Sveriges avloppsreningsverk står inför ett antal utmaningar, där en av utmaningarna är minskning av växthusgaser. Lustgas är en av dessa växthusgaser, som bildas vid rening av avloppsvatten. Lustgas är 300 gånger skadligare för klimatet i jämförelse med koldioxid. Dessutom påverkar den nedbrytningen av ozonskiktet. I dagsläget är det svårt att mäta och uppskatta lustgasutsläpp, på grund av att det pågår flera samtidiga processer på stora ytor. För att driften av avloppsreningsverk ska ske på ett effektivt sätt och med en ytterst liten miljöpåverkan måste man kunna förstå hur lustgas uppstår och hur bildningsprocesserna samverkar med de andra reningsprocesserna och driftparametrarna. Utsläpp av lustgas har studerats vid avloppsreningsverket i Göteborg. Syftet har varit att tillhandahålla resultat och mätningar från Gryaab AB reningsverk och fastställa vilka processer som ger upphov till störst eller minst lustgasemissioner. Utsläpp av lustgasemissioner har mätts från rejektrening med nitrifikation och denitrifikation process. Analyser på resultaten ska förhoppningsvist kunna hjälpa Gryaab AB med fortsatt studier om lustgas. Som mätningsmetod användes EPA-huvmätning som man mätte med ovanför vattenytan på bassängerna och mobilt extraktiv FTIR som åkte runt anläggningen. Den dominerande källan för lustgas visade sig bildas allra mest i nitrifikationsprocessen. Där mätningarna med huv-mätning och stickprov visade totala utsläpp motsvarande 1,8 ton N2O/år. Den totala lustgasemissionen från biologiska reningsprocessen visade totala utsläpp motsvarande 3,5 ton N2O/ år. Som en slutsats bör fler mätningar med olika mätningsmetoder och mer studier göras för att få en bättre överblick till varför och hur lustgas bildas. Samt vilka åtgärder som kan minska lustgasemission. Det finns ett behov av fortsatta studier med mätningar med olika mätningsmetoder på Gryaab AB. / Sweden's wastewater treatment plant faces several challenges, one of them is the reduction of greenhouse gases. Nitrous oxide is one of these greenhouse gases, which is formed during the purification of wastewater. Nitrous oxide is 300 times more harmful to the climate compared to carbon dioxide. In addition, it affects the depletion of the ozone layer. At present, it is difficult to measure and estimate nitrous oxide emissions, since several simultaneous processes are taking place on large areas. For the operation of sewage treatment plants to take place in an efficient manner and with an extremely small environmental impact, it is important to understand how nitrous oxide is formed and how the formation processes interact with the other treatment processes and operating parameters. Emissions of nitrous oxide have been studied at the wastewater treatment plant in Gothenburg. The purpose has been to provide results and measurements from Gryaab AB wastewater treatment plant and to determine which processes give rise to the highest nitrous oxide emissions. Emissions of nitrous oxide emissions have been measured from reject cleaning with the nitrification and denitrification process. Analysis of the results will hopefully be able to help Gryaab AB with further research. As a measurement method, EPA hood measurement was used, which was measured above the water surface in the basins and mobile extractive FTIR was driven around the facility. The dominant source of nitrous oxide was found to be formed most in the nitrification process. Where the measurements with hood measurement and sampling showed total emissions corresponding to 1.8 tons of N2O / year. The total nitrous oxide emissions from the biological treatment process showed total emissions corresponding to 3.5 tons of N2O /year. As a conclusion, more measurements with different measurement methods and more research should be done to get a better overview of why and how nitrous oxide is formed. And what measures can reduce nitrous oxide emissions. There is a need for further studies with measurements with different measurement methods on Gryaab AB.

This study describes the variation of an important greenhouse gas, nitrous oxide (N2O) at site-specific from the bio-lines unit at Wastewater Treatment Plant (WWTP) in Halmstad. The sampling campaign at the WWTP was carried out for three consecutive days during the weekdays in March 2021 with total of 144 samples were taken in GHG sample vials (exetainers) and analysed for N2O measurements using gas chromatography. Other nitrogen parameters data (NO2-N, NO3-N, and total nitrogen) were also collected. Using statistical analysis, comparisons were focused on a year period (March 2020 and 2021). This study found that N2O concentration generated in March 2021 was significantly lower than March 2020. Results also showed significant differences of N2O concentration between the three different zones (anaerobic, anoxic, and aerobic) among the bio-lines, where the highest N2O concentration was only found in aerobic zones. Correlation analysis showed only total nitrogen is negatively correlated with N2O-N in the aerobic zones. These findings will enable better understanding of processes along the bio-lines as a step for WWTP operators to improve N2O monitoring.

