Evaluating and Calibrating Reference Evapotranspiration Models Using Water Balance under Hyper-Arid Environment

This research investigates five reference evapotranspiration models (one combined model, one temperature-based model, and three radiation-based models) under hyper-arid environmental conditions at the operational field level. These models were evaluated and calibrated using the weekly water balance of alfalfa by EnviroSCAN to calculate crop evapotranspiration (ET_c). Calibration models were evaluated and validated using wheat and potatoes, respectively, on the basis of weekly water balance. Based on the results and discussion, the FAO-56 Penman-Monteith model proved to be superior in estimating ET_c with a slight underestimation of 2 %. Meanwhile, the Hargreaves-Samani (HS) model (temperature-based) underestimated ET_c by 20 % and the Priestley-Taylor (PT) and Makkink (MK) models (radiation-based) had similar performances underestimating by up to 35 % of the measured ET_c. The Turc (TR) model had the lowest performance compared with other models, demonstrating values underestimated by up to 60 % of the measured ET_c. Local calibration based on alfalfa evapotranspiration measurements was used to rectify these underestimations. The surprisingly good performance of the calibrated simple HS model, with a new coefficient 0.0029, demonstrated its favorable potential to improve irrigation scheduling. The MK and PT models were in third and fourth rank, respectively, reflecting minor differences between one another. The new coefficients obtained for the MK and PT models were 1.99 and 0.963, respectively. One important observation was that the calibrated TR model performed poorly, with an increase in its coefficient from 0.013 to 0.034 to account for hyper-arid environmental conditions; moreover, it required additional seasonal calibration to adequately improve its performance.     

Development of optimal water supply plan using integrated fuzzy Delphi and fuzzy ELECTRE III methods—Case study of the Gamasiab basin

This paper presents a novel method for the development of an optimal water supply plan showcased using data from the Gamasiab basin, located in Kermanshah province, Iran, concerning new dams that are being constructed in this semi-arid region. In this paper, a new group multi-criteria decision-making (MCDM) plan is proposed by combining two MCDM methods based on the fuzzy Delphi and fuzzy ELECTRE III methods that convert the experts' opinions to triangular fuzzy numbers based on the level of uncertainty associated with various quantitative and qualitative criteria. Considering the opinions of four non-stakeholder experts and data analysis using the fuzzy Delphi method, the criteria were evaluated. Then, by analysing the results using the fuzzy ELECTRE III method, the final ranking of scenarios is obtained. A sensitivity analysis was conducted to assess the effect of uncertainty on the performance of the decision-making system in scenarios ranking. The total expense, flood control, reservoir capacity and diversion and water transfer played a significant role in selecting the optimal scenario. Additionally, a hydrologic model was developed to evaluate the performance of the optimal scenario in terms of qualitative criteria. The data indicated that there was a good agreement between the results obtained from the hydrological model and the scenario ranking by the employed method. Altogether, a comparison of the proposed method with other MCDM methods, including fuzzy analytic hierarchy process and fuzzy technique for order preference by simulation of ideal solution, indicated that the results of the employed method matched more closely to the local experts' opinion.     

Effect of Flotation Reagents on the Activity of L. Ferrooxidans

Froth flotation is the most preferred processing technique for the enrichment of low-grade sulfides. Bioleaching is an eco-friendly method for metallurgical extraction from flotation products. Flotation reagents (collectors, frothers, etc.) have various impacts on bioleaching and bacterial activities. In this investigation, the effect of a number of sulfide flotation collectors [potassium amyl-xanthate, potassium isobutyl-xanthate, sodium ethyl-xanthate, potassium isopropyl-xanthate, and Dithiophosphate (Aero3477)], and frothers (pine oil and methyl isobutyl carbinol) with different dosages is studied on Leptospirillum ferrooxidans activities. The results of various measurements indicated that these flotation chemicals can have positive or negative influences on the bacterial activities, based on their chemical compositions and/or concentrations. These results can extensively be used for the selection of flotation reagents when bioleaching is chosen as the metallurgical extraction method after flotation enrichment.     

Acidophilic bioleaching: A Review on the Process and Effect of Organic–inorganic Reagents and Materials on its Efficiency

Bio-hydrometallurgical applications have been receiving more attention globally for processing of several metal bearing wastes. Developments in bioleaching enable this technique to be utilized as an alternative process for extraction of metals (ex-copper, gold, etc.) from complex ores or even concentrates, consequently solving several environmental issues. Organic and inorganic reagents or additives used during the process have been seen to affect the leaching efficiency of microbes for metal dissolution. The present review discusses the influence of certain organic–inorganic reagents and other materials or additives on the growth, oxidation activity, and bioleaching efficiency of acidophiles on metal dissolution.     

