Στις μέρες μας, η πρόοδος της τεχνολογίας έχει επιφέρει μια μεγάλη αύξηση στην ποσότητα των υγρών αποβλήτων. Ταυτόχρονα, υπάρχει η απαίτηση για βιολογική απομάκρυνση του αζώτου από υγρά απόβλητα με στόχο τη μείωση του συνολικού κόστους της διεργασίας. Προς αυτή την κατεύθυνση, τεχνολογίες για βιολογική απομάκρυνση αζώτου με παράκαμψη της παραγωγής νιτρικών, έχουν αναπτυχθεί. Ένας αριθμός παραγόντων όπως η αμμωνία, η θερμοκρασία, το PH, παίζει σημαντικό ρόλο στην παραγωγή νιτρικών. Τελευταία γίνεται και η χρήση ματηματικών μοντέλων με στόχο την μελέτη και τη βελτιστοποίηση αυτών των τεχνολογιών. Στην παρούσα εργασία μια τροποποίηση του μοντέλου ASM1 χρησιμοποιείται για την προσομοίωση μιας οξειδωτικής τάφρου, στην οποία πραγματοποιείται βιολογική απομάκρυνση αζώτου. Το σύστημα προσομοιάζεται με με 26 αντιδραστήρες CSTR, συνδεδεμένους σε σειρά. Αερόβιες και ανοξικές συνθήκες επικρατούν σε κάθε αντιδραστήρα. Παράγοντες όπως η κατανομή αερόβιων ανοξικών αντιδρστήρων, η ηλικία της λάσπης, ο λόγος ανακύκλωσης της λάσπης και του ανάμικτου υγρού και ο ογκομετρικός ρυθμός ροής μελετήθηκαν. Η συμπεριφορά του συστήματος ήταν παρόμοια.Σε όλες τις περιπτώσεις, πλην μιας, δεν παρατηρήθηκε παραγωγή νιτρικών. Τελικά οι επαναλαμβανόμενες αερόβιες-ανοξικές συνθήκες ευνοούν την παράκαμψη της παραγωγής νιτρικών. / Nowadays, the progress of technology has created a big increasement in the quantity of wastewater. Simultaneously, there is the demand of biological nitrogen removal from wastewater in order the cost of the process be reduced. In this direction, technologies of biological nitrogen removal, bypassing nitrate production, has developed. A number of factors such as ammonia, temperature, PH, play a significant role in nitrate production. Lately, mathematical models are used in great extend in order to study and optimize these technologies. In this study a modified ASM1 model is used to simulate an oxidation ditch, which performs biological nitrogen removal. The system is simulated with 26 CSTRS, connected in series. Aerobic or anoxic conditions prevail in each reactor. A number of factors such as the distribution of aerobic-anoxic reactors, sludge age, recycling rate of the sludge, recycling rate of mixed liquor and volumetric flow of wastewater was studied. The behavior of the system was the same. Nitrate production did not take place in all cases, except one. So repeated aerobic-anoxic conditions favor bypassing nitrate production.

