Browsing by Author "Amarasinghe, BMWPK"

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item: Conference-Extended-Abstract
Adsorption and desorption studies of heavy metals on to coconut shell char
(Department of Chemical and Process Engineering, University of Moratuwa, 2019) Abesekara, MS; Kosvinna, KNR; Amarasinghe, BMWPK; Rathnasiri, PG
Heavy metals in wastewater can be removed by several methods including adsorption. Activated carbon (AC) is widely used, but expensive adsorbent. Since AC derived from coconut shell (CS) is a good adsorbent, coconut shell char (CSC) as well might be an effective low-cost adsorbent. It was studied the possibilities of using CSC as an adsorbent. Results showed that, CSC has 13% and 12% removal efficiencies for Zn2+ and Ni2+ from solutions of 50 mg/l. Furthermore, desorption abilities of H2SO4, NaOH, Distilled water and NaCl as desorbing agents were analysed and found H2SO4 to be the most effective desorbing agent.
item: Article-Abstract
Adsorption of residual oil from oily wastewater using natural adsorbents
Anurangi, WAJ; Amarasinghe, BMWPK; De Alwis, AAP
Pollution of water due to oil contamination is a major environmental problem. This study focuses on the removal of emulsified oil from oily wastewater. Generally emulsified oil is treated using chemicals and therefore it causes series of problems. In this study, oil adsorption capacity of thermally treated rice husk prepared by carbonizing rice husk at 600 °C for 3 hours was tested. Batch experiments were conducted to determine the optimum value of process parameters. Adsorbent dosage, initial oil concentration, solution pH and adsorbent size affect the oil removal capacity. Oil removal was measured by the percentage of COD reduction. The experiments revealed that the optimum particle size range of carbonized rice husk for oil treating was 605~m.The adsorbent to solution ratio affects the degree of oil removal and percentage COD reduction of 40 and 100 were observed with 0.5g and 109 of adsorbent dose per litre of wastewater respectively. Kinetic data tend to fit well in second order kinetics and the Langmuir isotherm best represent the adsorption of oil onto carbonised rice husk. Monolayer oil adsorption capacity of 2.24mg of oil / g of carbonised rice husk was observed.
item: Conference-Full-text
Application of mebrane separation processes to the Sri Lankan industry
(2000) Amarasinghe, BMWPK; De Silva, IMBM
Membranes and membrane based separation techniques have developed rapidly over the last two decades with a considerable technical and commercial impact. The technology is now widely used for a range of applications including water treatment, wastewater treatment, separations in the Chemical and Process industries, food and biotechnological industries and in the medical field. Micro Filtration, Ultra Filtration, Reverse Osmosis, Electro Dialysis and Dialysis are the commonly used processes. Nano Filtration, Pervaporation, Osmotic Distillation and Membrane Distillation are now becoming popular with the development of novel membranes, which withstand a wide range of operating conditions. The Membrane Separation technique is attractive due to many reasons, such as suitability of the processes for heat sensitive materials, high product quality and possibilities of recovery and recycle of valuable materials. The survey shows very few applications of Membrane Processes in Sri Lankan industries. Normal Filtration and Ion Exchange are the widely used methods for water treatment. However, the application of a technique such as Reverse Osmosis or Ultra Filtration for water treatment in medical and pharmaceutical field, in drinking water production from high salinity level water and in food and beverage industries may largely help in improving the product quality. Wastewater is commonly treated using biological treatment and chemical treatment in combination with sedimentation. Approximately, 51% of the industries have the possibility of using Membrane Separation techniques not only to treat wastewater, but also to recover or recycle valuable materials, energy and water. Pulp and paper, Textile and Diary industries are the major uses of Membrane technology for wastewater treatment. Further, the novel separation techniques such as Pervaporation and Osmotic distillation can be experimented for the manufacture of range of new products. Application of Membrane Separation processes in Sri Lankan industry will be important in anticipation of future demands for high standards and minimal environmental impact.
