Browsing by Author "Mowjood, MIM"

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item: Conference-Full-text
Application of floating wetlands at tropical context for Lake water reclamation
(2013-11-19) Weragoda, SK; Tanaka, N; Mowjood, MIM; Jinadasa, KSBN
Pollution of lakes increases rapidly due to the urbanization in developing countries. Therefore, it is necessary to set up feasible mitigatory measures to address eutrophication issues, concurrently considering the lack of land availability as well as low cost involvement. This study was carried out to find out possible application aspects of floating wetland units for lake reclamation. Hence, two types of macrophytes, i.e. Typha angustifolia and Canna iridiflora, were employed in the pilot scale experiments with two floating wetland systems and monitored water quality for the removal of BOD5 and inorganic nitrogen. Over 80% of BOD5 and NH4 +-N removal capabilities were obtained while NO3 --N removal was recorded as over 40%. On the other hand, the root growth and its density of T. angustifolia was higher than that of C. iridiflora, resulting relatively better performance by T. angustifolia compared with C. iridiflora. Consequently, floating wetlands with T. angustifolia will be an appropriate solution in lake restoration, especially located at congested areas.
item: Conference-Full-text
Characteristics of municipal solid wastes from selected plots located at up-slope and down-slope of the dumping site: a case study in Udapalatha/Gampola
(2013-11-13) Wijewardane, NK; Takahiro, K; Mowjood, MIM; Ken, K; Kurukulasuriya, LC
Open dumpsite has become the most widely used and common practices in most of the developing countries in waste management due to their lack of will, technology, capital and virtuous attitudes. This has elevated the risk to the ecosystem and humans derived by the improper dumping of waste in bare lands, sloping lands (valleys, river banks), wet lands etc. Characterization of waste is an important primary stage in studying dumpsites in sloping lands to identify its effects and potential remedial actions, and to develop new technologies to reduce their adverse effects on the environment and society. In this research, waste characteristics of some selected plots located at up and down slope of a dumpsite were studied to identify the possible difference and their relationships with the slope. The results revealed that waste characteristics such as ash content, combustible content, ignition loss and aggregated soil content vary in the plots located at up and down slope, suggesting that the rolling and sliding of larger particles in high sloping dumpsites has a profound effect in varying waste characteristics. This was further confirmed by the particle size distribution of both plots.
item: Conference-Full-text
Flux measurements of greenhouse gases from an abandoned open dumping site of solid waste in Sri Lanka
(2013-11-13) Nagamori, M; Koide, T; Wijewardane, NK; Watanabe, Y; Isobe, Y; Mowjood, MIM; Ishigaki, T; Kawamoto, K
The investigation of greenhouse gas emission from a waste dumping site in Sri Lanka was conducted. The investigated site in this study is an abandoned waste dump site located at a hilly river bank in the Central Province of Sri Lanka (N 7º 09', E 80º 35'), consisting of two different sections with waste ages of around 0.5 year (New-section) and 7 years (Old-section). A simplified method for determination of methane gas flux using laser methane detector was considered to be effective to grasp the magnitude of methane flux. It was shown that the points those exhibited high value of methane gas flux also showed low EC-value compared with those of the other surround points. Furthermore, the low hardness of these points indicated that large amount of methane gas flux was caused by high permeability of surface as some stumps had been grown or as boundary between buried waste and ground line had been loosened. Measured fluxes for methane, carbon dioxide, and nitrous oxide in New-section ranged in <0.04-1800, 4.9-1800, and <0.0001-0.35 mL m-2 min-1, respectively. Little amount of methane gas was emitted from surface in Old-section. Relatively high fluxes of nitrous oxide were observed in some plots at middle and bottom for both sections, suggesting that nitrification was stimulated by aerobic condition due to the penetration of air from the slope of dumped waste.
item: Conference-Full-text
Investigation of landfill suitability based on semi quantitative risk matrix and GIS
(2013-11-13) Balasooriya, BMRS; Vithanage, M; Mowjood, MIM; Kawamoto, K; Komai, T; Zhang, M; Herath, GBB; Hara, J
Open dumping is the most widely practiced method in Sri Lanka to dispose municipal solid waste (MSW) because it is the cheapest and easiest method compared to other methods available to manage MSW.Currently, there are no guidelines available for a proper selection of landfill dump site which may minimize the environmental, social and economic problems in the country. Site selection for landfill sites is an important aspect from both environmental conservation and social/economical point of view. Data was collected from the Udapalatha area for analyzing. Considering priority of all criteria in comparison with others, a specific risk rate was decided to each criterion according to their total influence on the whole process of decision making. Suitable landfill site was analyzed by using the Geographic Information System (GIS) together with risk assessment. To identify appropriate landfill areas in the study area, five input map layers including surface water bodies, distance from transportation routes, distance from urban areas, land use/land cover, and elevation were used in the mapping. Based on these data a risk assessment wascarried out with a semi-quantitative matrix. The findings obtained from this study could be used for preliminary information to develop criteria for new landfill site selection. Finally, suitable low-risk regions in the area have been proposed for solid waste landfill disposal.