A ampla ocorrência de contaminação de águas por compostos de nitrogênio em concentrações superiores às recomendadas pela legislação tem suscitado interesse no desenvolvimento de tecnologias viáveis de remoção desses compostos. A remoção biológica de nitrogênio apresenta como principais vantagens os custos relativamente reduzidos e a possibilidade de maior eficiência. Compostos reduzidos de enxofre como sulfetos podem ser oxidados a enxofre elementar ou a sulfato por bactérias oxidantes de sulfeto que utilizam nitrato ou nitrito como receptor de elétrons. Esta desnitrificação reduz os requerimentos globais de carbono para a remoção de nutrientes, com menor produção de lodo, proporcionando grande economia. O objetivo desta pesquisa consistiu em contribuir para o conhecimento acerca dos aspectos microbiológicos do processo de desnitrificação com o uso de sulfeto. Foram avaliados os efeitos dos modos de operação dos reatores desnitrificantes sobre a biomassa em cada uma das diferentes configurações e monitorada a colonização microbiana por meio de técnicas de Biologia Molecular como PCR/DGGE, sequenciamento e análises filogenéticas. Os fragmentos do gene RNAr 16S foram relacionados aos gêneros Pseudomonas, Aeromonas, Acidobacteria, Chlroroflexi, Clostridium, Cupriavidus e Ralstonia. Filotipos dos clones para o sistema piloto foram associados a bactérias não cultiváveis e Firmicutes envolvidos na digestão anaeróbia em reatores tratando água residuária, Synergistetes, Deferribacteria e Proteobacteria. Foram identificados micro-organismos presentes nos reatores com reconhecida capacidade para desnitrificação: Pseudomonas, Desulfovibrio desulfuricans e Ralstonia. Amostras de ambos os reatores desnitrificantes apresentaram reações de amplificação positivas com primers específicos para bactérias semelhantes a Thiomicrospira associados a primers universais: 100% das amostras amplificaram com OST1F/1492R e 75% com EUB8F/OSTR1R. Para duas condições de operação do reator em escala de bancada foram identificados micro-organismos semelhantes a Sulfurimonas denitrificans, bactéria autotrófica redutora de nitrato e oxidadora de sulfeto. Chloroflexi também foram encontrados em digestores localizados em plantas de tratamento de águas residuárias recebendo essencialmente efluente doméstico e Propionibacterium foi associada a comunidade microbiana de reatores UASB tratando água residuária industrial. Bactérias em associações sintróficas com participação no ciclo do enxofre e/ou na digestão anaeróbia foram igualmente identificadas: Clostridium sulfidigenes e outros Firmicutes, Synergistetes, clones de bactérias de cultura de enriquecimento e bactérias do gênero Syntrophorhabdus. Os resultados deste trabalho proporcionaram associar a colonização microbiana com o desempenho e as características metabólicas de alguns micro-organismos com reatores desnitrificantes combinados para o tratamento de águas residuárias. / The widespread nitrate contamination in concentrations higher than recommended by legislation has raised interest in technologies for water and wastewater treatment. Biological nitrogen removal is relatively low cost and higher efficiency. Sulfide as electron donor can be oxidized to elemental sulfur or sulfate by sulfide oxidizing bacteria that can use nitrate or nitrite as electron acceptor. This type of denitrification reduces the overall requirements for removal of carbon nutrients and less sludge is produced. The aim of this research was to contribute to microbiological knowledge about denitrification using sulfide. The effects of operation conditions on the denitrifying biomass were monitored through molecular biology techniques such as PCR/DGGE, sequencing and phylogenetic analysis. 16S rRNA gene fragments were related to Pseudomonas, Aeromonas, Acidobacteria, Chlroroflexi, Clostridium, Cupriavidus and Ralstonia. Phylotypes of clones from samples of pilot-scale reactor were associated with non-cultivable bacteria and Firmicutes involved in anaerobic digestion of wastewater, Synergistetes, Deferribacteria and Proteobacteria. Microorganisms with ability to denitrification were identified in both reactors: Pseudomonas, Desulfovibrio desulfuricans and Ralstonia. Samples of denitrifying reactors showed positive amplification with specific primers for Thiomicrospira associated to universal primers: 100% of the samples amplified with OST1F/1492R and 75% EUB8F/OSTR1R. Sulfurimonas denitrificans-like were identified for two operational conditions of the bench scale reactor. Chloroflexi were also found in treatment plants digesters receiving domestic wastewater and Propionibacterium was associated with microbial community of UASB reactors treating industrial wastewater. Syntrophic bacteria participating in the sulfur cycle and/or anaerobic digestion were also identified: Clostridium sulfidigenes and other Firmicutes, Synergistetes, clone enrichment culture bacteria and Syntrophorhabdus. These results provide to associate this microbial colonization and metabolic characteristics of some microorganisms with performance of combined denitrifying reactors for treatment of wastewater.

