A Tool for Sustainability: A Case for Biogas in Sri Lanka

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ENVIRONMENTAL IMPACT IDENTIFICATION AND POSSIBLE MITIGATING STRATEGY FOR BORALESGAMUWA LAKE

The degradation of lake environments and resources is now a world-wide issue.Efforts urgently have to be made to restore the friendly coexistence of lakes andhumankind through appropriate management of lake/watershed systems to assurethe sustainable use of their resources.ln this project the Boralesgamuwa Lake,which is one of the most distinctive landmarks within the town limits ofMaharagarna had been studied. The rapid urbanization of the town has led to theenvironmental deterioration of the lake exacerbated by numerous out fallsdischarging nutrient rich water into this stagnant body of water.Objectives of the study were identification of sources of polluting theBoralesgamuwa lake, significant impact of pollution, and designing anddeveloping a suitable mitigating strategy. There isn't any water quality monitoreddata relating to the Boralesgarnuwa lake. During this study, pH, conductivity,temperature, DO, BOD, COD, nitrate, phosphate and the coliform levels of thelake water were examined & also several sources of polluting the lake wereidentified. About 30 surface water samples were analysed during Feb. 2000 toJuly 2000. Heavy metal pollution of the lake was also examined.Physicochemical characteristics of the Boralesgamuwa lake water showedsignificant site-specific & time-bound variations during the study period.The phosphate concentration in surface water close to wastewater dischargingpoint of one garment factory is comparatively high. During the month of Aprilphosphate concentration at that point was comparatively low, because at that timethe factory was not working. At the point, where the urban waste water drainageline is entering the lake, the nitrate concentration is fairly high. Most of the lakesurface is covered with macrophytes and with very high amount of the waterhyacinth (Eichorniai. The coli form count of the lake is also very high. TheMPN (Most Probable Number) is more than 1000 per 100 ml for the most of thelocations. The faecal coli form count is also very high. Unauthorized settlers andenchroachments are common factors of the lake reservation.The industry concerned is already doing primary treatments and they aredischarging their effluents according to the CEA standards. But the problem isstill there. There are no industrial effluent standards for phosphate in Sri Lanka.Proposed mitigating strategies for these negative impactsl.For phosphate reduction1.1Chemical treatment1.2Biological treatment2.For urban waste water2.1 A central waste water treatment plant should beinstalled3.For reduction of faecal contamination3.1 A sewerage system should be designed4.Unauthorized settlers and enchroachments4.1 Unauthorized settlers andenchroachers should be resettled.

ANTIMICROBIAL EFFECTS IN MANAGEMENT OF WASTEWATER TREATMENT PLANTS

Many wastewater treatment plants operating today in various industries have one or morebiological treatment component. which could he either aerobic or anaerobic. or acombination of hoth. The type of biological treatment utiliscd will vary from one plant toanother depending on the nature of the wastewater treated. Industries such as chemicalprocess. pharmaccutical etc. have to pay more attention to their wastewater sent to thewastewater treatment plant as these wastewaters may contain substances in quantitieswhich can cause harmful effects to the living organisms in the biological treatment system.thus action should he taken 10 reduce these antimicrohial substances entering the hiologicaltreatment component of the wastewater treatment plant to levels to which the biologicalpopulation is more capable of handling those in the degradation process. An action tomanage this type of situation will call for the need for monitoring techniques or quantities.In this concept paper. online and offline monitoring techniques of such substances and itsmanagemcnt concepts arc illucid.ucd. In monitoring wastewater the use of the parameterBOD and the inhibition chnractcristics of the microorganism were looked at with referenceto wastcwater from a pharmaceutical manufacturing industry.

HIGH RATE BIO METHANATION OF MUNICIPAL SOLID WASTE

Growing urbanization and industrialization have led to the generation of large quantities of solidwastes, which can be broadly classified as MSW (Municipal Solid Waste) and ISW (Industrial SolidWaste). Among the options available for solid waste management, biomethanation appears to be themost desirable because it is a technology with triple benefits: yields biogas which can replaceconventional fuels, provides digested sludge which can be used as a soil conditioner and manages theenvironment.This work involved the development of a three-stage leachate based bioreactor system for solid wastemanagement. The first stage involves extraction of high organic strength (high in chemical oxygendemand - COD) liquid called leachate from the solids. This stage is known as the hydrolysing stage.Acid formation takes place in the second or the acidification stage in a separate reactor known as theacidification reactor. Biogas is generated by treating the acidified leachate in an upflow anaerobicfilter (AF) reactor in the third (or the methanation) stage.Three stage anaerobic systems arc increasingly finding its place in biogas generation. Two kineticallydissimilar groups of bacteria, acetogenes and methogencs arc physically separated in acetogenicreactor and methanogenic reactor. This separation allows optimization of both acetogenesis andmethanogenesis stages making the process control easier.In this method, the organic solid waste is cut into small pieces, fed into the hydrolysing reactor withwater and circulated at a fixed rate to wash off organic acids formed until high organic strength isobtained. This is then fed in to the acidification reactor. The acidification phase has retention time ofG days. Anaerobic conditions prevail inside the reactor during the whole process. The residue leftinside from the first reactor is subjected to drying for manure preparation.The final concentrated leachate obtained after 6 days is fed in to the AF reactor for methanation. Thisphase has retention time of 5 days. The microbial consortia present in the AF sludge destroys highamount of COD, forming biogas comprising of 65% - 75% methane. This system is economicallyviable, the total space and the time required for the process is low compared to conventional singlephaseprocesses that takes 30-40 days. The system has low water consumption because of the reuse ofthe AF reactor overflow to the acidification reactor.

Synthesis of Magnetite Nanoparticles by Top-Down Approach from a High Purity Ore

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

The Development of a process to synthesize carbon nanotubes from biogas

Carbon nano tubes represent one of the most important materials in. nano science and nanotechnology. The unique properties of carbon nano tubes open new fields in science and technology. This paper explains a simple process developed towards synthesizing carbon nano tubes from bio gas by the method of chemical vapor deposition. In this process, Ni/SiC>2 was used as catalyst at 550 °C temperature. The bio gas was supplied to the reactor for one hour continuously. The final sample was investigated by means of scanning electron microscope (SEM)

The eco-social transformation of urban wetlands: A case study of Colombo, Sri Lanka

Recent studies in both the environmental sciences and geography highlight unforeseen ecological transformations occurring in eco-social landscapes. These transformations often result in 'novel' or 'hybrid' ecosystems that differ from the original ecosystems both in ecological character and social setting. However, little is known about the causes, consequences, and dynamics of such transformations in complex urban environments and the consequences for highly sensitive ecosystem types such as wetlands. This paper investigates the environmental history and recent ecological transformations in the urban wetlands of Colombo, Sri Lanka. Our methodology includes a combination of techniques from environmental history, wetland science and urban ecology. We investigate the ecological changes in the wetlands from colonial times to the present and establish relationships among wetland ecology (the hydro-soil-vegetation nexus), landscape change, community, and governance factors. We conclude that from 1980 onwards, the Colombo urban wetlands have undergone an overall transformation in both wetland type (composition and structure) and the social setting. Hydrological modification, watershed urbanization and the changes in ecosystem use were identified as the main causes of wetland transformation with the causes and consequences of the transformation having complex feedback loops. We synthesize these relationships into a post hoc conceptual model that will be of broader utility as a general framework to understand eco-social interactions in the governance of urban ecosystems