item: Article-Full-text
Application of membrane separation processes to the Sri Lankan Industry
Amarasinghe, BMWPK; De Silva, IMBM
Membrane separation is a relatively new technology applicable for a range of separations. The technique is attractive due to its ability to produce high quality products, suitability for processing heat sensitive materials and possibility of recovering and recycling of valuables from waste streams. Current applications of membrane separations for liquid systems in the Sri Lankan industry and possibilities for future developments were investigated. The survey shows that only 5% of the industries considered for the survey currently use membrane separations. However, 51% have the possibility of using membrane separations either for water treatment, wastewater treatment or for separations in the manufacturing processes. Normal Filtration and Ion Exchange are the widely used techniques for water treatment. Reverse Osmosis and/or Ultra Filtration can be used for purification of water for medical and pharmaceutical applications, for preparing drinking water and boiler feed water from high salinity water or seawater. Pulp and paper, Textile and Diary industries have the possibilities of using MS for wastewater treatment and recovery and recycle of valuables. However, novel techniques such as PV can be used for removal of tracers of hazardous components. Further, Pervaporation, Osmotic Distillation etc. can be experimented for the manufacture of new range of products in food and biotechnological fields and for obtaining highly purified products. Despite the relatively high capital and maintenance cost and the problems of concentration polarisation and membrane fouling application of the technique for many Sri Lankan industries will be important in anticipation of future demands of high standards and minimal environmental impact.
item: Conference-Abstract
Coir pith activated carbon for the removal of dyes from aqueous solutions
(2008) Dhanusekera, DW; Amarasinghe, BMWPK
Adsorption of methylene blue, malachite green and nylosan blue dyes onto carbonized coir pith from aqueous solutions was studied. Adsorbent was prepared by carbonizing coir pith at 700 C for l hr. Batch experiments showed that solution pH and adsorbent dose affects the adsorption capacity. The adsorption capacity was highest at solution pH 2 for nylosan blue and above pH 5 for methylene blue and malachite green. The kinetic data fits to second order model. The equilibrium data were satisfactorily fitted to Freundlich isotherm.
item: Thesis-Abstract
Coir pith activated carbon for the removal of dyes, organics and heavy metals from aqueous solutions
Dhanusekera, DW; Amarasinghe, BMWPK
Adsorption of textile dyes, organics and heavy metals onto coir pith based adsorbents from aqueous solutions were studied. Raw coir pith and thermally activated coir pith at 700°C were used as adsorbents. Batch experiments showed that both adsorbents are capable of binding appreciable amounts of impurities from aqueous solutions. Thermally activated coir pith was superior to raw coir pith for dyes and phenol removal. Heavy metal adsorption capacities for both adsorbents were similar. Batch adsorption experiments were conducted in detail for dye removal to determine the factors affecting adsorption and kinetics of the process. Fixed bed column experiments were performed to study practical applicability and breakthrough curves were obtained. The maximum adsorption was observed at solution pH values between 5-9 for Methylene blue and Malachite green. Solution pH value of 2 showed maximum adsorption for Nylosan blue. The adsorbent to solution ratio and the dye concentration in the solution affect the degree of dye removal. The equilibrium data were satisfactorily fitted to Freundlich isotherm. The kinetic data fits to pseudo second order model and kinetic parameters were calculated. Column experiments showed 'S' shaped breakthrough curves and the results followed Bed Depth Service Time (BDST) model. Fixed bed adsorption capacities were lower compared to batch experiments.
item: SRC-Report
Coir pith activated carbon for the removal of organics and dyes from aqueous solutions
(2008) Amarasinghe, BMWPK
Drinking water sources in developing and underdeveloped countries are facing serious threat from contamination problems due to both man-made industrial and agricultural activities and natural sources such as minerals. In many developing countries ground water is used for drinking purposes and it is pollutes with toxic anions, heavy metals, organic compounds and dyes due to effluent from industries. These unwanted chemicals cause health problems, when they exceed the tolerance limits in water. The removal of pollutants from wastewater can be carried out by Coagulation/Flocculation, Ozonation, Adsorption or membrane separation. Most of these methods suffer from, drawbacks such as high capital and operational cost and there are problems in disposal of sludge. The use of activated carbons to remove tracer pollutants from water is widely extended because of their high surface area, microporous character and the chemical nature of their surface.
item: Article-Abstract
Drying kinetics of black pepper dried in a spouted bed dryer with or without draft tubes
Jayatunga, GK; Amarasinghe, BMWPK
Drying of black pepper has been studied in a lab scale spouted bed dryer. Experiments were carried out in a spouted bed dryer cither with or without internal devices. The two different internal devices of the dryer are namely non porous draft tube and porous draft tube. Effect of drying temperature type of drat tube, diameter of draft tube and stagnant bed height wjthout degrading the quality of the material. periods, without existence of the constant rate period.
