abstract: Microbial fuel cells(MFC) use micro-organisms called anode-respiring bacteria(ARB) to convert chemical energy into electrical energy. This process can not only treat wastewater but can also produce useful byproduct hydrogen peroxide(H2O2). Process variables like anode potential and pH play important role in the MFC operation and the focus of this dissertation are pH and potential control problems. Most of the adaptive pH control solutions use signal-based-norms as cost functions, but their strong dependency on excitation signal properties makes them sensitive to noise, disturbances, and modeling errors. System-based-norm( H-infinity) cost functions provide a viable alternative for the adaptation as they are less susceptible to the signal properties. Two variants of adaptive pH control algorithms that use approximate H-infinity frequency loop-shaping (FLS) cost metrics are proposed in this dissertation. A pH neutralization process with high retention time is studied using lab scale experiments and the experimental setup is used as a basis to develop a first-principles model. The analysis of such a model shows that only the gain of the process varies significantly with operating conditions and with buffering capacity. Consequently, the adaptation of the controller gain (single parameter) is sufficient to compensate for the variation in process gain and the focus of the proposed algorithms is the adaptation of the PI controller gain. Computer simulations and lab-scale experiments are used to study tracking, disturbance rejection and adaptation performance of these algorithms under different excitation conditions. Results show the proposed algorithm produces optimum that is less dependent on the excitation as compared to a commonly used L2 cost function based algorithm and tracks set-points reasonably well under practical conditions. The proposed direct pH control algorithm is integrated with the combined activated sludge anaerobic digestion model (CASADM) of an MFC and it is shown pH control improves its performance. Analytical grade potentiostats are commonly used in MFC potential control, but, their high cost (>$6000) and large size, make them nonviable for the field usage. This dissertation proposes an alternate low-cost($200) portable potentiostat solution. This potentiostat is tested using a ferricyanide reactor and results show it produces performance close to an analytical grade potentiostat. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2018

This thesis paper introduces you about the process of how to build an inventory tracking system in a local Swedish company. The related project is to support the thesis paper, and is also for the company’ using. The software product of this project is an application that works for managing various types’ instruments in the company of SWECO-Vaxjo. It will play an important role in the further management work of the company. In this thesis paper, the candidate techniques and theories for implementing this system are discussed. And in the end a good solution for this problem will be presented in the paper.

Kraftelektronik AB i Växjö tillverkar en spänningslikriktare som kan konfigureras enligt kundens önskemål. Antalet parametrar som kan ändras uppgår till över 300 stycken och måste i nuläget konfigureras manuellt av en operatör. För att förenkla önskade de att vi utvecklade ett program så konfigurationen kunde utföras i Windows-miljö. / Kraftelektronik AB in Växjö manufactures a power rectifier which can be configured according to a customer’s wish. The number of parameters which can be changed reach above 300 and must today be configured manually by an operator. To simplify they wished that we developed a program so the configuration could be carried out in a Windows environment.

The human enters into the information age in 21st century; the computer science and technology are developed at full speed, and already infiltrate into various field extensively. Resultantly manual drawing gradually is phased out, for those designers who have no prior experience in the computer operation are concerned, they need to have a kind of two-dimensional graphical tool. Graphics editor system arose to the request for designing planar figures for people who have little knowledge in computer. This paper describes the development process of this system what is studied for the foundation, utilize object-oriented method to analyze, design with computer figure, and adopt Visual C ++ 6.0 as the developing platform. All these have been finished after 1 month or so. It designs to be two-dimensional graphical software with diverse function which operates simply, easy to study, mutual interface friendly graphics editor system and has satisfied some figure users at present with the new demand as well. The following main functions have been realized in this application: It can draw various figures, such as dot, line, circle, arc, parabola and curve, modify them and comprehensive editing. Figure editor includes translation, mirroring, rotating and some similar operations. Comprehensive drawing includes drawing polygon (sealed and arbitrary polygon), round tangent line, round circle contact, line circle contact, some circle contacts and so forth. Meanwhile obtain the point of intersect between the arbitrary crossing, and draw different figures basically according to the points of intersect. By the way, it is capable to cancel and redraw the editing.

