Chromium(III) biosorption onto spent grains residual from brewing industry : equilibrium, kinetics and column studies

The use of industrial wastes for wastewater treatment as a strategy to their re-use and valorisation may provide important advances toward sustainability. The present work gives new insights into heavy metal biosorption onto low-cost biosorbents, studying chromium(III) biosorption onto spent grains residual from a Portuguese brewing industry both in batch and expanded bed column systems. Experimental studies involved unmodified spent grains and spent grains treated with NaOH. Metal uptake followed a rapid initial step, well described by the pseudo-second-order kinetic model up to 27 h, indicating chemisorption to be the rate-limiting step. Beyond this period intraparticle diffusion assumed an important role in the uptake global kinetics. The best fit for equilibrium data was obtained using the Langmuir model, with unmodified spent grains having the higher maximum uptake capacity (q max = 16.7 mg g1). In open system studies, using expanded bed columns, the best performance was also achieved with unmodified spent grains: Breakthrough time (C/C i = 0.25) and total saturation time (C/C i = 0.99) occurred after 58 and 199 h of operation, corresponding to the accumulation of 390 mg of chromium(III), 43.3 % of the total amount entering the column. These results suggest that alkali treatment does not improve spent grains uptake performance. Changes in biomass composition determined by Fourier transform infrared spectroscopy suggested hydroxyl groups and proteins to have an important role in chromium(III) biosorption. This study points out that unmodified spent grains can be successfully used as low-cost biosorbent for trivalent chromium.The authors would like to thank the Portuguese brewing industry UNICER for all the support and FCT (Fundacao para a Ciencia e a Tecnologia) financial support through the Grant PRAXIS XXI/BD/15945/98

Heavy metal accumulation in the leaves, stem and root of the invasive submerged macrophyte Myriophyllum spicatum L. (Haloragaceae): an example of Kadin Creek (Mugla, Turkey)

In this study, the existence of heavy metals such as chromium (Cr), arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb) their distribution in the organs of plant and their bioaccumulation rates in water samples and Myriophyllum spicatum which were collected from the Kadin Creek in seasonal periods between 2011 and 2012 were analyzed. Heavy metal concentrations in the mineralized plant and water samples were determined with Inductive coupled plasma with mass spectroscopy (ICP-MS). Results showed the maximum heavy metal concentrations, in the root and minimum heavy metal concentrations, except chromium, in the stem. The distribution of heavy metals As, Cd, Hg and Pb was in the form of root > leaf > stem; the distribution of Cr was in the root > stem > leaf. There was a strong negative correlation between the suspended solid matter and heavy metal concentrations in the plant tissues. Heavy metal accumulation showed increase generally in fall. Heavy metals in the water were sorted as Pb > Cr > As > Hg > Cd by their mean concentrations. According to the factor data of bioconcentration, the order of heavy metal accumulation in the plant was As > Cr > Pb > Hg > Cd

Optical study of the effect of gamma radiation and heavy metals on microorganisms (Bacteria)

Radionuclide and heavy metal pollution are the main concerns for the environment nowadays as thousands of waste sites around the world pose a serious threat to all living organisms and humans, in particular. Therefore, the focus of this study is on the development of novel-sensing technologies for the detection of radionuclides and heavy metals in water utilizing microorganisms. Several optical methods, i.e., fluorescence microscopy, fluorescence spectroscopy, and UV-vis spectrophotometer were exploited here for studying the effect of γ-radiation (from Co-57 source) and one of the heavy metal ions (Cd+2) on two types of bacteria, namely Escherichia coli (E. coli) and Deinococcus radiodurans (D. radiodurans). All three optical methods gave consistent and correlated results in regards to the gamma radiation. An exponential decay in bacterial counts with the increase in γ-radiation dose was observed in E. coli bacteria samples, while D. radiodurans bacteria appeared to be much less affected by γ-radiation and showed even a small increase in the bacteria counts at low-radiation doses followed by a rather moderate decay at intermediate and high doses. The effect of Cd2+ on bacteria is more complex, however, and the method of fluorescence microscopy gave the most reliable account in live bacteria concentration. Both E. coli and D. radiodurans bacteria showed similar effects of a moderate decay of bacteria counts with the increase in CdCl2 concentration. Comparative analysis of the results obtained shows a clear possibility of pattern recognition of the presence of γ-radiation and heavy metals using the above two bacteria

An Investigation of the Biosorption of Radioactive Gallium-67 in an Aqueous Solution Using Rose Residue

This study investigates the adsorption of gallium-67, routinely used in nuclear medicine laboratories, in aqueous solution by using the waste of a rose-oil processing factory (rose residue). The experimental parameters were determined to be as follows: temperature, (10.0 to 40.0) degrees C; pH, (2.0 to 10.0); stirring speed, (300 to 720) rpm; particles size, (0.15 to 1.40) mm; and adsorbent dose, (1.0 to 15.0) g.L(-1). It was seen that the most important parameters were pH, temperature, particle size, and adsorbent dose. The adsorption mechanism of the rose residue was examined by comparing the Fourier transform infrared (FUR) spectra before and after adsorption. The Delta G and Delta H values were determined, and it was concluded that the absorption was endothermic and spontaneous. Absorption kinetics was studied, and it was observed that they fit a pseudo second-order model. As a result, it was found that the rose residue was a perfect absorbent for the adsorption of gallium-67