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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Pump scheduling under uncertainty

McCormick, Gregory January 2003 (has links)
No description available.
2

Filter beds for on-site wastewater treatment : Towards more reliable estimations of phosphorus retention / Filterbäddar för småskalig avloppsrening : Säkrare bedömning av fosforretention

Herrmann, Inga January 2014 (has links)
Phosphorus (P) is an important plant nutrient and essential for life. However, thephosphate rock used for fertilizer production is a non-renewable resource and itsproduction is expected to peak. At the same time, the discharge of P into naturalwaters is causing eutrophication, a severe problem in areas such as the Baltic Sea. Onsitewastewater treatment facilities in Sweden contribute substantially to this discharge because of their inadequate retention of P. Filter beds are a potentially useful technique to capture P in on-site facilities. However, many variables need to be considered when the P retention of potential filter materials is estimated in laboratory tests prior to designing full-scale filters. The overall aim of this thesis was therefore to increase the reliability of forecasting P retention in full-scale filters by increasing the understanding of P retention in P filters under varying conditions and by identifying measures that could lead to more reliable methods of testing filter materials at laboratory scale.The effects of influent type, influent P concentration, loading rate and ambienttemperature on the filter materials Filtra P, Filtralite P, Top16 and Polonite wereinvestigated in filter column experiments using 22 factorial designs. Furthermore, the P binding mechanism was studied using mineral phase investigations and by determining the reaction time of the P in the filter. In addition, filter performance was estimated by means of hydro-geochemical transport modelling.The investigated factors significantly (Į = 0.05) affected the retention of P in the filter materials showing that it is important to consider those factors when designing laboratory filter experiments and full-scale filters. Using secondary wastewater as an influent instead of P solution decreased the P binding capacity of Filtralite P, probably due to organic compounds contained in the wastewater. Increasing influent P concentration decreased the number of bed volumes treated before breakthrough in Filtra P by 82%. The loading rate was shown to be an important design parameter. Increasing the loading rate, something commonly done in the laboratory to accelerate the testing, significantly increased the amount of washed-out particulate P in Filtra P and Filtralite P. However, the residence time was also shown to be important; it should be maximised in filter tests as far as practical constraints allow. Increasing the temperature from 4.3 to 16.5°C increased the P binding capacity in both Top16 and Polonite which was attributed to an enhanced precipitation of calcium phosphates. This indicates that results obtained from experimental filters at room temperature might overestimate filter performance in the field where the temperature can be lower. In addition, full-scale filters might function better in warm rather than cool climates. The results further showed that it is crucial to measure both the concentration of dissolved P and particulate P in the filter effluent, as P-containing particles were observed to escape from the experimental filters in this study. Hydroxylapatite was detected in the outflow hose of the Filtra P columns indicating that this mineral phase may form in the filters under certain conditions. The geochemical models, however, indicated that the only precipitated calcium phosphate compound was amorphous tricalcium phosphate.Two hydro-geochemical transport models were developed that satisfactorily described the experimentally derived P breakthrough curves and effluent pH of the filter columns with Filtralite P. The simulations suggested that calcium oxide, calcite and the calcium-silicate phase wollastonite supplied the Ca2+ and OH- ions required for the precipitation of phosphate. / Godkänd; 2014; 20140408 (ingher); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Inga Herrmann Ämne: VA-teknik/Sanitary Engineering Avhandling: Filter Beds for On-Site Wastewater Treatment Towards More Reliable Estimations of Phosphorus Retention Opponent: Professor Petter Jenssen, Institutt for miljøvitenskap, Norwegian University of Life Sciences, Ås, Norge Ordförande: Professor Maria Viklander, Avd för arkitektur och vatten, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Fredag den 13 juni 2014, kl 10.00 Plats: F1031, Luleå tekniska universitet
3

Effekten av att separera ett befintligt kombinerat system till separat spill- och dagvatten : Vasastan, Stockholm

Bergenstråle, Terese January 2019 (has links)
No description available.
4

Kommunernas användning av avrinningsområdesperspektivet i dagvattenplanering: En kvalitativ undersökning / Municipalities’ use of watersheds- perspective in urban water planning: A qualitative study

