Global NEST Journal

One of the major challenges faced by researchers is to recycle industrial wastes in a manner that reduces their environmental impact in nature. An experimental study was carried out to determine the suitability of using chopped tire rubber as reinforcements in green and sustainable geopolymer concrete, with the purpose of using them as nonstructural products. The geopolymer mixture was made by mixing of fly ash powder, fine aggregate, and Superplasticizer in Na2SiO3/NaOH solution. Mixtures were divided into four different groups, with constant water to fly ash ratio of 0.12 and alkaline dosage of 45% by weight of fly ash, based on the recycled chopped tire rubber (CTR) content: 0, 10, 20, and 30% by volume of fine aggregate with two maximum sizes (2 and 4mm). Hardened properties of resulted geopolymer like compressive strength, density; and ultrasonic pulse velocity were examined at 28d. Besides that, X-Ray diffractometer and Scanning Electron Microscope were used in order to observe the microstructure of the resulted geopolymer concrete. In view of the consequences for this study, it is preferable to replace no more than 10% of fine aggregate in geopolymer concrete by CTR. In addition, according to SEM photographs, increasing the CTR content more voids will be pronounced and thus, decreasing the mechanical performance.

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.

The present study observed the removal of the organic content from the real effluent water produced by the oilfields. The proposed treatment process was the adsorption technique using the moringa peels as adsorbing agent. The effect of processing parameters such as adsorbent dosage, contact time and pH has been investigated using the batch adsorption method. The Langmuir isotherm provided a better fit for the adsorption equilibrium data than the Freundlich isotherm. It was observed that organic content adsorption was dependent on pH. The maximum removals of organic content were 65.4 % and 94.1% for moringa and activated moringa peels respectively at pH =3, 120 min, 1.5 gm dose. The outcome of this study exposes that activated moringa peels might be rummage-sale as a low-cost adsorbent for the removal of organic content from produced water.

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.