Numerical Simulation of Direct Contact Membrane Desalination in Conjugate Heat Transfer Configuration: Role of Membrane Conductivity
SWES, volume-06 , Issue 2 (2014), PP 81 - 87
Published: 28 Nov 2014
by Isam Janajreh, Dana Suwwan from Mechanical Engineering Program, Masdar Institute of Science and Technology, PO Box 54224, Abu Dhabi, UAE
Abstract: The Abstract- Direct Contact Membrane Distillation (DCMD) is modeled using the conjugate heat transfer Navies-stokes flow model. A uniform salty and relatively hot feed and colder fresh permeate flow are driven by the peristaltic pump are considered in parallel configuration across the membrane. Depending on the membrane parameters (permeability, thickness, pour size, and conductivity) the resulted temperature difference leads to a pressure gradient responsible for the vaporizing fraction of the feed and transport to the permeate side through the hydrophobic membrane. Under different flow conditions and membrane conductivity mass flux, heat flux, temperature polarization, and thermal efficiency are evaluated. Results showed a good agreement with the published theoretical work on the mass flow this followed with sensitivity study to two parameters one is operational and the other is designed to gain a better understanding of the system performance and metrics including temperature polarization, convective and conductive heat flux, and associated latent heat of evaporation. read more... read less...
Keywords: Direct Contact Membrane Distillation, Mass Transfer, Heat Transfer, Temperature Polarization
SWES, volume-06 , Issue 2 (2014), PP 61 - 72
Published: 24 Nov 2014
by Isam Janajrehcand Dinesh K. Saxena from Mechanical and Materials Engineering Department, Masdar Institute, Abu Dhabi, PO Box 54224, United Arab Emirates Bryology laboratory, Botany Department, Bareilly College, Bareilly-243005 (U.P), INDIA
Abstract: While others considering algae as the “light of hoop” to the energy crisis, and as a carbon neutral technology to combat global warming, uncontrolled growth and its eutrophication can be considered a challenging pollution issue. Nevertheless, in the last a few decades’ algae pollution has become a global issue. The occurrence of algal bloom in water source has posed a serious water safety and unaccounted control and maintenance at substantial added cost. Overgrowing algae have brought negative impacts on power plant and less frequently led to shutdown of the desalination or power plant. The eutrophication which is rarely is eliminated; it could be controlled by mechanical filtration and chemical biocidal methods. This adds another economic burden by the supply of chemical and their neutralizing agent to cope with tight EPA limits. In this work a review of the treatment of algae is carried out which involves chemical, mechanical, electromechanical and as well as the aid of scavengers directly or indirectly and their combination. As plausible results on the sonication treatment have been emerging, recent work of the author was presented as well to show the effectiveness of the sonication technology in the treatment of the Enteromorpha Prolifera Macro Algae. read more... read less...
Keywords: Enteromorpha prolifera, Algal Treatment, Sonication of Algae, Eutrophication
SWES, volume-06 , Issue 2 (2014), PP 53 - 59
Published: 24 Nov 2014
by Raina Pal, Mahima, Anshuman Gupta and Anamika Tripathi from Department of Botany, Hindu College, Moradabad, India 244001
Abstract: The present study deals with the assessment of ambient air quality with respect to Total Suspended Particulates (TSP), Respirable Suspended Particulate Matter (PM10), Sulphur dioxide (SO2) and Nitrogen dioxide (NO2) considered over a period of two years from Sep 2010 to Aug. 2012. Air quality index are used for local and regional air quality management in many cities of the world. The air quality index has been determined at three different sites i.e. PTC (SI), Buddh Bazar (SII) and Mughalpura (SIII) of Moradabad city. The experimental results obtained from the different air quality categories according to national ambient air quality standard at different site as PTC (SI) though looks a clean area, falls under moderate pollution category with 68.78 index value. This may be due to fossil fuel combustion at the outskirts of the parade grounds and burning of dry leaves inside the area. Buddh Bazar (SII) which is a commercial area falls under high air pollution category with 99.48 index value. This site near railway station is extremely congested resulting in slow movement of vehicles, long waits at the signals and a large number of vehicles running during the day and night time. Mughalpura (SIII) is an industrial area, falls under the very high pollution category with 120.99 index value, may be due to the industrial activities i.e. mainly brassware. Five heavy metals i.e. Cu, Zn, Fe, Cd and Pb were also observed at all the sites. Among the metals highest concentration of Zn was recorded at almost all the sites whereas Cu, Zn and Fe was found higher at industrial site, may be attributed to melting of Brass sillies to prepare the different Brassware items. read more... read less...