The removal of 34 per- and polyfluoroalkyl substances (PFAS) were compared in a 1 stagegranular activated carbon (GAC) filtration to a 2 stage GAC filtration in a pilot study at adrinking water treatment plant (DWTP). The PFASs that were present in the water wereperfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluoropentanoic acid(PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorobutanesulfonic acid (PFBS), perfluoropentane sulfonic acid (PFPeS) and perfluorohexane sulfonic acid(PFHxS). A cost comparison for the operation of a one stage GAC to a two stage GAC wascompared for PFAS4 (sum of PFOA, PFNA, PFHxS and PFOS) at treatment goals ranging from2 - 10 ng/L. The pilot was operated at three different flows and the three different bed volumes(BV)s resulting in three different empty bed contact times (EBCTs) at three different times.Therefore, the Lin & Huang adsorption model (1999) was used to model the concentrations ateach EBCT. It was found that the model worked good for PFBS, PFPeS, PFHxS, PFOS andPFOA but not for PFPeA, PFHxA and PFHpA (except for PFPeA and PFHxA during EBCT 5min) and did not work for desorbing PFASs. The removal comparison of PFASs was made,partly by comparing removal efficiencies between the first stage and the second stage GAC filterand by comparing the removal per weight of GAC per BV 1 stage and 2 stages. It was found thatthe removal efficiency decreases with decreasing chain length and increasing treated BVs forboth the first stage and the second stage. The short chain PFCAs were also desorbing after anumber of BVs. The removal per weight of GAC showed that the removal does not increasewhen comparing a one stage GAC to a two stage GAC for any the PFAS. The cost comparisonwas made using the adsorption model. It showed that it was cheaper to operate a 2 stage GAC forthe EBCT of 5 minutes and 8 minutes for the whole range of treatment goals. However, for theEBCT of 15 minutes the costs for the second stage was decreasing with decreasing treatmentgoal which is unrealistic result. This was caused by too few data points available for the model topredict reliable results.

The unsaturated zone could provide an effective barrier against pathogenic microbes entering the groundwater. Knowledge relating to microbial fate in this zone is therefore important for increased understanding of groundwater vulnerability. This thesis examines the published literature that is related to the transport, retention and survival processes that apply to the fecal indicator bacterium Escherichia coli in unsaturated porous media. The main focus concerns the research findings under steady-state flow in homogeneous filter media, and under unfavorable attachment conditions, which are the most common in the natural environment. Experimental results in the literature for the pore-, column- and field-scale are examined and compared to commonly applied theories and modeling approaches. An analysis of the main factors that influence attenuation and biofilm formation is provided. Further, the findings are illustrated in a model of an unplanted, vertical flow constructed wetland. The results indicate that retention at the solid-air-water interface is a major attenuation process. In addition, they suggest that the flow velocity (as dependent on the grain size and the saturation) is a key influencing factor. However, it has not yet been established how the research findings relating to the main processes and influencing factors can be incorporated into predictive models; in the literature, a multitude of models have been proposed and alternative theories could describe the same observation. In this study, the transport and fate of Escherichia coli in different sand filters is, therefore, modeled using various literature models - derived under similar experimental conditions - in order to assess the possibility to compare and generalize the equations, evaluate their implications considering the different saturation settings and filter depths, and to define the spectra of the reduction efficiencies. It is discovered that the bacterial attenuation behaviors vary largely. This calls for clarification regarding the underlying processes. Future research is also recommended to include the ef-fects of structured filter media and sudden changes in the flow rate. / QC 20111208

The urge for more sustainable living motivated the Stockholm Tiny House Expo. The project aims to build a floating, sustainable, man-made island for living and working outside of Stockholm. This paper proposes a waste management method with possible energy recovery for the island. It introduces a comprehensive system that integrates decentralized wastewater treatment with energy generation through anaerobic treatment. A by-product of the wastewater treatment process, the sludge, is combined with food waste to generate energy through biogas. The island’s organic waste (wastewater and food waste) is thereby managed sustainably. The results of this report require further research. The energy supply from the biogas reactor was calculated to be 52.19 MWh. The wastewater treatment process was designed with an objective of 90% reduction of BOD5, to comply with the Swedish regulations for wastewater discharge to natural bodies of water, including the ocean. The system's total volume proposed is 11.25 m3, which is the sum of the volumes of all the reactors, or tanks, needed to complete the treatment.

