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The !occulating activity of a bioflocculant produced by Pseudomonas aeruginosa ATCC-10145 using kaolin clay was assayed. The in!uence of carbon, nitrogen sources, pH and culture temperature on bioflocculant production was investigated. The effects of cationic compounds, bioflocculant dosage, pH and temperature on flocculating activity were also determined. Of the cations tested, Ca2+, K +, Na+, Zn2+, Mg2+ and Cu2+ improved flocculating activity whereas Fe3+ and Al3+ caused its inhibition. The highest flocculating activity was observed at pH 7.0.The bioflocculant had a good flocculating activity of 80.50% for kaolin suspension with a dosage of only 1%. The bioflocculant was heat-stable and its activity was only decreased to 60.16% after heating at 100°C for 60 min. Chemical analyses of the purified bioflocculant indicated that it was a sugar-protein derivative, composed of protein (27%, w/w) and carbohydrate (89%,w/w ) including neutral sugar, uronic acid and amino sugar as the principal constituents in the relative weight proportions of 30.6%, 2.35% and 0.78%, respectively. The elemental analysis of the bio!occulant revealed the mass proportion of C, H and N was 19.06, 3.88 and 4.32 (%), correspondingly. Fourier transform infrared analysis showed that the exopolymers consisted of carboxyl, hydroxyl, amino and sugar derivative groups. The heavy metal adsorption by the bioflocculant of Pseudomonas aeruginosa was found to be influenced by the initial metal concentration, bioflocculant concentration and pH of the biosorption solution. This study demonstrates that microbial bioflocculant has potential to be used as an alternative bioremedial tool for industrial efluents and wastewater treatments which are co-contaminated with heavy metals.
The paper describes two modified methods to determine the main parameters of the biosorption system. One of them - biomass amount, is an important technological parameter that is needed for technological calculations of the equipment, for the evaluation of oxidation potential and biomass growth in accordance with decomposed pollutants, etc. Typically, VSS (volatile suspended solids) are used as a measure of microorganisms, but accurate evaluation of the organic part of biomass on the sorbent surface is complicated. Thermal investigation methods are based on different sorbent and biomass burning temperatures and the obtained results are suitable for biosorption process control. Another important parameter is sorption capacity of the sorbent used in the process. The theoretical adsorption capacity of the activated carbon is usually estimated for a particular contaminant. The method, which in this case involves use of oil products, has been modified for the purpose of evaluation of this parameter. Quantitative analysis of oil products is quite complicated and time consuming. Therefore a colored and stable organic compound of large molecular size has been chosen. Concentration of this compound in spirit solution has been quickly and exactly estimated with a photoelectrocolorimeter.
Little is known about thallium behavior in the environment, especially its interactions with microorganisms such as fungi. This article evaluates basic interactions (bioaccumulation, biosorption and growth inhibition) between thallium and the common heat-resistant fungal species Neosartorya fischeri. The results suggest that the N. fischeri strain is relatively resistant to elevated concentrations of thallium in cultivation media up to 1 mg・l⁻¹. However, the toxic effect of thallium on fungal growth depends on the time of cultivation, and after 30-day cultivation growth inhibition was reduced. The bioaccumulation of thallium after 30-day cultivation by fungal strain was 35.74 mg・kg⁻¹ and 432.91 mg・kg⁻¹ for initial concentration 1.012 and 4.861 mg・l⁻¹ of Tl(I) in medium, respectively. The biosorption capacity was calculated to be 11.77 mg・kg and 62.01 mg・kg⁻¹ for initial concentration 1.012, and 4.861 mg・l⁻¹ of Tl(I) in medium, respectively.
Contaminations of industrial metals into the river possess major threat to environment. Chromium is a heavy metal which has the wide applications in tannery and electroplating industries. Above the permitted level of Chromium(VI) into surface water leads to severe health hazards. Therefore, biosorption is a technology used for the sorption of heavy metal. In this present study adsorption isotherm models was studied for the biosorption of chromium by cherry leaves. From the adsorption isotherms it was found that the experimental data fits well with the Langmuir isotherm than the Freundlich isotherm. The monolayer capacity Qm was fond to be 11.98 mg/l and the adsorption affinity was found to be positive which indicates the efficient biosorption of chromium.
