This article summarizes the results of a research study that was focused on the possibility of removing Cr (VI) from aqueous solution, using low-cost waste biomaterial in a batch mode. A set of seven biosorbents was used: Fomitopsis pinicola, a mixture of cones, peach stones, apricot stones, Juglans regia shells, orange peels, and Merino sheep wool. Three grain fractions (fr. 1/2, fr. 0.5/1.0, and fr. 0/0.5 mm) of biosorbents were studied. The aim was to find the most suitable biosorbent that can be tested with real samples. The influence of other factors on the course of biosorption was studied as well (chemical activation of the biosorbent, pH value, rotation speed during mixing, temperature, and the influence of biosorbent concentration). The use of chemical activation and adjustment of the pH to 1.1 to 2.0 make it possible to increase their sorption capacity and, for some biosorbents, to shorten the exposure times. Two kinetic models were used for the analysis of the experimental data, to explain the mechanism of adsorption and its possible speed control steps: pseudo-first and pseudo-second-order. The pseudo-second-order kinetic model seems to be the most suitable for the description of the experimental data. The thermodynamic parameters suggest that the biosorption was endothermic and spontaneous. In the biosorption equilibrium study, the adsorption data were described by using Langmuir and Freundlich adsorption isotherms. The Langmuir model was applicable to describe the adsorption data of all biosorbents. Both models are suitable for chemically treated sheep fleece and peach stones.
This article deals with the possibility of using a biosorbent in the form of a mixture of cones from coniferous trees to remove the residual concentration of hazardous metals contained in hazardous waste, which is disposed of in a neutralization station. The efficiency of the tested biosorbent in removing Ni, Zn, Cu, and Fe was monitored here. Laboratory research was carried out before the actual testing of the biosorbent directly in the operation of the neutralization station. With regard to the planned use of the biosorbent in the operational test, the laboratory experiments were performed in a batch mode and for the most problematic metals (Ni and Zn). The laboratory tests with real wastewater have shown that the biosorbent can be used to remove hazardous metals. Under the given conditions, 96% of Ni and 19% of Zn were removed after 20 min when using NaOH activated biosorbent with the concentration of 0.1 mol L−1. The inactivated biosorbent removed 93% of Ni and 31% of Zn. The tested biosorbent was also successful during the operational tests. The inactivated biosorbent was applied due to the financial costs. It was used for the pre-treatment of hazardous waste in a preparation tank, where a significant reduction in the concentration of hazardous metals occurred, but the values of Ni, Cu, and Zn still failed to meet the emission limits. After 72 h, we measured 10 mg L−1 from the original 4,056 mg L−1 of Ni, 1 mg L−1 from the original 2,252 mg L−1 of Cu, 1 mg L−1 from the original 4,020 mg L–1 of Zn, and 7 mg L−1 from the original 1,853 mg L−1 of Fe. However, even after neutralization, the treated water did not meet the emission limits for discharging into the sewer system. The biosorbent was, therefore, used in the filtration unit as well, which was placed in front of the Parshall flume. After passing through the filtration unit, the concentrations of all the monitored parameters were reduced to a minimum, and the values met the prescribed emission limits. The biosorbent was further used to thicken the residual sludge in the waste pre-treatment tank, which contributed to a significant reduction in the overall cost of disposing of residual hazardous waste. This waste was converted from liquid to solid-state.
The issue of wastewater is becoming more and more important today because of the new European Union laws leading to even stricter norms. Heavy metals belong to some of the negative elements present in wastewater. Their occurrence in wastewater caused by different industrial processes, such as electroplating, metal finishing, metallurgy, chemical production, mining, and production of paper or batteries, raises many questions because of their toxicity even in small concentrations [1].Sorption of heavy metals is one of the most promising technologies used for the removal of contaminants from water. It is a potential alternative to conventional procedures for its low cost, easy availability, and no nutritional requirements. Sorption minimizes the volume of chemical and/or biological sludge, which must subsequently be disposed of. It is also effective for detoxifying dilute wastewaters. Great attention has recently been paid to sorption of heavy metals from solutions using biological Pol. J. Environ. Stud. Vol. 26, No. 2 (2017) AbstractThe adsorption of selected metals (Cu, Mn, and Fe) from water solution using orange peel was studied by means of batch mechanism. The aim of this study was to determine the dependency of the sorption process on pH of the solution, the initial concentration of the sorbent, contact time, and temperature. The Langmuier and Freundlich isothermal models were used to describe the sorption isotherms of ions. In this case the Langmuier model is more suitable to describe the data. The adsorption efficiency of removing copper (q 20 = 5 mg/g) and manganese (q 20 = 15 mg/g) by using orange peel was approximately 90%. Under optimal conditions, the efficiency of removing iron (q 20 = 10 mg/g) was approximately 55%. When studying the kinetics we discovered that the sorption process will follow the pseudo second-order. The thermodynamic parameters show an exothermic character of sorption, and the processes are spontaneous and favourable. The results indicate that it is possible to use orange peel effectively for removing selected metals from wastewater.
The aim of the paper was to work out a new comprehensive methodology to monitor thermal activity at mine waste dumps. The methodology was tested through monitoring thermal phenomena occurring in the areas of extractive waste dumping facilities located in the Upper Silesian Coal Basin, Poland. Within the framework of the study, a comparative analysis of three waste dumps was performed; the first two of them, which were not previously reclaimed, are in part thermally active, whereas the third one comprises one section which was partially reclaimed and another section which is still being operated. The research objective was to observe the changes of atmospheric emissions of Polycyclic Aromatic Hydrocarbons (PAHs) from the three selected facilities within the period of 21 months of constant monitoring. The novelty of the methodology of thermal activity monitoring at burning mine waste dumps consisted in the application advanced chemometrics methods. The collected data were analyzed by means of the Hierarchical Clustering Analysis supplemented with a color map of the experimental results. Based on the newly developed methodology, it was determined that thermal processes occur in all of the three analyzed sites. The non-reclaimed waste dumps characterize of intense thermal phenomena covering the majority of the studied area. It was also observed that the most intensive thermal activity occurs in the central sections of the dumps with temperature values reaching the level of 600 °C accompanied by high emissions of PAHs. In addition, the research results demonstrate that despite the reclamation processes, there are certain areas which still remain thermally active in one of the studied extractive waste dumps. This manifested itself by high measured concentrations of all the analyzed PAHs and locally increased surface temperatures which, however, did not exceed 200 °C; the majority of the areas of the reclaimed waste dump characterized of temperatures in the range of 20–30 °C.
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