Master of Science in Environmental Management

Permanent URI for this collectionhttp://192.248.9.226/handle/123/44

Browse

Now showing 1 - 20 of 23

item: Thesis-Abstract
Physicochemical analysis, toxicity assessment and nutrition source potential of sugarcane distillery spent wash
(2022) Kuruppuarachchi HD; Manathunge J; Ruvinda KMS
Sugarcane molasses-based ethanol industries in Sri Lanka generate large volumes of high strength spent wash, causing severe environmental issues. The potential toxicity of spent wash on biological systems and the possibility of using it as a nutrition source in agriculture has been given less attention in Sri Lanka. The present study was conducted to assess the physicochemical characteristics of the raw spent wash and possible cytogenotoxic effects of diluted spent wash using a plant-based bioassay with Allium cepa (common onion). Further, to evaluate the potential of raw spent wash as a liquid nutrition source to improve the growth of commonly grown vegetable variety, tomato (Solanum Lycopersicum). Selected physicochemical parameters of raw spent wash collected from the distillery industry of Lanka Sugar Company (Pvt) Ltd, Pelwatta, were evaluated using APHA (2017) standard procedures. Toxicity assessment was carried out after exposure of Allium cepa bulbs to diluted spent wash (1:8) along with aged tap water (negative control) following standard protocols. The tomato crop experiment was conducted as an open field experiment using agricultural guidelines provided by the Department of Agriculture with certified organic fertilizer as positive control and tap water as a negative control. Growth morphometric attributes of the plants and fruits were monitored for 60 days. The data were statistically analyzed using univariate statistical methods. The physicochemical analysis revealed that the spent wash is highly acidic with high EC (21.93 ± 0.09 mS/cm), COD (92,101 ± 0.33 mg/L), BOD (26,116 ± 2.33 mg/L)TSS (4,076 ± 0.55 mg/L), TDS (68,656 ± 0.13 mg/L), Nitrate (255 ± 0.04 mg/L) and phosphate (38 ± 0.07 mg/L), and contained heavy metals viz. Cd, Cu, Ni, Zn, As and Mn and K in trace amounts. Significantly decreased root growth was found in Allium roots exposed to diluted raw spent wash with the highest root growth delay (92%) after two days of exposure compared to the negative control (p < 0.05). The mitotic index did not show any difference in all exposure conditions. Significantly increased nuclear abnormalities, including micronuclei, nuclear buds, binuclei and condensed nuclei, were observed in root tip meristematic cells of diluted spent wash compared to the negative control (p < 0.05). Among growth-related morphometric attributes of tomato plants treated with different spent wash doses (0.5, 1.5, 2.5, 5.0, 7.5 and 10 mL), shoot lengths, the number of leaves and number of buds and flowers were found to have less significant variations. In contrast, other treatment categories recorded significantly reduced fresh fruit weight compared with the positive control (p < 0.05). Measured fresh fruit weight was more favourable toward high-end doses. However, this should be confirmed by repeated scientific studies. Results of the experiments reflect that the raw spent wash may have a cytogenotoxic effect, and the spent wash may use as a nutrition supplement by mixing with other organic ingredients. Further experiments for different crops, soil testing, and frequent biological effects monitoring are recommended to verify the spent wash's nutritional use and toxic effects
item: Thesis-Abstract
Evaluation of water quality of community managed water supply schemes in southern province
(2022) Shanthi DAMN; Chaminda T; Manatunge JMA
Water is a crucial element that covers two-thirds of the surface area of the earth, and it is one of the main substances in the body of every living being on the earth. Thus clean, safe, and adequate freshwater is important for secure good health. The National Water Supply and Drainage Board (NWS&DB) is the main responsible institution for providing safe drinking water within Sri Lanka. However, NWS&DB is unable to provide safe water to the country’s entire population. Therefore, Community Managed Water Supply Schemes (CMWSS) were implemented as a solution for the existing water scarcity issues in rural areas of Sri Lanka. It was revealed that most of the CMWSS in Southern Sri Lanka are supplying raw water without proper treatment. So continuous monitoring, management, and evaluation of water quality in these schemes are essential to supply safe potable water. There are 172 CMWSS in the Galle district, and 10,814 families benefit from those schemes. On the other hand, there are 333 schemes in the Matara district, and 26482 families benefit from these CMWSS. In Hambanthota district, there are 182 CMWSS to provide drinking water for 38157 families. In this study, the water quality of selected CMWSS (71% out of total schemes) in the southern province of Sri Lanka was assessed by applying the Canadian Council Minister of Environment Water Quality Index (CCMEWQI). Altogether, water quality (WQ) of 488 (Galle 172, Matara 172, Hambanthota 144) CMWSS was evaluated under the 14 parameters such as temperature, turbidity, pH, electrical conductivity, total hardness, nitrate, iron, fluoride, E. coli, total coliforms, Mn, Pb, As and Cd, using Standards method of American Public Health Association and compared with the Sri Lankan Standards for drinking water (SLS 614 2013). Water Quality Index (WQI) was also developed for each source and rated as Excellent, Good, Medium, Bad, and Very Bad. Developed WQI revealed that none of the CMWSS in the southern province categorized as “Very Bad” quality (0-25). Among 488 schemes in the province, only (2.3%) 11 schemes belonged to the “Excellent” category (91100) based on this WQI. Majority of the schemes (39.1%) had the WQI between 26-50 and rated as “Bad” and need to have secondary treatment. There were 33.8% of CMWSS that belonged to the “Medium” category (51-74) of WQI and 24.8% in the “Good” category (7590) which were not suitable for drinking without preliminary treatment. More than half (56.3%) of CMWSS in Hambanthota district were in the ‘Bad’ category. Therefore, Hambanthota district CMWSS were highly contaminated than those in Galle and Matara districts. It was noted that raw water of (97.7%) 477 CMWSS in the southern province need to be further treated for E. coli, total coliforms, conductivity, hardness, iron, fluoride, pH, and turbidity. The questionnaire survey revealed, that 62.6% of consumers used water without any treatment. It is recommended to educate consumers of CMWSS on basic household treatment systems so that they can treat the water before consumption. It is also required to introduce more cost-effective treatment procedures for the consumers as the majority of the household in the southern province monthly income is less than Rs.25,000.
