The aim of the present work is to characterize the soil additive derived from sewage sludge as potentially economically acceptable material for agricultural production as well as for soil and environment protection. The soil additive consisting of sewage sludge obtained from the wastewater treatment plant Pannon-Víz Zrt. (Győr, Hungary) and agricultural byproducts represented by wastes from grain mill industry and crushed corn cobs was prepared using the low-capacity granulator equipment constructed by Energy Agency Public Nonprofit Ltd. (Hungary). The characterization of sewage sludge as primary composite and prepared soil additive includes the determination of physico-chemical parameters such as pH determined in suspension with distilled water, 0.01 mol/dm3 CaCl2 or 1 mol/dm3 KCl solutions, pHzpc predicted by potentiometric titration and ProtoFit software, water holding capacity (WHC), cationexchange capacity (CEC) and total organic carbon (TOC). The elemental analysis by X-ray fluorescence spectrometry revealed that sewage sludge as well as prepared soil additive contain significant amount of Zn and Cu as important microelements in plant nutrition. Also, it was found that prepared soil additive represents the considerable source of a significant proportion, strong bound and in this way gradually released microelements. Obtained results suggest on the application potential of prepared soil additive in agricultural production as well as in remediation and reclamation of contaminated or degraded soil.
Agricultural wastes can be used as an alternative to the existing sorbents for the removal of metals or synthetic dyes from contaminated liquids. In this work, the fine powdered biomass of the hop (Humulus lupulus L.) variety Osvald's clone 72 and variety Bohemie as a sorbent for the removal of Cd from aqueous solutions of CdCl2 spiked with radionuclide 109Cd and synthetic dyes thioflavine T (ThT) or methylene blue (MB) from single dye solutions under conditions of batch systems was used. The maximum sorption capacity Q = 264 µmol Cd/g (d.w.) was found in the case of the leaf biomass of hop (H. lupulus L.) variety Osvald's clone 72 at the initial concentration of CdCl2 10,000 µmol/dm3, whereby the sorption capacity decreased in the order Qleaves : Qstems : Qroots = 1.0 : 0.8 : 0.7. The sorbed amount of Cd was removed from the hop biomass with the following increasing desorption efficiency of the extraction reagents: deionised H2O << 0.1 mol/dm3 HCl ≤ 0.1 mol/dm3 EDTA-Na2. Similarly as in the case of Cd sorption, the kinetics of ThT and MB sorption by the leaf biomass of the hop (H. lupulus L.) variety Bohemie were also showed as two-phase processes. The maximum sorption of ThT approx. Q = 19 mg/g (d.w.) and MB approx. Q = 70 mg/g (d.w.) were found within the range of the initial values of pH 4 – 7. The sorption of both dyes by the leaf biomass from single dye solutions decreased with increasing biomass concentration and on the other hand increased with increasing the initial concentrations of ThT or MB. The process of ThT and MB sorption was better described by the Langmuir model than the Freundlich model of sorption isotherm. From the obtained values of Qmax, it was found that in the case of MB the dried leaf biomass showed more than 2-times higher sorption capacity (Qmax = 184 mg/g; d.w.) in comparison with the value predicted for ThT. Obtained results suggest that dried plant biomass of hop (H. lupulus L.) as agricultural by-products can be used as a potential sorbent for both types of studied contaminants.
A hydroponic study involving lettuce plants (Lactuca sativa L.) as a leafy vegetable was conducted to evaluate the 137Cs uptake and translocation in plant tissues in dependence on the presence or absence of K+ or/and NH4+ ions in cultivation media according to Hoagland (HM) during 8 d plants growth under hydroponic conditions. Significant increase of the 137Cs+ uptake by lettuce plants and the decrease of 137Cs+ translocation efficiency from roots to leaves were observed in 50 % HM deficient in K+ and NH4+ ions. Speciation analysis using Visual MINTEQ program showed that at micromolar concentration of CsCl (5 μmol/dm3) in 50 % HM at pH 6.0 and 25 °C, cesium was occurred practically only in the free cationic Cs+ form − 98.8 %, with minor proportions of other cesium species: CsCl − 0.4 %, CsNO3 − 0.4 %, and CsSO4 - − 0.4 %. Surplus of Cl-, NO3- and SO42- ions in HM causes the increase of proportions of the cesium species CsCl, CsNO3 and CsSO4-, respectively at the expense of bioavailable Cs+ form. Radiocesium 137Cs taken up via roots was removed from lettuce leaves with high efficiency by boiling in diluted NaCl solution. At ambient temperature the extraction of 137Cs with diluted acetic acid was concentration and time dependent process, and was succeeded by leakage of tissue components absorbing at 260 nm. These findings are important for the risk assessment of radiocesium entry into the food chain via contaminated leafy vegetable.
