Browsing by Author "De Alwis, A"

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item: Thesis-Full-text
Ambient air shed quality management with new coal power plant installation
Kumarasinghe, KAN; De Alwis, A
Average growth rate of electricity demand over last 15 years in Sri Lanka is about 6.5 % per annum. Energy demand in the country was mainly met by hydropower up to the year 1999, and with time thermal generation has become prominent.According to generation expansion planning study – Base case (2013 – 2032), coal is expected to dominate the thermal power sector consumption (75.7 % share) for the next decades in Sri Lanka. During the planning stage of a coal power plant, proper offset provisions should be implemented in order to minimize air shed degradation by achieving relevant emission standards stipulated in regulations. Different factors that influence on ambient air quality degradation should be investigated before the power plant comes fully on stream. Since coal is not considered as a cleaner fuel, health risk is always linked with its hazardous emissions. This assessment was carried out in order to investigate the impacts from three criteria pollutants, (SO2, NOx and PM) emitted from proposed 1200MW coal power plant in Sampoor. Three different scenarios were considered for the development of proposed power plant and four case studies to investigate different conditions under each scenario. Air Dispersion Modeling (AERMOD) was used to predict the ground level concentration within 20 km radius of the emission source. The results from the modeling assessment were used to identify the exposure assessment and then acute health risk impact was identified through dose response measures. The study shows that high efficient coal power plant can be satisfactorily employed in a place where degraded air quality is already prevailed and also when considering ground level ambient air quality concentrations, it is more favorable to install the coal power plants with less number of units having higher capacity. The results show that non carcinogenic human health impact was not identified from the population cluster locations in the vicinity to the power plant. Based on the assessment most preferred option for development of the proposed power plant with required mitigation measures was identified.
item: Thesis-Full-text
Analysis and development of high rate composting system using municipal solid waste in Sri Lanka
Manipura, WMJASB; De Alwis, A; Pilapitiya, S; Pathinathar, S
Municipal solid waste has become a major problem in every country in terms of public health and environmental damage. As a developing country, Sri Lanka too faces the same challenge not only by public health and environmental damage, but also in finding an affordable yet effective technology, which is socially and economically acceptable. Municipal Solid Waste (MSW) is qualitatively heterogeneous. Therefore, it is difficult to find a unique solution for proper treatment. I.e. The solution is always an integrated one, which consists of sorting, biological/thermal/chemical treatment, recycling and land filling. However quantification and characterization of solid waste in a given area are important factors prior to selecting suitable technology. Therefore, it is required to find waste quantity, composition, density, moisture content, annual rate of waste generation and calorific value of waste etc in a given area. In Sri Lanka, moisture content and organic fraction are reasonably high and lack of high thermal value materials in solid waste stream, have lead to an overall low calorific value of MSW. The general practice for handling the MSW is low rate compo sting systems. Most have been failed due to poor process management, lack of knowledge of proper operation (feedstock formulation, process control, end point indicators), poor product quality, long lead-time, weaker community participation and lack of public awareness. In all systems existing at present bad odor and leachate are unsolved issues. These systems have largely been controlled by default rather than by design. Thus, losing the public confidence on composting is inevitable. Properly engineered composting systems require to monitor and control of key parameters such as aeration, C/N ratio of feedstock, pile temperature, moisture content and particle size. The broad objectives of the research were, a detailed review of solid waste management practices in Sri Lanka and process of compo sting, Identification of composting strategies & evaluation of systems, and design of a high rate in-vessel composting system. During the design, it was considered to maintain the optimum environmental conditions for higher rate of decomposition by microbial activities, aeration demands, and required moisture content throughout the process. The main component of the model is a rotating drum reactor, which is operated under the thermophilic temperature conditions. The rate of decomposition at thermophilic temperatures is much higher (low residence time) than the mesophilic temperatures. A shredder could be used for size reduction of incoming feed in order to determine the optimum particle size. As source separation is very poor in Sri Lanka, this research addresses the possibility of using a semi-mechanized waste segregation device at the secondary stage. Special care was taken to control the odor and leachate of the system. On the other hand, the confidence on .low rate windrow / static pile compo sting among the people have been lost due to the process mismanagement. Therefore, the design offers to have an energy optimized semi mechanized system in which minimum labor contact with the waste occurs. The reactor is operated by a feedback control system, in which real-time monitoring of critical parameters are done. Based on the existing value and the set point (optimum value for each parameter: moisture and aeration), the control action is taken. Further, intermittent rotation of the reactor facilitates the proper temperature distribution inside, particle size reduction and uniform porosity throughout the mixture while reducing the energy consumption faced by the continuous operated system. Sensor setup at different heights of the reactor monitors the temperature and moisture content along the axis of the system. It has been observed that moisture is the limiting factor, when the temperature feedback control system is used in the composting. However, real-time monitoring of the moisture content avoids this difficulty. Further, weak pathogen inactivation is a major drawback found in most of the manually turned systems. Intermittent rotation and temperature feedback control system ensure the proper temperature distribution across the reactor and mixes the matrix properly in order to subject to uniform temperature throughout the mass. The modular basis helps for easy movement and it consumes less space compared to the windrow system. According to the national database on solid waste in Sri Lanka, 88% of Local Authorities collects less than 10 Tons per day. This shows the possibility of use of modular units in areas, where space is limited. Close monitoring of the critical parameters of the system helps to maintain optimal decomposition rates while ensuring consisted product quality during the decomposition. Since organic farming is a growing area in export-oriented agriculture (Tea, vegetables) in our country, this research helps to produce a good soil conditioner (with consistent finished product) using MSW while solving a major environmental problem. Tea plantation companies put special attention to identify the requirements of quality standards for the production of famous 'Ceylon Tea'. Hence as a part of this work, analysis of the critical parameters of the compost, manufactured by different organizations in the country that use solid waste as the substrate was carried out. It is important to match compo sting quality and the particular plantation requirement to develop a sustainable market for the compost produced using MSW. This has been particularly lacking in the Sri Lankan market with the compost producer hoping to realize a good price for anything that is produced; an expectation that had not been realized.
