Physicochemical Engineering Aspects, 316: 297–300.
• PEJIC, B., VUKCEVIC, M., KOSTIC, M., & SKUNDRIC, P., (2008). Biosorption of heavy metal ions from aqueous solutions by short hemp fibers: Effect of chemical composition. J Hazard Mater.
• PICARDO, M. C., FERREIRA, A. C., & DA COSTA, A. C., (2009). Continuous thorium biosorption - Dynamic study for critical bed depth determination in a fixed-bed reactor. Bioresour Technol, 100: 208-210.
• QUINTELAS, C., FONSECA, B., SILVA, B., FIGUEIREDO, H., & TAVARES, T., (2009). Treatment of chromium(VI) solutions in a pilot-scale bioreactor through a biofilm of Arthrobacter viscosus supported on GAC. Bioresour Technol, 100: 220-226.
• SCHIEWER, S., & VOLESKY, B., (1995). Modeling of the Proton-Metal Ion Exchange in Biosorption . Environ Sci Technol, 29: 3049-3058.
• SEN, M., & GHOSH DASTIDAR, M., (2007). biosorption of cr by resting cells of aspergillus sp. iran. J .Environ. Health.sci.eng, 4: 9-12.
• TEMKIN, M., & PYZHEV, J. A. V., (1940). Kinetics of ammonia synthesis on promoted iron catalysts. Acta Physiochim 12: 217-222.
• VEGLIO, F., & BEOLCHINI, F., (1994). Biosorption of lead and nickel by biomass of marine algae. Biotechnol. Bioeng. Biotechnol. Bioeng, 43, 1001.
• VITOR, V., & CORSO, C. R., (2008). Decolorization of textile dye by Candida albicans isolated from industrial effluents. J Ind Microbiol Biotechnol.
• VOLESKY, B., (1990). Removal and recovery of heavy metals by biosorption. In: Volesky B, editor. Biosorption of Heavy Metals. Boca.Ration, pp. 7- 43.
• XING, W., NGO , H. H., KIM, S. H., GUO, W. S., & HAGARE, P., (2008). Adsorption and bioadsorption of granular activated carbon (GAC) for dissolved organic carbon (DOC) removal in wastewater. Bioresource Technology, 99: 8674–8678.
• YURTSEVER, M., & SENGIL, I.. A., (2008). Biosorption of Pb(II) ions by modified quebracho tannin resin. J Hazard Mater.
• ZHI-YAN, H., HUA-LI, N., CHRISTOPHER, B.-W., LI-MIN, Z., YU-TING & ZHOU, Z., (2008). Removal of Cu2+ from aqueous solution by adsorption onto a novel activated nylon-based membrane. Bioresource Technology, 99: 7954–7958.

© Copyright 2009 - Tehran University of Medical Sciences Publications

The following images related to this document are available:

Photo images