DOBLIN, MA & CLAYTON, MN 1995, 'EFFECTS OF SECONDARILY TREATED SEWAGE EFFLUENT ON THE EARLY LIFE-HISTORY STAGES OF 2 SPECIES OF BROWN MACROALGAE - HORMOSIRA-BANKSII AND DURVILLAEA-POTATORUM', MARINE BIOLOGY, vol. 122, no. 4, pp. 689-698.
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Sewage effluent has a deleterious effect on the early life-history stages of Hosmosira banksii (Turner) Decaisne and Durvillaea potatorum (Labillardiere) Areschoug. High concentrations of sewage effluent (28 and 40% in seawater) inhibit zygote germinatio
NGO, HH & VIGNESWARAN, S 1995, 'APPLICATION OF FLOATING MEDIUM FILTER IN WATER AND WASTE-WATER TREATMENT WITH CONTACT-FLOCCULATION FILTRATION ARRANGEMENT', WATER RESEARCH, vol. 29, no. 9, pp. 2211-2213.
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Conventional granular filtration, although successfully used in water treatment and tertiary wastewater treatment, suffers from some disadvantages such as limited retention capacity and high energy requirement for backwashing. Use of floating filter medium overcomes these shortcomings especially when direct filters are used in the treatment plants. A laboratory-scale study carried out indicated that the floating medium filter with downflow direct filter arrangement was a good pretreatment unit to reduce the pollutant load in rapid filters used as polishing filter units. Due to its ability to form uniform micro-flocs of the order of 26â40 μm throughout the filter run, the floating medium filter can serve as an excellent static flocculator.
NGO, HH, VIGNESWARAN, S & DHARMAPPA, HB 1995, 'OPTIMIZATION OF DIRECT-FILTRATION - EXPERIMENTS AND MATHEMATICAL-MODELS', ENVIRONMENTAL TECHNOLOGY, vol. 16, no. 1, pp. 55-63.
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A laboratory-scale set-up consisting of helicoidal flocculator and rapid sand filter was used to study the implication of flocs in direct filtration for optimizing the design parameters. Two different methods, one using a flocculation and filtration mathematical model and other using Ives' filterability number were used to optimize the direct filtration. The results indicated that (i) there is an optimum range of floc size which resulted in prolonged filter run, (ii) alum dose played an important role in floc size and density, (iii) a good compromise between velocity gradient and flocculation time is essential in optimizing the direct filtration performance, and (iv) the optimum filter depth increased with higher filtration rate. The simulation results indicated that a floc size of 62 µm was found to be optimum for direct filtration which corresponded to 2.5 minutes of flocculation time at the velocity gradient values of 26.5 s-1. This optimum value shifted with filter medium size, depth and filtration velocity. On the other hand, Ives' filterability number indicated that a floc size of 57-76 µm was found to be optimum which corresponded to 4.8 - 7.2 minutes of flocculation time and at a velocity gradient values of 33.6 - 79.6 s-1. These methods will help in optimizing the design parameters of direct filtration in a rational manner using minimum number of experiments with the specific raw water and chemicals.
RALPH, PJ & BURCHETT, MD 1995, 'PHOTOSYNTHETIC RESPONSES OF THE SEAGRASS HALOPHILA-OVALIS (R BR) HOOK F TO HIGH IRRADIANCE STRESS, USING CHLOROPHYLL-A FLUORESCENCE', AQUATIC BOTANY, vol. 51, no. 1-2, pp. 55-66.
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With the increasing threat of destruction to diminishing seagrass resources, there is a need for an accurate stress monitoring procedure to be developed for species of this community. In this study chlorophyll a fluorescence (20 degrees C) was used to mo
Vigneswaran, S, Ngo, HH, Maheswaran, S, Ostarcevis, E & Potter, A 1995, 'Improved phosphorus and bacterial removal in sewage treatment plants: A pilot-scale study', Water Treatment, vol. 10, no. 1, pp. 75-80.
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Studies have shown, superior removal of phosphorus (up to the level of less than 0.03 mg/L in the treatment plant effluent) is essential to the improvement of water quality of Hawkesbury-Nepean River in New South Wales, Australia. But the chemical precipitation presently adopted in the secondary treatment step can only decrease phosphorus level to about 1 mg/L. A detailed pilot-scale filtration study conducted with secondary effluent in a sewage treatment plant indicated that tertiary filtration with a prior alum flocculation is essential in achieving superior B removal. The best results were obtained with sand (ES = 0.85-0.95; U = 1.25-1.50 mm) as filter medium and 4.4 min of preflocculation. Alum at 40 mg/L was found to be the most suitable chemical. Dual media filter also produced comparable effluent quality (although slightly inferior) while leading to longer filter runs.
Khalili, N & Khabbaz, MH 1970, 'On the theory of three-dimensional consolidation in unsaturated soils', UNSATURATED SOILS, VOLS 1 AND 2, 1st International Conference on Unsaturated Soils (UNSAT 95), A A BALKEMA, PARIS, FRANCE, pp. 745-750.
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A more complete and unified treatment of the theory of three-dimensional unsaturated consolidation is presented. The governing differential equations based on the equations of equilibrium, the effective stress concept, Darcyâs law, Fickâs law and the conservation of fluid mass are derived.