Dagens intensiva användning av plast genererar mikroplaster som på olika sätt sprids ut i vår omgivning och medför risker för naturliga system världen över. Dessa mikroplaster härrör från bland annat hushåll, industrier och deponier, och färdas ofta med avloppsvattten och i viss utsträckning dagvatten till reningsverk. Där renas vattnet och en stor del av mikroplasterna ansamlas i det slam som bildas i samband med vattenreningen. Slammet består till stora delar av organiskt material och näring, och betraktas ofta som en resurssnarare än avfall. Cirka 50 % av det slam som bildas i europeiska reningsverk används som gödningsmedel inom jordbruk. Det innebär att slamgivor potentiellt är källor för spridning av stora mängder mikroplast. Idag är kunskapen om mikroplaster i slam relativt liten och en standardiserad metod för extrahering av mikroplaster ur slam saknas, vilket begränsar möjligheten att se problemets magnitud. Detta examensarbete strävar efter att bidra till utformandet av en sådan metod, och undersöker förekomsten av mikroplaster i slam från Ekeby reningsverk i Eskilstuna och Käppalaverket på Lidingö utanför Stockholm med hjälp av två olika metoder. De båda metoderna kombinerar oxidativ nedbrytning med hjälp av fenton-reagens och densitetseparering för att skilja mikroplaster från organiskt och inorganiskt material. Skillnaden mellan de olika metoderna är att den ena innehåller ett oxiderande moment och den andra två. Rapporten behandlar huruvida det extra oxiderande momentet har någon betydande skillnad för utvinningen av mikroplaster ur slam, samt om förekomsten av mikroplasterskiljer sig åt mellan slam från de två olika reningsverken. Resultaten visar att det finns en skillnad mellan de två extraheringsmetoderna samt viss skillnad mellan förekomsten av mikroplaster i de olika slammen. I rapporten diskuteras huruvida skillnaden mellan resultaten av de två olika metoderna beror på det extra oxiderande momentet, eller andra tillkommande effekter. Vad gäller mikroplasters förekomst i slam från de olika reningsverken fastslås att de skiljer sig åt kvantitativt, och i viss mån även kvalitativt.

Vid vattenrening produceras slam som restprodukt. Slam innehåller en stor mängd ämnen, såsom metaller, medicinrester och olika näringsämnen. I Sverige produceras flera hundra tusen ton årligen. Innehållet måste hanteras, men hur görs det idag och hur kommer det att hanteras i framtiden. Vanligast idag är att återvinna fosfor och kväve genom att sprida slam som gödning inom jord och skogsbruk. Däremot metaller som finns i slam utvinns inte idag, även om det vore värdefullt ur miljösynpunkt.  Denna litteraturstudie beskriver hur slamhantering ser ut idag, med fokus på Sverige. Därefter beskrivs forskningsläge och möjlig framtida utveckling i hantering. Slamhantering är problematisk ur flera aspekter. Slamhantering behöver hantera följande svårigheter: En logistisk aspekt är de stora volymer som behöver hanteras och att de produceras på många olika platser.Forskning på konsekvenser av slamspridning är relativt liten. Det gäller den påverkan som medicinrester, tungmetaller och andra ämnen utgör.Vilka utvinningsbara ämnen ska prioriteras, eftersom metoder för utvinning ställer maximerad utvinning av gödning i motsats till maximerad utvinning av metaller. / When purifying water, sludge is produced as a residual product. Sludge contains lots of different substances, such as metals, medical waste and different nutrients. In Sweden there is many hundred thousands of tons of sludge produced annually. The content must be managed, but how is it handled today and how will it be managed in the future. Commonly today phosphorus and nitrogen recycles by spreading sludge as fertiliser in agriculture and forestry. Metals in sludge is not recycled, even if it would be positive from an environmental point of view. This literature study describes how sludge treatment is today with a focus in Sweden. Then it describes the current state of research and possible future development in management. Sludge handling is problematic from many different aspects. Sludge treatment must have to address these challanges: One logistic aspect is that there are great volumes that needs to be handled and that it is produced in many different places. The research in consequences of sludge spreading is a relatively small base. That goes for the influence of medical waste, heavy metals, and other substances in sludge. What recyclable substances needs to be prioritised, since the methods of extraction puts the maximal extraction of fertiliser against the maximised extractions of metals

This project investigated the bacteria in water entering and leaving the slow sand filters at Ringsjö Water Works using flow cytometry. The purpose was to explore the possibility of utilising flow cytometry as a monitoring method for optimising water production using slow sand filters. Data describing the bacterial community in water was collected over seven weeks and analysed with FlowJo, flow cytometric image comparison and Minitab. The total cell count, intact cell count and the percentage of high nucleic acid bacteria were analysed. These parameters were highly dependent on scraping events, water entering the filters and season. The results indicated that flow cytometry has great potential for use as a monitoring method, although more data should be collected to establish expected trends and secure baseline values for routine comparisons. / <p>Fördröjning av publikation fram till 31 december 2020.</p>

