Browsing by Author "Witharana, A"

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item: Article-Abstract
Are Green jobs sustainable for Sri Lankan Economy?
Jayaweera, M; Manatunge, JMA; Witharana, A
It is imperative that Sri Lanka grasps the concepts of green jobs to meet the most vital but intricate challenge of the 21st Century, which is the transformation to a sustainable and a low-carbon economy. Such a transformation or a paradigm shift, which can be gradual or rapid depending on the circumstances, will undoubtedly have a considerable positive effect on the way we produce and/or consume goods and services. The speed at which this transformation would occur is likely to accelerate in the near future as there is a trend of global transition from a traditional to a low-carbon economy, in order to attain sustainable economies. Such trends will help create an array of different forms of green jobs across many sectors, and most probably can become a catalyst for further development. The International Labour Organization (ILO) has defined green jobs as “Jobs created when they help in reducing the negative environmental impacts ultimately leading to environmentally, economically and socially sustainable enterprises and economies”. Green jobs, in general, stand on two pillars: decent work and environmental sustainability. Thus, green jobs can be defined as decent work that contributes to environmental sustainability. In a broader sense decent work needs to address the core of international labour standards such as freedom of association and effective recognition of the right to collective bargaining, elimination of all forms of forced or compulsory labour, effective abolition of child labour, elimination of discrimination in respect of employment and occupation, occupational health and safety, etc. whilst aligning to laws applicable to Sri Lanka. Environmental sustainability addresses issues such as effectively combating climate change, pollution prevention and control, conservation of eco-systems and biodiversity etc. (ILO, 2007).
item: Conference-Abstract
Investigation of Zinc removal capacities of different sorbent materials to be used in constructed wetlands
Witharana, A; Jayaweera, M; Manatunge, JMA
It has been found over the past couple of years that health hazards associated with heavy metals have been on the rise, particularly the chronic diseases. Lack of tertiary treatment of wastewater may have contributed to this emergent problem, mainly due to the high costs involved in the removal of heavy metals. Constructed wetlands have therefore received great attention as a tertiary treatment method or a polishing technique of wastewater due to its low construction and operation costs. However, finding a low-cost sorbent material to be used as the wetland filter material, which can be used as an alternative to activated carbon, has been a problem for decades. Therefore, the present study focuses on applicability of low-cost sorbent materials: viz., clay tile, brick, saw dust and rice husks, as filter mediums. Laboratory-scale experiments were performed with a synthetic Zinc solution. Results revealed that clay tile material has the highest adsorption capacity (47.6 mg/g) and removal efficiency, (98%), while brick (37.0 mg/g, 86%), sawdust (20.4 mg/g, 80%) and rice husks (15.8 mg/g, 64%) have relatively low adsorption capacities and removal efficiencies, respectively. The separation factor of equilibrium (RL) indicates favourable isotherms (0< RL<1) for all tested sorbent materials. Among the studied materials clay tile, brick and rice husks are good adsorbents for Zinc (n>2) while sawdust is a moderately difficult material for adsorption of Zinc (n <2).
item: Conference-Full-text
Long term performance of a constructed wetland planted with Typha angustifolia
(Department of Civil Engineering, University of Moratuwa, 2011-12) Jayaweera, M; Witharana, A; Ratnayake, N
Constructed wetlands are often utilized for wastewater treatment' including removal of metals. The removal mechanism is phytoremeditation, in which plants are manipulated to immobilize the pollutants. Physico-chemical properties of substrate and its potential tor removal of pollutants also effects the performance of constructed wetlands. Many engineering studies of treatment by wetlands use a black box approach.This paper discusses the Zn uptake by Tvpha angustifoha and its distribution within the shoot (leaves and stem) and root. This was investigated by introducing different operation conditions to the constructed wetland during acclimatization with nutrients, and gradual variation of Zn loading with incremental increases. The relative changes in the substrate (clay tile) were also investigated by means of XRD, FT-IR and SEM analysis. The results revealed that the clay tile is a promising adsorption material for Zn. In addition,Typha angustifolia is found to contribute to metal trapping into the senescing plants via rhizodeposition and act as a catalyst for biochemical reactions. The interesting feature noted in the wetland was that after nearly two years of operation, almost all clay tiles around the rhizosphere of Typha angustifolia were disintegrated completely, back to the original clay, suggesting that nature helps to sustain the plants by providing an environment with less toxicity. lt could be concluded that the long term adaptation of wetland plants to heavy-metal rich environments would not help the sequestration process, and they cannot be considered to be heavy metal sinks in the aquatic system once this stage is reached.
item: Conference-Full-text
Zinc adsorption by lowcost sorbent materials: clay tile, Brick, sawdust and rice husk
(2013-11-19) Witharana, A; Jayaweera, M; Manatunge, JMA
It has been found over the past couple of years rapid growth of population, industrialization and urbanization has first and foremost contributed to the severe water pollution in both surface and ground water. The health hazards associated with heavy metals have been on the rise, particularly the chronic diseases. Lack of tertiary treatment of wastewater may have contributed to this emergent problem, adsorption process is considered as the best available water treatment method and activated carbon has proven to be the best sorbent material which can be used in removing wide variety of pollutants. However, usage of this activated carbon becomes restrict due to its high cost and regeneration cost. Therefore, the present study focuses on low-cost sorbent materials: viz., clay tile, brick, sawdust and rice husks. Laboratory-scale experiments were performed with a synthetic Zinc solution. Results revealed that clay tile material has the highest adsorption capacity (47.6 mg/g) and removal efficiency, (98%), while brick (37.0 mg/g, 86%), sawdust (20.4 mg/g, 80%) and rice husks (15.8 mg/g, 64%) have relatively low adsorption capacities and removal efficiencies, respectively. The separation factor of equilibrium (RL) indicates favourable isotherms (0< RL<1) for all tested sorbent materials. Among the studied materials clay tile, brick and rice husks are good adsorbent for Zinc (n>2) while sawdust is a moderately difficult material for adsorption of Zinc (n <2).