Biological nitrogen removal was simulated for a Vacuum Rotating Membrane (VRM) type membrane bioreactor (MBR) operated in METU campus. In order to simulate the biological MBR plant, a dynamic model that describes the process is needed. In this thesis, the Activated Sludge Model No.1 (ASM1), which still is the most widely used model developed by the International Association on Water Quality (IAWQ), has been used to simulate the carbon oxidation, nitrification and denitrification processes occurring in the plant using AQUASIM software package. Once the model was established, sensitivities of the model parameters were analyzed. Then, parameter estimation was carried out for the optimization of the sensitive parameters. As we have several distinct data sets available two parallel modeling study was carried out for the calibration of the model. Finally, the calibrated model by different data sets was validated by using the remaining data sets. The model results were consistent with the measured data especially in terms of MLSS concentration in the system. However model results for the nitrogen removal were not extremely successful / the reason for this might be the inadequate available data on nitrification-denitrification process occurring in the system.

Many control systems of practical importance are multivariable. In such systems, each manipulated variable (input signal) may affect several controlled variables (output signals) causing interaction between the input/output loops. For this reason, control of multivariable systems is typically much more difficult compared to the single-input single-output case. It is therefore of great importance to quantify the degree of interaction so that proper input/output pairings that minimize the impact of the interaction can be formed. For this, dedicated interaction measures can be used. The first part of this thesis treats interaction measures. The commonly used Relative Gain Array (RGA) is compared with the Gramian-based interaction measures the Hankel Interaction Index Array (HIIA) and the Participation Matrix (PM) which consider controllability and observability to quantify the impact each input signal has on each output signal. A similar measure based on the <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Cmathcal%20H_2" /> norm is also investigated. Further, bounds on the uncertainty of the HIIA and the PM in case of uncertain models are derived. It is also shown how the link between the PM and the Nyquist diagram can be utilized to numerically calculate such bounds. Input/output pairing strategies based on linear quadratic Gaussian (LQG) control are also suggested. The key idea is to design single-input single-output LQG controllers for each input/output pair and thereafter form closed-loop multivariable systems for each control configuration of interest. The performances of these are compared in terms of output variance. In the second part of the thesis, the activated sludge process, commonly found in the biological wastewater treatment step for nitrogen removal, is considered. Multivariable interactions present in this type of bioreactor are analysed with the tools discussed in the first part of the thesis. Furthermore, cost-efficient operation of the activated sludge process is investigated.

The aeration process is often the single largest consumer of electricity in a wastewater treatment plant. Aeration in biological reactors provides microorganisms with oxygen which is required to convert ammonium to nitrate. Ammonium is toxic for aqueous ecosystems and contributes to eutrophication. The importance of aeration for the treatment results in combination with the high costs motivates automatic control of the aeration process. This thesis is devoted to ammonium feedback control in municipal wastewater treatment plants. With ammonium feedback control, the aeration intensity is changed based on a measurement of the outlet ammonium concentration. The main focus of the thesis is design, implementation, evaluation and improvement of ammonium PI (proportional-integral) controllers. The benefits of ammonium feedback control are established through long-term experiments at three large wastewater treatment plants in Stockholm, Sweden. With ammonium feedback control, energy savings up to around 10 % were achieved compared to keeping the dissolved oxygen concentration constant. The experiments generated several lessons learned with regard to implementation and evaluation of controllers in full-scale operation. The thesis has established guidelines on how to design ammonium feedback controllers for situations when cost-effective operation is the overall aim. Simulations have demonstrated the importance to limit the dissolved oxygen concentration in the process and under what conditions the energy saving with ammonium feedback control is large. The final part of the thesis treats improvements of ammonium PI control through minor modifications to the control structure or controller. Three strategies were studied: gain scheduling control, repetitive control, and a strategy reacting to oxygen peaks in the last aerobic zone. The strategies all had their benefits but the ammonium feedback controller was the key factor to improved aeration control.