item: Conference-Abstract
Investigation on neutralizing agents for palm oil mill effluent (POME)
Kalansuriya, MH; Mowjood, MIM; Dharmasena, DAN
Proper treatment of palm oil mill effluent (POME) is necessary to sustain the progress of palm oil industry in Sri Lanka. A case study was conducted to improve existing wastewater treatment system in a palm oil factory located in Galle district. The system consists of a neutralization tank, anaerobic ponds followed by anaerobic biogas digesters. Lime has been used to neutralize before sending to ponds for biological treatment. However, this treatment did not bring optimum pH for microbial action in anaerobic ponds. Therefore, performance of lime, caustic soda, iron lathe shavings and boiler ash from the same factory were studied for pH adjustment. A lab scale leaching bed with boiler ash was tested as it is freely available. Total carbon and total nitrogen in effluent were also measured. It was found that the Ca(OH)2 availability in commercially available lime was 31% and less effective. The effective dosage of caustic soda to obtain neutral pH was 5 kg/m3 thus lead to high cost. Iron lathe shavings and boiler ash of palm oil mill were effective and economically feasible in balancing pH. The boiler ash has shown significant effect in pH neutralization with the rate of 60 g/l with 4 days hydraulic retention time. Leaching bed with an ash layer shows an acceptable performance.
item: Conference-Full-text
Landfill gases at an abandoned open dump: a case study at Udapalatha/Gampola site in the Central Province of Sri Lanka
(2013-11-13) Koide, T; Nagamori, M; Wijewardane, NK; Watababe, Y; Isobe, Y; Mowjood, MIM; Kawamoto, K
There are very limited studies on landfill gas on uncontrolled open dumps in developing countries. In this study, landfill gas samples at 1 m depth from an abandoned open dump (AOD) in the Central Province of Sri Lanka (N 7º 09', E 80º 35') were collected and the typical landfill gas composition such as O2, N2, CH4, CO2, H2, H2S, and N2O were measured. Buried waste samples at 1 m depth were also taken from the site and organic carbon and nitrogen contents in the residue (< 2 mm) were measured. The samples were taken from some marked plots inside the dump with waste ages of around 0.5 and 7 years (AOD0.5 and AOD7) and outside intact (AODint). Measured CH4 concentration for AOD0.5 and AOD7 ranged in 19–58 % and 0–12 %, respectively, suggesting that the dumped waste at 1 m depth was in the process to be the ‘stabilization phase’ at least 7 years after dumping. This is likely to be a much shorter time period to reach the phase after dumping than those in mid-latitude regions (typically in several decades). The carbon contents in the waste residue in AOD0.5 and AOD7 were 151±67 and 29±7 mg g-1, respectively, implying that high waste decomposition and leaching of organic compounds might have been enhanced due to high temperature and precipitation at the site. A further study for the landfill gas and waste quality in the deeper layer is required to judge whether whole of the dumpsite had reached the stabilization phase rapidly.
item: Conference-Full-text
Performance evaluation of sub-surface flow constructed wetland systems under variable hydraulic loading rates
(2013-11-19) Mowjood, MIM; Herath, GBB; Jinadasa, KBSN; Weerakoon, GMPR
Wastewater treatment has given an immense attention in the field of pollution control throughout the world. This has become a challenge in developing countries due to the limitations of resources and expertise. Constructed wetlands where water, plants and microorganisms interact to improve the quality of water have been proven to be an effective low-cost wastewater treatment technology in many parts of the world, which does not necessarily require skilled personnel to run the system. However, these systems are not yet widely spread in developing countries due to lack of information. Constructed wetlands can be designed as surface flow or subsurface flow systems, depending on the level of the water column. This study compares the performance of vertical subsurface flow (VSSF) and horizontal subsurface flow (HSSF) constructed wetland systems at laboratory scale at tropical condition. This paper also evaluates the effects of Hydraulic Loading Rate (HLR) on treatment capacity of wastewater parameters such as Five day Biochemical Oxygen Demand (BOD5), Total Suspended Solids (TSS), Nitrate Nitrogen (NO3 —N), Phosphate (PO4 3-), Ammonia Nitrogen (NH4-N ), Fecal Coliforms (FC) and Total Coliforms (TC). Six wetland models of size 1.4 m x 0.5 m x 0.5 m (L x W x H) were constructed and arranged: 1) Two models as VSSF system with plants, 2) Two models as HSSF system with plants, 3) One model as a VSSF control without plants and 4) One model as a HSSF control without plants. An emergent macrophyte specie; cattail (Typha angustifolia), gravel media (size 10 – 20 mm) and synthetic wastewater with average concentrations of BOD5 ; 29.51 ± 4.21 mg/L, NO3 - - N ; 3.22 ± 1.25 mg/L, NH3 - - N ; 15.14 ± 2.65 mg/L, PO4 3- ; 6.78 ± 5.67 mg/L, Fecal Coliform 495.12 * 103 ± 307.12 * 103 counts/100 mL and Total Coliform 915.5 * 103 ± 719.83 * 103 counts/100 mL were used in this study. The HLR was increased from 2.5 – 25 cm/day at 12 days interval during two and a half months period. Sampling was carried out with each HLR from both influent and effluents of each wetland system after 12 days of constant flow rate, and wastewater quality parameters such as the BOD5, TSS, NH4-N, NO3 --N, PO4 3-, pH, Conductivity, FC and TC were measured in all samples. Results show that VSSF systems perform better than horizontal systems, but the treatment performance declines with the increasing HLR in all six wetland models.