Unoson, Lars, Bardh, Jonathan January 2019 (has links)
Purpose: The purpose of the report is to examine how the municipality's VA- organizationtakesintoaccountandusesthecatchmentarea'sperspectiveatstormwater planning, and to investigate the extent to which the VA-organization has the tools needed to solve the task. The goal is to highlight the challenges that the municipality's VA-organization is experiencing with implementing a watershed-perspective in order to achieve sustainable stormwatermanagement.   Method: The study is conducted as a qualitative case study with abductive approach where the authors move between theory and empiricism. Semistructured qualitative interviewshavebeenconductedwithliteraltranscription,whichtogetherwithliterature studies created coherence and achieve thegoal.   Findings:Theresultsuggeststhatlargermunicipalitiesstudywatershedandimplement stormwater measures in line with the watershed-perspective. Basis such as deluge- mapping or structural-plans are used to locate suitable locations to implement sustainable stormwater measures with maximum benefit for the entire watershed area. Modeling tools facilitate work with sustainable stormwater measures for all municipalities. Sustainable stormwater measures in urban areas is difficult to implement due to lack of space. A challenge that needs to be resolved is the question ofresponsibility,bothintermsofadministrativecooperationinthefieldofstormwater issues, but also cooperation concerning the watershed betweenmunicipalities.   Implications: The results indicate that smaller urban areas are not taken into account inthewholewatershedarea.Thiscanhaveconsequencesdownstreaminthewatershed area. By locating suitable sites and plan for how to implement a stormwater measure, the entire watershed area is favored instead of individual development plan. Issues regarding responsibilities in the watershed area is seen as severe, and there is potential for development in this area. The respondents argue that there is a need for clearer consequencesfornon-compliancewithenvironmentalqualitystandardsforstormwater process.   Limitations:Thestudyislimitedtothreemunicipalities'VA-organizationsinsouthern Sweden.Thisdidnotgivethestudyacomprehensivepictureofthemunicipality'swork withthewatershed-perspective,onlytheVA-organization.Asonlythreemunicipalities were studied, the result cannot be considered generally or valid in other municipalities ' VA-organization. The result did not have any generalconclusions.   Keywords: Stormwater management, sustainable stormwater management, watershed.
5

A rockwool biofilter for the treatment of restaurant emissions

Andersson-Chan, Anneli January 2000 (has links)
Over the past 20 years, the use of biological air pollution control has become a popular treatment alternative for contaminated gas streams. The objective of this licentiate thesis was to investigate the feasibility of a compact rockwool biofilter to treat emissions from a restaurant, to identify an appropriate microbial population for the inoculation of the biofilter, and suitable environmental conditions for this culture. Rockwool mats with pre-set structures were shown to have a good structural stability, developed low pressure drop, did not compact, and seemed to be a appropriate habitat for microorganisms. Bacteria from different environments were enriched in batch cultures; it was found that all cultures were able to oxidize rape-seed oil. Nutrients, mainly phosphorus and nitrogen, must be added occasionally to the bacterial culture. Clogging due to high depositions of grease could be prevented by using a mechanical collector installed upstream of the biofilter. The off-gas from the fryer consisted of a complex mixture of partially oxidized hydrocarbons and the short residence times (<10 s) provided in the filter were not sufficient to achieve a significant reduction of aldehydes or fatty acids. / Godkänd; 2000; 20070317 (ysko)
6

Cost-benefit analysis for sustainable stormwater management : A case study for Masthuggskajen, Gothenburg / Kostnadsnyttoanalys vid införande av  hållbar dagvattenhantering : En fallstudie för Masthuggskajen, Göteborg