item: Thesis-Abstract
Bio methanation and composting for managing sugar processing waste
Ariyaratne, WKH; De Alwis, A; Gunasekera, M; Hettiarchchi, M
In Sri Lanka, two integrated sugar cane based sugar plants cum distilleries are running with satisfying around 12% sugar requirement of the country. As the other countries, we are also facing the waste disposal problem of sugar and distillery waste. At present, few of the wastes generated in the plant are being used by the factory it self as material or energy source, but still some wastes are released to the environment with out any proper treatment. The major objective of this research is to find out the potential of in vessel high rate composting of sugar press mud along with maximum contribution of spent wash and other wastes generated in an integrated sugar plant cum distillery. The major draw back of high rate composting is high energy requirement and it is expected to satisfy through biomethanation of spent wash. A series of experiments were carried out in a 210 L compost unit to determine possible feedstock composition for in vessel composting. By in-vessel high-rate method, the compo sting period could be dramatically brought down to about 12 Press mud: spent wash ratio of 18:1 (spent wash added initially) appeared to be best composition for in vessel high rate composting. However, 9: 1 ratio could be achieved if spent wash is applied after reaching the highest temperature in the However 183 T of annual nitrogen supply could be achieved through production compost. Also a senes of experiments were carried out to observe biornefhanation potential of distillery spent wash. All the experiments were carried out in specially designed laboratory scale apparatus. It was calculated that energy .needed to achieve above rates of composting could be easily achieved by simple, single-stage batch type bio-rnethanation without mixing. 65-70% COD reduction and 9.4 m3/m3 feed to specific gas production could be obtained, by this method with optimum conditions
item: Article-Full-text
Biogas - a review of Sri Lanka's performance with a renewable energy technology
(Elsevier, 2002) De Alwis, A
Sri Lanka's experience with a renewable energy technology, namely biogas, is reviewed in this paper. The discussion looks at biogas technology as adapted and utilized in Sri Lanka. It is shown that the technology has received attention from the initial days of the energy crisis in 1973, including a “Colombo Declaration” calling for regional development of biogas technology. However, there has been limited popularization and application of biogas in the country. Biogas systems have been promoted for their capability to provide lighting and as a cooking gas, both energy needs, and then as a way to produce bio-fertilizer from solid waste streams for agricultural needs. Biogas systems, used and in use, are identified and reasons for failures are summarized. The ways in which the process has been promoted are also considered and it is seen that the container approach has been given more weightage than the process itself. The process taking place during biogasification has been largely ignored and taken for granted in the dissemination of the technology. Also shown is the fact that promises made in trying to get the technology accepted are impossible to fulfil when a simple analysis is performed. This is shown with respect to cattle-owning families of Sri Lanka. The paper concludes with the recent developments in attempts to introduce biogas systems in the country. From a developing country perspective the paper argues that the ways in which this technology has been promoted are unacceptable. Biogas utilization can take place professionally if a systematic approach is adopted and if the advocates look at the technology in an objective manner. Images such as “Biogas is from wastes” and “This energy is for rurals” need to be discarded, the paper argues.
