Ben-Aim, R, Vigneswaran, S, Prasanthi, H & Jegatheesan, V 1997, 'Influence of particle size and size distribution in granular bed filtration and dynamic microfiltration', Water Science and Technology, vol. 36, no. 4, pp. 207-215.
View/Download from: Publisher's site
View description>>
Panicle size and size distribution is an important parameter in solid liquid separation process especially in granular bed filtration and in dynamic microfiltration. This paper discusses their effects on the above processes from extensive experimental data obtained. In granular bed filtration, the experimental results showed that the initial efficiency follows the pattern reported by previous experimental and theoretical studies, i.e., lower efficiency for particles which fal! in the range of critical size of 1 μm. However, the particle removal during the transient stage increased with an increase in particle size for the range of sizes studied. An attempt was made to quantify these effects in granular bed filtration using semi-empirical approach. In dynamic membrane filtration also, the particle size plays a major role in the retention. However, despite the relative thickness of the membrane (compared to particle size) dynamic microfiltration appears more as a sieving process; the retention is mainly related to the largest pore size
Jegatheesan, V & Vigneswaran, S 1997, 'Interaction between organic substances and submicron particles in deep bed filtration', Separation and Purification Technology, vol. 12, no. 1, pp. 61-66.
View/Download from: Publisher's site
View description>>
NA
Jegatheesan, V & Vigneswaran, S 1997, 'The effect of concentration on the early stages of deep bed filtration of submicron particles', Water Research, vol. 31, no. 11, pp. 2910-2913.
View/Download from: Publisher's site
View description>>
The removal of mono-dispersed suspensions of 0.46 μm and 0.816 μm particles in the early stages of deep bed filtration was found be higher at a certain range of influent mass concentration. For both equal number concentrations and equal surface area concentrations of mono-dispersed suspensions of 0.46 μm and 0.816 μm particles, the removal of particles of 0.816 μm size was higher during the early stages of filtration than 0.460 μm particles, at lower concentrations. Specific surface coverage was higher for 0.816 μm particles compared to 0.460 μm particles, for influents of these mono-dispersed particles having same number concentrations. However, it was similar for influents of these mono-dispersed particle suspensions, having equal surface area concentration.
Kwon, DY, Vigneswaran, S, Ngo, HH & Shin, HS 1997, 'An enhancement of critical flux in crossflow microfiltration with a pretreatment of floating medium flocculator/prefilter', WATER SCIENCE AND TECHNOLOGY, vol. 36, no. 12, pp. 267-274.
View/Download from: Publisher's site
View description>>
In this study, use of a combined system of flocculation-microfiltration was assessed for its capability in removing solids and organics. The improvement of flux by the preflocculation was also investigated. The experimental set-up consisted of (i) Millipore flat plate microfiltration module with constant permeate withdrawal arrangement and (ii) a floating medium flocculator/filter consisting of polypropylene beads as a pretreatment. Commercial ferric chloride(FeCl3) was used for flocculation. The purpose of floating medium filter was primarily to produce filterable flocs and also to achieve partial solids and organics removal. The critical flux of kaolin clay suspension of 10 - 100mg/L was measured for membrane of pore size of 0.2m in the presence of 0 - 4mg/L of fulvic acid in the suspension without any pretreatment. The critical flux was found to decrease with the increase in kaolin clay concentration. The results also indicated that there was no significant effect of organic (fulvic acid) concentration on critical flux. The pretreatment of floating medium filter alone without flocculant addition removed 30 - 40% of solids and resulted in a significant improvement of critical flux in crossflow microfiltration. Degree of solids and organic removal and the variation in critical flux were then studied in detail for the preflocculated/filtered kaolin clay suspension in the presence of organics. The pretreatment of flocculation/prefiltration removed approximately 50% of organics while producing uniform microflocs of 13 - 16 m size. In addition, it enhanced the critical flux by 70% and resulted in 30 - 70% of the remaining organic removal in the crossflow microfiltration.
Lee, SH, Vigneswaran, S & Chung, Y 1997, 'A Detailed Investigation of Phosphorus Removal in Soil and Slag Media', Environmental Technology, vol. 18, no. 7, pp. 699-709.
View/Download from: Publisher's site
View description>>
Kinetic studies on phosphorus (P as orthophosphate) sorption onto a sandy loam soil from North Sydney, Australia, and a slag (waste products from the BHP steel industry, Australia) revealed that more than 90% of the P was adsorbed within 70 and 12 hours for the soil and slag respectively. The pH of the P solution played a critical role in the rate of P removal. Removal was at a minimum at pH 2. Dominant removal mechanism of P at pH less than 8 was physical sorption, while it was chemical precipitation at pH greater than 10. Adsorptive capacity of the slag was 225 and 53 times of that of the soil for the static and dynamic systems respectively. Breakthrough curves obtained from the column experiments are S-shaped and more spreaded with the decrease of influent P concentration. Simulated results from an equilibrium sorption model (ESM) and Freundlich isotherm constants did not always match the corresponding experimental breakthrough data. Mobility of P is restricted by the adsorbent due to its high sorption capacity of P.
