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Cr(III) removal from tannery effluent by waste biomass

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International Journal of Integrative Biology A journal for biology beyond borders

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Chromium (III) removal from tannery effluent by Streptomyces sp. (MB2) waste biomass of fermentation process Indu Sharma, Dinesh Goyal * Dept. of Biotechnology and Environmental Sciences, Thapar University, Patiala, Punjab, India Submitted: 17 May. 2009; Revised: 24 Jul. 2009; Accepted: 9 Aug. 2009

Abstract Removal of chromium (III) from aqueous solution and tannery effluent by biomass waste, mainly Streptomyces sp. (MB2) generated from large-scale fermentation process was investigated. A series of batch experiments were conducted at different pH values, adsorbent dosage and initial chromium concentration. Maximum chromium removal capacities of Streptomyces sp. (MB2) biomass were 68.2 % and 73.9% with corresponding equilibrium uptake of Cr(III) were 0.084 to 2.89 mg/gm and 0.17 to 4.5 Streptomyces sp. (MB2) mg/gm from aqueous solution and tannery effluent respectively with increasing Cr(III) concentration in batch mode. The adsorption parameters were determined using both Langmuir and Freundlich isotherms model. FTIR studies revealed involvement of C=C, C=O and O–H functional groups in binding of chromium. Such waste biomass from fermentation industry is a potential alternative source of adsorbent for the removal of Cr(III) from aqueous solution as well as tannery effluent. Keywords: Streptomyces sp, Fermentation waste, Chromium (III), Tannery effluent, Langmuir and Freundlich isotherms, FTIR.

INTRODUCTION Chromium containing wastes are generated by industries such as leather tanning, electroplating, paint and pigment manufacturing, metal plating and other applications, is responsible for environment pollution (Mohan et al., 2006). Chromium is not biodegradable and tends to accumulate in living organisms, causing serious diseases and disorders (Bailey et al., 1999; Barrera et al., 2006; Mohan et al., 2006). Leather tanning is an oldest and fastest growing industries in India and there are about 2161 tanneries excluding cottage industries, which process 500,000 tonnes of hides and 314 kg of skins annually with overall annual discharge of 9,420,000 m3 wastewater (Mohan et al. 2006). In this process about 60%-70% of chromium reacts with the hides and 30-40% of chromium remains in the solid and liquid wastes and is discharged to open fields, cultivable land, river streams and water bodies causing large scale pollution of soil and water posing ecotoxicological risks. Tanning process using chromium compounds is one of the most common

methods for processing of hides (Esmaeili et al. , 2005; Fahim et al. , 2006). Chromium recovery and detoxification are practiced in modern units, but still many of the older and smaller units resort to conventional effluent treatment (Alexander et al. 1992; Covington and Alexander et al. 1993). The precipitation, oxidation/reduction, lime neutralization have traditionally been the most commonly used (Boddu et al., 2003; Mohan et al., 2006). Biosorption appears to be an economically feasible means for the removal and/or recovery of heavy metals from industrial wastewaters (Volesky 1994; Boddu et al., 2003; Greenberg et al., 1998). The low cost of biosorbents is a tangible advantage over other technologies, such as ion exchange and reverse osmosis. Extensive efforts have been made to explore new types of biosorbent materials capable of effectively sequestering heavy metals (Bailey et al., 1999; Ozer and Ozer, 2003; Jalali et al., 2002; Ahluwalia and Goyal, 2007).

*

Corresponding author: Dinesh Goyal, Ph.D. Department of Biotechnology and Environmental Sciences, Thapar University, Patiala, 147004, Punjab, India Email: [email protected]

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The microbial biomass originating as byproducts from industrial bioprocesses have been tested for biosorption of heavy metal ions such as bacterial biomass Streptomyces pimprina (Puranik et al., 1995), Streptomyces rimosus (Addour et al., 1999; Chergui et IJIB, 2009, Vol. 6, No. 3, 148


al., 2007), Streptomyces griseus (Ashwini et al., 2009), Aspergillus niger (Chandrasekhar et al., 1998), waste biomass from Brazilian alcoholic beverage (Dias et al., 2000), Bacillus lentus, Aspergillus oryzae or Saccharomyces cerevisiae (Vianna et al., 2000), Rhizopus nigricans (Kogej and Pavko, 2001), wine processing waste sludge (Li et al., 2004), Corynebacterium glutamicum (Choi and Yun, 2004), olive oil industry waste (Malkoc et al., 2006) and olive stone (Blázquez et al., 2009). The use of waste biomass from fermentation industry as a biosorbent would increase the economic competitiveness of a microbial based technology because such biomass is cheap, easily recovered at the end of fermentation and is produced in large quantities (Vianna et al., 2000). In this study, Streptomyces sp. (MB2) biomass generated as a waste from an industrial fermentation process was evaluated as a biosorbent material for the removal of chromium from tannery effluent and Langmuir and Freundlich adsorption models were employed for mathematical description of experimental equilibrium data.