Submitted by Neusa Fagundes (neusa.fagundes@unioeste.br) on 2017-09-06T13:24:19Z No. of bitstreams: 1 Adelcio_Giongo2016.pdf: 1383735 bytes, checksum: ddf849e35c040eb04a0c84af1eeb643f (MD5) / Made available in DSpace on 2017-09-06T13:24:19Z (GMT). No. of bitstreams: 1 Adelcio_Giongo2016.pdf: 1383735 bytes, checksum: ddf849e35c040eb04a0c84af1eeb643f (MD5) Previous issue date: 2017-07-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The swine industry has shown strong development and, thus, has produced large volumes of effluents that must be correctly managed. Therefore, when such effluent cannot be released into soil, a treatment must be carried out to avoid environmental impacts of swine wastewater. Nitrogen is one of the elements that takes part in swine waste and it must be under constant evaluation, but, in some cases, it must be removed. Nitrification/denitrification (NDF) process is a frequent applied technology. However, when the effluent presents low C/N ratio, such as effluents after anaerobic processes, there is some decrease on denitrification efficiency and the total nitrogen removal can be affected. In this case, Nitritation/denitritation (NDT) process can be used to improve the system performance as well as save energy cost with aeration and external source of carbon due to the lower C/N requirement. Thus, this study aimed at evaluating swine wastewater based on NDF and NDT processes at different C/N ratios in order to obtain a system with efficient nitrogen removal and low oxygen and carbon consumption. Four phases were carried out during this experiment: Phase I) DO from 2.0-3.0 mgO2L-1 to 1.5 C/N; Phase II) DO from 0.6-0.7 mgO2L-1 to 1.5 C/N; Phase III) DO from 0.6 to 0.7 mgO2L-1, different C/N ratios (1.5, 0.9, 0.75 and 0.6); Phase IV) DO from 2.0 to 3.0 mgO2L-1, different C/N ratios (1.5, 0.9, 0.75, and 0.6). The best operational condition was obtained at nitritation/denitritation process, whose C/N ratio was 0.9, and the optimum N removal was 86.3%. Under this condition, the system saved almost 36.8% of total organic carbon consumption and nearly 74% of dissolved oxygen consumed when compared to the conventional process for N-removal. This strategy can be very useful for nitrogen removal with low carbon rates, as the digestate from anaerobic processes. / A atividade suinocultura tem apresentado forte crescimento, e assim vem produzindo grandes volumes de efluentes que devem ser corretamente administrados. Portanto, quando não é possível a aplicação deste tipo de efluente no solo, o tratamento deve ser aplicado para que se evitem impactos ambientais. O nitrogênio é um dos elementos presentes nos dejetos de suínos que deve estar sob constante avaliação, e em alguns casos deve ser removido. O processo de nitrificação/desnitrificação (NDF) é uma tecnologia frequentemente aplicada, porém, quando o efluente apresenta baixa relação C/N, como efluentes pós-processos anaeróbios, a eficiência da desnitrificação é reduzida e a remoção de nitrogênio total pode ser afetada. Neste caso, o processo de nitritação/desnitritação (NDT) pode ser utilizado para melhorar o desempenho do sistema e economizar energia com aeração e com fonte externa de carbono, devido ao requisito de baixa relação C/N. Assim, o objetivo deste estudo foi avaliar a água residuária de suinocultura utilizando nitrificação/desnitrificação e nitritação/desnitritação em diferentes relações C/N, a fim de se obter um sistema com eficiente remoção de nitrogênio e baixo consumo de oxigênio e carbono. Quatro fases foram realizadas durante o experimento: Fase I) OD entre 2,0-3,0 mgO2 L-1 (nitrificação) e C/N 1,5; Fase II) OD entre 0,6-0,7 mgO2 L-1 (nitritação), e C/N 1,5; Fase III) OD entre 0,6-0,7 mgO2 L-1, diferentes relações C/N (1,5, 0,9, 0,75 e 0,6); Fase IV) OD entre 2,0-3,0 mgO2 L-1, diferentes relações de C/N (1,5, 0,9, 0,75 e 0,6). A melhor condição operacional foi encontrada no processo nitritação/desnitritação, com relação C/N de 0,9, cuja remoção de N considerada ótima foi de 86,3%. Nesta condição, a economia do sistema foi de 36,8% do consumo total de carbono orgânico e de cerca de 74% do consumo de oxigênio dissolvido, quando comparado com o processo convencional de remoção de N. Esta estratégia pode ser muito útil para a remoção do nitrogênio de efluentes de baixo teor de carbono, como os provenientes de processos anaeróbios.