This diploma thesis deals with the modelling of the piezoelectric composite material using the finite element method. The thesis is divided into three parts. Research study is done in the first part. It focuses on the possibility of use of the piezoelectric layers as sensors. The second part concerns the homogenization of MFC (macro fiber composite). Material and piezoelectric parameters are obtained by modelling elementary structural cell under different loading conditions. Determined characteristics are verified with experimental data. The third part proposes the design of the experimental device, which allows the simulation of the rotor excitation by rotating unbalance. Excitation responses of MFCs placed in specific locations are calculated using FEA model of the device. The conclusion includes the description of the suitability to vibration measurement on the device.

Textile wastewater contains very high concentration of color, COD, suspended solids and other pollutants. Methods such as reverse osmosis, nano-filtration and ultrafiltration are known to be effective to remove some pollutants but these methods are very expensive. A new treatment approach which is the combination of freezing technology and Microbial Fuel Cell technology has been studied in this thesis work and seems to have great potential to remove color and COD from textile wastewater. Freezing splits a diluted stream into two different streams; one stream in which water is transferred into ice with a low pollutant concentration leaving a concentrated stream with pollutants. Microbial fuel cell uses the concentrated stream to convert biochemical energy into electrical energy. Three different types of substrates, KMnO4 solution, municipal wastewater and orange juice, were studied. Freezing technology can produce high quality water by neutralizing pH-value; close to 7.0, removal of COD is more than 95% and separating color by almost 100%. Similarly MFC can remove color, and COD by 88.8% and 73.6% respectively. The maximum generation of electrical power by MFC was estimated to 1.03 mW/m2 of electrode area. The findings suggest that this new approach of textile wastewater treatment can be a costeffective way to remove pollutants from textile wastewater while generating some electricity.