Influence of important factors on flotation of zinc oxide mineral using cationic, anionic and mixed (cationic/anionic) collectors

In this study, the influences of important factors on smithsonite flotation are investigated. Dosages of sulphidizing agent and collector, desliming prior to flotation and the use of sodium hydroxide instead of sodium carbonate as the pH regulator are essential to the effective recovery of smithsonite in cationic flotation. The appropriate temperature for flotation was found to be 30–40 °C. Sodium hexametaphosphate (SH) and sodium silicate had the greatest selectivity between smithsonite–calcite and smithsonite–quartz, respectively. The results of oleic acid flotation showed that the grade and recovery of zinc were relatively low in comparison with the sulphidization-cationic flotation method. Despite using sodium silicate and SH as depressants in oleic acid flotation, flotation was not selective. Flotation using mixed collectors (Armac C + Potassium Amyl xanthate) showed promising results. The ratio of the mixed collectors and the sequence of addition of mixed collectors were important criteria in attaining true mixed collector flotation.     

Evaluation of AnnAGNPS in cold and temperate regions.

Identification of the pollution sources and understanding the processes related to runoff generation and pollution transportation is effective for the water quality management and selection of the Best Management Practices. The ANNualized AGricultural Non-Point Source (AnnAGNPS) model was applied to a watershed in Southern Ontario to evaluate the hydrology and sediment component from the non-point sources. The model was run for two years (1998 to 1999); one year's data was used to calibrate and the second year's data was used for validation purposes. The model has under predicted runoff amount and over predicted the sediment yield. However, the simulated runoff and sediment yield compared fairly well with the observed data indicating that the model had an acceptable performance in simulation of runoff and sediment. The study is still in progress to assess its performance for estimation of TMDL and improvements needed for the model to use under Ontario conditions.     

Thermodynamical and catalytic aspects of zinc separation from aqueous solution

The present research work examines extraction mechanism of zinc by D2EHPA (Di-2-ethyl hexyl phosphoric acid) and comprehensively studies the main effective parameters on the process. Results of thermodynamic experiments showed that zinc extraction by D2EHPA was endothermic and spontaneous, and thermodynamic parameters including entropy and enthalpy were+27.37 J·mol^-1·K^-1 and 25.21 kJ·mol^-1, respectively. Gibbs free energy was varied between -7.21 kJ·mol^-1 and -8.41 kJ·mol^-1 with the variation of temperature from 20℃ to 70℃. Solution ionic strength was increased by addition of potassium and lithium sulfate solution while addition of calcium sulfate decreased ionic strength whereby zinc extraction efficiency was also decreased. TBP showed positive synergism at concentration of 5% (v/v) and negative synergism effect at concentrations of 2% and 10%. Simultaneous addition of both TBP and salt caused extraction efficiency to drop significantly and lower both TBP and ionic strength efficiency. Results showed that a continuous addition of TBP tends to effectively improve the zinc extraction efficiency. Experiments in the presence of catalyst Ni-Raney demonstrated that zinc extraction kinetic increases remarkably and due to easy recycling of the catalyst, we can propose a novel idea in solvent extraction field.     

Short to Long-Term Forecasting of River Flows by Heuristic Optimization Algorithms Hybridized with ANFIS

Water Resources Management - Accurate forecast of short-term to long-term streamflow prediction is of great importance for water resources management. However, with the advent of novel hybrid...     

Study of the effects of conventional reagents for sulfide flotation on bio-oxidation activity of Acidithiobacillus ferrooxidans

Bioleaching as a low cost and environment-friendly process could be a promising option for the enrichment of froth flotation products. Flotation reagents (collectors, frothers, etc.) are effective on the bacteria growth and oxidation activity; however, their impact has not been widely investigated. In this study, the effect of conventional reagents for sulfide flotation; collectors: potassium amylxanthate (KAX), potassium isobutyl-xanthate (KIBX), sodium ethylxanthate (NaEX), potassium isopropyl xanthate (KIPX) and Dithiophosphate (Aero3477), and frothers; pine oil (PO) and methyl isobutyl carbinol (MIBC) in various concentrations have been examined on Acidithiobacillus ferrooxidans activities. The results of this study demonstrate these flotation surfactants may have positive or negative influences on the bio-oxidation, based on their chemical compositions and/or concentrations. In general, the inhabitation effects of collectors would be increased in higher dosages and based on differences between results of various conditioning tests with the control test (without reagent) in different days, this effect could be considered by the following order: for 0.01?g/L: KAX?>?KIPX?>?KIBX?>?Aero3477?>?NaEX, 0.1?g/L: NaEX?>?KIPX?>?KAX?>?KIBX?>?Aero3477, and 1?g/L: NaEX?>?KIPX?>?KIBX?>?KAX?>?Aero3477, and for frothers: MIBC?>?PO in all concentrates. These outputs potentially can be used for the selection of flotation surfactants when the flotation products are going to be further processed by bioleaching for the metallurgical extraction.