The reduction in energy consumption is nowadays of increasing importance also within the field of waste water treatment. In combination with increasing requirements for the WWTP (waste water treatment plant) outlet quality, the energy optimization becomes very challenging for the plants operators. This thesis presents possible approaches to the energy optimization and summarizes technologies and measures, where some of them are in the research phase while others are already implemented successfully. In particular, the contribution of the activation tanks aeration process to the overall energy consumption of a plant is highlighted. A change in the aeration control is tested using a mathematical model of WWTP in Mikulov, South Moravia in Czech Republic. In the new setting the aeration is regulated based on the concentration of nitrogen compounds in the activation tank. There is also a brief survey of the energy consumption of the plant and an outline of other possible energy conservation measures.

It has been illegal to deposit household waste in Swedish landfills since 2005. The large amount of waste deposited prior to this does however continue to pose an environmental concern, mainly in the form of leachate water. This study focused on enhancing the denitrification process in a leachate water treatment plant through bioaugmentation. The two strains Brachymonas denitrificans and Comamonas denitrificans as well a commercial seed mix from ClearBlu Environmental® (CBE-mix) containing amongst others, Pseudomonas putida AD 21 and Pseudomonas fluorescens, were investigated as candidates. Nitrite, nitrate, and ammonium concentrations were measured in laboratory-, and pilot-scale studies to follow the processes of nitrification and denitrification. The pilot study was conducted for 10 days in the middle of May 2020 with leachate from the treatment plant in an aerated and nonaerated setup in open field conditions. C. denitrificans and B. denitrificans were both shown to be able to adapt to growth in landfill leachate. The addition of these strains led to a higher rate of nitrate reduction compared to the control during the first days of the pilot experiment but showed no difference in the total amount of nitrate reduced. The combined nitrogen concentration of ammonium, nitrate, and nitrite was 6.7% lower than the control when using a culture augmented with the CBE-mix in the aerated setup. This could indicate aerated denitrification. The amount of nitrate reduced during the pilot experiment was increased with 32% when augmenting the community with the CBE-mix in a nonaerated setup. An explanation could be that certain strains in the mix were able to utilize hard to degrade organic carbon present in the leachate or that the mix had a higher ratio of reduced nitrate to consumed organic carbon than the indigenous community. / Det har varit olagligt att deponera hushållsavfall i Sverige sedan 2005, den stora mängd avfall som deponerats innan dess fortsätter dock att utgöra ett miljöproblem, främst genom genereringen av lakvatten. Den här studien fokuserade på möjligheten att förbättra denitrifikationen i ett reningsverk för lakvatten genom bioaugmentation. Två stammar tillhörande Brachymonas denitrificans, och Comamonas denitrificans, samt en kommersiell bakterieblandning från ClearBlu Environmental® innehållande bland andra Pseudomonas putida AD 21 och Psedomonas flourescens, undersöktes som möjliga kandidater. Ammonium-, nitrat- och nitritkoncentrationer mättes i odlingsstudier i labbskala och i en pilotstudie för att undersöka nitrifikation och denitrification. Pilotstudien utfördes i en luftad och en o luftad konfiguration utomhus i mitten av maj 2020, med lakvatten från reningsverket under en 10 dagars period. C. denitrificans och B. denitrificans klarade båda av att anpassa sig till tillväxt i lakvatten. Tillsats av dessa arter ledde till en ökning i nitratreduktionshastighet i början av pilotexperimentet men gav ingen total minskning av nitratmängden. Den sammanlagda slutkoncentrationen av ammonium-, nitrat- och nitritkväve var 6,7% lägre än i kontrollen när en kultur argumenterad med den kommersiella bakteriemixen användes i den luftade konfigurationen. Mängden reducerat nitrat ökade med 32% när en kultur augmenterad med den kommersiella mixen användes i den oluftade konfigurationen. En möjlig förklaring är att vissa stammar i mixen klarade av att tillgodogöra sig svårnedbrytbara kolföreningar i lakvattnet eller att ration mellan reducerat nitrat mot konsumerat organiskt kol var högre än i det ursprungliga microbsamhället.