Lee, SH, Vigneswaran, S & Moon, H 1997, 'Adsorption of phosphorus in saturated slag media columns', Separation and Purification Technology, vol. 12, no. 2, pp. 109-118.
View/Download from: Publisher's site
View description>>
Adsorption of phosphorus (P as phosphates) in saturated slag media (dust and cake) columns was studied to assess the slag media's capability in removing P from wastewater. Prior to the experiments, slag media were completely washed to rinse off the soluble metal ions which are generally responsible for forming insoluble precipitates. Experimental data revealed that the adsorption capacities of washed slag media are still much higher than that of a sandy roam soil. Two dynamic models were tested for simulating the adsorption behavior of phosphorus in columns packed with slag media. The model employing the intraparticle transport through surface diffusion is successful, while a simplified model based on the linear driving force approximation (LDFA) could not predict the column behavior properly at low concentrations, particularly on the cake slag.
Prasanthi, H, Vigneswaran, S & Miller, SC 1997, 'Effect of particle concentration on the entire cycle of filtration', Water Science and Technology, vol. 35, no. 8, pp. 91-102.
View/Download from: Publisher's site
View description>>
In this present study, submicron polystyrene latex beads of sizes 0.46 μm and 0.825 μm were used to study the effect of concentration on the entire cycle of filtration. Experiments were carried out at constant mass, number and surface area as influent concentrations in order to observe the variation in filtration of the two sizes of particle. At constant mass concentrations, the initial removal was found to be higher for smaller particles (0.46 um) (in the submicron range); but when the number or surface area of particles was considered, it was found to be higher for larger particles (0.825 μm). The transient stage removal was found to increase with an increase in particle size, either with constant mass, number or surface area as an influent concentration. The Vigneswaran and Chang 1986 model was used to quantify the results. The model parameters estimated using the experimental results are useful in quantifying and understanding the performance of the filter
Schreiber, U, Gademann, R, Ralph, PJ & Larkum, AWD 1997, 'Assessment of photosynthetic performance of Prochloron in Lissoclinum patella in hospite by chlorophyll fluorescence measurements', PLANT AND CELL PHYSIOLOGY, vol. 38, no. 8, pp. 945-951.
View/Download from: Publisher's site
View description>>
Two new PAM fluorometers (pulse amplitude modulated) were used in an investigation of photosynthetic performance of Prochloron resident as a symbiont in the ascidian Lissoclinum patella, growing in a coral reef of Heron Island on the Great Barrier Reef.
Vigneswaran, S, Ngo, HH & Jeyaseelan, J 1997, 'Application of non-conventional filtration technologies in pollution control', ENVIRONMENTAL MONITORING AND ASSESSMENT, vol. 44, no. 1-3, pp. 231-240.
View/Download from: Publisher's site
View description>>
Deep bed filtration is becoming increasing important in wastewater treatment particularly in tertiary treatment as stringent water quality standards are emphasized. A detailed pilot-scale filtration study conducted with secondary effluent in a sewage treatment plant indicated that tertiary filtration with prior alum flocculation is capable of producing high quality effluent, particularly an effluent with phosphorus content of less than 0.3 mg/L (Vigneswaran and Ngo, 1994). Main problem of dual media filter has been rapid headloss development thus frequent backwash requirement. To overcome this problem two independent experimental studies were conducted: one with mobile bed filtration (MBF) and the other with combined downflow floating medium flocculator/prefilter (DFF) and coarse sand filter (CSF) system. A semi-pilot scale mobile bed filtration study conducted using oxidation pond effluent indicated that MBF with contact-flocculation arrangement was good in removing COD, T-P and turbidity with practically no headloss development. Sand of 0.6-0.84 nm dia and 50 cm depth was sufficient to reduce the COD and P from 55 mg/L and 4.5 mg/L to 15 mg/L and 0.5 mg/L respectively at a filtration rate of 7.5 m3/m2.h. Another experimental study with combined DFF-CSF system indicated that the DFF with in-line flocculation addition is a good pretreatment unit to reduce the phosphate upto 80-90%. The fact that DFF resulted in uniform filterable-flocs, it can also successfully be used as a static flocculator/prefilter unit. The introduction of DFF on top of a coarse sand filter increased the filter run time and removal efficiency (more 90-95% of NH3-N and T-P removal respectively). Most importantly, the backwashing of this system was achieved with small quantity of water at low backwash indicated that the removal efficiency was also superior with this system apart from the major advantage of low operating cost.
Zhou, JL & Rowland, SJ 1997, 'Evaluation of the interactions between hydrophobic organic pollutants and suspended particles in estuarine waters', Water Research, vol. 31, no. 7, pp. 1708-1718.
View/Download from: Publisher's site
Zhou, JL, Rowland, SJ, Fauzi, R, Mantoura, C & Lane, MCG 1997, 'Desorption of tefluthrin insecticide from soil in simulated rainfall runoff systems—Kinetic studies and modelling', Water Research, vol. 31, no. 1, pp. 75-84.
View/Download from: Publisher's site