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Chemical leasing and nanotechnology for agriculture sector
Edrisinghe, LGLM; De Alwis, A; Bandara, JMRS
During recent years the service-oriented business approach of Chemical Leasing has been researched and implemented at various companies of different industry sectors around the globe. The novel business model promotes sustainable use of chemicals through linking the supplier’s sales income to chemical performance. Experiences show that key elements of a successful application of chemical leasing are know-how exchange and process optimization. Excessive use of chemicals in the agriculture sector emphasizes the potential in application of chemical leasing in the country. Nanotechnology is a major emerging technology, which can revolutionize the agriculture sector by employing special nanoscale properties of matter. It can be applied to agrochemicals and fertilizer in order to improve quality and safety, as well as reduce environmental and health effects. Sri Lanka as a country based on an agricultural economy has the potential to use these new technologies for its socio- economical development. Global need of ecologically sustainable farming system, increasing global nano food market, growing demand for safe and healthy food, threat from changing weather conditions and increasing risk of diseases to plants highlight the opportunities. The proposed model performs as a national frame work for management of agrochemicals in the country. The research “chemical leasing & nanotechnology in agriculture sector” introduces the use of Blue Ocean strategy to enter the sustainable farming system.
item: Thesis-Abstract
Computer Modeling industrial emissions
Illangasinghe, NK; De Alwis, A; Gunasekera, MY
Air being an important part of the environment is always required to be in a satisfactory condition for the proper functioning of the entire eco system. Air quality is being affected adversely due to several reasons such as increasing number of industries without having proper emission handling systems and increasing number of vehicles. Many industrial stacks observed in Sri Lanka today are not constructed according to the proper stack design requirements. The quality of stack emissions or the dispersion of pollutants from a specific stack is seldom analyzed mainly because of the high costs involved. Even analysis is done on the dispersion from a specific stack it is difficult to get good representative results because the meteorological conditions vary frequently. In this study a stack emission dispersion model named AUSPLUME which is developed by the Victorian Environmental Protection Authority and recommended by several organizations for 'regulatory purpose was studied. This work mainly looks at the following: 1. The applicability of the model in the Environmental Impact Assessment (EIA) 11. Model emissions from the stacks at Holcim Lanka cement plant at Puttlam with the use of AUSPLUME before and after installing a new dust handling system The purpose of the EIA is to predict and identify potentially significant environmental impacts of development projects and to suggest mitigation measures to minimize the negative impacts and maximize the positive impacts. Main stages in the EIA process are, 1. Screening ( find out whether an EIA is required) 11. Scoping ( identification of main issues) lll. Collection and analysis of information IV. Public involvement v. Communicating the findings In the process of analyzing the information AUSPLUME can be used. With available information about the stack, emissions and the meteorological data of the area of concern, the model can predict the concentrations of selected constituents at ground level or elevated levels in the down wind direction. The areas of worst impact, limit of the buffer zone, effects to the high rise buildings or effects to the selected areas of important like high bio diversity, archeology, and residences can be identified using the results obtained with AUSPLUME. For the analysis of the stack emission dispersion from the Holcim Lanka cement plant at Puttlam, the meteorological data obtained at the Palavi weather monitoring station of the Meteorological Department were used. There are two similar stacks at the factory which are placed close by and therefore both of them were considered as a single point source with an equivalent diameter. The area was considered to be a flat terrain since there were no disturbances in the vicinity. The analysis results on the dispersion of particulate matter, NOz and SOz emissions from the stack were compared with ambient air quantity standards for Sri Lanka and European Guideline values which were established by considering human health hazards other than carcinogenity. Certain values were found to be above the limits and the rest below the limit. Anyway in this analysis raw emission data were used and in the real life the raw emissions are mixed with clean air before released to the atmosphere. Therefore due to the dilution the real values can be expected to be much lower. Predicted values were compared with field measurement values available and with predicted values from SCREEN3 model. The results obtained can be used for decision making purposes with a good understanding about their inaccuracy.