Chromium is a heavy metal which has widely used in tannery and electroplating industries. Contaminations of these industrial metals into the river possess major threat to an environment. Therefore, biosorption is a technique which is applied for the sorption of heavy metal by a biomaterial. In the present study reveals that cherry leaves was used as a biomaterial and for that the thermodynamic properties was evaluated for the biosorption of chromium. From the thermodynamic studies it was found that the reaction was feasible, spontaneous and exothermic because the values of ΔG = negative, ΔS = negative and ΔH = positive. So, it was concluded that the experiment was thermodynamically feasible.
Biosorption is an attractive technology which is used for the sorption of substances by a biomaterial. In this present work the heavy metal chromium was subjected to biosorption because of their non-degradability nature and causes water and land pollution. Cherry leaves were used as a biomaterial for the biosorption. Kinetic studies were performed for the biosorption experiment. From the experiment it was found that the reaction follows pseudo first order reaction because of the larger value of regression coefficient R2 and lower value of standard errors (χ2) for pseudo first order reaction than second order reaction.
Recently, increased interest in the application of various biosorbents in metal ions removal has been observed. The paper presents a systematic characterization of new and commonly abundant low-cost bio- sorbents: above-ground plant parts of wheat straw and grass. Cr(III) was chosen as a model sorbate. The effect of the most significant process parameters (temperature, pH, initial concentration of Cr(III) ions on kinetics, as well as temperature and pH) on biosorption equilibrium was studied. Biosorption was found to be a quick process. The equilibrium was reached within 10-20 minutes. Biosorption capacity of the studied sorbents was intermediate when compared with other sorbents of plant origin ca. 20 mg/g, but since these materials are commonly abundant and of minimal cost, it is possible to improve wastewater treatment ef­ficiency by increasing the concentration of the sorbent. The kinetics of the process in the case of both biomaterials was described with pseudo-second order equation and the equilibrium of biosorption by wheat straw was described with the Freundlich equation and by grass with the Langmuir model. The above equations were chosen to achieve the best consistency of experimental data with the model results. Also, the mechanism of biosorption was investigated, and was determined to be physical adsorption. The paper also discusses the possible methods of utilization of metal-laden biomass, including non-de­structive elution with the regeneration of the biosorbent and ashing as the method of destruction and further concentration of metal.
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Removal of chromium by biosorption method (chitosan)

63%
Discharge of metal containing effluents into water has been a cause of major concern. Traditional treatment methods are proving to be ineffective and expensive. Chitosan was studied as a potential biosorbent due to its positive charge and relatively low cost. The study involves evaluating the metal binding performance of chitosan in a Polymer Enhanced Diafiltration (PEDF) system which uses an ultra filtration membrane to retain the chitosan which, in turn, binds the metal, thereby preventing passage into the permeate stream. Conditions for binding such as pH, concentration of polymer and chromium were studied. Optimal performance was obtained when the system was operated at pH values lower than the pKa of chitosan i.e. 6.3. Using 6 g/L chitosan at pH 4.0, chromium concentration was reduced to less than 1mg/L from a feed concentration of 20 mg/L. Equilibrium dialysis experiments were done to study the kinetics of binding and the uptake of metal per gram of polymer. Rheological measurements demonstrated that in the presence of 1-100 mM chromate, chitosan was found to be slightly shear thickening at low concentrations such as 4 g/L and 6 g/L whereas it was slightly shear thinning at higher concentrations like 12 g/L and 20 g/L This suggests that neutralization of chromium anions is due to the interaction of multiple chitosan molecules. This result is consistent with the relatively stiff nature of the polysaccharide. Overall, this study suggests that some modification of the native polymer would be required to improve uptake and make it an industrially workable process.