item: Thesis-Abstract
Health quality assessment of a highland stream using selected physico - chemical parameters, biological factors and microplastic level
(2022) Dilini RMA; Manathunga J; Thushari GGN
Ella is a popular tourism destination in Sri Lanka due to its salubrious climate and aesthetic quality of the surrounding environment. Beeralla stream (tributory of Kirindioya) flow through the Ella city by increasing recreational value of Ella City. Present study performs the health quality assesement of Beeralla stream with respect to the selected physico chemical parameters, biological factors and microplastic levels in suface water. Ten physicochemical parameters (pH, Water temperature, Total Suspended Solids (TSS), Turbidity, Conductivity, Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Nitrate and Total Phosphorous (TP) concentration) of stream water were monitored at 05 sampling locations in January, March, July, Septemberand November 2020 as representing the intermonsoonal and monsoonal periods. Sampling sites were selected for the study at Ella GN area after preliminary observations to cover the area close to different land use patterns. A microplastic level of surface water of the stream was investigated from March until December 2020 by analyzed by wet peroxidation method. Results revealed that the measured water quality parameters significantly vary (<0.05) both spatially and temporally. Oneway Anova resulted that mean values of all parameters were significantly vary (<0.05) spatialy. Further, DO, TSS, Nitrate concentration, BOD, COD and TP concentration were significantly higher (<0.05) in January and March. Highest average TSS, BOD, COD and TP were recorded in the midstream (Site 3 and 4) indicating possible uncontrolled wastewater discharges and high urban waste runoff. Although average values of TSS, turbidity, DO, phosphate, COD and BOD levels are exceeded the Sri Lankan ambient water quality standards in sampling site 02, 03, 04 and 05. Aquatic macroinvertebrates of each sampling sites were examined at the time sample collection for physicochemical parameters. A total of 15 individuals of macroinvertebrates representing 5 orders (Odonata, Hemiptera, Diptera, Coleoptera and Haplotaxida) were successfully collected from January until December 2020. Shannon Weiner Diversity Index was ranged 1.17 – 1.94 and Family Biotic Index ranged in between 5.56 to 8.26. The values of Family Biotic Index indicate that all sites of stream are subjecting to the organic pollution with poor water quality. Samples collected from all sampling locations were contained microplastics with the average density of 5-13 Items/L. Mean micoplastc density levels of surface water were significantly varied among sampling periods (<0.05). Present study results reveal that water quality of the Beeralla stream is deteriorated with micoplastic pollution, vast nutient inputs with organic matter. Also, water quality is exceeded the iv ambient water quality standards in Sri Lanka. Since Ella is a main tourism attracted area in Sri Lanka, it is vital to maintain its aesthetic quality and recreational value. Therefore, it is needed to identify point source and non- point sources of pollutants of Beeralla stream and control with an appropriate short-term and long-term technique.
item: Thesis-Abstract
Post evaluation of operational performance of compost projects of local authorities funded by Pilisaru national solid waste management project
(2021) Dinushika LGT; Jayaweera M
The highest percentage (80%) of organic waste generation was recorded in Sri Lanka compared to the other Asian region countries with higher moisture content and low calorific value (Waste Management Outlook, 2017). Total waste generation in the country is about 8,700 Tons/Day and from that 4,480 Tons of waste has been collecting per day (NSWMSC,2019). Considering the waste composition and prevailing socioeconomic parameters, composting can be considered as a most convenient technology that can be applied for organic waste having high moisture content. Pilisaru National Solid Waste Management project has been initiated as a long term solution for solid waste management in the country towards zero waste in 2030. Considering the necessity and suitability, Pilisaru Project provides financial and technical assistance to the requested local authorities in the country to initiate compost projects and other requirements to manage solid waste in a sustainable manner. According to the Pilisaru data, majority of compost plants are in operational stage (83%) and 17% of sites are not in operational states either those sites were totally ended or inactive due to many reasons. The cumulative financial progress of the Pilisaru project is Rs. 2629.74 Million by 31.12.2018. Compost yards implemented under the Pilisaru Project produce about 386 Tons/month of compost and it is about 67% of the total designed capacity. This study aims to evaluate the performance of projects implemented by Pilisaru National Solid Waste Management Project in Southern and Western part of Sri Lanka based on analyzing data and information through field visits, questionnaire survey, formal and informal discussion and expert interviews. According to the findings sites were failed due to poor waste management such as inadequate financial assistance and technical expertise in waste management, failures in site selection and design considerations, low institutional commitment and community involvement, produced compost in poor quality and no regular monitoring of composting process and quality of produced compost etc. Furthermore, gaps identified by analyzing existing solid waste management practices conducted by the local authorities at a significant level and this study proposed practices that can be used by local authorities to rectify the identified gaps. Therefore, best practices in solid waste management need to be practiced further to overcome issues related to waste management in the country. This revealed that out of 20 selected sites, 07 sits show over 75% performance level, 08 sites show 75% - 50% performance level and only 5 sites show below 50% lower performance level.
