Kandasamy, JK & Melville, BW 1998, 'Maximum local scour depth at bridge piers and abutments', JOURNAL OF HYDRAULIC RESEARCH, vol. 36, no. 2, pp. 183-198.
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Khalili, N & Khabbaz, MH 1998, 'A unique relationship for χ for the determination of the shear strength of unsaturated soils', Géotechnique, vol. 48, no. 5, pp. 681-687.
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Kwon, D & Vigneswaran, S 1998, 'Influence of particle size and surface charge on critical flux of crossflow microfiltration', Water Science and Technology, vol. 38, no. 4-5, pp. 481-488.
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The effect of particle size and ionic strength of the feed suspension on critical flux was studied. The critical flux was defined in two different ways (strong and mild definition). The fouling, the increase of resistance (which is the basis of the mild definition of the critical flux) was relatively sensitive to the deposition of particles of 0.46 μm on the membrane of 0.2 μm mean pore. On the other hand, the deposition of large particles of 3.2 μm to a certain value on the membrane surface of 0.2 μm mean pore did not lead to the increase in resistance. In case of 11.9 μm particles, the transmembrane pressure did not increase even with significant amount of deposition of particles. The ionic strength of suspension had significant effect on the critical flux. For an ionic strength less than 1Ã10â1.5 M, there was a decrease in the critical flux. This could be due to the dense layer of deposit which is the result of less diffuse layer thickness of particles. Above this ionic strength, a significant increase in critical flux was noticed which may be due to the aggregation of particles.
Li, H, Fane, AG, Coster, HGL & Vigneswaran, S 1998, 'Direct observation of particle deposition on the membrane surface during crossflow microfiltration', Journal of Membrane Science, vol. 149, no. 1, pp. 83-97.
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In the crossflow microfiltration of particles, a deposit cake layer tends to form on the membrane and this usually controls the performance of the filtration process. This paper presents observations of particle deposition on membrane surfaces using a non-invasive, in situ, continuous direct observation through the membrane (DOTM) technique. The particles used in the experiments were typical of microfiltration processes, yeast (mean diameter 5 μm) and latex beads (3, 6.4 and 12 μm). The filtration tests were conducted in the imposed flux mode, so that the flux could be controlled at, below, or above the âcritical fluxâ. Below the critical flux, the particle deposition was negligible; near the critical flux the particle deposition was significant; and above the critical flux, particle layers were formed on the membrane surface. Rolling of the particles was observed during the filtration of 6.4 μm latex near the critical flux whereas a flowing cake layer was observed during the filtration of 3 μm latex. The particle size distribution of the deposited particles changed with the crossflow velocity, with smaller particles deposited on the membrane at higher crossflow velocity. Comparison of the normalised flux (J/ÎP) with the membrane area coverage by the particles revealed that for filtration of latex particles âflux percentage (with respect to the clean membrane)â was marginally greater than the percentage of uncovered membrane area, whereas for filtration of yeast, the âflux percentageâ was significantly less than the uncovered area percentage due to the deposition of smaller cell debris species. This paper demonstrates that DOTM is a powerful technique for the study of fundamentals of particle deposition and interactions between the particles and the membrane.
Ngo, HH & Vigneswaran, S 1998, 'Process optimisation of a combined system of floating medium and sand filter in prawn farm effluent treatment', WATER SCIENCE AND TECHNOLOGY, vol. 38, no. 4-5, pp. 87-93.
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A treatment technology known as "a combined system of floating medium and sand filter (FMSF)" was developed and tested successfully with prawn farm effluent. This system has a remarkable techno-economical advantages. Laboratory and semi pilot-scale studies were carried out to optimise the filter bed depth, backwash method and other operating conditions. The dewatering characteristics of sludge from filter backwash was also analysed. The filter was operated at a high rate. The experimental results indicated that: (i) in case of no in-line chemical addition, the smaller ratio between floating medium and sand filter depth gave rise better filter performance. At the filtration rate of 7.5 - 20 m3/m2.h and with an in-line chemical addition, the suitable depth of floating medium varied from 400-1000 mm for a sand filter depth of 400 mm; (ii) frequent (once in every 90-120 minutes) but short duration of backwash (not more than 60 seconds) was found to be suitable. During the backwash, the water and air were sent for 30 seconds in upward direction and then followed with upflow of water for another 30 seconds. Backwash water amount comprised only 1.2-1.8% of the filtered water production. A mechanical backwash system using rotating paddles is a promising alternative for floating medium filter; and (iii) the filterability of the sludge from filter backwash was low in case of no in-line chemical addition (specific resistance, r = 9.34 1010 m/kg) but improved with in-line flocculant addition (r = 3.07 109 - 1.29 1010 m/kg).
Peiris, P, Bailey, JJ, Ngo, HH & Vigneswaran, S 1998, 'Bacterial removal from secondary sewage effluent by a combined downflow floating medium flocculator/prefilter and sand filter', INDIAN JOURNAL OF ENGINEERING AND MATERIALS SCIENCES, vol. 5, no. 4, pp. 217-222.
