Training system for conceptual design and evaluation for wastewater treatment

Rising population, rapid urbanisation and growing industrialisation have severely stressed water quality and its availability in Malawi. In addition, financial and institutional problems and the expanding agro industry have aggravated this problem. The situation is worsened by depleting water resources and pollution from untreated sewage and industrial effluent. The increasing scarcity of clean water calls for the need for appropriate management of available water resources. There is also demand for a training system for conceptual design and evaluation for wastewater treatment in order to build the capacity for technical service providers and environmental practitioners in the country. It is predicted that Malawi will face a water stress situation by 2025. In the city of Blantyre, this situation is aggravated by the serious pollution threat from the grossly inadequate sewage treatment capacity. This capacity is only 23.5% of the wastewater being generated presently. In addition, limited or non-existent industrial effluent treatment has contributed to the severe water quality degradation. This situation poses a threat to the ecologically fragile and sensitive receiving water courses within the city. This water is used for domestic purposes further downstream. This manuscript outlines the legal and policy framework for wastewater treatment in Malawi. The manuscript also evaluates the existing wastewater treatment systems in Blantyre. This evaluation aims at determining if the effluent levels at the municipal plants conform to existing standards and guidelines and other associated policy and regulatory frameworks. The raw material at all the three municipal plants is sewage. The typical wastewater parameters are Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), and Total Suspended Solids (TSS). The treatment target is BOD5, COD, and TSS reduction. Typical wastewater parameters at the wastewater treatment plant at MDW&S textile and garments factory are BOD5 and COD. The treatment target is to reduce BOD5 and COD. The manuscript further evaluates a design approach of the three municipal wastewater treatment plants in the city and the wastewater treatment plant at Mapeto David Whitehead & Sons (MDW&S) textile and garments factory. This evaluation utilises case-based design and case-based reasoning principles in the ED-WAVE tool to determine if there is potential for the tool in Blantyre. The manuscript finally evaluates the technology selection process for appropriate wastewater treatment systems for the city of Blantyre. The criteria for selection of appropriate wastewater treatment systems are discussed. Decision support tools and the decision tree making process for technology selection are also discussed. Based on the treatment targets and design criteria at the eight cases evaluated in this manuscript in reference to similar cases in the ED-WAVE tool, this work confirms the practical use of case-based design and case-based reasoning principles in the ED-WAVE tool in the design and evaluation of wastewater treatment 6 systems in sub-Sahara Africa, using Blantyre, Malawi, as the case study area. After encountering a new situation, already collected decision scenarios (cases) are invoked and modified in order to arrive at a particular design alternative. What is necessary, however, is to appropriately modify the case arrived at through the Case Study Manager in order to come up with a design appropriate to the local situation taking into account technical, socio-economic and environmental aspects. This work provides a training system for conceptual design and evaluation for wastewater treatment.

Jäähdytysjärjestelmän vaikutus kiinteistön elinkaaren aikaisiin tuottoihin

Ilmastoinnin jäähdytys yleistyy toimisto- ja hotellikiinteistöissä jatkuvasti. Perinteinen tapa tuottaa jäähdytysenergia on kiinteistökohtainen vedenjäähdytysjärjestelmä. Helsingissä on ollut vuodesta 2000 lähtien mahdollista liittyä Helsingin energian kaukojäähdytysverkostoon. Jäähdytysjärjestelmien ominaisuudet poikkeavat toisistaan ja niistä aiheutuu kiinteistönomistajalle erilaisia kustannuksia. Kiinteistöstä saataviin tuottoihin vaikuttaa kustannusten lisäksi vuokralaisen tyytyväisyys. Tämän vuoksi työssä selvitettiin vuokralaisen tarpeet jäähdytysjärjestelmälle haastattelemalla vuokralaisen edustajia. Tässä diplomityössä vertaillaan kaukojäähdytyksen ja kiinteistökohtaisen jäähdytysjärjestelmän kustannuksia, sekä vaikutuksia kiinteistön elinkaarituottoihin kiinteistönomistajan näkökulmasta. Kerättyjen kustannusten perusteella suoritetaan elinkaarikustannuslaskenta GaBi-ohjelmalla. Vuokralaisen tarpeista jäähdytysjärjestelmälle tunnistetaan olennaisiksi toimintavarmuus, ympäristöystävällisyys sekä hiljainen äänitaso. Nämä ovat lisäarvotekijöitä, joille työssä määritetään painoarvo ja jotka huomioidaan laskennassa. Diplomityö osoitti kaukojäähdytyksen kannattavaksi vaihtoehdoksi kiinteistökohtaiselle järjestelmälle, kun huomioidaan hankinta- ja käyttökustannusten lisäksi asennustöiden, käyttöönoton, huollon ja kunnossapidon sekä loppusijoituksen kustannukset. Myös valikoituneet lisäarvotekijät puoltavat kaukojäähdytystä ja niiden kompensointi lisää kiinteistökohtaisen järjestelmän kustannuksia.