item: Thesis-Abstract
Treatment of textile wastewater containing dye stuff by fenton oxidation process and adsorption
(2021) Parimalarajah D; Jayaweera MW
Environmental pollution is the most severe global issue threatening our ecosystem in the current scenario. Pollution is present in every strata of the earth, and the negative effects associated with it are a major source of concern in the modern era. Textile industry hazardous effluents are regarded as one of the major contributors to water pollutants discharged untreated into bodies of water. The discharged effluents from these industries have been demonstrated to bear a high pollution load (high dissolved solids, COD, colour and chloride content) with poor biodegradability. Therefore, untreated textile wastewater causes severe damage to the environment if discharged without treatment. Many techniques like electrochemical coagulation, reverse osmosis, nanofiltration, adsorption using activated materials etc., draw attention to treatment. With traditional approaches, treating textile wastewater, which is of great strength and complexity, has become a significant challenge. Advanced oxidation processes represent a powerful treatment for refractory and toxic pollutants in textile wastewaters. The present investigation is focused on COD removal, using Fenton oxidation and combined treatment with materials of TiO 2 , Commercial activated carbon and TiO 2 impregnated activated carbon (AT). Initial COD level of 2100mg/l decrease up to 710 mg/l through Fenton oxidation process. Further to discharge treated wastewater into the water body (<250mg/l) is achieved with 8g of TiO 2 ,7 g of CAC, and 6g of TiO 2 impregnated AC. CAC was selected as the best material economically for post-treatment. Many factors influenced the degradation rate in the Fenton process, such as initial hydrogen peroxide concentrations(0.65ml/l), initial iron concentration (1.5 g/l) and pH (2-3). CAC gave maximum COD removal at pH 2. The data were fitted to the Langmuir adsorption isotherm, with a maximum adsorption capacity of 8.16 mg/g and monolayer dye adsorption to the material. The Langmuir adsorption separation factor was 0.033, indicating that the Langmuir adsorption is favourable. The reaction proceeded in a pseudo-second-order, implying chemisorption to the substance. The optimum regeneration agent was found to be NaOH, and the material was exhausted after two regeneration cycles. From the results Fenton with CAC adsorption is most efficient treatment method at higher dye concentrations and for textile industry effluent.
item: Thesis-Full-text
Defluoridation of potable water in CKDu prevalent areas enriched with hardness using modified-fly ash functionalized with iron oxide
(2020) Priyadarshani EAC; Jayaweera MW; Gunawardana WB
Chronic Kidney Disease of Unknown Etiology is a major health issue reported in countries around the equator including Sri Lanka, Tunisia, Andra Pradesh India, and El Salvador. In Sri Lanka, CKDu is prevalent in the North-Central Province and now it is being progressed in the dry zone. The exact causal factor for the disease is not known yet where scientists now mainly suspect that the multiple ion interaction in potable groundwater may be the root cause for the disease. Further, fluoride ion concentration is higher in CKDu prevalent areas and the interaction of fluoride ion with other constituents (Cd, As, Al, hardness) is mainly suspected as the cause for the disease. The synergistic effect of hardness and fluoride on the CKDu had been discussed in many studies worldwide where the prevalence of other ions is very less, and it is below the WHO maximum allowed concentrations. The hardness and fluoride distribution are relatively higher in CKDu prevalent areas in Sri Lanka and the nephrotoxicity of hardness and fluoride in their mutual presence is proven by experiments with mice. Our preliminary studies found that there is no CKDu when the hardness and fluoride concentrations of water are below 200.00 mg/L and 0.47 mg/L, respectively. Therefore, this study was carried out to remove the hardness and fluoride concentrations of water to the level of 200.00mg/L and 0.47mg/L, respectively. Initially, a divalent cation exchange column was designed using a commercially available cation exchange resin, ECO A, to remove excessive hardness level up to 200.00mg/L. The eluent from the cation exchange column was further treated for defluoridation. Coal derived fly ash was further modified using the hydrothermal method. The Modified Fly Ash (MFA) was further treated with Fe (III) Chloride to generate positive charges on the surface. FTIR, SEM, EDX, confirmed the incorporation of Fe into MFA and, the defluoridation ability of Fe functionalized MFA. FTIR spectra (400cm-1 – 600cm-1 region) showed the incorporation of Fe into MFA. The average crystalline size obtained from XRD analysis was 23.3nm and the synthesized material was in nanoscale. The batch experiments showed that 1.3g of the Fe functionalized MFA resulted in the maximum defluoridation for a 100.00 ml of water sample containing 200.00 mg/L hardness and 2.00 mg/L fluoride within 40 minutes of contact time at pH 6. The material gave optimum defluoridation at pH 6 and therefore there is no need of altering the pH of water for the defluoridation. The adsorption data fitted with the Langmuir adsorption isotherm where the maximum adsorption capacity was 10.00mg/g. The separation factor for the Langmuir adsorption was 1.23 and therefore the Langmuir adsorption is favorable. The reaction followed pseudo second order kinetics. Regeneration studies of the Fe functionalized MFA showed that iii NaOH was the best regeneration agent and the material was exhausted after two regeneration cycles. The material synthesize cost to purify water for a five-member family for three months was LKR 6923.07 (37.52USD) and the cost for the regeneration was LKR 174.46 (0.95USD). Therefore, the synthesized material is ideal and cost effective to remove fluoride in potable ground water in CKDu prevalent areas.
item: Thesis-Full-text
Defluoridation of potable water in CKDu prevalent areas of Sri Lanka by functionalized modified-fly ash
(2019) Perera WDMC; Gunawardana WB
The last two decades marked a progressive increase in an epidemic of Chronic Kidney Disease of unknown (‘u’) origin (CKDu) among the farming communities in Sri Lanka. In the presence of the combination of fluoride, with other potential nephrotoxic ions or constituents can lead to the development of CKDu, even at lower concentrations of individual ions. The Na/Ca ratio and fluoride combination in potable water, has been identified as one of the plausible causes of CKDu. The toxicity of potable water from CKDu prevalent areas could be minimized, if the fluoride level of the CKDu prevalent areas can be brought below 0.4 mg/L, to overcome the synergistic effect between Na/Ca ratio and fluoride. The effects of solution Na/Ca ratio, on the adsorption of fluoride onto functionalized modified fly ash (FMFA) were investigated in this work. (FMFA)opt was selected as the optimized FMFA from a series of synthesized adsorbents, with varying degrees of functionalization with CaO, MgO and Al2O3. It was found that the maximum adsorption took place at pH 6.8 and the maximum monolayer adsorption (Qm) increased from 0.452 mg/g to 0.755 mg/g when the Na/ Ca ratio of the solution was changed from 01 to 07. The adsorption studies confirm that the Ca2+ ions in the solution were rejected by (FMFA)opt while giving preference to F- ion adsorption, according to the Donnan coion exclusion rule. The defluoridation reaction fits the Langmuir Model and pseudo second order kinetics. NaOH was identified as the best desorbent for (FMFA)opt. regeneration. (FMFA)opt is a low cost, an effective and efficient adsorbent to remove fluoride irrespective of the Na/Ca ratios present in CKDu prevalent areas.
