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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.
Wastewater (WW) volume generated from both domestic and industrial sectors has increased due to rapid industrialization and urbanization. WW is increasingly used on farms because it is cheap and easily available all year, causing various environmental and health implications. In order to evaluate Multan WW, this study characterizes 154 WW samples collected from 11 disposal stations. These samples were analysed for 23 parameters related to organic matter, nutrients, inorganic matter, and pathogens to determine pollution extent distribution, agricultural reuse potential, and WW treatment database. A major contamination concern was found regarding biological oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), total coliform, and E-Coli. The average values of BOD and COD were found to be 2.7 and 3.8 times higher than the permissible limits respectively. The microbiological parameters such as total coliform and E-Coli were found to be 10.6 and 36 times higher than the permissible limits, respectively. However, heavy metals and nutrients were found within the permissible limit except phosphorus. Here, the correlation study on selected WW parameters indicated the direct or indirect relationship among WW constituents and the impact of different sources of pollution on WW characteristics. The present study also presents a critical review of different treatment options according to contamination strength in disposal stations.
The need of wastewater (WW) treatment is increasing along with the production of WW and its disposal without treatment. With a smaller footprint, ease of operation, and relatively less cost, trickling filter (TF) wastewater treatment systems have been considered to be more adoptable for domestic and industrial WW treatment in underdeveloped and/or developing countries – particularly for Asia and Africa. A relatively low-cost and operationally effective TF wastewater treatment system was developed using farm waste cotton sticks as biofilm support media. During the operation of the TF system, flow rates vary from 1.7 to 4.6 m³/hr. The attained removal efficiency for BOD (biological oxygen demand) was 69-78% and for chemical oxygen demand (COD) was 65-80%. The solids removal in TF system was 38-56% for total suspended solids (TSS) and 20-36% for total dissolved solids (TDS). Other aggregates such as turbidity and color removal were 32-54% and 25-42%, respectively. Four to five months of trouble-free operation of the developed TF system indicated the robustness and reliability of the system. Cotton sticks appeared to be a degradation-resistant alternative filter media for the TF system. Moreover, it is useful for reducing potential impacts of WW re-use at the farm level. Treated effluents through the TF system can be re-used as an irrigation water supplement in under-developed and/or 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.
In this study we investigated the projections of climate change and its impacts on the water resources of the Xin’anjiang watershed and optimal hydropower production using future run-offs (the decades of the 2020s, 2050s, and 2080s). The arc SWAT hydrological model and change factor downscaling technique were integrated to detect the run-offs and to downscale CMIP5 future climate variables, respectively. Optimal hydropower generation using future runoff was predicted by developing a mathematical model and by applying the particle swarm optimization technique within its paradigm. The results depict an increase of up to 5.9ºC in monthly mean maximum temperature, and 5.58ºC in minimum temperature until the 2080s. There will be a 63% increase in flow magnitudes more than the base year flow during the 2020s, whereas up to 70% and 31.40% increments have been observed for the 2050s and 2080s, respectively. The results revealed potential hydropower generation of 19.23*10⁸ kWh using 2020s runoff of rainy years. Similarly, 19.35*10⁸ kWh and 14.23*10⁸ kWh were estimated from the flows during the 2050s and 2080s, respectively.
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