item: Conference-Full-text
Spatial variation in landfill gas composition under different precipitation condition and waste age in Sri Lanka
(2013-11-13) Koide, T; Nagamori, M; Watanabe, Y; Isobe, Y; Wijewardane, NK; Herath, GBB; Mowjood, MIM; Kawamoto, K
A study was conducted to assess the effect of precipitation and age of waste on the stabilization of the dumped waste. Landfill gas samples at 1-m depth were collected from 13 waste landfill sites in Sri Lanka with different annual precipitation ranging from 1,000 to 4,000 mm and waste age ranging from 1 to 120 months. Typical landfill gases O2, N2, CH4 and CO2 were measured quantitatively by a gas chromatograph. Buried waste samples at 1-m depth were also taken from all locations to determine organic carbon contents in the residue (< 2 mm). With the age of wastes, the measured O2 and N2 concentration (ranged in 1 - 20% and 2 - 80% respectively) in collected landfill gas samples were increased and the CH4 and CO2 concentration (ranged in 0-60% and 1-68%, respectively) decreased, implying the buried wastes are getting stabilized within 120 months after dumped (typically in several decades in mid-latitude regions). However, the correlations between measured gas concentrations and the annual precipitations at the sampling site show no definite results. Organic carbon contents in the waste residues (ranged in 24-236 mg g-1) were not fully related to the waste age and the precipitation amount, while significant time-dependent decreases of the organic carbon contents can be observed in some investigated landfill sites. Further studies are needed with continuous monitoring of rainfall with gas emission.
item: Conference-Full-text
A statistical approach for landfill classification in Sri Lanka based on waste characteristics
(2013-11-13) Wijewardane, NK; Takahiro, K; Ken, K; Mowjood, MIM; Herath, GBB
Several parameters have been used to characterize wastes in dumping sites. It is not possible to measure all the parameters and also those parameters are not equally important for management options which are decided on priority basis. In fact some parameters are closely related to other parameters. Therefore, parameters have to be clustered for classifying the wastes in dumping sites. A study was conducted to develop a statistical procedure using available tools to cluster landfills based on landfill waste characteristics. Five waste samples were collected from three landfills in the central province of Sri Lanka to compare the waste characteristics followed by the use of data to elaborate the clustering procedure. Correlation diagrams, principle component and cluster analysis have been applied for eight parameters; Moisture content, Ash content, Unit Volume mass, Lower heating value, Particle density < 2mm, Plasticity index, pH and Electrical Conductivity. Statistical analysis was able to extract two main principle components as primary, and secondary which accounted for 92.1 % of the total variability establishing two main classes which can be further improved to be more representative and precise with the increased number of samples subjected to the analysis.
item: Conference-Full-text
Water Pollution in a Natural Stream and Its Impacts on Society and Environment: A Review of Studies on Meda Ela, Sri Lanka
(2016-01-04) Kumara, GMP; Perera, MDD; Wijekoon, WMSM; Pathmarajha, S; Dayawansa, NDK; Mowjood, MIM; Galagedara, LW
Abstract: Meda Ela which originates from Kandy Lake and runs through Kandy city is considered to be one of most polluted tributaries of Mahaweli River. The objective of the study was to critically review the published research findings related to Meda Ela pollution to existing problems, research gaps and the means to rectify the situation. The review was carried out under the categories of socio-economic background, land use changes, sources of pollution, solid and waste water disposal, water quality, cost due to water pollution, economic benefits and major stakeholders and their interactions of Meda Ela. Study identified a very high urbanization rate in the watershed during the last decade compared to previous 30 years. Major point sources include the hospital, bus stand, railway station, central market and the residences on either side of Meda Ela. According to the literature, elevated pollution levels are reported during wet season and NO- 3, NH+ 4, PO3- 4, suspended solids, heavy metals, DO, BOD and COD showed above threshold limits. This is an indication of non-point source pollution which is responsive to hydrological conditions. Impacts of water pollution include vector borne diseases such as Dengu and Chickengunya, bad odour, flash floods and contamination of shallow groundwater with heavy metals. The social and management setup in the watershed is very complex since many stakeholders are involved in polluting and managing Meda Ela. The analysis revealed that the relationship among different stakeholders is highly diverse and as a result, their contribution to control water pollution in Meda Ela is also very different. Hence, a strong connection should be established between community and other stakeholders to develop an efficient and effective management plan to safeguard Meda Ela stream and its watershed.