Ajith De Alwis

Test burn with PCB–oil in a local cement kiln in Sri Lanka

The production and use of polychlorinated biphenyls (PCBs) have ceased and most developed countries have disposed off their stocks long time ago. PCBs can however still be found in the environment and one important source is accumulated stocks in developing countries. Sound treatment of PCB is costly and most developing countries do not have dedicated hazardous waste incinerators or non-combustion technologies available for domestic disposal and can usually not afford export. High temperature cement kilns have been used to treat organic hazardous wastes in developed countries for decades and shown to constitute a sound option if well managed and controlled. In contrast to dedicated hazardous waste incinerators and other treatment techniques, cement kilns are already in place in virtually every country and may constitute a treatment option. The objective of this study was therefore to carry out the first test burn with PCB-oil in a developing country cement kiln and to assess its feasibility and destruction performance. The 3 d test burn demonstrated that the Sri Lankan cement kiln was able to destroy PCB in an irreversible and environmental sound manner without causing any new formation of PCDD/PCDF or HCB. The destruction and removal efficiency (DRE) was better than 99.9999% at the highest PCB feeding rate.

Biogas – a review of Sri Lanka's performance with a renewable energy technology

Sri Lankas 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.

BESTCOMP: expert system for Sri Lankan solid waste composting

Abstract A user friendly expert system, BESTCOMP was developed for better management of solid waste composting by local authorities in Sri Lanka. BESTCOMP expert system mainly focussed on the behaviour of the physical, chemical and biological process in composting. The intention had been to provide distant users with scientific and techno-economic information using modern tools but at a much lower cost. This research has put very strong emphasis on allowing the user to browse around the knowledge that has being extracted from books, published research articles, reports, audio, video, Internet, case studies and the domain experts who involved in solid waste management activities, so the user can get an accurate and a real feel for the solid waste management subject.

Urban wetlands and disaster resilience of Colombo, Sri Lanka

Purpose – This paper aims to present a long-term research project to understand the nature and extent of degradation in a selected segment of the Colombo Flood Detention Area (CFDA) wetlands. It qualitatively explores the gradual process of change in watersheds and the wetland ecology affecting flood control services, thereby leading to full-blown disasters. It underlines the importance of protecting ecosystem health of urban ecological features for strengthening the disaster resilience of cities. Design/methodology/approach – Through analyzing the long-term change of landscape level parameters, water-quality, vegetation and soil quality, the authors emphasize the potential of an outright ecological regime change and the effects on ecosystem services of the wetlands. Findings – Colombo is a city surrounded by a large and interconnected system of natural wetlands that provides a valuable flood control service. The rapid and partly ad hoc urbanization in the past 15-25 years has caused a steady degradation ...

Development of an Expert System for Landfilling Applications in sri Lanka

An expert system was developed to assist proper implementation of landfill technology in Sri Lanka. The knowledge base was acquired through text books, manuals, technical reports, research publications and domain experts. An object oriented expert system shell, ACQUIRE 2.1 was used as the building tool for the prototype development. BESTFill expert system contains several sub modules by which the user can obtain a comprehensive background of the domain. The output is expected to support effective integrated solid waste management.

Synthesis of magnetite nanoparticles by top-down approach from a high purity ore

This study attempts to synthesize magnetite nanoparticles from a high purity natural iron oxide ore found in Panvila, Sri Lanka, following a novel top-down approach. Powder X-Ray diffraction, elemental analysis, and chemical analysis data confirmed the ore to be exclusively magnetite with Fe2+: Fe3+ ratio of 1 : 2. Surface modified magnetite nanoparticles were synthesized by destructuring of this ore using a top-down approach in the presence of oleic acid. These oleic acid coated nanoparticles were further dispersed in ethanol resulting in stable nanomagnetite dispersion. Interestingly, the nanoparticles demonstrated a spherical morphology with a particle size ranging from 20 to 50 nm. Magnetic force microscopic data was used to confirm the topography of the nanoparticles and to study the magnetic domain structure.

Municipal Waste Biochar for Energy and Pollution Remediation

Municipal solid waste has become a hassle in many developing countries due to haphazard disposing to open dumpsites, which has zero management. This way of disposing the waste has negative impacts in the environment that can directly contribute to the climate changes and atmospheric pollution through greenhouse gas and volatile organic compound emission and water and soil pollution via landfill leachate as well. Biochar, a carbonaceous material produced by limited or no oxygen pyrolysis of biomass is an emerging efficient substitute for activated carbon. Its production utilizes different feedstock including municipal solid wastes, which is the “greener” approach of transforming the existing municipal waste into a value added product that can be used in contaminant mitigation and resource recovery by using it as an adsorbent and as a hybrid with soil for better plant growth. The long term benefits of these biochar additions to soil and water can be manifold and potential as an improved nutrient retention and availability to plant growth; this gives the impetus of having the “greener transformation” from municipal wastes to biochar. This chapter outlines the ways of production of biochar derived from municipal solid waste, its significance as an adsorbents and its promising potential in landfill cover, leachate treatment and for permeable reactive barriers.

Bestcity: Developing Clean Cities

Artificial Intelligence applications have immense potential to fill the knowledge gaps that exist in developing countries. During the past decades, many AI applications have developed to solve structured problem domain and less concern about complex problem domain such as solid waste management. Hence, solid waste management is a burning environmental issue in developing countries due to lack of expertise and information assimilation paths. To fill this knowledge gap a user-friendly decision support system (DSS), BEST City is developed. This paper describes the techniques used for the development stage and robustness of BEST City DSS. Much evident clean cities in developed economies with the huge amount of knowledge available could be intelligently managed to solve issues in developing countries, which is the main objective of BESTCity.