Berglund, Petter January 2018 (has links)
Densication and intensied precipitation patterns due to climate change, has increased the need for sustainable stormwater management. Sustainable stormwater management can be implemented as blue-green infrastructure (BGI), which integrates green features for natural inltration and detention such as green roofs and rain gardens. Through the use of BGI, added values can be provided as ecosystem services. Authorities and organizations in Sweden imply the need for valuation of ecosystem services for future integration in decision-making. This thesis include monetary estimations of ecosystem services within the use of a cost-benet analysis (CBA), for two alternatives of stormwater management in Masthuggskajen, Gothenburg. The applied valuation methods are methods commonly used in economic analysis. The ecosystem services identied and monetarily estimated as benets within this project were  ood protection, water treatment, air quality regulation, noise regulation and added recreational value. The result of the CBA indicated that the most protable alternative was considered to be the implementation of BGI rather than underground solutions. The ecosystem services contributing the most to the result was added recreational value, noise regulation and  ood protection. A sensitivity analysis was concluded by altering the value of costs and benets. Further analysis of the uncertainty in monetary estimates is of importance in order to integrate ecosystem services in decision-making. The diculty in covering the full extent of benets generated by BGI indicates the need of complementary tools in decision-making. However, this study highlights the importance of inclusion of ecosystem services in decision-making.
7

Condensation irrigation : simulations of heat and mass transfer

Lindblom, Jenny January 2006 (has links)
There is a growing water demand in the world. Along with the deterioration of existing water supplies, the escalating world population leads to the assumption that two out of three people will lack sufficient freshwater by the year 2025. As competition for freshwater increases, water of lower quality, for example saline or waste water, is often used in irrigation at the risk of seriously degrading the farmland. Desalination is the only possible way to produce more freshwater. Each day, 23„ª106 m3 of freshwater is produced from seawater by Reverse Osmosis, Multi Stage Flash and Multi Effect distillation. Most of these plants are driven by fossil fuels and only 0.02% by renewable energy. A sustainable development requires simple inexpensive desalination systems driven by renewable energies. Condensation irrigation (CI) is a newly developed idea that meets these requirements. CI is a combined system for solar desalination and irrigation and/or drinking water production. Solar stills are used for humidifying ambient air flowing over the saline water surface in the still. This warm, humid air is then led into an underground pipe system where it is cooled and vapour precipitates as freshwater on the pipe walls. If drainage pipes are used the water and some of humid air percolate through the pipe perforations and irrigates and aerates the ground. Drinking water can be collected at the pipe endings when using non-perforated pipes. The CI system has attracted attention from several North African countries. Pilot plants are now in operation in Tunisia and Algeria where LTU is collaborating with the Tunisian Institute for Research on Rural Engineering, Water and Forestry and the University of Tlemcen in Algeria. LTU is also collaborating with Al Fatah University and the International Energy Foundation in Tripoli, Libya. Ongoing work aims at developing a design tool and monitoring program for the CI system to be used in the design and operation of a demonstration plant in Libya. Mass and heat transfer in the soil around the buried pipes has been modelled in Matlab to evaluate the theoretical potential for these types of systems and to gain understanding of the mechanisms governing their productivity. It was concluded that CI could be used for both irrigation and drinking water production at relatively low operational costs. For a presumed reference system, the mean water production rate in the drinking water system was 1.8 kg per meter of pipe and day. When using drainage pipes for subsurface irrigation, this number increased to 3.1 kg/m/d, corresponding to 2.3 mm/d of supplied irrigation water. The main parameters affecting the water production efficiency were inlet air temperature and humidity, and the pipes were in both systems recommended to be placed at shallow depths. However, since the numerical models disregard from solar radiation and crops, somewhat different conclusions on how the pipe configuration affect the irrigation yield is expected when these factors are included in succeeding models. When irrigation is intended, the pipe spacing must be determined with respect to the soil and local climate as well as the type of crops to be cultivated. Future work on the CI system will include validation of numerical simulations, studies on how solar irradiation and vegetation affect the system, and the construction of a full-scale pilot plant in Libya. / Godkänd; 2006; 20070109 (haneit)
8