Keywords: AQI, Heavy Metals, Air Quality Management
SWES, volume-06 , Issue 1 (2014), PP 45 - 51
Published: 24 Nov 2014
by Mahwish Chughtai, Sana Mustafa, Majid Mumtaz from Department of Chemistry, University of Karachi-75270, Pakistan Department of Chemistry, Federal Urdu University of Arts, Science & Technology, Gulshan-e-Iqbal Campus, Karachi75300, Pakistan
Abstract: Local Precipitation (Rain) is a good source of surface water and could be a safe source of drinking water if it is free from contaminants. Many Asian countries do not have access to safe drinking water; therefore, they have no alternative but to use water from contaminated sources that poses a health hazard. In the present study, thirty-three rain water samples were collected from Karachi, Pakistan during monsoon season of year 2007. The pH, electrical conductivity (EC), total dissolved solids (TDS), dissolved oxygen (DO) and hardness were immediately monitored after sample collections and possible sources of NH4, Na, K, Mg, Ca, F-, Cl-, NO3 -, CO3 -2 and SO4 -2 concentrations in rain water of Karachi city, Sindh, Pakistan were analyzed in order to distinguish safe source of drinking water. All samples were completely free from fluoride contamination while the concentration of chloride and sulfate was in range of 15.11-125 mg/l and 10.02- 72.02 mg/l indicate their presence from air pollution. Moreover, the study showed that the rain water can be harvested to extend potable and non-potable water supplies in this city read more... read less...
Keywords: rain water, air pollution, physicochemical parameters, Karachi, drinking water
SWES, volume-06 , Issue 1 (2014), PP 35 - 43
Published: 24 Nov 2014
by Sushil Kumar Singh from Botanical Survey of India, Eastern Regional Centre, Shillong – 793 003, India
Abstract: A review of Indian Riccia’s has been made and 36 valid species are accepted. 12 species viz., R. attenuata, R. ciliata, R. crispatula, R. crozalsii, R. curtisii, R. glauca, R. haskarliana, R. hirta, R. mangalorica, R. perssonii, R. stricta and R. warnstorfii are rare and found in restricted pockets of the country. Except Riccia abuensis and R. fluitans (aquatic species) all are terrestrial. Riccia poihaiana A.E.D.Daniels & P.Daniel is proposed to place under synonymy of R. billardieri Mont. & Nees. The occurrence of Riccia squamata, R. duplex and R. dictyospora recorded in Indian bryoflora is treated here doubtful. The notes on Riccia lucknowensis A.Gupta &Udar and R. nagalandensis D.D.Pant & Bhowmik ex S.K.Chaturv. & S.Chaturv. (both invalid species) are given. The taxonomy, diversity and distribution and notes wherever required are provided. read more... read less...