Mathematical models of a nitritation: anaerobic ammonia oxidation (anammox)-coupled biofilm in a counter-diffusion hollow fiber membrane bioreactor (HFMBR) and a nitritation: anammox-coupled biofilm in a co-diffusion rotating biological contactor (RBC) were developed and implemented using AQUASIM. Four different start-up scenarios on the nitritation: anammox-coupled biofilm in an HFMBR were investigated. The supply of oxygen was simulated with the flow through the lumen of the hollow fiber membrane. For the four scenarios, two scenarios investigated the start-up when nitrite was supplied in the feed while the other two scenarios investigated when the source of nitrite was through nitritation only. The results showed that the presence of nitrite in the feed facilitated the start-up of the reactor. In addition, the results also showed that increasing oxygen flux through the membrane up to a certain ratio of ammonia flux with oxygen flux affected reactor performance by improving nitrogen removal and reducing start up time. For the nitritation: anammox-coupled biofilm in an RBC, four different process options were investigated: the number of reactors, the initial anammox (AnAOB) biomass fraction, the bulk oxygen concentration and the maximum biofilm thickness. Modeling results revealed that the steady state total nitrogen removal in RBC reactors in series occurred primarily in the first and second reactors. It is concluded that the number of reactors in series dictates the effluent performance and, therefore, this number can be selected depending upon the desired total nitrogen removal. Simulation results also revealed that increasing the initial AnAOB biomass fraction from 0.01% to 1.0% had no effect in the steady state nitrogen removal but had an effect in the required time to reach the steady state total nitrogen removal and the maximum biofilm thickness. Modeling results of the third process option showed that increasing the bulk oxygen concentration in the reactor from 0.2 g/m3 to 5 g/m3 linearly increased the steady state total nitrogen removal and reduced the time to reach the maximum biofilm thickness. Beyond 5 g/m3, steady state total nitrogen removal decreased. In addition, simulation results revealed that the thicker biofilm clearly showed a more linear correlation between the increase in bulk oxygen concentration and the increase in the steady state total nitrogen removal within a range of bulk oxygen concentrations. The results showed that RBC performance could be controlled by several process options: the number of reactors in series, initial biomass fraction, the bulk oxygen concentration and the maximum biofilm thickness. The mathematical modeling results for the HFMBR and RBC have shown that both have potential as carriers for nitritation: anammox-coupled biofilms targeted at the removal of nitrogen in the wastewater. / Master of Science

I takt med att Uppsala växer behöver kapaciteten för avloppsvattenrening på Kungsängsverket byggas ut. För att möta en framtida ökad belastning bedömer Uppsala Vatten &amp; Avfall AB att en kolkälla kommer behöva tillsättas i den biologiska kvävereningen för att effektivisera den heterotrofa denitrifikationen på Kungsängsverket, som idag sker utan tillsats av kolkälla. Potentialen till förbättrad denitrifikation med olika kolkällor utvärderades genom satsvisa laboratorieförsök och litteraturstudier. Syftet var att bättre förstå de studerade kolkällornas funktion och prestanda i denitrifikation för att ge underlag inför en framtida fullskalig implementering av kolkälla. Det övergripande målet var att identifiera vilken eller vilka kolkällor som är mest fördelaktiga med avseende på reningseffektivitet, processpåverkan, doseringsbehov, ekonomi och miljöpåverkan. Triplikata försök genomfördes som denitrifikationstester med aktivt slam vid en genomsnittlig slamtemperatur på 14 ℃ och pH 7-8, där fem externa