Hule- ja suotovesien hallintajärjestelmän kehittäminen Ämmässuon nykyisellä kaatopaikalla

Työssä käsitellään hule- ja suotovesien hallintajärjestelmän kehittämistä Ämmässuon nykyisellä kaatopaikalla. Hallintajärjestelmää kehitettäessä on huomioitu ympäristölliset tekijät kuten topografia, sadanta, pinta- ja pohjavesiolosuhteet, maa- ja kallioperä sekä kaatopaikkaa ympäröivä alue. Vallitseva lainsäädäntö ja kaatopaikkaa koskevat luvat on selvitetty ennen hallintajärjestelmän kehittämisen suunnittelua. Kaatopaikkojen hule- ja suotovesien hallintajärjestelmän tärkeimpinä osina ovat olleet hule- ja suotovesien määrät ja niiden muutokset esim. kaatopaikan täyttösuunnitelman tai viimeistelysuunnitelman muutoksen vaikutuksesta. Määräarvioiden jälkeen on selvitetty vesien keräily, tasaus ja johtamistavat. Näitä osa-alueita suunniteltaessa on määritetty olemassa olevat rakenteet ja tarvittava lisärakennustarve. Myös mahdolliset poikkeustilanteet, kuten heikentynyt huleveden laatu, on huomioitu johtamisjärjestelyitä suunniteltaessa. Tämän lisäksi hallintajärjestelmään on liitetty suotoveden erillis- ja esikäsittelytarpeet sekä mahdollinen kierrättäminen takaisin jätetäyttöön paremman biohajoavuuden aikaan saamiseksi. Vesien keräilyn, virtauksen tasaamisen ja johtamisen lisäksi hallintajärjestelmään kuuluvat mittaavat ja ohjaavat automaatiojärjestelmät sekä tiedonkeräily- ja käsittelyjärjestelmät. Varsinainen mittaus- ja automaatiosuunnittelu on jätetty tämän työn ulkopuolelle. Työhön on lisäksi liitetty aikataulu- ja kustannustarkastelu. Näin on mahdollista varautua järjestelmän rakenteellisten osien toteuttamiseen sekä niistä aiheutuviin kustannuksiin

Assessing e-procurement System for Improving the Purchasing Operations

Diplomityön tavoitteena oli luoda suunnitelma elektronisen hankintatoimen aloittamiseksi, analysoimalla nykyisiä ostoprosesseja ja konsernin laajuista elektronista hankintajärjestelmää. Työ pohjautuu yritysten väliseen elektroniseen kauppaan, elektroniseen hankintatoimeen ja systeemisuunnitteluun liittyvään kirjallisuuteen. Työssä tehdyn suunnitelman tarkoituksena on auttaa Siemens Oy:tä siirtymään uuteen elektroniseen ostotoimintaan. Elektroniselle ostotoiminnalle suunniteltiin tavoitteet ja näitä vastaavat vaatimukset. Elektronisen hankintajärjestelmän analysointi perustuu kirjallisuudessa esitettyihin järjestelmän elinkaari-mallin vaiheisiin. Analysoinnin tarkoituksena oli saada selville järjestelmän soveltuvuus Siemens Oy: n liiketoimintaympäristöön, prosesseihin ja vaatimuksiin. Elektronisen hankintatoiminnan etuja ovat liiketoiminta prosessien johtamisen parantuminen, kustannusten väheneminen sekä taloudellisen suorituskyvyn lisääntyminen. Elektronisen hankintatoiminnan aloittaminen vaatii kuitenkin huolellista suunnittelua. Työssä tehdyt suunnitelmat ja analysoinnit auttavat arvioidessa järjestelmän sopivuutta Siemens Oy: n vaatimuksiin. Oikean ja toimivan järjestelmän valinta ei kuitenkaan takaa elektronisesta hankintatoiminnasta hyötymistä. Tärkeimpiä jatkotoimenpiteitä onkin suorittaa kustannus/hyöty analyysi ja arvioida toimittajien halukkuutta ja kykyjä osallistua markkinapaikkaan.