MATERIALS AND METHODS Collection and characterization of microbial biomass and tannery effluent Microbial biomass which is generated as a byproduct of pharmaceutical fermentation industry involving fermentative production of certain antibiotics by Streptomyces sp. (MB2) was collected from Ranbaxy (fermentation industry) Paonta Sahib, Himachal Pradesh, India. This biomass was characterized for physical and chemical parameter such as pH, moisture, ash content, bulk density, calorific value and CHN analysis, as per the procedure (MacDonald et al., 1996). Tannery effluent was collected from A.V. Tanneries, Kapurthala, Punjab, India. Characterization of effluent was performed as per procedure described elsewhere (Clesceri et al., 1998) for physico-chemical parameters such as pH, electric conductivity, total solids (TS), total dissolved solids (TDS), total suspended solids (TSS), biochemical oxygen demand (BOD) and chemical oxygen demand (COD), colour, chlorides, ammonical nitrogen and TNK (Total Kjeldahl Nitrogen). Besides this other heavy metals such as Cr(III), Fe, Pb, Co, Cu, Cd and secondary elements (Ca, Mg, Na) in tannery effluent were determined based on the standard methods for water and waste water examination.

Preparation of aqueous chromium solution and effluent dilution Aqueous solution of trivalent chromium was prepared by dissolving 0.38 gm of chromium sulphate (Cr2(SO4)3) in 100 ml distilled water. Stock solution and tannery effluent were diluted with distilled water to obtained


working solution (5 to 50 mg/l) for further experiments. Desired pH of solution was adjusted with 1 N NaOH and 1 N HCl.

Batch adsorption studies The ability of Streptomyces sp. (MB2) microbial biomass to remove trivalent chromium was determined in batch adsorption experiment which were conducted in 250 ml of Erlenmeyer flask with different biomass dosage (0.25-2%) by keeping the concentration of Cr(III) constant (25 mg/l) and suspension was shaken at 120 rpm, 28±2ºC for 24 h. Similarly, experiments were conducted at different pH range (2 to 5) and Cr(III) concentration (5-50 mg/l) in aqueous solution. The studies were also carried out with different dilution of tannery effluent (5-50 mg/l) obtained from tannery. Sample were drawn at different time intervals and residual concentration of Cr(III) in solution was measured by atomic absorption spectrophotometer (GBC 932AA, Australia). Working standard solution of Cr(III) was prepared from stock (1000 mg/l) procured from Acros Organic Ltd, New Jersey, USA. Triplicates of each sample were analysed and mean value and relative standard deviation as given by AAS were recorded. Chromium uptake (qe) was calculated as follows (Ci  C f )V (1) qe  m where, Ci and Cf represents initial and final Cr(III) concentrations in mg/l respectively, V is volume of Cr(III) solution in ml, m is weight of biomass in gm (Mohan et al. 2006). The (R%) removal of Cr(III) ions from aqueous solution was calculated using mass balance Eq. (2) (Fahim et al. 2006) (Ci  C f ) (2) R(%)   100 Ci

Fourier transform infrared (FTIR) spectroscopy Infrared spectra of the native dead biomass and metal exposed biomass were obtained after drying the biomass at 70ºC. The finely powered biomass was encapsulated with the potassium bromide to prepare the translucent sample disks and the spectra were recorded by the Fourier Transform Infrared Spectroscope (Bomem Canada).

RESULTS AND DISCUSSION

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Characterization of microbial biomass and tannery effluent

(Dias et al., 2000; Mohan et al., 2006; Fahim et al., 2006).

Physico-chemical characteristics of Streptomyces sp. (MB2) biomass are shown in Table 1 [Supplementary data]. It had acidic pH with ash content ranging from 5-6%. The CHN analysis showed that Streptomyces sp. (MB2) is rich in nitrogen content and had calorific value of 1617 MJ/kg-, which coincides with the relative calorific value (17.5 MJ/kg) of solid fuels such as biomass, municipal waste, industrial waste, peat and brown coal (MacDonald et al. 1996). Characterization of tannery effluent is shown in Table 2 [Supplementary data] . Tannery effluent is acidic (pH 3.73), greenish in colour (2150 pt.co) and contains chlorides (12,300 mg/l), sulphide (1.35 mg/l). The data shows that 1700.9 mg/l chromium (III) is discharged from tannery. Besides this effluent also contains other heavy metals such as Fe (110.11 mg/l), Pb (15.26 mg/l), Co (0.8125 mg/l), Cu (0.1mg/l), Cd (0.012 mg/l) and secondary element Ca (154.1 mg/l), Mg (115.52 mg/l) and Na (42.55 mg/l). The effluent had highest concentration of TS (96,000 mg/l), TDS (80,000 mg/l), TSS (16,000 mg/l), BOD (290 mg/l), COD (332.8 mg/l) and total nitrogen (210.14mg/l) since raw hides and skins are used as the starting material in tanning process (Fahim et al., 2006).