item: Thesis-Full-text
Attitude of affected households towards the mode of compensation and possible issues due to land acquisition for expressway projects in Sri Lanka
Dharmawardhana, HMT; Manatunge, JMA
Road and highway projects are intended to either build new roads or widen or improve existing ones. Opening up a corridor for a new road requires more space resulting land acquisition and the resultant negative impacts are usually more severe than in road rehabilitation or upgrading. In this thesis, the methodology is discussed in two phases. In the first phase, data were collected using a questionnaire from the households who were affected due to the land acquisition for Southern Expressway and Extension of Southern Expressway. The survey was conducted from 20th May to 17th June 2017. Altogether 86 affected households were selected and interviews who were resettled in Matara and Colombo districts. In the second phase, quantitative data was collected from secondary data sources such as databases available at Government Institutions, published books, journals, and newspaper, etc. Attitudes of the affected households depend on their expectations. If the expectations are fulfilled as they wish, affected people are satisfied with what they received. Almost all the affected households are concerned about the amount of compensation. Because they should find new land to re-build their residence/housing unit or continue livelihoods or bear dedicatory assets. In the selected sample of the present study, 27% of the affected households expressed their satisfaction regarding the amount of compensation. Around 43% of the affected households gave affirmative answers (i.e., yes), while 57% did not answer positively on impacts related to developing of social infrastructures. Further to that, nearly 50% of the affected households had a satisfied attitude on the development of transportation facilities within their new settlements. Around 33% of the affected households had a positive attitude on improving the quality of living, especially among those who were interviewed in the Colombo district. This is due to around 28% of affected households did not face the risk of flooding twice a year after resettlement. Remaining 5% of the affected households were squatters who received 10 perch land by the government. These may create a positive attitude in the minds of the affected households on improving the quality of living when they were adapting to the new location. Nearly, 72% of the affected households, loss of relatives, neighbours and/or friends were the most cited negative social impacts of the project. The opinions of the people were significant and they mentioned that the social relationship among relatives, neighbours, and friends who were isolated. When adapting to the new location, the difficulties that they experienced due to isolation has been one of the factors which caused negative or positive attitudes in the minds of people. v Around 80% of affected households were affected by property loss, such as the acquisition of residential and commercial buildings, shops, and stores. Wells, gates, part of roofs and parapet walls were peripherals that were lost together with the buildings. When the affected households are pushed away, they have to build their life from scratch when adapting to another location than the original place. The living standard and living quality of the affected households were deteriorated due to project activities. Most obviously, the amount of compensation may be insufficient to fulfill their expected requirements. Therefore, the projects should pay particular attention to people with vulnerable conditions (21% woman-headed families) when monitoring and evaluating their situation for their living pattern and income restoration. The government policies are geared to pay adequate compensation regarding money and other provisions for landowners to be able to meet their resettlement requirements based on the criteria given. However, most of the projects have adopted their compensation methods based on the market value. The market value is not sufficient to rebuild their standard of living to a level that was there before the acquisition. Therefore, when valuing the properties of the affected people, replacement cost is the most appropriate one.
item: Thesis-Full-text
Evaluating the performance of subsurface horizontal flow constructed wetland for tertiary treatment of sanitary landfill leachate
Jeganathan SSD; Jayaweera MW
The difficulty in detecting and quantifying the typical composition characteristics of landfill leachate, limit successful treatment of it. High quality effluent that can be discharged to surface waters could be achieved by using the two stage leachate treatment systems with a constructed wetland at the final stage. This pilot scale study was conducted with the aim of evaluating the tertiary treatment of pre-treated leachate obtained from Sanitary Landfill located at Dompe, by a subsurface horizontal flow constructed wetland comprising Phragmites karka and Calicut tiles as substrate. The removal efficiency of BOD5, COD, TSS, NO3--N and PO43--P was evaluated. The study period was from June to August 2017. Sixty liters of diluted pre-treated leachate (i.e. Containing 80% of the pre-treated leachate by volume) was fed per day with a hydraulic retention time of 1 day. Concentration based average removal efficiency of the system was 63% for BOD5, 62% for COD, 96% for TSS, 49.11% for NO3- -N and 85.28% for PO43--P. Long term research is necessary to examine the effects of continuous feeding and shock loadings on the growth response of Phragmites karka.
item: Thesis-Abstract
Comprehensive guideline for sustainable involuntary resettlement : special case study on problematic Tsunami resettlement site in Galle district
Senevirathna, AD; Manathunga, JMA
Resettlement has a long history in the world. According to the way of resettling, it can be categorized in to two. Depending on the method of resettlement it can be categorize in to voluntary and involuntary resettlement. Several Law enacted by parliament, guidelines and policies at the different occasions of resettlement history. In fact, there was large scale resettlement program in Srilanka after the Tsunami devastation in December 2004. For the post Tsunami recovery program, the National Housing Development Authority (NHDA), under the Ministry of Housing & Construction, formulated a detail guideline to be used by the prospective house builders in the disaster prone coastal belt in Sri Lanka. Apart from this, Nongovernmental organizations and international organizations prepared guidelines and policies regarding the resettlement program. However there are several policies and guidelines available for resettlement, it was not happening in effectively. As a result involuntary resettlement sites have become partially and completely abandoned. This may attributed to the prevailing social, environmental, socio economic problems. The main issue is whether in voluntary resettlement has been correctly address by the resettlement project plan. Most resettlement projects not correctly follow the available guidelines correctly. Beside some guidelines developed by the government bodies do not to address the real ground level situation. In this research, the prevailing environmental, social, socio economic and physical problems of in involuntary resettlement have been identified and suggestions have been made to enhance NHDA guideline in to a comprehensive and more practical guideline for sustainable resettlement by considering the ten years experience of Tsunami resettlement in Galle district.