item: Article-Full-text
Drying kinetics, quality and moisture diffusivity of spouted bed dried Sri Lankan black pepper
(Elsevier, 2019) Jayatunga, GK; Amarasinghe, BMWPK
Drying of black pepper has been investigated in a lab-scale conventional spouted bed dryer. Spouting behavior of black pepper was studied, and the minimum spouting velocity was determined. The effect of operational conditions; drying temperature, air velocity and stagnant bed height on drying kinetics was analysed. The higher values of drying rates were achieved when the dryer was operated with moderately high temperatures, high airflow rates and shallow beds. The results show an increase in effective moisture diffusivity with increasing drying temperature. The highest effective moisture diffusivity of 2.03×10-10m2/s was obtained at a hot air temperature of 75 °C. Extraction and analysis of essential oil from dried black pepper showed that the variation of oil yield with drying temperature is significant for drying temperatures from 45 °C to 75°C 65 °C was selected as the best drying temperature for black pepper drying in the conventional spouted bed dryer.
item: Article-Abstract
Effect of configuration of non-porous draft tubes drying kinetics of black pepper in a spouted bed dryer
Jayatunga, GK; Amarasinghe, BMWPK
Drying of black pepper has been studied in a lab scale spouted bed dryer. Experiments were carried out m a spouted bed dryer with non porous draft tubes and without non porous draft tubes. The highest drying rate was achieved when biack pepper was dried without draft tubes. Comparison of the minimum spouting velocities with draft tubes and without draft tubes reveals that the non porous draft tube fitted spouted bed had the lowest value. Further influence of the geometricfactors of non porous draft tubes such as height, diameter and height of entrainment zone on the drying kinetics of black pepper was analysed. Experimental data showed that increase in draft tube diameter, height and entrainment height increases the rate of moisture removal and reduces the drying time.
item: SRC-Report
Effect of hot air temperature on high moist paddy drying in a conical spouted bed
(2019) Maduwanthi, MKC; Jayatunga, GK; Amarasinghe, BMWPK
Parboiled paddy of two varieties namely Samba and Nadu were dried in a lab scale spouted bed dryer. Spouting behaviour, drying kinetics and heat and mass transfer characteristics of parboiled paddy were investigated. The minimum spouting velocity was determined for parboiled paddy of two varieties for three different bed heights. Drying experiments were carried out to analyse the effect of drying temperature and air velocity on drying kinetics, moisture diffusivity and heat transfer coefficient. Results revealed that spouted bed drying operation with elevated temperatures show higher drying rates. The spouted bed dryer spouting at different air velocities had almost similar drying rates at stable spouting state for a selected drying temperature and bed height.
item: Article-Full-text
Effect of method of stabilization on aqueous extraction of rice bran oil
(Institution of Chemical Engineers, 2009) Amarasinghe, BMWPK; Kumarasiri, MPK; Gangodavilage, NC
Rice bran oil is widely used in pharmaceutical, food and chemical industries due to its unique properties and high medicinal value. In this study aqueous extraction of rice bran oil from rice bran available in Sri Lanka, was studied. Key factors controlling the extraction and optimal operating conditions were identified. Several methods of bran stabilization were tested and the results were analyzed. The yield and quality of aqueous extracted oil was compared with hexane extracted oil. Aqueous extraction experiments were conducted in laboratory scale mixer–settler unit. Steaming, hot air drying, chemical stabilization and refrigeration better controls the lipase activity compared to solar drying. Steaming is the most effective stabilization technique. The extraction capacity was highest at solution pH range 10–12. Higher oil yield was observed at higher operating temperatures (60–80 °C). Kinetic studies revealed that extraction was fast with 95% or more of the extraction occurring within first 10–15 min of contact time. Parboiling of paddy increases the oil yield. Highest oil yield of 161 and 131 mg/g were observed for aqueous extraction of parboiled bran and raw rice bran respectively. The aqueous extracted oil was low in free fatty acid content and color compared to hexane extracted rice bran oil and other commonly used oils. Major lipid species in rice bran oil were oleic, linoleic and palmitic.