Effect of pH

Batch studies Batch sorption studies on Streptomyces sp. (MB2) was carried out by optimizing various parameters such as adsorbent dosage, pH and Cr(III) concentration in aqueous solution and tannery effluent.

Effect of adsorbent dosage Effect of adsorbent dosage (0.25-2%) on sorption of Cr(III) from aqueous solution containing 25 mg/l of Cr(III) at pH 4 with agitation rate of 120rpm at ambient temperature was studied (Fig. 1a [Supplementary data] ). Removal of Cr(III) increased rapidly from 24.3 to 94.6% by Streptomyces sp. (MB2), when the adsorbent dosage was increased from 0.25 to 2%. Biomass of Aspergillus sp. (Chandrasekhar et al. 1998) and Streptomyces noursei (Kapoor and Viraraghavan (1997) were able to remove 70-75% of Cr(III) from aqueous solution and exhibited an adsorption capacity of 1.8-2.0 mg/gm (Mattuschka and Straube, 1993) comparable with Streptomyces sp. (MB2) biomass (2.24 mg/gm) and commercial activated carbon 2.7 mg/gm (Mohan et al., 2006). The decrease in the sorption capacity was more pronounced at adsorbent dosage 2-4 gm/l (Nomanbhay and Palanisamy, 2005; Bishnoi et al., 2007). Maximal Cr(III) uptake of 45-60 mg/gm was found for the oxidized activated carbon samples (Ramos et al., 1995). The data obtained for the sorption capacities are in agreement with those referred in the literature for the most efficient heavy metals adsorbents


Effect of pH on removal of Cr(III) by Streptomyces sp. (MB2) biomass shows that, amount of Cr(III) adsorbed increased from 0.27 to 1.21 mg/gm (72.38%) by Streptomyces sp. (MB2) biomass as pH increased from 2 to 5 (Fig. 1b [Supplementary data] ). Initially, the immediate solute uptake was achieved within 2-4 h, subsequently the second stage of solute uptake continued for longer time (24 h) (Mohan et al., 2006; Blázquez et al., 2009). The lower adsorption values observed at low pH can be attributed to the competition between protons and Cr(III) for available binding sites of biomass. The adsorption increases at pH range (4-6), since Cr(III) species are cationic and predominant interactions in adsorption process must have been electrostatic. Yun et al. 2001 reported that below pH 2.0 almost all the binding sites were occupied by protons and the metal binding could not be expected. As the pH increased, Cr(III) species began to bind to the functional groups, and the maximum binding of this species occurred at pH 4.3. At lower pH, the CrOH2+ binding remained at a level lower than that of Cr(III). However, it gradually increased with the pH, eventually exceeding the level of Cr(III) binding at pH > 4.5. While the concentrations of Cr(III) and CrOH2+ in the aqueous phase were identical at pH 3.55, the uptake of the two species were same at pH 4.5. Studies were not performed beyond 6.0 due to possibility of Cr(III) precipitation (Ramos et al., 1995; Li et al., 2004). The increase of chromium removal was 2.0-2.6 times (from 20-30% to 50-60%) at pH 2 and of 1.6-2.0 at pH 3.2. These findings suggested that, in the pH (pH of 2-3.2) range, the adsorbent surface might have different affinities to the different species of chromium existing in the solution, and their affinity towards chromium ions are strongly affected by the solution pH (Fahim et al., 2006). The adsorption at pH 4 was found to be rapid and almost accomplished (Bishnoi et al., 2007; Blázquez et al., 2009). Similar observations were made for biowaste generated as a by-product of large-scale industrial fermentation (Dias et al., 2000; Fahim et al., 2006).

Effect of chromium concentration Kinetic studies of Cr(III) removal by Streptomyces sp. (MB2) biomass was conducted at varying initial concentrations (5-50 mg/l) of Cr(III) in aqueous solution and tannery effluent. Maximum chromium removal capacities of Streptomyces sp. (MB2) biomass were 24.9 to 68.2 % and 41.2 to 73.9 % from aqueous solution and tannery effluent respectively. Equilibrium uptake of Cr(III) increased with increasing Cr(III) concentration (5 to 50 mg/l) from 0.084 to 2.89 mg/gm from aqueous solution and 0.17 to 4.5 mg/gm from

IJIB, 2009, Vol. 6, No. 3, 150


tannery effluent in batch mode (Fig. 1c [Supplementary data] , Fig. 2). The increase in initial concentration of chromium results in the increased uptake capacity (q) and decreased percent removal since at high initial concentrations, the number of moles of chromium available to the surface area are high and adsorption depends upon initial concentration (Zubair et al., 2008). Previous reports also suggests that removal of Cr(III) is dependent on concentration of chromium because the increase in the initial chromium concentration (50-300 mg/l) increased the amount of Cr(III) adsorbed (Fahim et al., 2006).