item: Thesis-Abstract
A Critical evaluation of wastewater disposal facilities in selected underserved settlements in the Colombo municipal area and recommendations for improvements
(2015-02-07) Irshadh, AG; Ratnayake, N
Sanitation has become a problem in many developing countries. According to reports from WHO and UNICEF in 2012 about 2.6 billion people around the world lack this facility and that counts to half the developing world lack even simple improved latrine. An underserved settlement (USS) is where communities live lacking access to basic services. Half the Colombo city’s population lives in the USSs. It is essential to provide better sanitation and improved wastewater (WW) disposal systems. To assess the type of water supply available, prevailing wastewater disposal methods and the sanitation system and to identify the types of toilets, six USSs were selected considering the municipal districts and the different types of WW disposal systems prevailing in the Colombo Municipal area, and surveyed. The results were evaluated against the standards provided by Joint Monitoring Programme of the WHO. During the study period there were 371 households (HHs) in six selected USSs. About 90% of the HHs has individual water connection. One for each 10 to 12 HHs that have individual septic tanks, and minimum one cluster of HHs that use a common septic tank, from each USS were chosen as representatives for detail study in the aspects of water usage and WW disposal. The results for satisfactory septic tanks are varying from 40% to 100%. Nevertheless none of the household has septic system and that results in diverting the septic tank effluent to the storm water drains ending up polluting the water bodies. In the toilet usage, only in one USS all the HHs have access to the improved sanitation facility. Except one USS in the other five, 50% of the HH which have improved toilets are named using unimproved toilets, because sharing. Only in two USSs less than 15% HHs directly dispose WW to the storm water drains. It is commendable that approximately 75% of the HHs, which has permanent housing, is willing for sanitation improvements. Based on these results recommendations are given to enhance the sanitation in the USSs.
item: Thesis-Abstract
Comparison and performance evaluation of submerged attached growth aerobic system versus suspended growth aerobic systems designed for factory sewage
Athukorala, IASL; Jayaweera, M; Manatunge, J
Most factories found in Sri Lanka do not have proper sewage treatment systems and due to the high number of employees these factories are always encountered with the problem of handling large quantities of low strength sewage generated from lavatories, canteens and kitchens. In such factories sewage is usually handled using conventional septic tank - soakage pit systems. Such systems are commonly found infested with insects, and promote further breeding. They cause nuisance due to obnoxious odor, and is a major cause for severe ground and surface water pollution. It has been noted that these factories have critical problems of handling sewage during rainy season, especially when the factory is located in areas with high ground water table such as a marshy land or near a surface water body. However, some factories consist of a conventional activated sludge system and a higher percentage of activated sludge processes found in these factories are in the malfunctional stage due to the least attention by the factory management. The activated sludge systems require a very high attention for the proper operation. The major problem of such factories is the giving of the least priority for the above issue and therefore the allocation of competent personal to operate plant is neglected. ,.' Therefore, their key demand is to provide them a treatment system to treat sewage with minimal operational difficulties and minimal labour involvement to overcome above problem. This research was therefore carried out with the following objectives to fulfill the above requirement. The broad objective is the study and compare the performance of aerobic attached growth and aerobic. suspended growth processes designed for factory sewage and recommend the most appropriate treatment regime for the factory sewage with regard to less operational and maintenance issues. Therefore, BOD removal efficiency and nitrogen removal efficiency have been compared for both processes in order to evaluate the performance of the each process. The estimation of sludge wasting, appropriation of process control parameters and operational issues in both processes are studied for the justification of the operational feasibility of each process. The land utilization and operational and maintenance cost have been estimated to identify the economical feasibility of each process. This study has proved that the BOD removal efficiencies of each process are equal and the nitrogen removal percentages are 43 % and 37% in attached growth process and suspended growth process respectively. Sludge production is 27 % less in attached growth process and thereby sludge handling is easy and esthetically good. The operational issues have been proved less in attached growth process. Annual operational and maintenance cost for the attached growth aerobic process is 30 % less over suspended growth aerobic process. Land requirement (foot print) is 13 % less in attached growth process over suspended growth process. Unit cost Rsl m3 of treated water for attached growth process has been proved that 32% less. Therefore, submerged attached growth system is, recommended as a less complicated, trouble free method for treatment of the factory sewage.
item: Thesis-Abstract
Conservation of masbedda (Gymnemasylvestre R.Br.) through propagation
Kumara, KKIUA; Subasinghe, S; Jayaweera, M
Several activities could be undertaken aimed at conservation and sustainable use of medicinal plants. Some of them are undertaken directly at locations where plants are naturally occurring. while others are less direct, such as commercial cultivation systems. Cultivation of medicinal plants is particularly important for species, which already have a good market demand. Gymnema sylvestre is one such rare medicinal plant. Therefore, the present study was aimed at developing cost effective and simple propagation techniques for Gymnema sylvestre. Investigations on both sex-ual and vegetative means of propagation of Gymnema have been carried out, at the Faculty of Agriculture, University of Ruhuna, Mapalana, Kamburupitiya from October 2002 to November 2003. Viable, uniform seeds were screened and used for seed propagation studies. The effect of sowing media on germination of Gymnema seeds has been investigated using four kinds of sowing media; sand, coir dust, a mixture of top soil and sand (1:1) and a mixture of sand top soil and coir dust (1: 1:1). Seeds were stored in an open system under room temperature (30°C) and germination percentage was recorded at 15-day intervals. This was to find out the effect of storage period on germination of seeds. Complete Randomized Design was used for the experiments with five replicates, each contained ten seeds. Germination percentage was calculated and the experiments were repeated to confirm the results. For vegetative propagation studies, three separate experiments were carried out using stem cuttings. Double nodal semi-hard wood cuttings were rooted in polybags filled with different rooting media including sand, a mixture of sand and top soil (1: 1), a mixture of sand, top soil and compost (1:1:1) and top soil alone to investigate the effect of media on rooting. Hard wood, semi-hard wood and soft wood cuttings were planted in polybags filled with a mixture of sand, top soil and compost (1:1:1), to determine the effect of maturity of cuttings on rooting. Effect of watering on rooting of cuttings was investigated using semi-hard wood cuttings planted in polybags contained a potting mixture of sand, top soil and compost (l:1: 1) with three watering frequencies. Complete Randomized Design was used for the studies with ten replicates. Number of roots, root length and root biomass accumulation were measured at the end of 6,10 and 14 weeks after planting. Results showed that germination percentage of seeds was significantly (p≤0.05) high (92 %) in coir dust, whereas the lowest germination percentage (28 %) was observed from top soil media. There were no significant (p ≤ 0.05) differences in germination of seeds throughout the first two months of storage under normal condition. Results of the vegetative propagation studies revealed that a mixture of sand, top soil and compost (1:1:1) was the most suitable rooting media for Gymnema cuttings, whereas the semi-hard wood cuttings rooted significantly (p ≤ 0.05) higher than the hard wood and soft wood cuttings. With regard to the watering frequency, cuttings watered once in two days rooted and performed significantly (p≤ 0.05) better than the other treatments. Results can be concluded that Gymnema sylvestre can be propagated by means of both sexual and asexual methods. Semi-hard wood cuttings, which appear to be more amenable to rooting and potting mixture of sand, top soil, and compost watered once in two days, showed the best results, while high germination percentage of seeds could be obtained within first two months of storage.