item: Conference-Abstract
Effect of method of treatment of rice husk on adsorption of textile dyes from aqueous solutions
Amarasinghe, BMWPK; Jayathunga, GK
Adsorption of textile dyes onto rice husk based adsorbents was studied. Batch experiments were conducted to determine the effect of method of treatment of rice' husk on adsorption of Basic Green 4 and Acid Blue 80 from aqueous solutions. Rice husk (RH) obtained from ten varieties of paddy were tested. Raw rice husk, chemically or thermally treated rice husk were tested for adsorption. The maximum adsorption was observed at solution pH values above 6 for Basic Green 4 and below 3 for Acid blue 80. .The adsorbent to solution ratio, solution dye concentration and adsorbent particle size affect the degree of dye removal. Carbonizing at 700°C for I hr was observed as the optimum condition for thermal activation. Sodium hydroxide treated RH and carbonized RH showed high adsorption capacities compared to acid treated RH, oxidized RH and raw RH. Basic green 4 dye showed high adsorption compared to acid blue 80 for all the varieties of RH based adsorbents tested. RH based adsorbents were compared with the commercial activated carbon. Adsorption capacities for Raw RH, NaOH treated RH, Thermally treated RH and Granular Activated Carbon were 5.8, 7.5, 7.5 and 7.4 for Basic green 4 and 3.4, 6.1,6.5 and 6.5 mg of dye/g of adsorbent for Acid Blue 80 respectively. Kinetic data were fitted to the Pseudo second order model and initial adsorption rates and rate constants were determined.
item: Article-Abstract
Extraction and degradation of chlorophyll a and b from AlternantheraSessilis
Jinasena, MAM; Amarasinghe, ADUS; Amarasinghe, BMWPK; Prashantha, MAB
The use of Alternanthera sessilis, which is commonly known as Mukunuwenna in Sri Lanka as a source of chlorophyll was examined. The extraction of chlorophyll was carried out using buffered 80 % (v/v) aqueous acetone. The optimum operating conditions such as solvent to A. sessilis ratio, extraction temperature and extraction time were found to be 5 mL/g, 50 °C and 45 minutes, respectively. The yield of chlorophyll a and chlorophyll b under these optimum operating conditions were 659 and 261 μg/g of A. sessilis, respectively. Mechanical grinding of A. sessilis gave a higher yield as compared to blanching and drying. Refrigeration at 15 °C was found to be ideal for storing of fresh A. sessilis up to 3 days without a considerable loss of chlorophyll content. Chlorophyll extraction could be modelled successfully using basic mass transfer equations up to 30 °C. It failed above this temperature due to the degradation effect. Kinetic study on the degradation of chlorophyll extracted from A. sessilis confirmed first order reaction model and the effect of temperature on the rate constant was also adequately modelled by the Arrhenius equation.
item: Conference-Extended-Abstract
Extraction of chlorophyll from 'mukunuwenna'
(2006) Dissanayake, DMMB; Amarasinghe, ADUS; Amarasinghe, BMWPK
Chlorophyll is the green colouring matter found in many plants formed in the chloroplast of their cells usually under the influence of sunlight and is necessary for the process of photosynthesis. Amongst the main types of chlorophyll exist in natural plants; chlorophyll a and chlorophyll b are very important. Chlorophyll and chlorophyll derivatives are used in the industry as a stable, non-toxic, physiologically harmless colorant of foods, cosmetics and medicines. Chlorophyll with 0.1% or less metal can be used as gasoline additive and has a definite antiknock effect. Chlorophyll accelerates the vulcanization of rubber [1]. Furthermore the anti-mutagenic and anti-carcinogenic activities of chlorophyll have been proved and hence some studies are being carried out to use it in medicines [2].