Biofiltration technologies for stormwater quality treatment

Blecken, Godecke-Tobias January 2010 (has links)
Due to high runoff volumes and peak flows, and significant contamination with (inter alia) sediment, metals, nutrients, polycyclic aromatic hydrocarbons and salt, urban stormwater is a major cause of degradation of urban water ways. Since current urban drainage systems, which heavily rely on piped sewer networks, may not be sustainable, attempts are being made to develop and refine sustainable urban drainage solutions, notably in Water Sensitive Urban Design (WSUD) and Low Impact Development (LID) concepts. Promising systems recommended for application in both WSUD and LID are stormwater biofilters (also known as bioretention systems or rain gardens) using vegetated filter media. Besides their capacity to attenuate flows and minimise runoff volumes, stormwater biofilters have proven efficacy for enhancing effluent water quality. Furthermore, they can be aesthetically pleasingly integrated even in dense urban environments. However, there are still gaps in our knowledge of the variability of biofilters' pollutant removal performance, and the factors that affect their performance.In the studies this thesis is based upon, the effects of various ambient factors, stormwater characteristics and modifications of filter design on the removal of metals, nutrients and total suspended solids (TSS) in biofilters, and pollutant pathways through them, have been investigated. For these purposes, standard biofilters and variants equipped with a submerged zone, a carbon source and different filter materials were exposed to varying temperatures and dry periods, dosed with stormwater and snowmelt, and the inflow and outflow concentrations of the pollutants were measured.Although removal percentages were consistently high (>70%), demonstrating that biofilters can reliably treat stormwater, the results show that metal outflow concentrations may vary widely depending on the biofilter design and the ambient conditions. Prolonged drying especially impaired their removal efficiency, but variations in temperature and filter media variations had little effect on metal removal rates. The adverse effects of drying could be mitigated by using a submerged zone, and thus providing a more constant moisture regime in the filters between storm events. Combined with embedded organic matter, the submerged zone especially significantly enhances Cu removal, helping to meet outflow target concentrations. Similarly, installing a mulch layer on top of the filter provides additional sorption capacity, hence metals do not ingress far into the filter and are mainly trapped on/in the top layer by sorption processes and/or mechanical trapping associated with TSS. This leads to significant metal accumulation, which facilitates biofilter maintenance since scraping off the top layer removes high proportions of previously accumulated metals, thus delaying the need to replace the whole filter media. However, removal of accumulated pollutants from the filter media is crucial for successful long-term performance of the filters to ensure that no pollutant breakthrough occurs.Nitrogen removal was found to be more variable than metal removal, and to be adversely affected by temperature increases, leading to high nitrogen leaching in warm temperatures. Phosphorus removal rates were consistently high, since most phosphorus was particle-bound and thus trapped together with TSS. However, in initial stages phosphorus was washed out from the filter media, indicating that filter media that do not have high levels of labile phosphorus should be used to avoid high effluent concentrations. Given that most outflow concentrations were far lower than those in the stormwater, biofilters are appropriate stormwater treatment systems. Dependent on the ambient conditions, the target pollutants and the sensitivity of the recipient, adaptation of the filter design is recommended. Further work is required to investigate the winter performance and improve the reliability of nitrogen removal, which is highly variable. / Dagvatten är en viktig orsak till ekologiska försämringar av urbana vattendrag p.g.a. stora avrinningsvolymer, och höga flöden samt en tillförsel av diverse föroreningar, t.ex. sediment, tungmetaller, näringsämnen, polycykliska aromatiska kolväten och salt. Dagvattenhanteringen har länge varit fokuserad enbart på att leda bort vattnet i rörledningar utan att hänsyn har tagits till retention av stora flöden eller till vattenkvalitén. På grund av dessa problem har utvecklingen av uthålliga dagvattensystem blivit allt viktigare och koncept som Lokalt Omhändertagande av Dagvatten (LOD), Water Sensitive Urban Design (WSUD) och Low Impact Development (LID) har utvecklats. En uthållig lösning inom dessa koncept är dagvattenbiofiltrering.Dagvattenbiofilter är infiltrationsbäddar med växter där dagvattnet infiltrerar och renas av växterna och