Genom laborativa försök skulle avvattning och retention av nanocellulosa i en DDA (Dynamic drainage analyzer) undersökas. Detta genom att tillsätta retentionskemikalier i varierande mängder för att se hur det påverkade avvattningen. Uppdragsgivaren var Innventia och laborationerna utfördes på SP:s laboratorium där DDA instrument fanns tillgängligt. DDA instrumentet liknar den maskin som används för papperstillverkning och därför anses det vara möjligt att kunna avvattna nanocellulosa på liknande instrument. Målet med examensarbetet var att få fram en nanocellulosafilm med goda barriärsegenskaper men också se hur tillsats av bärarfibrer påverkar filmens egenskaper. Målet var också att se om retention och avvattningstiden för nanocellulosa hänger ihop och om det går att få fram repeterbara resultat. Två olika viror undersöktes också i de laborativa experimenten i DDA, en som benämns som Albanyviran och en som benämns som Stratexviran. Albanyviran är tätare än Stratexviran och effekten av viratäthet på retention och avvattningstid undersöktes. Nanocellulosa eller Mikrofibrillär cellulosa (MFC) är ett nytt och förnybart material som utvinns ur träfibrer och karakteriseras av sitt geléaktiga utseende[4]. Nanocellulosan lämpar sig utmärkt för en mängd olika produkter t.ex. som barriär, enskilt i form av filmer eller i blandade produkter. Vid tillverkning av nanocellulosa används en homogenisator som sönderdelar cellulosafibrer till fibriller och fibrillaggregat. Detta var tidigare ett problem då fibrerna satte igen homogenisatorn och tillverkningen var mycket energikrävande[4]. När det gäller filmtillverkning av nanocellulosa kvarstår problemet när det kommer till avvattningen. Nanocellulosan späddes till önskad koncentration och innan de laborativa försöken kördes den genom en homogenisator för att dispergera fibrillerna i vätskan efter spädningen. Bärarfibrerna slogs upp i en uppslagare med två liter kranvatten för att sedan tillsättas till den homogeniserade nanocellulosan. Under försöket i DDA varierades mängden och andelen MFC (mikrofibrillär cellulosa) och bärarfibrer (Modorefmassa). Till MFC och bärarfibersuspensionen i DDA:n tillsattes sedan två retentionskemikalier vid varje försök, C-PAM PL-1520 och EKA NP-780 i varierande mängder. Efter avvattningen i DDA:n pressades filmen vid olika tryck och tider för att därefter mäta filmernas ytvikt och syrgasbarriär. Den film som ansågs mest lämplig gällande avvattning i DDA under försöken var vid 0,2 % med 90 % MFC och 10 % bärarfibrer. Filmen gav den högsta retentionen, en god syrgasbarriär och var lätt att hantera. Det som kan ses från resultaten av syrgasbarriären är att vid 0,2 % med 90 % MFC och 10 % bärarfibrer erhölls det lägsta OTR (oxygen transmission rate) -värdet på 0,53 vilket visar på en bra syrgasbarriär. Retentionen för det försöket var det högsta på 87,1 % medan avvattningstiden låg på närmare 250 sekunder. Avvattningstiderna var höga, dock så var det vid denna totalkoncentration ibland svårt att se när avvattningen avslutades då tiden klockades manuellt. Det som kan ses utifrån resultaten är att bärarfibrerna inte påverkar filmerna negativt utan kan gynna både så retentionen och syrgasbarriären blir bättre, dock fås en högre ytvikt och avvattningstiderna blir längre. / Through laboratory experiments, dewatering and retention of nanocellulose in a DDA (Dynamic Drainage Analyzer) were analysed. By adding retention chemicals in varied amounts, the effects on the dewatering was shown. The Job initiator was Innventia and the laboratory work were made at SP's laboratory where the DDA instrument was available. The DDA instrument is similar to the machine that is used for paper manufacturing in a large scale and therefore, it could be possible to dewater nanocellulose on a similar instrument. The goal of the thesis was to develop a nanocellulose film with good barrier properties but also to see how adding carrier fibers effect the properties of the film. The goal was also to see if the retention and dewatering time of nanocellulose are connected and whether it is possible to obtain repeatable results. Two different wires were also examined in the laboratory experiments in a DDA, the Albanywire and the Stratexwire. The Albany wire was denser than the Stratex wire and the effect that the density caused on retention and dewatering time was examined. Nanocellulose or Microfibrillated cellulose (MFC) is a new and renewable material that is made from wood fibers and is characterized by its gelatinous appearance. [4] Nanocellulose is suited for a variety of products, such as barriers, alone in the form of films or mixed in products. In the manufacture of nanocellulose a homogenizer is used which decomposes cellulose fibers to fibrils fibril aggregate. This was previously a problem while the fibers clogged the homogenizer and the production had a high energy consumption. [4] When it comes to making a nanocellulose film the problems with dewatering remains. The nanocellulose was diluted to the desired concentration and before the laboratory experiments it was run through a homogenizer, to disperse the fibrils in the liquid after the dilution. The carrier fibers was prepared in a blender with two liters of tap water before it was added to the homogenized nanocellulose. During the experiment in the DDA the amount and proportion of the MFC (microfibrillar cellulose) and carrier fibers (Modorefmassa) was varied. To the MFC and carrier fiber suspension in the DDA two retention chemicals were added in each experiment, C- PAM PL -1520 and EKA NP- 780 in varying amounts. After the dewatering of nanocellulose in the DDA the films were pressed at different pressures and times, thereafter the oxygen permeability was analyzed. The film that was considered the most suitable referring to dewatering in the DDA during the attempts was at 0.2 % with 90 % MFC and 10 % carrier fibers. The film gave the highest retention, a good oxygen barrier and was easy to handle. What can be seen from the results of the oxygen barrier measurement is that at 0.2 % with 90 % MFC and 10% carrier fibers obtained the lowest value OTR (oxygen transmission rate), which indicates on a good oxygen barrier. Retention at this concentration was the highest at 87.1 %, while the drainage time was nearly 250 seconds. The dewatering time was high, however during this concentration it’s sometimes difficult to see when the dewatering ended while the time was clocked manually. Conclusions from the results are that the carrier fibers doesn’t have a negatively effect on the films, rather they can benefit both the retention and oxygen barrier, however a higher paper weight was obtained and the dewatering time became longer.