Enteromorpha prolifera green algae is the main species that causes green tide in China’s Yellow Sea. To effectively realize the resourceful utilization of this biomass, batch experiments were carried out to investigate factors that impact the Acid Bordeaux B (ABB) absorption of E. prolifera powder, such as exposure time, pH, adsorbent dose, and oscillation frequency. The dye adsorption onto adsorbent was confirmed by Fourier transform infrared spectroscopy (FTIR). Results showed that amide, hydroxy, carboxylate, and C-O groups were involved in the adsorption process. The treatment conditions for dye concentration of 100 mg·L⁻¹ were optimized: contact time 60 min, pH value 4 to 9, water temperature 303 to 313 K, adsorbent dosage 0.25 g·L⁻¹ and oscillation frequency 150 rpm. Equilibrium data were analyzed by using the Freundlich and Langmuir models. The data fit well in both models. The maximum equilibrium adsorption capacity calculated by the Langmuir equation was 1,111.11-3,333.33 mg·g⁻¹. To clarify the sorption kinetic, the fitness of the Pseudofirst- order model, the Pseudo-second-order model, and the intra-particle diffusion model were tested, showing that the pseudo-second order model was suitable to describe the adsorption process. The sorption process was complex, and both the boundary of liquid film and intra-particle diffusion contributed to the rate-determining step. Thermodynamic parameters (e.g. ΔG⁰, ΔH⁰, and ΔS⁰) were calculated, which implied the exothermic and spontaneous nature of biosorption as well as the type of adsorption (physisorption). Results illustrate that the removal ratio from the wastewater with 100 mg·L⁻¹ ABB reached 90.86%, indicating that E. prolifera could be a potential biosorbent used for the removal of ABB from industrial effluents.
Our aim was to investigate the biosorption of Pb²⁺, Hg²⁺, Cd²⁺ from aqueous solution by Aspergillus terreus (both free and immobilized on loofa sponge discs). Our results show that the adsorption capacity of fungal biomass on loofa sponge (FBLS) is superior to free fungal biomass (FFB). The adsorption selectivity by FBLS was in the order Pb²⁺>Hg²⁺>Cd²⁺. The maximum metal ions adsorbed was 247.2,37.7, 23.8 mg/g FBLS for Pb²⁺, Hg²⁺ and Cd²⁺, respectively. Metal uptake by FBLS was affected by the pH of the metal solution, but independent of temperature (10-50°C). The Langmuir model was more suitable than the Freundlich model to describe the biosorption process of FBLS. The regenerated FBLS was found to be effective for repeated use for five cycles without significant loss in adsorption capacity. This research demonstrates that FBLS possesses excellent capacity for Pb²⁺ biosorption from aqueous solution and industrial wastewaters.
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Removing lead from Iranian industrial wastewater

63%
Metals and chemicals have been increased in industrial processes which they contain a high level of toxic heavy metals and cause a lot of disadvantages for the environment and human health .Biosorption of Pb (П) ions has been studied from aqueous solutions in a batch system by using a bacterial strain isolated from petrochemical wastewaters. Strain 8-I was selected to study the impact of different factors on removal rate. According to morphological, physiological and biochemical characterizations of the strain and in comparison with other studies the strain was tentatively identified as Bacillus sp strain 8-I. The maximum Lead biosorption capacity of 8-I isolate was determined to be 41.58 % at pH 4.0 with 80 mg/l concentration in 48 hours equilibrium time. The comparison between the biosorption capacity of live (45.50 mg/g), heat inactivated (30.23 mg/g) and NaN3 pretreated biomass (26.86 mg/g) were indicated that the ability of live biomass for both of active and passive uptake of lead.
Pseudomonas fluorescens BM07 was characterized as a producer of cold-induced biopolymer by decreasing the temperature down to as low as 10°C. It was previously shown that the synthesis of BM07 biopolymer was inhibited at 30°C. The present study was conducted to investigate the biosorption of mercury (Hg²⁺) ions on the BM07 cells grown on Ml minimal medium at two temperatures (10°C and 30°C). The effects of various factors including pH, contact time, initial concentration of metal and cell biomass on the biosorption yield were also studied. Study of the effect of pH on mercury removal indicated that the metal biosorption increased with increasing pH from 3.0 to 7.0. The optimum adsorption pH value was found to be 7.0. Our results showed that, at optimum pH, BM07 cells were able to uptake the mercury up to 102 and 60 mg Hg²⁺/g dry biomass for 10°C and 30°C grown cells respectively. The removal capacity of cells increased when the cell biomass concentrations increased. The maximum removal efficiency was obtained when cells concentration was 0.83 mg dry biomass/ml for both conditions. The initial metal ion concentration significantly influenced the equilibrium metal uptake and adsorption yield. The equilibrium data were analyzed using Langmuir adsorption model. The qmax was 62.9 and 82.25 mg Hg²⁺/g dry biomass for cells grown at 30°C and 10°C respectively. The results suggest that, the existence of residual cold-induced biopolymer on the external surface of cells may play an important role in biosorption efficiency, as P. fluorescens BM07 cells which were grown at 10°C under similar conditions showed higher efficiency to biosorbe mercury than non-polymer producing cells grown at 30°C.
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