Master of Science in Environmental Management

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

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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
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
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
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
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
Removal of chromium in aqueous solutions using powdered activated carbon treated with humic acid
Sooriyabandara, BH; Weerasooriya, R; Manatunge, JMA
Because of its toxicity, Chromium (VI) causes water pollution and threatens to the environment. Its solubility in nature is strongly inf1uenced by adsorption process. Relatively few studies have focused on adsorption properties onto the Powdered Activated Carbon (PAC). In this work. the PAC and humic acid treated PAC adsorption properties were compared.This study proposed humic acid treated Powdered Activated Carbon as a low cost adsorbent for removal of Chromium from aqueous solution. Adsorption of Cr (VI) by PAC was conducted using batch tests. The int1uence of pH, contact time, initial Chromium concentration on removal of Chromium (VI) was investigated. This test was also repeated with humic acid treated PAC. The optimum initial pH for maximum adsorption of Cr (VI) from aqueous solution was found to be 4.0. The removal efficiency was found to be correlated with the initial Cr (VI) concentration, ionic strength, as well as the contact time between the Chromium (VI) and the adsorbent. For humic acids treated PAC, the optimum adsorption also was found at 4.0. Therefore acidic medium is favorable to the Chromium removal.According to the experimental data obtained from this study, the percentage metal removal increased with increasing PAC dosage at the same initial metal concentration. After using humic acid treated PAC increased the metal removal percentage with same adsorbent dosage.When the effluent is in acidic medium, the PAC is more suitable as the adsorbent while the humic acid treated PAC is more suitable for basic effluent.
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-Abstract
Zero effluent solution for detergent industry
Dayananda, DH; Jayaweera, MW; Wijeyekoon, SLJ
Reuse of industrial wastewater is an important strategy for reducing freshwater consumption and wastewater generation as well as minimizing the potential impact of effluent on the environment. From an economic perspective, wastewater reuse reduces the costs of freshwater consumption and wastewater disposalWastewater is to be adequately treated prior to disposal. Surfactants including detergents are refractory organics that resist conventional treatment methods and therefore need an advance wastewater treatment. However, the cost of wastewater regeneration and treatment rises exponentially with increasing contaminant removal efficiency. In order to balance these competing cost factors wastewater disposal costs vs. wastewater regeneration and treatment cost has to be considered.This case study of the zero effluent solution provides experience in cost effective management of eff1uent as a resource, with minimizing the potential impact of eff1uent on the environment. The overall objective was to recycle wastewater as a resource for liquid detergent manufacturing process. Special attention is being given to control of unpleasant odour, maximization of reuse of surfactants and establishment of proper hygienic conditions in treated eff1uentThe results of wastewater characterization showed that the concentration of the organic matter is very high, expressed as COD ranging from 6,200 mg/1 to 34,400 mg/1, while the biodegradable portion was very low, since BOD/COD ratio was low. These values indicate that organic compounds are not easily subjected to biological treatment. In order to ensure the maximum reuse of surfactants and other important chemicals only physical treatments were adopted. They were aeration, filtration followed by UV disinfection. Two major limiting factors in the case of reuse wastewater were identified specific to this case study. (ie. Unfavorable odour experienced in collection sumps and contaminated with pathogenic micro organisms.) The proposed treatment can successfully solve these issues ensuring maximum reuse of important constituents in the eff1uent. More than this, it can reduce TSS up to 5!-l particle size, which is more beneficial in reuse for production process. The treated eff1uent is best foruse in coloured products.

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