item: Thesis-Abstract
Strategies for the improved management of coastal zone of Sri Lanka
Dissanayake, UAPK; Hettiarachchi, SSL; Samarawickrama, SP
Sri Lanka has a fully operative Coastal lone Management Plan (ClMP), which is periodically updated. The 2003 Coastal lone Management Plan has followed and built upon the 1997 Coastal lone Management Plan with additional components introduced to address the current requirements. However, some areas have not been addressed in great detail even in ClMP 2003. The Costal Erosion Management Plan does not include green engineering measures and the Conservation Plan does not include the Estuary and Lagoon management in depth .It has been emphasized that a national recommendation regarding policy design is inappropriate and site specific policy design is required. Fisheries concerns, which were not addressed earlier, are included in ClMP 2003. Extending the SAM process. to all areas requiring site specific and integrated sustainable resource management are key objectives in the ClMP 2003. Sea level rise is one of the more certain responses to global warming and presents a major challenge to human kind. The average global sea level rise estimated by IPCC is at 31 em to II0cm by the year 2100 with a best estimate of 66cm. The land loss estimated using the simple drowning concept on the southwest coast is 6.0 to 11.5 km2 when the low and high scenarios of sea level rise are concerned respectively. In assessing the vulnerability to sea level rise the new techniques such as GIS, Remote Sensing and Aerial Video Tape assisted analysis should be used. Brunn Rule is another very widely used technique to assess the land loss. It has been estimated that the Coastline of Sri Lanka will recede by as much as 50 to 500mwithin the next century purely due to rise in sea level. Therefore, it is extremely important to pay attention to sea level rise in the future in the design, planning and implementation stages of coastal development, coastal protection and coastal management activities. The estuary management plans should be consistent with the tenets of total catchment management and ecologically sustainable development. It is important to realize that basic methods to understand the distribution of pollutants in estuaries can be a management tool and an aid in decision-making but nothing more. The recommended ratios of nutrients in estuaries are given by Redfield Ratios, however, a review of the literature indicates that optimum N: P ratio can vary between seven and eighty-seven. The greatest uncertainty with estuary nitrogen budgets concerns the contribution of atmospheric deposition. The principal management objective identified for Sri Lanka is conserving lagoons and estuaries to sustain and enhance environmental functions of and promote socio-economic activities connected with them. Three budgets were created for Negombo estuarine system using CABARET. The one layer I box budget indicates that the system is net heterotrophic and denitrification is dominant. The 2 box I layer budget indicates that the estuary is net heterotrophic in the wet season. In the dry season the system box I is net autotrophic while system box 2 is net heterotrophic. In 2 box I layer system too denitrification is dominant in the estuary both in wet and dry seasons. In the 3 box 1 layer model there are some regions in the estuary, which are autotrophic while rest of the regions, are heterotrophic. And in some region nitrogen fixation is the dominant process. Therefore, it is more suitable to use a multiple box model to understand the nutrient pollution problems and biogeochemical processes in the estuary. From the types of management programmes, which have been adopted globally, the use of an effective Integrated Coastal Zone Management Framework is most relevant to the management of Coastal zone of Sri Lanka. When compared to applications of management frameworks from different countries, legal, institutional and organizational requirements are not a serious problem in Sri Lanka. Community based approach which is already in use should be extended and management tools such as GIS and Vulnerability Assessments should be incorporated into the ICMF.
item: Thesis-Abstract
A Study of the present status of management of PCBs, and development of a preliminary inventory for PCB contaminated transformers in Sri Lanka
Panditharatne, CR; Ratnayake, N
Polychlorinated biphenyls (PCBs) have wide applications and one of its main uses is as the dielectric fluid in electric equipment. During 1970s PCBs were identified as a substance dangerous to health and environment and was banned in most countries since 1980s. Assuming that 60% of its uses are as dielectric fluid in electrical equipment, this survey was concentrated on transformers. In Sri Lanka, CEB, LECO, LTL are the main service sector stakeholder agencies that own and manage transformers and capacitors that could be contaminated with PCBs. Other than these institutions there are transformers owned by private sector users. Small scale recyclers also handle transformers for smelting of copper and recycling of waste oil. The objective of this study is to estimate the extent to which there are PCB contaminated equipments in the country; to identify issues faced by stakeholders and to provide recommendations for the management of PCB contaminated equipment. Questionnaires, surveys and field visits were undertaken for the collection of information. In the survey, information about transformers manufactured on or before 1986 were collected. There are 14,354 transformers owned by CEB and 2700 owned by LECO. In the survey, 354 in-use transformers and 296 decommissioned transformers were investigated. 118 In-use transformers were tested with the Dexsil Field Test Kit and 52 decommissioned transformers were tested. Dexsil Field Test Kit was used to eliminate PCB negative transformers. In Sri Lanka, there are a few pure PCB transformers, but a considerable potion of contaminated mineral oil transformers exist in the country. According to the findings of the study, with 95% confidence level, it can be stated that 73% to 56% of in-use transformers in the population are contaminated with PCBs, while at the same confidence level, 78% to 52% of decommissioned transformers are contaminated. There are several HS codes under which PCB oils, contaminated material and waste oils could be imported to Sri Lanka. There is no legal requirement for a 'PCB free certificate'. Possibility of informal recyclers being contaminated with PCBs is quite high because there are no controls over disposal of PCB contaminated transformers. Recyclers are completely unaware about the hazards of PCBs. Storage of contaminated transformers/material is not environmentally acceptable and there is a high possibility for environmental contamination. Main recommendations of the study; 1. Establishment of a complete Inventory and a Database on contaminated transformers. 2. Identify all Pure PCB transformers and have a phasing out plan. 3. Establish procedure for Operation and maintenance of contaminated transformers to prevent further cross contamination. 4. Prevent new entry of contaminated capacitors, transformers and oils to Sri Lanka 5. Proper disposal of decommissioned transformers. 6. Establishment of proper storage; identification and remediation of contaminated sites. 7. Establishment of necessary regulations for the implementation of the above.