This work deals with sorption of cationic synthetic dye thioflavine T (ThT) onto the river sediment obtained from the Váh River under conditions of batch and column system using spectrophotometric methods. We found that sorption of ThT onto river sediment was a rapid process with reaching of concentration equilibrium within 2 h of interaction. The values of distribution coefficient (DC) defined as concentration ratio [ThT]sediment : [ThT]solution were linearly increased with increasing concentration of river sediment in solution within the range Csediment 1.25 - 10.0 g/dm3 and minimally changed in the range of initial pH values 2 - 6. The increasing concentration of ThT in model solution caused exponentially decrease in the value of DC. The sorption processes characterized by dependence between equilibrium specific sorption Qeq and ThT concentration Ceq in solution were better described by adsorption isotherm according to Freundlich (R2 = 0.979) than according to Langmuir adsorption isotherm (R2 = 0.914). From evaluation of ThT sorption onto river sediment in column system containing of 5 cm sediment layer with 30 cm of water column on the basis of ThT concentration changes in infiltrated water we found that these processes were significantly dependent on the rate of infiltrated water flow through the sediment layer Riw as well as on qualitative and quantitative composition of water. The highest ThT desorption from the sediment layer was found in seepage of 50 % (v/v) ethanol (EtOH) solution through the sediment and efficiency of ThT desorption decreased in the order: 50 % (v/v) EtOH > 0.1 mol/dm3 HCl > deionized water. Obtained data from the point of view of physico-chemical characteristics of the river sediment, such as pH, pHzpc (potentiometric titration), cation-exchange capacity (CEC) and elemental composition (X-ray fluorescence spectrometry), was also discussed
The aim of the present work was to compare the accumulation and translocation of Cd and Zn in plants of tobacco (Nicotiana tabacum L.), celery (Apium graveolens L.), maize (Zea mays L.), giant reed (Arundo donax L.), and alpine pennycress (Noccaea caerulescens L.) under conditions of short-term hydroponic experiments using nutrient solutions spiked with radionuclides 109Cd or 65Zn, and direct gamma-spectrometry. It was found that the time-course of metals accumulation in studied plants was not different in terms of target metal, but it was significantly different on the level of plant species. The highest values of Cd accumulation showed plants of giant reed, whereby the accumulation decreased in the order: giant reed > tobacco > alpine pennycress >> maize and celery. On the basis of concentration ratios (CR) [Me]shoot / [Me]root calculation for both metals, it was found that Cd and Zn were in prevailing part accumulated in the root tissues and only partially accumulated in the shoots, where the amount of accumulated Cd and Zn increased from the oldest developed leaves to the youngest developed leaves. The CR values corresponding to these facts were calculated in the range 0.06 – 0.27 for Cd and for Zn 0.06 – 0.48. In terms of plant species, the CR values obtained for Cd decreased in the order: maize > celery > tobacco and giant reed > alpine pennycress. The similarity between studied objects – individual plant species on the basis of the obtained variables defining Cd or Zn accumulation at different conditions of the experiments as well as the relationships between obtained variables and conditions of the experiments were subjected to multivariate analysis method – cluster analysis (CA). According to the findings and this analysis, it can be expected that plants of tobacco and giant reed will dispose with similar characteristics as plants of alpine pennycress, which are classified as Zn/Cd hyperaccumulators, in terms of Cd or Zn accumulation and other positive parameters for their utilization in phytoremediation processes and techniques.