item: Thesis-Abstract
Conversion of dye sludge to RDF
(2014-08-08) Rubasingha, SN; De Alwis, A; Wijekoon, S
In Sri Lanka the Dye sludge production from textile industry is large. The large amount of produced dye sludge needs to be properly managed otherwise it will cause lot of environmental problems. Currently textile industries in Sri Lanka use the landfilling method to dispose dye sludge. Because of the landfilling method lot of environmental problems are surfaced, such as emission of toxic gases, ground water pollution and bad odour in environment. This study investigates the feasibility of using the waste dye sludge as fuel called Refused Derived Fuel (RDF). The method is used to produce RDF from dye sludge is mix dye sludge with other wastes available in textile industry. Other waste types which are supposed to use mix with dye sludge are fabrics, paper waste and saw dust. The mixing of waste dye sludge with other wastes in different compositions are investigated. Also different quality parameters of waste sludge and mixtures (after mixing with other wastes) are analysed.Calorifc values of waste sludge with different moisture content and mixtures with different waste fractions ,ash content,sulfer content,chlorine content,heavy metal content are main characterization parameters. Results analysed and it revealed that by mixing dye sludge with other wastes calorific value can be increased from 6 MJ/Kg to 22 MJ/Kg. By considering availability of the waste types during the last year most commonly used mixture composition is selected. We propose that waste dye sludge mixed with other waste types in textile industry is a suitable and effective alternative energy source in Sri Lanka
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A Critical analysis of environmental taxation for Sri Lanka in a sustainomic framework
(2015-09-17) Chathurika, GDPN; De Alwis, A
Sustainomics is to transform ongoing activities and planning of future developments more sustainable; balancing its key elements society, economy and the environment. Sri Lanka introduced environmental taxes by the Environmental Conservation Levy Act No. 26 of 2008 as another strategy to reach the sustainable development. A cess on polythene and plastic raw materials has been imposed previous to the said Act. The present study evaluates the effectiveness of the cess as a lesson for future taxation. When it was assumed that there were no other taxes imposed on importation of polythene and plastic raw materials, there was no a significant direct impact of the cess on the amount of polythene plastic raw materials imported into the country during the period from January 2008 to March 2009. The percentage of polythene and plastic waste amount recycled was 4.27% in 2008 and it was 3.05 % in 2007 compared to the total importation in respective years. The study recommends introducing a tax to be imposed on polythene bags which is a tax to the consumer as it has been successful in some other countries. Another area studied was on the life cycle of mobile phones within Sri Lanka imported from 2006 to 2010. There is a rapid growth in use of mobile phones in Sri Lanka. The estimated stock of waste mobile phones generated in 2011 is 598 MT. The estimated value of the expected stock of recoverable metals from waste mobile phones in 2011 is Rs. 1094.695 million. Expected Gold stock has the highest value of Rs. 811 million. Calculated amount of waste mobile phones that would be generated in year 2012 is 284 MT and 342 MT in 2013, if the lifespan of a mobile phone is 5 years. Therefore the study recommends carrying out a feasibility study considering environmental, technical, economic as well as social factors to establish a material recovery plant in Sri Lanka. The study finally proposes two options for disbursement of the fund generated by the taxes imposed under the Environmental Conservation Levy Act. It can be recommended a methodology based on a weighting system according to the importance of each sector that will utilize total amount of revenue for environmental management in the country.
item: Conference-Extended-Abstract
Design of in-vessel continuous composting process for handling sugar industrial waste
(2006) Ariyaratne, H; Ishiyama, EM; De Alwis, A; Hettiarachchi, M; Gunasekera, MY
During the past decades Sri Lanka has not satisfactorily processed agricultural products which were a major burden to the national economy. Realizing the importance of value addition, the relevant processing of agricultural products have magnified significantly, resulting in a parallel generation of processed agricultural wastes. The major focus of this paper is the introduction of a high rate in-vessel composting process for handling one of the process wastes in the sugar industry.
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Developing wound dressing from bacterial cellulose
(2015-02-22) Gamage, NS; Ismail, M; Chinniah, TR; De Alwis, A
Developing Wound Dressing from Bacterial Cellulose Cellulose produced by bacterium Acetobacter xylinum has unique properties including high mechanical strength, high water absorption capacity and highly pure fiber network structure. These properties have enabled bacterial cellulose to be used in applications such as Nata de Coco, enzyme immobilization, artificial skin and wound dressings. The objective of this project was to investigate the production and properties of bacterial cellulose as appropriate for wound dressings using coconut water as the main substrate medium. Preliminary focus of the research was to identify and isolate Acetobactor xylinium from a kombucha mixed culture. Bacterial cellulose pellicles were prepared by static fermentation of Acetobacter xylinum containing culture in coconut water while supplementing with glucose and (NH4)2H2PO4 at an initial pH of of 4.3. Properties of resulting bacterial cellulose pellicles were investigated for its strength, structure and permeability characteristics. The average thickness of each pellicle was 3 mm in wet form and 0.25 mm after oven drying. Young’s modulus was in the range of 1 - 3 G Pa up to 15% moisture content. Fourier Transform \infrared spectroscopy (FTIR) on oven dried bacterial cellulose were very much similar to commercial products of bacterial cellulose wound dressings. Water vapor transmission rate (WVTR) through the dressing was in the range of 5-15 ( g/hr-1 m-2) while increasing the moisture content decreased the WVTR. These investigations proved that there is an optimum moisture content of 15% that gives the most appropriate properties for a wound dressing. Further the wound dressings that were prepared and packed in sterile conditions were applied on selected patients. The results showed that dry dressings were more appropriate than wet dressings. However, dry dressings lose their strength when reabsorbing moisture. In conclusion, it could be said preliminary research showed coconut water can be used in preparation of bacterial cellulose as wound dressing since it has suitable characteristics. However, further research is required to find the variation of properties with moisture content and re-absorption characteristics of bacterial cellulose. Key words: bacterial cellulose, Acetobacter xylinum, coconut water, wound dressing