Figure 2: Effect of chromium concentration and contact time on Cr(III) removal from tannery effluent at different dilution (pH: 4; adsorbent dosage: 1%; agitation rate: 120 rpm). 12

Ce/qe(mg/g)

10 y = 6.0021x - 2.5906 R2 = 0.9928

8

Adsorption isotherms

6 4 2 0 0.0

0.5

1.0

1.5

2.0

2.5

Ce(mg/g)

Figure 3: Langmuir adsorption plot for the adsorption of Cr(III) from tannery effluent. 0.7

ln qe (mg/g)

0.6 0.5 0.4 0.3

y = -0.399x + 1.023 2

R = 0.943

0.2 0.1 0.0 0.0

0.5

1.0

Increase in contact time from 0.08 to 4 hours led to an increase in Cr(III) removal from 40-70% and 11.5-57% from aqueous solution and tannery effluent respectively, whereas 65% and 57.34% removal from aqueous solution and tannery effluent respectively was observed within first 2 h by Streptomyces sp. (MB2) (Fig. 1d), which represents the time at which equilibrium of chromium biosorption is presumed to have been attained. This suggests that adsorption is rapid and typically 40-50% of the ultimate adsorption occurs within the first hour of contact and saturation is reached with in next 48 h (Chandrasekhar et al., 1998; Mohan et al., 2006). The chromium removal occurred in two steps: an initial fast step which lasts for 30 min (shorter time) followed by the slower second phase which continued until the equilibrium was reached within 240 min and further increase in contact time did not show an increase in removal (Bishnoi et al., 2007; Zubair et al., 2008). A contact time of 2-4 h was enough to achieve significant Cr(III) removal at pH higher than 3.5 and lower than 2.0, however an elapsed contact time was necessary to establish equilibrium. In previous work, using Streptomyces biomass as adsorbent, it was observed that at pH 2 and 3.2 the chromium removal was initially rapid for all the adsorbents studied. As the contact time increases, the rate of adsorption decreases depending on the chemical characteristics of the surface (Chergui et al., 2007; Ashwini et al., 2009).

1.5

2.0

2.5

ln Ce (mg/g)

Figure 4: Freundlich adsorption plot for the adsorption of Cr(III) from tannery effluent.

The capacity of the Streptomces sp. (MB2) biomass for Cr(III) was determined by Langmuir and Freundlich isotherms. The Langmuir isotherms model is valid for monolayer adsorption on to surface containing finite number of identical sorption sites which is described by the following Eq. (3) Q bC (3) qe  L e 1  bCe Where qe and QL are observed and maximum uptake capacities (mg/gm biosorption); b equilibrium constant; Ce equilibrium concentration (mg/l). The Langmuir equation can be rearranged to linear form for convenience of plotting and determining the Langmuir constants as below defined as in Eq. (4) Ce 1 C (4)   e qe bQL QL The Freundlich isotherm model (Freundlich 1906) is nonlinear sorption model is purely empirical based on heterogeneous surface, which commonly defined as in Eq. (5) 1

qeq  K F Ce n

(5)

Where KF and n are Freundlich constants related to adsorption capacity and intensity, respectively. The Freundlich equation can be linearized in logarithmic

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IJIB, 2009, Vol. 6, No. 3, 151


form for determination of Freundlich constants as below Eq . (6)

ln qe 

1 ln Ce  ln K F (6) n

The correlation coefficient values obtained from the Langmuir and Freundlich isotherms (Table 3 [Supplementary data] ; Fig. 3, Fig. 4) indicates that the adsorption pattern for Streptomyces (MB2) followed both Langmuir isotherms (R2 =0.94 to 0.99) and the Freundlich isotherms (R2 =0.91 to 0.96) at all chromium concentrations (Fig. 3, 4). According to the Langmuir model, the maximum Cr(III) adsorption capacity was obtained at 20 mg/l with a value of QL of 1.19 mg/gm represents a Cr(III) adsorption. The values obtained for Cr(III) from Freundlich model at different concentration showed a maximum adsorption capacity (KF) of 82 mg/gm at different concentration with an affinity value (n) equal to 0.99 which represents a favorable adsorption of Cr(III) from tannery effluent. Decrease in the concentration resulted in decrease in the adsorption capacity in both models. Typical values found in earlier literature are 0.6