Keywords: Marchantiophyta, Riccia, India, Taxonomy, Distribution
Phosphorus and Emerging Micro-pollutants in Surface Waters: Challenges and Prospects for Water Quality Improvements
SWES, volume-06 , Issue 1 (2014), PP 27 - 33
Published: 24 Nov 2014
by Peter S. Hoodaa, John Jr. Wilkinson and Helen K.G.R. Millier from Kingston University London, Kingston upon Thames KT1 2EE, UK
Abstract: An oversupply of Phosphorus in water bodies accelerates growth of algae and higher forms of plant life to produce undesirable impacts on overall water quality. Phosphorus inputs to surface waters arise from a variety of point and nonpoint sources. However much of the P is contributed by agricultural runoff and outfall of treated (or untreated) wastewater in receiving water-bodies. Point sourced-P inputs to waters have considerably decreased in recent years, at least partly driven by regulatory requirements, e.g. the EU Water Framework Directive. This has largely been achieved by removing P from treated wastewaters at sewage treatment works (STWs). Studies have shown that introducing an additional treatment step (“P-stripping”) can significantly reduce P in STW outfalls. Given P deposits are depleting, there is much interest in phosphorus recovery from wastewaters. A few STWs have already started to recover P as struvite (NH4MgPO4.6H2O) mineral – a substitute for commercially produced P-fertilizers. This requires major investment and is not economically viable at small STWs. Nonetheless it is a major breakthrough in terms of P recovery and its use. Effluents from sewage treatment works (STW) can often contain a complex mixture of residual microcontaminants, not removed during wastewater treatment. Organic micro-pollutants have been found in rivers receiving STW effluents. Such residual contaminants have become the focus of an emerging field of water quality study and are collectively referred to as pharmaceuticals and other personal healthcare products, PPHCPs. Many of these chemicals have the ability to effect the hormonal signaling of organisms and are called endocrine disrupting compounds (EDC). Such chemicals have shown some of the most damaging biological effects in aquatic organisms. Biological effects in the aquatic environment are typically related to the development of intersex in fish. Recent research shows the use of STW practices such as upgrading from using a combined trickling filter contact process to activated sludge treatment, ozonation, membrane filtration and use of suspended biofilm reactors reduces the amount of EDCs in waste effluent. It is thus possible to remove contaminants from STW effluents, but it will not be possible without major infrastructure improvements. This paper presents the challenges and prospects of P and micro-organic pollutants in surface waters. read more... read less...
Keywords: Phosphorus, Agricultural Runoff, Sewage Effluents, Phosphorus Stripping, Emerging Micro-pollutants (EMP), Pharmaceutical and Personal Healthcare product (PPHCP), Sewage Treatment Works (STW)
SWES, volume-06 , Issue 1 (2014), PP 1 - 15
Published: 24 Nov 2014
by Dinesh K. Saxena, Isam Janajreh, and Dheeraj Gahtori from a Bryology laboratory, Botany Department, Bareilly College, Bareilly-243005 (U.P), INDIA, Mechanical and Materials Engineering Program, Masdar Institute, Abu Dhabi, PO Box 54224, UAE
Abstract: Bryophytes have been used as a terrestrial bio-monitors and bio-indicators of air pollution and are recognized as more sensitive to pollution than other plants. In present study common moss species, i.e., Rhodobryumgiganteum (Schwaegr) Par., Rhynchostegielladivaricatifolia (Renauld&Cardot), PohliaelongataHedw, Racomitriumcrispulum (Hook. f. et Wils.), Pleuroziumshcreberi, Hylocomiumsplendens, Hypnumcupressiforme, Brachytheciumrutabulum, Homalotheciumsericeum, Racomitriumcrispulum were collected from monitoring sites and were validated for their tolerance potential by measuring chlorophyll fluorescence signals. Amongst above species validated for tolerance, moss Racomitriumcrispulum (Hook. f. et Wils.) is inducted for monitoring program. Collected samples were air dried, then cleaned and digested. The levels of Zn, Cu, Cd and Pb have been determined in transplants of the moss Racomitriumcrispulum (Hook. f. et Wils.) from the area of Almora, Nainital and Pithoragarh of Kumaon hills. High metallic load was measured in moss harvested from locations in proximity of higher traffic density areas, which is attributed to the enhanced tourism during summer and monsoon season. In rural areas high value of Zn and, Cu attributes to their use in fertilizers. Positive significant correlations were obtained between Pb-Zn and Zn-Cu that suggest a common origin of these metals. Elemental concentration in moss Racomitriumcrispulum was in order Zn>Pb ~ Cu> Cd in summer while, same was Zn> Cu >Pb> Cd in winter season and in rain Zn> Cu >Pb> Cd that reflects atmospheric trace elemental load. Bioaccumulation ability of this moss was evaluated statistically using DMR test and cartographically presented on contour maps obtained from SURFER program. read more... read less...
Keywords: Metal Emission, Kumaon hills, moss Racomitriumcrispulum (Hook. f. etWils.), active monitoring.