BOD (Biochemical Oxygen Demand) is one of the important parameters in wastewater treatment technology,  it normally takes five days to get the result. Using MFC (Microbial Fuel Cell) to build up a small on-line system to measure BOD will reduce to operating time to 20 minutes. In this report, the MFC BOD on-line measurement was processed in order to test if this rapid way would work in practical usage. The experiment used secondary sedimentation sludge as the bacteria source on the MFC anode pattern with GGA (Glucose and Glutamic Acid solution) as an electron producer, and the 30 minutes voltage value changing curves was gotten by measuring the voltage. At the end the curve was analyzed and compared with the real BOD value in order to get the conclusion. The BOD on-line measurement is quite promising and efficient when multi-samples are needed to be tested.

Shewanella spp. are model electroactive bacteria (EAB) and well-known for their broad metabolic capabilities and extracellular electron transfer (EET) properties, which allow them to utilize a diverse range of carbon substrates, such as formate, lactate, pyruvate, and amino acids. However, the majority of Shewanella spp. cannot metabolize glucose, a naturally occuring carbon and energy source. Here, we examine the electrode respiring potential of Shewanella chilikensis JC5T- and its coexistence with acetoclastic EAB, Geobacter sulfurreducens in glucose-fed microbial electrolysis cells (MECs) operated at a set anode potential condition of 0 V vs. Ag/AgCl. Chronoamperometry analysis revealed that the maximum current density was 0.04523 mA/cm2 (CE: 14.55%) in S-MEC (only S. chilikensis JC5T) and 0.299 mA/cm2 (CE: 53.85%) in CC-MEC (S. chilikensis JC5T and G. sulfurreducens) which is 6.6-folds higher in current density and 3.7-folds higher in coulombic efficiency than S-MEC. Cyclic voltammetry analysis demonstrates presence of biofilm and redox mediator for EET mechanisms. Metabolic analysis showed that S. chilikensis as a monoculture and co-culture with G. sulfurreducens can metabolize glucose and produce intermediates such as acetate, formate, and lactate. These intermediates are likely used to generate electrical current. Collectively, these results provide novel insights on electrode respiring properties of S. chilikensis and its coexistence with acetoclastic EAB, G. sulfurreducens to enhance the current density and coulombic efficiency from glucose-fed MEC.

The aim of the project was to investigate a green and sustainable replacement for boric acid in polyvinyl alcohol (PVA) adhesives for solid paperboard production. Boric acid acts as a cross-linker and tackifier in the adhesive but is classified as a harmful substance. Microfibrillated cellulose (MFC) was therefore investigated as a possible replacement for boric acid since it is produced from renewable and sustainable resources. In addition, it has hydroxyl groups available for interaction with the PVA, can be used to modulate the viscosity and can function under a variety of pH-values.  For the industrial process, there are three basic characteristics which must be met by the newly developed adhesive, which have to be the same as for the boric acid-containing reference. These three are the viscosity, the pH-value, and the dry content. Furthermore, it is important that the initial wet tack and the final adhesive strength are at least as high as the reference’s.  In this context, eight types of samples were investigated in total. Two were references, one prepared on industrial and the second on a laboratory scale according to a current industrial recipe. In the other six samples, the boric acid from the recipe was replaced by three different weight percentages of MFC of two different industrial grades. Both the dry content and the pH-value were not noticeably influenced by the addition of MFC. The viscosity however increased drastically with the increasing amount of MFC. The addition of MFC was enough to reach the three basic characteristics. In addition it was observed positive effects on a couple of other parameters that is beneficial for the glue.   A test method for evaluating the initial wet tack of the adhesive was developed. It was shown, that the tack of the adhesive containing MFC is 40 % lower than the one of the reference material. Therefore, five additives were tested in the formulation, in combination with MFC. The most promising result led to a comparable initial tack and final strength as the reference.