Articles in Press

Synthesis of Magnetic Multiwalled Carbon Nano Tubes and Investigation of isotherm and kinetic models for cleanup of Carbaryl pesticide

Khaghani R. Esrafili A. Zeynalzadeh D. Bahrami Asl F.

DOI:

Abstract

Abstract: Water is the main factor of movement and transport of pesticides and contamination of water by these pollutants is one of the most important challenges due to their widespread use and increased concentrations. Moreover, these compounds are on the U.S.EPA Priority Pollutant list because of the potential of accumulation and the property of damaging effects. In this study, multiwalled carbon nanotube-based magnetic nanoparticles were synthesized and used as an affective adsorbent for carbaryl pesticide. The properties of the synthesized Fe3O4@MWCNTs were characterized by TEM images and XRD analysis. The obtained data were studied by isotherm and kinetic models. Carbaryl adsorbed onto the synthesized adsorbent was compatible with the Langmuir isotherm (R2 =0.993). The maximum adsorption capacity (qmax) of the pesticide onto the Fe3O4-MWCNTs was obtained at 68.2 mg/g. The kinetic studies of the reactions showed that the adsorption process followed the pseudo-second order model with R2 ≥0.99 for all initial carbaryl concentrations. The adsorbent was extracted by magnet reused several times (six rounds) with a reasonable efficiency. The Fe3O4-MWCNTs have great potential for adsorption of carbaryl from water and wastewater due to high efficiency, easy separation and reusability.

Ammonia and COD Removal From Landfill Leachate Using MAP Precipitation Method

Kuleyin, A., Yeni, Ö., Şişman Y.

DOI:

https://doi.org/10.30955/gnj.003088

Paper Topic:

Water and Wastewater Treatment

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Abstract

Most of the major cities in our country are opposed to the problem of water pollution due to the uncontrolled leachate resulting from the decomposition of solid wastes in irregular landfills. The waste waters that have high nitrogen content such as leachate cause various problems like eutrophication. In this study; the preliminary treatment of leachate which formed on the landfill site storing solid wastes of Samsun Metropolitan Municipality by MAP (Magnesium ammonium phosphate) precipitation was examined. For this purpose, optimization of the parameters that affecting the MAP precipitation was performed and the conditions for optimum removal efficiency were investigated. As a result of MAP precipitation, various mole ratios were tested with the aim of providing the best ammonia removal efficiency. The maximum ammonia removal was found to be 90.63% at pH 9.5 and at Mg:NH4:PO4 ratio of 4: 1: 2.2. At this conditions the ammonia concentration was decreased from 1792 mg/L to 168 mg/L. Experimental data were also evaluated and the regression equations of ammonia and COD removal were obtained using Minitab 16 statistical software.

Uncertainties and nonstationarity in streamflow projections under climate change scenarios and the ensuing adaptation strategies in Subarnarekha river basin, India

Chintalacheruvu M. R. Bardhan A.

DOI:

https://doi.org/10.30955/gnj.003328

Paper Topic:

Water Resources Management

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Abstract

The present study analyses the various uncertainties and nonstationarity in the streamflow projections of Subarnarekha river basin in Eastern India using two widely used hydrological climate models: 1) general circulation model (GCM), and 2) forcing climate change scenarios. These two climate models are used to force the ArcSWAT model. Subsequently this model is calibrated using SUFI-2 optimization technique. The downscaled and bias-corrected data from an ensemble of 10 climate projections with representative concentration pathways (RCP) 4.5 and 8.5 scenarios (five each) were used in first model, whereas in second model a total of 63 (7 perturbed precipitations and 9 perturbed temperatures) combinations of hypothetical climate change scenarios were used. The results show very good correlation during monthly calibration time steps and relatively good agreement between the observed and simulated streamflows in daily calibration time steps. The uncertainties are expressed in probabilistic terms using probability density function (PDF) and cumulative distribution function (CDF) as they provide significant information for decision process in climate change adaptation in the river basin. The uncertainties associated with climate models, return periods and streamflow extremes are also analysed in the present work. The RCP 8.5 scenarios seem more appropriate than RCP 4.5 scenarios in quantifying the uncertainties under nonstationarity assumptions. The mean values of water balance components and their percentage variation for both historic and future periods reveal that the water balance components get affected significantly due to climate change in a future period. Consequently, the streamflows are likely to decline in the river basin. The present study also highlights the comprehensive approaches that are being planned to facilitate adaptation to climate change as well as those that are specific to the water resources management in the study region. The findings in this work are useful for overall well-being of people in the study area.