kolkällor (etanol, Brenntaplus VP1 och tre industriella restprodukter) samt försedimenterat avloppsvatten testades. I litteraturstudien inkluderades även metanol. Från försöksdata bestämdes specifika denitrifikationshastigheter, COD/N-kvoter och utbyteskoefficienter. Även bieffekter såsom nitritackumulering och fosforsläpp studerades. Därefter uppskattades doseringsbehov och kostnader baserat på erhållna resultat och antaganden om framtida produktionsmål för nitratkväve. En likartad prestanda erhölls med en av restprodukterna (RTP-vätska) och etanol som uppnådde högst denitrifikationshastigheter och reduktionsgrader (98 % respektive 97 %). Doseringsbehovet uppskattades vara 4 gånger högre med RTP-vätska jämfört med etanol. Med de två andra restprodukterna (dextrandrank och sackaroslösning) uppnåddes lägst denitrifikationseffektivitet och reduktionsgraderna uppgick till 79 % respektive 47 %. Vid test av sackaroslösning observerades dessutom ofullständig denitrifikation samt höga fosforsläpp. Dextrandranken uppträdde på liknande sätt. I egenskap av restprodukt är RTP-vätskan intressant för fortsatt utvärdering. Fullskalig implementering av RTP-vätska förutsätter att doseringsbehoven kan tillgodoses samt att lämplig distribuering och lagerhållning kan ordnas på Kungsängsverket. / The city of Uppsala is expanding and consequently enhanced capacity at the wastewater treatment plant of Kungsängen will be required in the future. As for the biological nitrogen removal process, Uppsala Vatten &amp; Avfall AB expects an additional carbon source to be necessary in the future denitrification process. Currently, the nitrogen removal is employed without the addition of a carbon source. The potential of enhancing denitrification with different carbon sources was evaluated by conducting lab-scale batch tests and compiling literature data. The objective of this work was to better understand the performance of the chosen carbon sources as electron donors in heterotrophic denitrification and thereby provide groundwork for a future full-scale implementation of a carbon source. Based on information drawn from batch tests and literature, the carbon sources were evaluated with respect to removal efficiency, process compliance, quantitative dosing requirements, costs, and environmental sustainability. Lab-scale trials were conducted as denitrification tests (triplicate) at a mean sludge temperature of 14 ℃ and pH 7-8 with five external carbon sources (ethanol, Brenntaplus VP1, and three industrial waste products) and pretreated wastewater. In the literature review, methanol was included as well. Results obtained from the batch tests were used to determine kinetic parameters, mainly specific denitrification rates, COD/N ratios, and anoxic yield coefficients. Moreover, unwanted side effects due to addition of carbon sources were examined. Dosing requirements and costs were assessed based on previously determined kinetic parameters and supposed future production guidelines for effluent quality with respect to nitrate concentration. Similar performance was observed with one of the waste products (RTP liquid) and ethanol which achieved the highest denitrification rates and degree of removal (98 and 97 %, respectively). The estimated dosing requirement was 4 times higher with the RTP liquid compared to ethanol. The other two waste products, solutions of fructose (dextran) and sucrose, reached the lowest denitrification efficiency and removal degrees were 79 and 47 %, respectively. During tests with sucrose solution, incomplete denitrification and release of phosphorous were observed. The fructose solution showed somewhat similar behavior but to a lesser degree. Being a waste product, the RTP liquid is interesting for future evaluation. Full-scale implementation needs further considerations regarding dosing requirements, distribution, and storage conditions at the site of Kungsängsverket.