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Development of a decision support system for landfilling applications in Sri Lanka
Manamperi, A; De Alwis, A; Pilapitiya, Sumith
With increasing awareness of the harmful effects of solid waste mismanagement such as wild dumping, open burning and uncontrolled landfilling, many local authorities in Sri Lanka are now willing to invest in Engineered Sanitary Landfills. However, the lack of know-how and expertise is a general barrier for the rapid implementation of this approach in Sri Lanka. In addition, the expertise is not cheap when it comes to a narrow domain such as engineered sanitary landfilling and in most cases, local, authorities cannot afford to employ such experts, within their budgets The aim of this research is to develop a decision support system that will help local authorities in Sri Lanka to better manage and implement the landfilling projects. A decision support system is computer program that provide expert advice as if a real person had been consul led. These systems capture and deliver knowledge that is not easily represented using traditional computing approaches. It could be used by Local Authorities in planning and implementing landfill facilities. It can training tool for the staff while avoiding the cost of living a human expert. The central core of the knowledge base of BESTFill was acquired from the published text books and manuals. This knowledge consists of well established facts, rules, theory and guidelines that had been practiced over many years. The knowledge base was divided into four categories as site, technology, safety and post closure. The production rules were applied for the site related questions (site selection etc..) and objects or frames were used for other divisions namely technology, safely and post-closure. A unique feature of BESTFill is that it contains several sub modules by while the user can obtain a comprehensive background knowledge on landfilling and integrated solid waste management. The sub modules were named as literature, info desk, training tool, photo gallery, landfill rapid assessment tool, economics & costing, regulations and reports. As effort was made to make the system more user friendly, by using several user interfaces. The user not require process advantaged background in mathematical programming and computing methods. The BESTFill decision support system was validated in two steps. The first step involved the internal validation of the system through program debugging, error analysis, input acceptance and output generations. The second step involved in validating the system under real application situation. The landfill site at Nuwara Eliya was considered as the most appropriate site for the field validation of the since it comprises the basic essential criteria of an engineered sanitary landfill. BESTFill will serve as a guidance tool for landfilling applications in Sri Lanka. It is useful in planning, implementing, and trouble shooting at various stages of landfilling for the designers and operators. It helps the user to obtain every single aspects of the landfilling from the planning stage to the closure and post closure maintenance. The main beneficiary of the system will be the local authorities in Sri Lanka, which amounts 311. In the developing process it has been specially taken into consideration by analyzing the requirements, capabilities, weakness of the local authorities as the main largest group of the system
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Development of a high rate biomethanation reactor system
(3/25/2011) Jayasuriya, PI; De Alwis, A
A pilot scale two-phase anaerobic reactor system was constructed and the feasibility of Biometha nation using two-phase systems was evaluated. As the raw materials, a batter mixture washing eft1uent from a wafer biscuit manufacturing plant was used. This effluent has a high COD due to vegetable fats and oils .Acetogenic reaction was allowed to take place in the first reactor and when the VFA level came to around 12000 mg/l it was fed to the methanogenic reactor. Without an initial seeding of microbial population and a growing media the trial was not successful. So a filter bed was introduced to the second reactor with a 20liters of rnethanogenic bacterial sludge from a running reactor. Research trials indicate that the two-phase system works successfully with proper controlling. It also gave out biogas with 84% methane, which is very rich in methane. From these pilot trials, it was able to find out design process parameters for a suitable large-scale two-phase system where the biogas can be generated in large scale with the same waste effluent These findings help industries to generate energy from their organic waste, hence reducing the dependency on fossil fuels as well as reducing waste disposal problem.
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Development of a PFD for a nanolubricant based on Ceylon vein graphite
Wagaarachchige, JD; Rathnasiri, PG; De Alwis, A
The thesis presented the information on Sri Lankan natural vein graphite resource, world nanotechnological approaches in tribology and the connection between nanotechnology, tribology and Sri Lankan vein graphite. Along with the case study on chronological timeline of vein graphite, exploitation started in 1829, peaks at 1916 and has been dropped down since 1917. Considerable damage for graphite resource of Sri Lanka has happened in British colonial era. The market analysis of graphite export industry in Sri Lanka indicates several reasons for decline of graphite export market. The potential of graphite based industries are broad due to its versatile properties without any processing. With the discovery of graphene the importance of graphite moves to a new era of advancement in applications. Therefore Sri Lankan vein Graphite should not be supply to outside of the country without value addition. Need to come*up local investor and technologists to start new graphite era. In nanotechnology, tribology using nanometerials is a burgeoning research field and there are few nanolubricant products in the market. Information on world tribological approaches on nonmaterial is reviewed. Carbon, Metal dichalcogenides, soft metals, boron based materials and some micelles and encapsulated materials are under exploration of advance tribology. Further to the lab identifications and literature reviews reflected the potential of nano* engineered lubricant using natural vein graphite. PFD for vein graphite based nanolubricant is presented with some optimization options and advanced techniques as the recommendation for future work.