filtermaterialet. De har en god förmåga att fördröja stora flöden samt att reducera föroreningar i dagvattnet innan det släpps ut till recipienten. Dessutom är det en estetisk och naturnära teknik som mycket väl kan integreras arkitektoniskt i både nya och befintliga stadsmiljöer. Dock saknas det fortfarande mycket kunskap om de processer som styr reningsförmågan samt hur de påverkas av varierande omgivningsförhållanden. I denna avhandling har därför effekterna av olika omgivningsfaktorer, dagvattenegenskaper och design av biofilter på reningen av metaller, näringsämnen och sediment undersökts. För att undersöka detta har biofilter, som delvis försetts med olika filtermaterial eller en vattenmättad zon, till dels kombinerad med en kolkälla, och utsatts för olika temperaturer och torra perioder. Biofiltren har bevattnats med dagvatten eller smältvatten. Prover har tagits på ingående och utgående vatten och föroreningskoncentrationerna har analyserats. Trots att reduktionsförmågan av metaller var hög (>70%), vilket bekräftar att biofiltren har förmågan att effektivt rena dagvattnet, visar resultaten att de utgående metallkoncentrationerna kan variera mycket beroende på utformningen av biofilter och varierande omgivningsfaktorer. Torra perioder som är längre än 3 till 4 veckor minskar metallavskiljningen i biofilter, medan växlande temperaturer och olika filtermaterial hade mindre betydelse för metallreningen. Dock kan en vattenmättad zon i filtermaterialet minimera (Cu och Zn) eller till och med avlägsna (Pb) den negativa effekten av torka med avseende på reningsförmågan. I kombination med en kolkälla kan en vattenmättad zon öka reningseffekten för framför allt Cu (som inte är lika bra i standardutförande av biofilter) på grund av en ökad komplexbildning och partikulärt organiskt material. Sediment, metaller och partikelbundna dagvattenföroreningar hålls tillbaka redan i det översta filterlagret vilket leder till en hög metallackumulation. Detta underlättar filterunderhållet: genom att skrapa och ersätta bara det översta jordlagret kan en hög andel ackumulerade föroreningar tas bort från filtret. Således kan utbyte av det hela filtermaterialet fördröjas.Kvävereningen var inte lika effektiv som metallreningen. I varma temperaturer (20°C) har kväveutlakning i stället for reduktion observerats. Fosforreningen var dock hög eftersom fosfor var mestadels partikelbunden och blev därför filtrerat tillsammans med sedimentet i det översta filterlagret. I början av biofilterdriften har dock fosforurlakning från filtermaterialet observerats vilket tyder på att det inte ska innehåller höga halter av fosfor för att undvika utlakning från filtret. Eftersom de flesta föroreningskoncentrationer i det utgående vattnet var betydligt lägre än i dagvattnet är biofilter en uthållig och tillförlitlig teknik för dagvattenrening. Beroende på olika omgivningsfaktorer samt de ekologiska förhållandena i recipienten rekommenderas dock anpassning av filterdesignen. Framtida forskning behövs för att undersöka biofiltrens reningsförmåga under vinterförhållanden och för att förbättra den varierande kvävereningen. / Godkänd; 2010; 20100812 (godble); DISPUTATION Ämnesområde: VA-teknik/Sanitary Engineering Opponent: Professor Jean-Luc Bertrand-Krajewski, INSA de Lyon, Frankrike Ordförande: Professor Maria Wiklander, Luleå tekniska universitet Tid: Fredag den 8 oktober 2010, kl 10.00 Plats: F1031, Luleå tekniska universitet
9

LV Filter : Ett partikelfilter för hushåll i mindre gynnsamma levnadsförhållanden

Ingheden, Felix, Gabrielsson, Jonathan January 2017 (has links)
LV Filter is a product designed to provide drinkable tap water to households around the world. With a power source, the system manages itself with automatic cleaning. A safe and easy source of particle-free water. The product is intended as a complement to the client's product portfolio in order to offer a complete solution for water purification. LV Filter is developed in such a way that it can be manufactured in the country in which it is to be sold. This helps the product not only provide drinking water for households but also contributes to economic growth and job creation. In this way, one can contribute to a long-term change for both users and those who manufacture the product. Manufacturing is adapted in such a way that expensive and complicated methods will not be required to facilitate manufacturing in less developed places. The need that the product satisfies is imminent to a large number of people. The poor countries in the world are growing rapidly, so LV Filter can eventually increase the living standards of these people because they demand the absolute cheapest solutions and can not afford systems from the western world.
10

Urban Runoff and Snowmelt : Quantity and Quality Processes in Snow Deposits and Hydrologic Abstractions

Moghadas, Shahab January 2016 (has links)
No description available.

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