Microbial Fuel Cell is a novel technology that can be used for a waste water treatment in order to simultaneously remove carbonaceous matter and nitrogen while producing electrical power. Even if it is not an established technology so far, MFC could be a cost effective option for waste water treatment and the major challenge of this process will be the device scale-up. Exoelectrogenic bacteria are capable of converting the chemical energy of organic matter into electrical energy by transferring the electrons produced in the oxidation to the anode electrode. This project focused on developing a single device for nitrification, denitrification and carbon removal. Two double air-cathode single chamber MFCs are used to test the feasibility of this process that could replace the biological unit in a waste water treatment train. The cells tested in this study were manufactured with the purpose of achieving a high surface area on both the anode electrode (vitreous carbon foam) and the air-cathode electrodes (metallic mesh with diffusion layer and active layer) with different catalysts for the reduction reaction (cobalt and platinum). The bacterial biofilm growth is a fundamental step and the cells Open Circuit Potential was monitored during all the start-up period to determine the microorganism acclimation: a three days lag period was observed in both cells before the potential rise. The second cell was forced to reach higher voltage through an anode polarization and that seems to positively affect the biofilm stability at lower voltages transferring a greater amount of electrons and hence obtaining a higher current and power generation. For this reason after three weeks of inoculation the second cell reached an open circuit potential of 0.76 V which is a promising value for such a system. Electrochemical and biological tests were conduced in order to test the power production of the cell and the substrate removal from the waste water. Polarization curves were used to evaluate power generation (and the maximum production under a specific external load) and the cell voltage trend which is characterized by activation and ohmic losses: 32 mW/ and 41 mW/  are the power density normalized by cathode surface (72 ) reached by respectively first and second cell. The experimental conditions were varied from low to high temperature and from low to high inlet flow rate but the most affecting phenomenon seems to be the biofilm formation since significant voltage drops were noticed after long closed circuit operation. Higher cell voltage characterized the second cell thanks to more active cathode (platinum catalyst used) and more negative bacterial biofilm but a bigger drop in current generation over time affects the system performance and the most reliable reason is the shorter acclimation time compared to the first cell. Cyclic voltammetry tests were carried out on both electrodes to study the potential range of activity and determine an optimal operational voltage despite of mass transport or kinetic limitations. Substrate removal tests at different retention times in power generation conditions (external load 100 Ω) showed a relatively high total nitrogen consumption (maximum 72.2 %) for the first cell while lower values were achieved by the second system meaning that a longer acclimation period is beneficial for nitrifying and denitrifying bacteria to thrive on the cathode biofilm. Effluent pH level are almost similar to the initial values probably because of nitrification and denitrification protons offset.

Municipal wastewater contains a significant amount of nutrients such as phosphorus (P) and nitrogen (N). Therefore have the interest of recovering these nutrients at wastewater treatment plants (WWTP) increased. Nutrient recovery would generate revenue for the WWTP, as it is possible to sell the products as fertiliser. Today, there are several techniques on the market to recover P as magnesium ammonium phosphate (MAP) and N as ammonium sulphate (AMS). Urine is the fraction contributing with the highest concentration of nutrients. Techniques to separate urine from the rest of the wastewater have been developed. These techniques enable the possibility to recover nutrients from the urine fraction separately; this is beneficial since the nutrient concentration would be higher. The purpose with this study was to examine the possibility for increased nutrient recovery at centralised WWTPs through urine separation.   Different techniques for nutrient recovery were compared by their recovery efficiency, chemical demand, and hydraulic retention time (HRT). A WWTP with enhanced biological P removal was modelled with Danish Hydraulic Institute’s (DHI) software WEST. Eight scenarios, with different percentage of the population equivalents using urine separation techniques, were simulated. The P recovery was calculated from phosphate (PO4) in the hydrolysed excess sludge and the separated urine. The N recovery was calculated from the ammonium (NH4) in the supernatant from the anaerobe digester. The theoretical biogas production was also calculated, from the modelled sludge.    The comparison of P recovery techniques showed no substantial differences in their recovery efficiency, chemical demand, and HRT. The comparison of N recovery techniques showed three techniques with a higher efficiency than the other methods. Ekobalans Fenix AB, CMI Europe Environment, and Organics developed these techniques. To determine which method to use, requests for proposal from different providers are recommended. As the urine separation increased, the influent P and N load decreased. When the urine separation increased and the operational parameters were kept constant, the effluent concentration of P and N decreased. The ratio of total Kjeldahl nitrogen (TKN) and total nitrogen (TN) however increased as the urine separation increased. The total MAP production calculated from the modelled hydrolysis showed that the production increased as the urine separation increased. On the other hand, the total MAP production from calculated hydrolysis showed a decrease in production as the urine separation increased. The difference in these results could be because of the performance of the modelled hydrolysis was better with a smaller nutrient load, resulting in a larger release of PO4 as the urine separation increased. The total AMS production increased as the urine separation increased. This, due to the increase of the TKN:TN ratio. The biogas production was not substantially affected by the increased urine separation.