item: SRC-Report
Development of an expert system for better management of solid waste composting by pradeshiya sabhas in Sri Lanka
Ranasinghe, M; De Alwis, A; Pilapitiya, S; Pathinather, S; Abeygunawardena, I; Jayawardhana, HMLC; Manipura, A
The increasing population and the ever-changing life style of the public have begun to add to the growing solid waste problem in Sri Lanka. As a solution, Local Authorities, NGOs, researchers and environmentalists have implemented several composting projects. Unfortunately, most of these projects are either abandoned or operating under poor conditions due to social, economic and technical problems encountered and none of options have solved the solid waste management problem itself. A key issue that is highlighted is the lack of qualified personnel (experts) to advise and assist Local Authorities to adopt the best solid waste management practices. Decision Support Systems and Expert Systems are favourable tools to overcome these problems. Therefore by capturing past mistakes, weak points and considering past experience, a user friendly Expert System called BESTCOMP was developed for better management of solid waste composting by Pradeshiya Sabhas in Sri Lanka. This research mainly focused on the behaviour of the physical, chemical and biological process in composting. The model is geared towards decision making as well as providing required expertise to solid waste composting hierarchy.
item: Thesis-Abstract
Development of an expert system for better management of solid waste composting by pradeshiya sabhas in Sri Lanka
Jayawardhana, HMLC; Ranasinghe, M; De Alwis, A; Pilapitiya, S; Abeygunawardena, I
The increasing population and the ever-changing life style of the public have begun to add to the growing solid waste problem in Sri Lanka. As a solution to the growing solid waste management problem in Sri Lanka, Local Authorities, NGOs, researchers and environmentalists have implemented several compo sting projects. As waste characteristics of municipal solid waste in Sri Lanka show a very high proportion of organic matter (60-85%), high moisture content (60- 75%) and low calorific value (l000-1200kcal/kg). Most of these projects are currently abandoned or operating under poor conditions due to social, economic and technical problems encountered and none of options have solved the solid waste management problem itself. A key issue that is highlighted is the lack of qualified personnel (experts) to advise and assist Local Authorities to adopt the best solid waste management practices. Decision Support Systems and Expert Systems are favourable tool to overcome these problems. Therefore by capturing past mistakes, weak points and considering past experience, a user friendly Expert System called BESTCOMP was developed for better management of solid waste composting by Pradeshiya Sabhas in Sri Lanka. This research mainly focused on the behaviour of the physical, chemical and biological process in compo sting. The model is geared towards decision making as well as providing required expertise to solid waste composting hierarchy. BESTCOMP consists of many decision models such as compost process and control, pictorial database, site selection, technology selection, waste analysis reports, expertise information, Government laws and regulation on solid waste management, information desk for researchers and training tool, such that the user can identify problems faster, examine various alternatives and make prudent choices. It performs all the functions of a decision support system. The developed system will guide the Local Authorities of Sri Lanka to find the most suitable composting solution to solve solid waste management problem with the available resources in their area and aid their decision making process on solid waste composting. It also helps in determining resource deficiencies when the user utilizes the data provided in an instructive manner.
item: Conference-Abstract
Dye sensitized solar cells using natural dyes derived from chaetomorpha, microcladia borealis, elisolandia elongate and sea lettuce
(Department of Chemical & Process Engineering University of Moratuwa., 2023-08-17) Illlankoon, HMUB; Sumudushantha, WANT; De Alwis, A; Perera, U; Walpalage, S; Gunawardena, S; Narayana, M; Gunasekera, M
Natural dye-sensitized solar cells (DSSCs) are a promising area in renewable energy. These innovative devices employ natural dyes extracted from plants to absorb sunlight and convert it into electricity. The dyes (anthocyanins in berries or chlorophyll in green plants), act as sensitizers, absorbing sunlight and generating excited electrons. One of the significant advantages of natural DSSCs is their eco-friendly nature, as they utilize renewable resources and have a low environmental impact compared to traditional solar cells. Moreover, their production is cost-effective and can be easily scaled up for industrial applications. With ongoing R&D efforts, natural DSSCs have the potential to contribute significantly to a cleaner and sustainable energy future. Reinforcing above, this study investigated the efficiencies of DSSCs produced using dyes of novel seaweed varieties (Microcladia borealis, Ellisolendia elongata, sea lettuce and Chaetomorpha) from shallow seas in Sri Lanka. Dye extracts from sea weeds have been studied sparsely with DSSCs. This research dives into the extensive color resources contained in the Sri Lankan seaweeds. The absorption of the dye and the electron emitting efficiency of the dye showed a clear relationship which can be further used in research for better dyes without following the full procedure of producing the cell. Additionally, the research opens a path for further research whether nano TiO is a mandatory factor in producing a DSSC. The highest efficiency was shown by dye extracted from Microcladia borealis which was 1.7x10 %.