Liquid transportation and distribution during (re)wetting : impact on coated papers in printing

In many industrial applications, such as the printing and coatings industry, wetting of porous materials by liquids includes not only imbibition and permeation into the bulk but also surface spreading and evaporation. By understanding these phenomena, valuable information can be obtained for improved process control, runnability and printability, in which liquid penetration and subsequent drying play important quality and economic roles. Knowledge of the position of the wetting front and the distribution/degree of pore filling within the structure is crucial in describing the transport phenomena involved. Although exemplifying paper as a porous medium in this work, the generalisation to dynamic liquid transfer onto a surface, including permeation and imbibition into porous media, is of importance to many industrial and naturally occurring environmental processes. This thesis explains the phenomena in the field of heatset web offset printing but the content and the analyses are applicable in many other printing methods and also other technologies where water/moisture monitoring is crucial in order to have a stable process and achieve high quality end products. The use of near-infrared technology to study the water and moisture response of porous pigmented structures is presented. The use of sensitive surface chemical and structural analysis, as well as the internal structure investigation of a porous structure, to inspect liquid wetting and distribution, complements the information obtained by spectroscopic techniques. Strong emphasis has been put on the scale of measurement, to filter irrelevant information and to understand the relationship between interactions involved. The near-infrared spectroscopic technique, presented here, samples directly the changes in signal absorbance and its variation in the process at multiple locations in a print production line. The in-line non-contact measurements are facilitated by using several diffuse reflectance probes, giving the absolute water/moisture content from a defined position in the dynamic process in real-time. The nearinfrared measurement data illustrate the changes in moisture content as the paper is passing through the printing nips and dryer, respectively, and the analysis of the mechanisms involved highlight the roles of the contacting surfaces and the relative liquid carrier properties of both non-image and printed image areas. The thesis includes laboratory studies on wetting of porous media in the form of coated paper and compressed pigment tablets by mono-, dual-, and multi-component liquids, and paper water/moisture content analysis in both offline and online conditions, thus also enabling direct sampling of temporal water/moisture profiles from multiple locations. One main focus in this thesis was to establish a measurement system which is able to monitor rapid changes in moisture content of paper. The study suggests that near-infrared diffuse reflectance spectroscopy can be used as a moisture sensitive system and to provide accurate online qualitative indicators, but, also, when accurately calibrated, can provide quantification of water/moisture levels, its distribution and dynamic liquid transfer. Due to the high sensitivity, samples can be measured with excellent reproducibility and good signal to noise ratio. Another focus of this thesis was on the evolution of the moisture content, i.e. changes in moisture content referred to (re)wetting, and liquid distribution during printing of coated paper. The study confirmed different wetting phases together with the factors affecting each phase both for a single droplet and a liquid film applied on a porous substrate. For a single droplet, initial capillary driven imbibition is followed by equilibrium pore filling and liquid retreat by evaporation. In the case of a liquid film applied on paper, the controlling factors defining the transportation were concluded to be the applied liquid volume in relation to surface roughness, capillarity and permeability of the coating giving the liquid uptake capacity. The printing trials confirmed moisture gradients in the printed sheet depending on process parameters such as speed, fountain solution dosage and drying conditions as well as the printed layout itself. Uneven moisture distribution in the printed sheet was identified to be one of the sources for waving appearance and the magnitude of waving was influenced by the drying conditions.

