Volume 21 - 2019

In the present work, the degradation of phenol from aqueous solutions was investigated using periodate/zero valent iron nanoparticle (nZVI) in the presence of ultrasound at a batch reactor. The Experimental tests were carried out using pre-designated amounts of nZVI, periodate, and pH ranging from 1-7 mM, 0.5-5 mM, 3-11 respectively. During the all experimental tests the ultrasonic reactor was operated at a fix frequency (40 kHz), temperature (33±1) and power (350 W). The results of nZVI/periodate/ultrasound system on degradation of phenol showed that the removal efficiency was frankly affected by the amount of produced free radicals to initiate the oxidative decomposition of phenol. As, with enhancing the nZVI loading to 3 mM and periodate concentration to 3 mM, the removal efficiency of phenol was increased. Besides, the acidic pH (pH=3) was found to be more effective than neutral and alkaline pH in degradation of phenol.

A 28-day bioassay with the earthworm (Dendrobaena veneta) was used to assessing the ecotoxic effect of mercury in study soils and sediments. This article deals with quality evaluation of the soils, sediments and plants (assimilation organs) from three localities, Rudňany, Krompachy, and water reservoir of Ružín, Eastern Slovakia (Europe) in consideration of their toxic effect on the environment. These areas are well - known for its mercury mining and metallurgical activities for several centuries. Within the frame of evaluation it was found that the concentrations of mercury exceeded some of the MPC (Max. Tolerable Risk) and IV (Serious Risk) values. The samples Rudňany tailing-SED (188.5mg/kg), Krompachy a-SED (69.4mg/kg), and Krompachy b-SED (93.4mg/kg) were the most polluted by mercury, which is evident according to it is the highest mortality on the earthworm (Dendrobaena veneta). The high mercury concentrations were obtained in the soils of the Rudňany-tailing-S (82.5mg/kg), Rudňany-tailing, valley-S (57.8mg/kg), and Krompachy 4KO-S (20.6mg/kg). A significant positive correlation is found between highest concentrations of mercury Rudňany-tailing SED Hg=188.5mg/kg (r=0.87) with the highest mortality of Dendrobaena veneta after 28 days bioassay.

Municipal solid waste (MSW) landfills are one of the major and most preferred waste management options in the United States and many other countries across the globe. The waste in conventional MSW landfills undergoes very slow decomposition due to limited amount of moisture. In this regard, the bioreactor landfills have emerged as an effective waste management option, wherein leachate recirculation/injection is carried out to enhance the moisture levels within the waste thereby facilitating rapid waste decomposition and leading to early waste stabilization. However, in practice the performance of bioreactor landfills has remained inconclusive due to the lack of sound basis for effective design and operation of such landfills. This further stems from the fact that there is a limited understanding of the physical, chemical and biological processes and their coupled interactions on the MSW behavior in landfills. Hence, it becomes imperative to understand the influence of the coupled processes on the waste behavior to predict the overall performance of bioreactor landfills. Several researchers have developed numerical models to simulate waste behavior but only a few models have considered the simultaneous interactions of hydraulic, mechanical, and biological processes within the waste in their numerical model. In this study, newly developed numerical framework incorporating coupled thermo-hydro-bio-mechanical processes is presented. The numerical model can predict the spatial and temporal variation of waste temperatures, moisture distribution, gas generation, pore pressures, waste settlement, waste slope stability, and interface shear response in the landfill liner system. The numerical model has been validated with lab-scale and field-scale experiments and could be used to design and operate stable and effective bioreactor landfills.

This paper describes the adsorption of Al3+ ions from aqueous solutions, by natural clay (from Sakarya's Yenigün district) and coconut shell modified by means of acid treatment. Batch experiments were carried out to determine the effect of various factors such as initial pH (4-9), temperature (20, 40, 70 oC), initial concentration (10 to 200 mg L-1) and contact time (1-120 minute) on the adsorption process. The adsorption experiments were performed at a temperature of 20 ±2 oC), at 200 rpm agitation rate, with an adsorbent level of 1 g L-1, produced 98.95% (at pH 6) and 92.83% (at pH 7) maximum Al3+ removal efficiency for clay and coconut shell based adsorbents respectively. Furthermore, the process was found to be exothermic for clay and endothermic for coconut. XRF and XRD analyses of the clay variety used in adsorption analyses revealed it to be saponite clay, within the larger group of smectite clay minerals. The application of Langmuir revealed maximum adsorption capacity of 149.25 mg g-1 for natural clay adsorbent (NCA), and 120.482 mg g-1 for coconut shell adsorbent (CSA). Moreover, adsorption kinetics were found to be consistent with the second order kinetics (R2 > 0.95). The result shows that, natural clay and coconut shell adsorbents are effective adsorbents to remove Al3+ from aqueous solutions with good adsorption rate (>92.8%).