item: Article-Full-text
The eco-social transformation of urban wetlands: A case study of Colombo, Sri Lanka
(Elsevier, 2014) Hettiarachchi, M; Morrison, TH; Wickramsinghe, D; De Alwis, A; McAlpine, CA
Recent studies in both the environmental sciences and geography highlight unforeseen ecological transformations occurring in eco-social landscapes. These transformations often result in ‘novel’ or ‘hybrid’ ecosystems that differ from the original ecosystems both in ecological character and social setting. However, little is known about the causes, consequences, and dynamics of such transformations in complex urban environments and the consequences for highly sensitive ecosystem types such as wetlands. This paper investigates the environmental history and recent ecological transformations in the urban wetlands of Colombo, Sri Lanka. Our methodology includes a combination of techniques from environmental history, wetland science and urban ecology. We investigate the ecological changes in the wetlands from colonial times to the present and establish relationships among wetland ecology (the hydro-soilvegetation nexus), landscape change, community, and governance factors. We conclude that from 1980 onwards, the Colombo urban wetlands have undergone an overall transformation in both wetland type (composition and structure) and the social setting. Hydrological modification, watershed urbanization and the changes in ecosystem use were identified as the main causes of wetland transformation with the causes and consequences of the transformation having complex feedback loops. We synthesize these relationships into a post hoc conceptual model that will be of broader utility as a general framework to understand eco-social interactions in the governance of urban ecosystems.
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Effect of antimicrobial discharges into wastewater treatment plants in the pharmaceutical industry
Gunasekera, MY; Abeygunawardane, I; De Alwis, A
Pharmaceutical manufacturing industry is expected to generate effluents having a wide variety of antimicrobial substances. The biological wastewater treatment processes should thus be capable of handling effluents, containing these inhibitory materials, without being adversely affected. In this investigation, the study of the wastewater treatment system of a Pharmaceutical Manufacturing facility is carried out with special reference to antimicrobial discharges. The manufacturing process studied dealt with formulation, filling and packaging of preparation for prescription products. Thus this facility falls into the 'dry formulation' category. A good clean supply of water is essential in this industry. The water used in the manufacturing areas is mainly for cleaning/washing of processing equipment and accessories. Water is also used for cooling the housing of the moving parts in machines. All liquid effluents generated pass through a wastewater treatment plant prior to discharge into an inland surface water body. The wastewater treatment plant in this facility consists of an activated sludge treatment process. For a primary understanding of this wastewater treatment plant a study of the general characteristics were done. The effect on the overall efficiency of the wastewater treatment plant was observed while studying the washing/cleaning activities carried out in the production zones on each sample collecting day. The findings of this study showed an overall efficiency less than the design efficiency of the wastewater treatment plant. It is seen that plant inputs and generated waste loads are low even when compared with typical waste characteristics of such facilities. A large fraction of the BOD/COD ratios determined showed low values. About 92% of the BOD/COD ratios determined in the equalization tank were less than 0.5. The analysis of BOD, with different dilutions was done in order to determine whether there is an effect by any antimicrobial substance on the biological activity. IV The BOD test carried out for a series of wastewater sample dilutions showed decreasing BOD values as the dilution percentage increasing on certain days. In some days results showed 31% to 34% reduction in BOD value indicating the presence of an antimicrobial substance in the wastewater sample on that day. Further, in order to study the antimicrobial activity of the wastewater discharged from this facility, E. coli was tested in liquid culture medium. The growth of E. coli was monitored as absorbance at 600nm in the presence and absence of waste samples. The results indicated the growth of E. coli in wastewater was not as high as the growth shown in the peptone water medium. It was also indicated that the growth of this organism in the wastewater sample was not inhibitory as in the solution containing amoxycillin (1011g/ml). A study of the effect on the same organism was also carried out using the antibiotic diffusion technique. The inhibition zones created from a concentration series of an antimicrobial substance were studied with the inhibition zone produced by wastewater. The study carried out using the cylinder plate test showed an inhibition zone for wastewater. For a wastewater sample taken from the wastewater treatment plant after cleaning Rifampicin processed machines, a clear zone was observed giving an effect equivalent to a concentration of2.9 ug of amoxycillin per milliliter. From the observed results, heavy impact on the wastewater treatment plant operation from discharges was not indicated. However the precautions are needed to be taken when contemplating expansion etc. as the present observations and conclusions apply only to current loading conditions. Close monitor of waste effluent would be necessary in future if expansion is sought by the company.
