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In developing countries, good-quality water is contaminated due to the disposal of untreated municipal and industrial wastewater (WW) into natural water reservoirs. Most of the wastewater is not treated properly according to international standards, and usually is disposed of and/or utilized for irrigation without appropriate treatment. The main hurdles in providing wastewater treatment (WWT) in developing countries include high costs, and the poor design, installation, and operation of conventional WWT systems. Therefore, the present study explores the maize cobs trickling filter-based (MCTF) low-cost WWT option for developing countries like Pakistan, India, and Bangladesh. In this regard, indigenous media trickling filter was designed and developed using maize cobs as packing material for biofilm growth. The MCTFWWT system was continually operated and monitored for six months at constant hydraulic wastewater loading of about 113±2 m3 per m2 per day. The experimental data covers winter and summer seasons with temperature variations from 23ºC to 43ºC. System performance was evaluated by means of various WWT parameters, including biological and chemical oxygen demands (BOD5 and COD), total suspended and dissolved solids (TSS and TDS), turbidity, and color – before and after WWT. Experimental results showed that the MCTF-WWT system successfully removed about 79% BOD and 75% COD on average. The key reason for effective BOD and COD removal was rapid development of microbial film (within the first two weeks). Furthermore, the MCTF-WWT system removed 42-46% TSS, 28-30% TDS, 43-46% turbidity, and 33-37% color. The study concludes that the MCTF-WWT system is an effective and economical WWT option for irrigation/agricultural applications in developing countries.
Water pollution has become a major environmental concern for public and environmental health in developing countries. Water resources are being contaminated mainly due to mixing of domestic, municipal, and industrial wastewaters. The wastewater management and treatment situation is deplorable mainly because of financial constraints, the unavailability of technically trained human resources, and electricity shortages. Moreover, there is a challenge for the scientific community and wastewater management experts to explore cost-effective, simple, reliable, and efficient wastewater treatment systems. Therefore, the present review highlights the option of trickling filter (TF) systems for wastewater treatment in developing countries like Pakistan, India, Bangladesh, and African regions, etc. In addition, the solutions to the operational/performance issues of the TF system are explored and discussed in greater detail for designing/construction of new TF systems and retrofitting the existing TFs.
In the present research, a “green” recipe was used to produce innovative phytogenic magnetic nanoparticles (PMNPs) from leaf extract of Fraxinus chinensis Roxb without employing any additional toxic surfactants as capping agents. The convenient reaction between metal salt solution and plant biomolecules occurred within a few minutes by color changes from pale green to intense black, hinting at the production of magnetic nanoparticles (MNPs). The formation of PMNPs was verified by employing different techniques such as UV-visible spectrophotometry, Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray (EDX). The fabricated PMNPs were further utilized as a catalyst for removing toxic dyes, i.e., Crystal violet (CV) and Eriochrome black T (EBT) from aqueous solutions in the presence of hydrogen peroxide (H2O2). The concentrations of CV and EBT were calculated using ultraviolet-visible (UV-vis) spectroscopy throughout all the experiments. The results indicated that PMNPs showed >95% removal of both dyes within 10 min of contact time over a wide range of concentration, 10-300 mg/L. The degradation kinetics were also investigated using first- and second-order rate equations, and the results indicated that kinetic data of both CV and EBT followed first-order degradation rate. Moreover, the removal efficiency of the fabricated PMNPs was alsocompared with chemically synthesized magnetic nanoparticles (CSMNPs), and the results indicated that our fabricated PMNPs were more effective in terms of extent and speed to remove dyes. Finally, we have also proposed a possible removal mechanism. Altogether, the developed “green” recipe can easily be implemented to produce potentially biocompatible and non-toxic PMNPs for treatment of wastewater and can also easily be employed in low-economy countries.
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