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semi pilot-scale study conducted with the combined downflow floating medium flocculatorperprefilter and sand filter indicated that, it is an effective filter system for removing bacteria from the secondary sewage effluent. Since the filter system can rem
Ralph, PJ 1998, 'Photosynthetic response of laboratory-cultured Halophila ovalis to thermal stress', MARINE ECOLOGY PROGRESS SERIES, vol. 171, pp. 123-130.
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Chlorophyll a fluorescence was able to rapidly detect responses of laboratory-cultured Halophila ovalis to acute changes in temperature. Six heating (27.5, 30.0, 32.5, 35.0, 37.5 and 40.0 degrees C) and 6 chilling (10.0, 12.5, 15.0, 17.5, 20.0 and 22.5 d
Ralph, PJ 1998, 'Photosynthetic responses of Halophila ovalis (R. Br.) Hook. f. to osmotic stress', JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY, vol. 227, no. 2, pp. 203-220.
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Chlorophyll fluorescence was used to monitor the onset, development and recovery from hyper- and hypo-osmotic stress effects of the seagrass, Halophila ovalis (R. Br.) Hook. f. H. ovalis was able to tolerate rapid transfer from normal (35 ppt) seawater t
Ralph, PJ & Burchett, MD 1998, 'Impact of petrochemicals on the photosynthesis of Halophila ovalis using chlorophyll fluorescence', MARINE POLLUTION BULLETIN, vol. 36, no. 6, pp. 429-436.
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Laboratory-cultured Halophila ovalis showed tolerance to petrochemical exposure up to 1% (w/v) solution of Bass Strait crude oil, an oil dispersant (Corexit 9527) and a mixture of crude oil and dispersant, Quantum yield, as measured by chlorophyll fluore
Ralph, PJ & Burchett, MD 1998, 'Photosynthetic response of Halophila ovalis to heavy metal stress', ENVIRONMENTAL POLLUTION, vol. 103, no. 1, pp. 91-101.
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This paper deals with the photosynthetic effects of a range of heavy metals on the seagrass Halophila ovalis. In this study, the photosynthetic response of laboratory-cultured II. ovalis to four heavy metals (Cu, Cd, Pb, Zn) was investigated. The results
Ralph, PJ, Gademann, R & Dennison, WC 1998, 'In situ seagrass photosynthesis measured using a submersible, pulse-amplitude modulated fluorometer', MARINE BIOLOGY, vol. 132, no. 3, pp. 367-373.
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Assessments of photosynthetic activity in marine plants can now be made in situ using a newly developed, submersible, pulse-amplitude modulated (PAM) fluorometer: Diving-PAM. PAM fluorometry provides a measure of chlorophyll a fluorescence using rapid-li
Ralph, PJ, Morrison, DA & Addison, A 1998, 'A quantitative study of the patterns of morphological variation within Hormosira banksii (Turner) Decaisne (Fucales : Phaeophyta) in south-eastern Australia', JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY, vol. 225, no. 2, pp. 285-300.
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Homzosira banksii shows a considerable degree of morphological variability throughout its range in south-eastern Australia, apparently in relation to the local habitat, and there have been several previous qualitative attempts to categorize this variatio
Sundaravadivel, M, Doeleman, JA & Vigneswaran, S 1998, 'Combined surface sewerage: a low-cost option for effective sanitation in semi-urban areas of India', Environmental Engineering and Policy, vol. 1, no. 3, pp. 181-189.
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Current prescriptions for sanitation technologies in developing countries are predominantly in the context of either large cities or rural areas. In India, however, there are a large number of small cities and towns with population in the range of 20000±100000 that account for over 50 million of the country's urban population. This paper discusses the inappropriateness (in terms of techno-economic viability and environmental desirability) of commonly recommended on-site sanitation technologies and capital intensive conventional sewage collection systems for these `semi-urban' areas. While emphasising the need for a different approach for provision of sanitation services to such cities and towns, it identifies the limitations of recent developments of non-conventional sewerage systems. Based on the field research carried out in four `semi-urban' towns in India, the paper proposes the concept of `combined surface sewerage' that can utilise existing infrastructure to a maximum to effect better sanitation at lower costs. The suggested system involves converting the existing open drains on the roadsides, as decentralized networks with simple structural modifications and covering them with concrete slabs. These decentralized networks would convey sullage, septic tank overflow and storm water run-off for appropriate low-cost treatment prior to disposal.
Zhou, JL, Fileman, TW, Evans, S, Donkin, P, Llewellyn, C, Readman, JW, Mantoura, RFC & Rowland, SJ 1998, 'Fluoranthene and pyrene in the suspended particulate matter and surface sediments of the Humber Estuary, UK', Marine Pollution Bulletin, vol. 36, no. 8, pp. 587-597.
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Zhou, JL, Huang, PL & Lin, RG 1998, 'Sorption and desorption of Cu and Cd by macroalgae and microalgae', Environmental Pollution, vol. 101, no. 1, pp. 67-75.
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