item: Thesis-Abstract
Phytoplankton as bio indicators in management of eutrophication problem of Kandy Lake
Jayasekara, HPS; Piyasiri, S; Ratnayake, N
Eutrophication through the process of nutrient enrichment of stagnant waters due to urbanization & agricultural practices is becoming a significant water pollution issue in Sri Lanka. The appearance of thick Microcystis aeruginosa bloom in 1999 indicates that the Kandy Lake is also becoming the victim of nutrient enrichment. Therefore an effective Lake Management and Lake monitoring programmes with integrated catchment management have to be adopted and it is a prior necessity in planning of the management practices of the catchments to get firsthand information through research on trophic status of the lake. This study is focused on the evaluation of trophic status of the lake using Phytoplankton as indicators. The objectives of the study were to find out the species composition, variation of species richness & their diversity towards the trophic nature of Kandy lake through responses of the species towards different nutrient levels of the lake, and to develop different diversity index ranges which could be used as indicator levels of Lake Eutrophication, thus making it possible to determine the status of the water body through diversity index values. To achieve these objectives, the overall physico-chemical nature of the water body, was investigated by the parameters such as water level, water transparency, dissolved oxygen, temperature, conductivity, pH, alkalinity, nitrate, orthophosphate and biological nature by the parameters such as chlorophyll - a and the phytoplankton densities and species composition were determined. The laboratory experiments also were conducted using a series of diluted lake water as culture media to monitor the effect or Nitrate & Phosphate on indicator organisms. Sampling was carried out in Kandy Lake from October 2001 to March 2002 (six months), once a month during the day time. The total number of individual species collected at 08 selected stations at each depth surface, mid and bottom were quantified and the phytoplankton density was expressed as the number of cells per cubic meter of the lake water. These data were used in calculating diversity indices. During this study an attempt was made to develop a curve to predict the number of cells in a colony according to the size of the colony of Microcystis. According to the curve there were 20 cells per unit area (1 μm2) of Microcystis colony. Low Secchi Depth value «1 m) and high chlorophyll a concentration (100-250 mg/rn ') indicates Hyper-eutrophic nature of the Lake. High nutrient loading observed through out the study period (Average values of Nutrients varied between 204.65μg/L and 512.95μ/L for Orthophosphate and 0.114 mg/L and 0.243 mg/L for Nitrate) triggers that situation and it probably maximized by the mixing nature of the lake. Only a few (06) phytoplankton species were recorded in Kandy Lake during the study period; namely Microcystis aeruginosa. Microcystis incerta, Pediastrum duplex. Merismopedia tenuissima. Melosira granulata. Diatoma elongata. Out of them Mtc...rocystis and Melosira were found in greater abundance indicating the eutrophic nature of the lake. The calculated diversity index values for water samples of entire Kandy Lake throughout the investigation period were below 10 According to previous studies diversity index 3 is clean water. Therefore values obtained for Kandy Lake indicates the eutrophicated status of the lake. Even during different seasons the values have never increased indicating permanent eutrophic status of Kandy Lake. The diversity index value of < I found for Kandy Lake could be used as a reference value to monitor the trends during restoration of the Lake. According to the physico chemical and biological observations of the present investigations, Kandy lake water is already eutrophic and therefore its bottom sediment may contain high nutrient concentrations adsorbed to the bottom sediment Therefore even if further nutrient inputs are controlled, the blooming could occur due to accumulated nutrient loads in the bottom and there is a need for quick remedial efforts if the Lake is to be saved from this bad situation. Diversity index values could be used as a monitoring tool in Management of Eutrophication in Kandy Lake even without time consuming and costly chemical analysis procedures.
item: Thesis-Full-text
A Study of the Negombo lagoon with respect to the salinity variation and pollution of the lagoon water and effects of proposed dredging activities
Malawaraaratchi, RN; Rathnayake, N; Samarawickrama, SP
Negombo Lagoon is a shallow basin estuary, located on the West coast of Sri Lanka, serving important functions including fishing and tourism. It drains water carrying nutrients and organic matter from the heavily populated catchment area and has faced the threat of the degradation of water quality. The objectives of this research are to study the seasonal and diurnal variation of salinity in the estuary, study the pollution status of the estuary; study the effects of dredging on the water quality and to recommend remedial measures. 17 sampling locations were selected for the study, which included points in the estuary and fresh water feeders. A Sampling programme of 6 days which covered both wet and dry weather as well as the spring and neap tidal periods was carried out. Salinity, nutrients and COD were measured at the flood and ebb tides. According to the salinity measurements, in the dry period, the estuary is fully mixed. Stratified conditions occur when the fresh water flow rate increases. Chl a measurements were used to assess the trophic state of the estuary and fresh water feeders. The estuary is eutrophicated both in the wet and dry periods and some locations are even hypertrophic. Out of the fresh water feeders, Hamilton canal is mesotrophic and has faced the threat of eutrophication. According to the literature, limiting potential of the tropical estuaries has been found to shift from N to P with higher fresh water flow rates and results of this study agree well with the above finding. Limiting P inflows is a remedial measure to improve the water quality. Where the loads of DIN and TN are concerned, Dandugam-Oya was found to bring the highest loads irrespective of the climatic conditions. Where the Phosphate loads are concerned, Ja-ela brings significant, constant loads on rainy season, while Dandugam-Oya brings the highest load with the highest flow rate. Out of the 7 dredging options studied, option 6 is the most feasible one.