item: Thesis-Abstract
Emission inventory for Sapugaskanda industrial area
Jasinghe, SR; De Alwis, A
In this thesis an emission inventory for an industrial area is developed, and mathematical modeling on emissions and comparisons with air quality criteria are presented. With emission data recorded in a scientific manner, an emission inventory is a powerful tool used for sound environmental management all over the world. It provides the foundation for all air quality management programs providing information on assessments of the air emissions, interactions among air pollution sources in a region, as input data for air quality models, implementation and tracking of control strategies in air pollution emissions. It has several branches, which depends on the methodology adopted in the preparation stages. One of the main branches is that area emission inventory. Area Emission Inventory collectively represents individual sources that are small and numerous and that have not been inventoried as specific point, mobile, or line sources. Generally, air emissions are calculated by using emission factors. These emission factors are available in the world and they are developed based on the experienced gathered by the developed countries. However, the use of those emission factors in the preparation of inventories is questionable in the developing countries. A set of emission factors for the particular systems studied have been developed in arriving at the final inventory. Spugaskanda area had been selected to develop an area emission inventory. This area is the most vulnerable for air quality degradation in Sri Lanka at present. There are 03 thermal power plants having capacity of 260MWe at the Sapugaskanda area. Apart from that, the Ceylon Petroleum Corporation (CPC) is doing its refinery activities in the vicinity of the site, which is the only petroleum refinery in the island. Further a well developed industrial estate borders this site. The calculated emissions from the Sapugaskanda are 13,331 metric tons of Sulfur Dioxide, 1,070,608metric tons of Carbon Dioxide, 17,166 metric tons of Nitrogen Dioxide and 323 metric tons Particulate per annum. Further study was carried out to run a dispersion model using the calculated emission load from the selected area to check whether the predicted pollution concentrations exceed the present ambient air quality standards. Meteorological inputs for this model was prepared using the real time data collected in the selected area. The model prediction was done for 04 monsoon periods. The predicted pollution concentration at North East (NE) monsoon is comparatively high when compared to that of South West (SW) monsoon. But the occurrence of stability classes during these monsoon periods is almost same. Therefore, the relatively low wind velocities experienced during the North East monsoon could be the reason for high pollution levels during this period. The monitored pollution concentration at the downwind direction in the Sapugaskanda area during the periods of NE & SW supports this observation. Finally further developments necessary are forwarded for consideration.
item: Thesis-Full-text
Energy potential of invasive plants in Sri Lanka
(2016-01-16) Bandara, ERJC; De Alwis, A
Invasive Alien Species (IAS) is a great threat to biodiversity in many of the natural ecosystems in Sri Lanka. Water hyacinth, Prosofis juliflora, Mimosa pigra, Lantana camara and Panicum maximum are found to be the most critical IAS plants which are threatening in lakes, Bundala, Mahaweli catchment, Udawalawa and island wide respectively. With the drawbacks of launched controlling mechanisms those of physical, chemical and biological, there is a much necessity for initiating more sophisticated program with the participation of public, especially rural community where there will be more benefits for them. As far as the Sri Lankan energy balance is concerned about 45% comes from biomass while rest from imported petroleum (45%), hydro (8%) and unconventional renewables. About 25% of the imports expenditure is accounted for petroleum imports. On the other hand, the demand for fuel wood is increasing due to rapid industrialization and it will be always questionable whether the existing feed stocks are sufficient. Further, currently identified biomass species such as Gliricidia, Ipil, Eucalyptus and etc are not the best as far as the annual yield is concerned. Learning from the nature, has been a key scenario in invention and development. IAS itself shows the characteristics which are suitable for dedicated energy crops those of high yield, low nutrition requirement and survival in mild environmental conditions. The two IASs; Guinea grass and Arundo donax, were analyzed to be used as energy feedstock. Their perennial nature along with high yield as high as 75 tons per hectare provide evidence their suitability as energy plants. Guinea grass was further tested in an updraft gasifier and the flame was not stable for a long time but only for 6 to 7 minutes. The performances were different from batch to batch where gas analysis showed that it was composed with around 11% combustibles. In trial 2 sample, 50% of nitrogen suggests that the presence of oxygen is low and hence, the unaccounted 18% could be composed with tars which were not detectable by used column in GC analysis. Further, the heterogeneous nature of feedstock along with the uneven compaction caused uneven combustion throughout the cross section and height. Hence it was suggested again that the homogeneous nature of feed material is a crucial factor in gasification.