All

The main objective of this study was to determine the effect of land use change on runoff in Chenar Rahdar watershed. Land use map of the studied basin was determined using Landsat satellite imagery for 2004 and 2015 using ENVI software. After applying the necessary corrections to the images and field surveys to take the educational points, supervised classification technique and maximum probability algorithm were applied to mapping land use change in the study area. According to results, 6 classes of land use were investigated (bare land, rain fed land, forest land, water agriculture land, rangelands and urban lands). In this study, 21 model parameters were calibrated with monthly runoff using 2004-2012 data and validated using 2012-2015 data. The efficiency coefficient for calibration and validation were between 0.88 and 0.94, respectively. The land use changes trend within the time interval showed that the highest percentage of incremental changes is related to urban lands with 108.45%, whereas, the highest decline was observed for agricultural land with 12.46%. In order to investigate the effect of land use change on surface runoff, different land use maps were applied to SWAT model, supposing constant condition for other parameters of the model. The results show that surface runoff increased by 11%, in 2015 compared to 2004. Comprehensive water management can reduce surface runoff in the watershed. The results showed that if all uncertainties were minimized, the calibrated SWAT model can give acceptable runoff simulation results regarding the land use change. These results can be useful for water and environmental resource managers.

Two identical four air-cathode single chamber membrane-less microbial fuel cells were stacked and tested under in series and in parallel electrical configurations. Fermentable household waste extract (FORBI; 0.8 g COD/L) was used as substrate, in all cases. Linear Sweep Voltammetry (LSV) was carried out for the construction of polarization curves which revealed that the highest power ouput (3.88 mW) was obtained under parallel connection as in series connection was found lower due to voltage drop phenomena. Electrochemical Impedance Spectroscopy measurements (EIS) gave an insight in the electrochemical processes occurring within the stack under both electrical connections. The contribution of the individual resistances to the overall internal resistance was defined, designating the significant role of the solution resistance (Rs) and the charge transfer resistance (RCT) under closed circuit conditions.

This study highlights the potential of steel slag, which is an industrial by-product of steel making industry as treatment media for metal-rich acid mine drainage (AMD). A series of batch adsorption studies has been done to demonstrate the effects of contact time, solution pH, initial concentration of metal, adsorbent dosage and size, and the effect of competing ions on the performance of steel slag. Results indicated that metal removal efficiencies were found to be >90% when pH of AMD has reached near-neutral state (6.8-7.5) that were mostly occurring within the first 14 hours of contact time. Optimum equilibrium time was found at 24 hours, i.e. 99-100% of metals were removed. An increased adsorption capacity with decreased removal efficiency was observed as initial metal concentration increased. In contrast, increasing adsorbent dosage leads to increased removal efficiency. Fe was not affected despite the presence of other metal ions (100% removal) compared to Mn (59.3% removal) in mixed AMD solution. Adsorption behavior of Fe, Cu, Zn and Mn fits appropriately with Langmuir isotherm model with adsorption capacity of 1.06, 1.03, 0.97 and 0.73 mg g-1, respectively. The adsorption kinetics followed the pseudo-second-order kinetics and is supported by intra-particle diffusion process. Therefore, steel slag can be potentially used as an effective media for passive AMD remediation.

The intent of this research is the investigation of the nitrate reduction from aqueous solution using biomass (pine cone (PC) and PC activated carbon (PCAC)) – supported zero valent iron nanoparticles (PC-Fe0 and PCAC-Fe0). The synthesis of these nano-bio-composites was based on the reduction of ferrous iron with borohydride, in which PC and PCAC acted as porous-based support materials. The structure of the adsorbents was characterized by SEM, XRD, FTIR and BET analysis. The SEM images revealed that nZVI immobilized on PC-Fe0 and PCAC-Fe0 were spherical and uniformly dispersed on the surface of the stabilizers. Batch experiments indicated that the nitrate removal efficiency decreased with the increase in the initial nitrate concentration and initial pH, but increased with the increase in the sorbent dosage and temperature. The maximum adsorption capacities of PC-Fe0 and PCAC-Fe0 for nitrate were 18.16 and 22.30(mg/g), respectively. The nitrogen mass balance calculations revealed that zero valent iron nanoparticles in both PC-Fe0 and PCAC-Fe0 beads could generally reduce nitrate into ammonium, and nitrite usually was occurred as intermediate. Subsequently, PCAC-Fe0 absorbs completely un-wanted ammonium, while PC-Fe0 releases little ammonium in the solution.