item: Thesis-Abstract
Comparative study on two different wastewater treatment processes at crepe rubber factories
Vithanage, D; Ratnayake, N
In Sri Lanka most commonly used treatment methods for crepe rubber factories are pond/lagoon system and activated sludge system. The objective of this study is to identify the most cost effective and commercially viable treatment system to treat the effluent generated from crepe rubber factories. Mechanically aerated lagoon/pond system at Eheliyagoda Rubber Factory and activated sludge system at Parakaduwa Rubber Factory have been selected for this study. The average flow rates during the study period for the ETP at Eheliyagoda Factory is 30m3/d and it is 60m3/d for the ETP at Parakaduwa Factory. Also it is observed that the Eheliyagoda Factory uses 19% more water and the Parakaduwa Factory uses 43% more water than the water quantity stated in the Guidelines for Natural Rubber Industry. Considerable variations of influent BOD5 & COD to the treatment plants have been observed due to the changes in weather pattern and latex tapping activities are generally affected by the weather. pH of the wastewater generated in both factories is always less than 6.0 and the BOD5& COD removal efficiencies of the anaerobic treatment unit in both plants are less than 30%. The average BOD5 & COD of the treated wastewater obtained from the ETP at Eheliyagoda Factory is 53 mg/l and 229 mg/l respectively. Also the 60% of BOD5 readings and 90% of COD readings of the treated wastewater obtained from the ETP at Eheliyagoda Factory meet CEA standards. The average BOD5 & COD of the treated wastewater obtained from the ETP at Parakaduwa Factory is 77 mg/l and 340mg/l respectively. The 22% of BOD5 readings and 78% of COD readings of the treated wastewater obtained from the ETP at Parakaduwa Factory meet CEA standards. The average TSS values of the treated wastewater obtained from the treatment plants at Eheliyagoda & Parakaduwa Factories are 315mg/l &171mg/l. Total BOD5, COD & TSS removal efficiencies of the ETP at Eheliyagoda Factory are 93.5%, 94.5% & 67.5% respectively. Such removal efficiencies for the ETP at Parakaduwa Factory are 90.5%, 91.3% and 68.3% respectively. When considering the removal efficiencies of the aerobic facultative unit of each treatment system, they are higher in the MAL than the Activated sludge tank. The initial capital cost of the activated sludge process at Parakaduwa Factory is lower than the mechanical aerated lagoon system at Eheliyagoda Factory. But when comparing the cost for operation & maintenance of the treatment systems, it is lower in the treatment plant at Eheliyagoda Factory and it is 54.5% of the cost for the treatment system at Parakaduwa Factory. For the period of 10 years of the operation of the treatment plants, the unit cost for wastewater treatment in terms of Rs/kg at Parakaduwa Factory and Eheliyagoda Factory are Rs 1.59 and Rs 1.53 respectively. Also the one kilogram of BOD load, treatment costs for Parakaduwa Factory and Eheliyagoda Factoty are Rs 46.14 and Rs 47.11 respectively. Since the low operational & maintenance cost and high treatment efficiency of MAL system, it can be concluded that the mechanical aerated lagoon system is more cost effective wastewater treatment process for natural rubber industry where the land is available. Gravity flow to each treatment unit where ever possible and daily pH correction of the raw wastewater should obtained to achieve cost effective performance in both systems. It is also recommended to maintain a correct DO &. MLSS in the aeration tank at Parakaduwa Factory and to install a sand bed as a last unit for the plant at Eheliyagoda Factory
item: Thesis-Abstract
Waste minimization and wastewater treatment in an electroplating industry
Jayawardana, KGS; Ratnayake, N
Electroplating has been introduced to Sri Lanka more than a hundred years ago and there are more than 80 electroplating units in Sri Lanka, including household units. However, it has been found that the electroplating technology in Sri Lanka is lagging behind the world level and several problems of electroplating facilities with regard to plating technology and wastewater treatment had been identified. The objective of this study was to investigate the possibilities of waste minimization and optimization of wastewater treatment in the electroplating industry using readily available resources and technologies in the country, focusing on the nickel and chromium-plating process and treatment of wastewater generated in that process. Methodology of this study consisted of making observations of the existing process estimating water and energy consumption, analysis of process solutions and treated wastewater, studying process parameters used in the production process and wastewater treatment, and carrying out a designed experiment to study optimum pH for heavy metal precipitation. It was found that quality control of the product is poor and the industry lacks technical know-how to carry out the electroplating process and wastewater treatment efficiently. However, the industry has already implemented a few quality control and waste minimization activities such as quality control of intermediate product within the process, two stage rinsing, and dragout recovery. Possibilities to reduce electricity and water consumption without affecting the quality of the product through introduction of temperature control units for heaters, removal of unnecessary unit operations employed in the production process etc. and the necessity of proper stripping of rejects before recycling them into the production process in order to avoid unnecessary contaminations of bath solutions were identified. With regard to the wastewater treatment, it was found that the optimum pH for hydroxide precipitation of nickel and chromium in a mixture is pH 8.0. It is recommended to introduce drain boards, stripping for rejects, temperature feed back control system for heaters and improved process control in nickel-plating activity immediately and , to study the possibility of working longer hours a day than the normal 8hr shift, which would increase the savings on electricity used for bath heating. It is also recommended to omit unnecessary unit operations and to change over to Cr3+ chromium plating solution instead of Cr6+ solutions, while proper quality control procedures such as corrosion resistance test & Adhesion tests are carried out to increase the value of the product and reduce wastage. Measures recommended to improve the wastewater treatment system include carrying out chromium reduction at pH 3 for a minimum period of 30 minutes, strict control of Cr6+ discharge into the Heavy Metal Precipitation Tank, carrying out nickel and chromium precipitation at a pH value between 8 - 8.5 and filtering supernatant of the sedimentation tank to avoid escape of suspended material with the supernatant.
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.