Model-based estimation of liquid flows in the blast furnace hearth and taphole

This thesis presents a set of methods and models for estimation of iron and slag flows in the blast furnace hearth and taphole. The main focus was put on predicting taphole flow patterns and estimating the effects of various taphole conditions on the drainage behavior of the blast furnace hearth. All models were based on a general understanding of the typical tap cycle of an industrial blast furnace. Some of the models were evaluated on short-term process data from the reference furnace. A computational fluid dynamics (CFD) model was built and applied to simulate the complicated hearth flows and thus to predict the regions of the hearth exerted to erosion under various operating conditions. Key boundary variables of the CFD model were provided by a simplified drainage model based on the first principles. By examining the evolutions of liquid outflow rates measured from the furnace studied, the drainage model was improved to include the effects of taphole diameter and length. The estimated slag delays showed good agreement with the observed ones. The liquid flows in the taphole were further studied using two different models and the results of both models indicated that it is more likely that separated flow of iron and slag occurs in the taphole when the liquid outflow rates are comparable during tapping. The drainage process was simulated with an integrated model based on an overall balance analysis: The high in-furnace overpressure can compensate for the resistances induced by the liquid flows in the hearth and through the taphole. Finally, a recently developed multiphase CFD model including interfacial forces between immiscible liquids was developed and both the actual iron-slag system and a water-oil system in laboratory scale were simulated. The model was demonstrated to be a useful tool for simulating hearth flows for gaining understanding of the complex phenomena in the drainage of the blast furnace.

Analysis and modelling of chemical looping combustion process with and without oxygen uncoupling

Effective control and limiting of carbon dioxide (CO₂) emissions in energy production are major challenges of science today. Current research activities include the development of new low-cost carbon capture technologies, and among the proposed concepts, chemical combustion (CLC) and chemical looping with oxygen uncoupling (CLOU) have attracted significant attention allowing intrinsic separation of pure CO₂ from a hydrocarbon fuel combustion process with a comparatively small energy penalty. Both CLC and CLOU utilize the well-established fluidized bed technology, but several technical challenges need to be overcome in order to commercialize the processes. Therefore, development of proper modelling and simulation tools is essential for the design, optimization, and scale-up of chemical looping-based combustion systems. The main objective of this work was to analyze the technological feasibility of CLC and CLOU processes at different scales using a computational modelling approach. A onedimensional fluidized bed model frame was constructed and applied for simulations of CLC and CLOU systems consisting of interconnected fluidized bed reactors. The model is based on the conservation of mass and energy, and semi-empirical correlations are used to describe the hydrodynamics, chemical reactions, and transfer of heat in the reactors. Another objective was to evaluate the viability of chemical looping-based energy production, and a flow sheet model representing a CLC-integrated steam power plant was developed. The 1D model frame was succesfully validated based on the operation of a 150 kWth laboratory-sized CLC unit fed by methane. By following certain scale-up criteria, a conceptual design for a CLC reactor system at a pre-commercial scale of 100 MWth was created, after which the validated model was used to predict the performance of the system. As a result, further understanding of the parameters affecting the operation of a large-scale CLC process was acquired, which will be useful for the practical design work in the future. The integration of the reactor system and steam turbine cycle for power production was studied resulting in a suggested plant layout including a CLC boiler system, a simple heat recovery setup, and an integrated steam cycle with a three pressure level steam turbine. Possible operational regions of a CLOU reactor system fed by bituminous coal were determined via mass, energy, and exergy balance analysis. Finally, the 1D fluidized bed model was modified suitable for CLOU, and the performance of a hypothetical 500 MWth CLOU fuel reactor was evaluated by extensive case simulations.

Water chemistry management for future large experimental facilities

The thesis focuses on the water chemistry of the experimental test facilities and their reference VVER reactors. The main objective of the thesis is to provide recommendations for water chemistry management for laboratory facilities (VEERA, PACTEL) simulating the VVERs and for the large future facilities of the Lappeenranta University of Technology. In the beginning, the concept of nuclear power generation and the applicability of the nuclear power usage is discussed. Next, different water chemistry and water purification systems in primary and secondary circuits currently used at the power plant have been outlined. Also the construction geometry and design of test facilities PACTEL and VEERA, as well as the operation principles of their main equipment has been described. Finally, the appropriate water chemistry and water treatment system have been proposed for the existing and future experimental facilities of LUT.