item: Thesis-Abstract
Extraction of rice bran oil using aqueous media
Kumarasiri, MPM; Amarasinghe, BMWPK
Rice bran oil is widely used in pharmaceutical, food and chemical industries due to its unique properties and high medicinal value. In this study extraction of rice bran oil from rice bran available in Sri Lanka, using aqueous media has been studied and key factors controlling the extraction and optimal operating conditions were identified. Several methods of bran stabilization were tested and the results were analyzed. The yield and quality of aqueous extracted oil was compared with hexane extracted oil. Aqueous extraction experiments were conducted in laboratory scale mixer-settler unit. Steaming, hot air drying, chemical stabilization and refrigeration control the lipase activity. Steaming is the most effective stabilization technique. The extraction capacity was highest at solution pH range 10 to 12. Higher oil yield was observed at higher operating temperatures (60°C - 80°C). Kinetic studies revealed that extraction was fast with 95 % or more of the extraction occurring within first 10 to 15 min of contact time. Highest oil yield of 161 mg! g and 131 mg! g were observed for aqueous extraction for par boiled bran and raw rice bran respectively. The quality of the aqueous extracted oil was compared with that of hexane extracted oil and it was found low in free fatty acid content. Iodine value and saponification value was similar to hexane-extracted oil, but the peroxide value was higher. Furthermore, the colour of aqueous-extracted oil was paler than solvent-extracted oil
item: Article-Abstract
Fixed bed adsorption column studies for the removal of aqueous phenol from activated carbon prepared from sugarcane bagassa
(2015-08-18) Karunarathne, HDSS; Amarasinghe, BMWPK
Fixed bed adsorption has become a frequently used industrial application in wastewater treatment processes. Various low cost adsorbents have been studied for their applicability in treatment of different types of effluents. In this study, the potential of activated carbon derived from sugarcane bagasse was studied for the removal of aqueous phenol in a fixed column. Sugarcane bagasse was thermally activated under 600 °C in absence of air. A series of batch experiments were performed in order to identify the appropriate adsorption isotherm. Both Langmuir and Freundlich equilibrium isotherms were analyzed according to the experiment data and related parameters were estimated. Results revealed that the Langmuir isotherm provides the best fit with experimental data. Fixed bed experiments were performed and, breakthrough curves were drawn by varying activated carbon bed height. Accordingly the ideal breakthrough curves (IBC) were prepared and bed capacity (BC), length of the unused bed (LUB), the time required for full bed exhaustion at infinite rapid adsorption TS and the breakthrough times Tb were calculated for each scenarios.
item: Article-Full-text
Fixed bed adsorption column studies for the removal of aqueous phenol from activated carbon prepared from sugarcane bagasse
(2014-06-26) Karunarathne, HDSS; Amarasinghe, BMWPK
Fixed bed adsorption has become a frequently used industrial application in wastewater treatment processes. Various low cost adsorbents have been studied for their applicability in treatment of different types of effluents. In this study, the potential of activated carbon derived from sugarcane bagasse was studied for the removal of aqueous phenol in a fixed column. Sugarcane bagasse was thermally activated under 600 0C in absence of air. A series of batch experiments were performed in order to identify the appropriate adsorption isotherm. Both Langmuir and Freundlich equilibrium isotherms were analyzed according to the experiment data and related parameters were estimated. Results revealed that the Langmuir isotherm provides the best fit with experimental data. Fixed bed experiments were performed and, breakthrough curves were drawn by varying activated carbon bed height. Accordingly the ideal breakthrough curves (IBC) were prepared and bed capacity (BC), length of the unused bed (LUB), the time required for full bed exhaustion at infinite rapid adsorption TS and the breakthrough times Tb were calculated for each scenarios. Â© 2013 The Authors. Published by Elsevier B.V.
item: Conference-Full-text
Heat transfer analysis during chili drying in a packed bed dryer
(Department of Chemical and Process Engineering, University of Moratuwa, 2024-06-27) Rajapakshe, M; Premanath, MK; Jayatunga, GK; Amarasinghe, BMWPK; Subasinghe, T
item: Article-Full-text
Industrial pollution reduction programme : waste minimization project at DCSL Seeduwa
Amarasinghe, BMWPK; Fonseka, PNP
Distilleries Corporation of Sri Lanka (DCSL) at Seeduwa produces various brands of Alcohol from toddy such as; a) Extra special arrack - 33.5% vol alcohol, 6 month maturity b) Blue label arrack - 33.5 vol% alcohol, 6-12 month maturity c) VSOA - 36.8 vol% alcohol, 2-3 years maturity d) Double Distilled alcohol - 36.8 vol% alcohol, 2-3 years e) Tappers arrack - 33.5 vol% alcohol, 1 year maturity Approximately 120 hi of abs. Alcohol is produced per day. The plant has a capacity of processing 6.62 m3 of toddy per hr. The objective of the work is to Analyse the process, Identify Waste Minimization options, Suggest suitable waste minimization solutions, Evaluate technical feasibility, viability and environmental aspects and Implement waste minimization options