This essay has been done at the request of Marinfloc AB. It consists of various measurements and experiments investigating the sewage water treatment on a number of different plants. The measurements were executed in the part of the plants called secondary treatment. The objective with secondary treatment is to let micro-organisms remove dissolved and suspended biological and organic matter. The factors which were investigated were which methods are used to oxygenate the sewage water, what level of oxygen saturation is obtained with each method and the power consumption required oxygenating the sewage water. An experiment was carried out on Marinflocs’ own sewage treatment plant with the objective to determine if there is any time difference in oxygenating pure water versus unprocessed sewage water. The conclusion reached was that the four land-based sewage treatment plants that were investigated oxygenate by the same principle. The oxygenation is done by aeration from the bottom in respective aeration tank. The level of oxygen saturation was between 1, 8 – 5, 9 mg oxygen per liter sewage water in all plants. Marinflocs’ current sewage treatment plant uses another principle to oxygenate and its oxygen saturation was measured to a level of 12 mg/l. The experiment on Marinflocs’ own sewage treatment plant concluded that there is a time difference in oxygenating pure water versus unprocessed sewage water. The pure water gets oxygenated faster. 

Denna studie genomfördes på uppdrag av det statliga forskningsinstitutet Formas. Syftet med rapporten var att undersöka hur effektiva våtmarker är som tilläggsrening av avloppsvatten, detta med avseende på reducering av läkemedel samt skadeeffekter på akvatiska organismer. Rapporten baserades på en tidigare studie utförd av Breitholtz et al. (2012) där mätningar av läkemedelshalter samt mortalitet och larvutveckling hos hoppkräftor, Nitocra spinipes, gjordes i fyra olika våtmarker.  De fyra våtmarkerna ligger i Eskilstuna, Oxelösund, Nynäshamn och Trosa. Deras mätningar undersökte mortalitet och larvutvecklingskvot för hoppkräftor i prover utspädda med bräckt vatten vid koncentration avloppsvatten på, 11,25 %; 22,5 %; 45% och 90 %. Proverna för läkemedelshalter späddes inte ut och enbart ett mätvärde per våtmark togs vid inflödet och utflödet.

I denna rapport undersöktes dessa frågeställningar: (1) Är anlagda våtmarker som tilläggsrening en effektiv metod med avseende på skadeeffekter hos hoppkräftor, (2) till vilken grad reduceras halten läkemedel när våtmarker används som tilläggsrening samt (3) finns det ett samband mellan läkemedelsrester och hoppkräftornas överlevnad?

För att besvara de tre frågeställningarna genomfördes en metaanalys av data från studien av Breitholtz et al. (2012). Hoppkräftors mortalitet, larvutvecklingskvot (LDR) och koncentration av läkemedel analyserades. Endast mortalitet och larvutvecklingskvot hade tillräckligt med data för utförande av en metaanalys. Läkemedelsanalysen kunde bara göras på en grundläggande nivå.

Metaanalysen programmerades i MATLAB R2019b, där skillnaden i medelvärdet för mortalitet respektive larvutvecklingskvot beräknades mellan in- och utflöde för de fyra våtmarkerna. Skillnaderna för varje våtmark vägdes samman med invers-varians metoden för att få ett sammanvägt medelvärde. Analysen av läkemedel gjordes på nio läkemedel från Breitholtz et al. (2012). De nio valdes ut då de har pekats ut av Svenska Miljöinstitutet som intressanta ur ett avloppsreningsperspektiv. Excel användes för att göra enklare statistiska analyser mellan in- och utflöde i våtmarkerna. Slutligen gjordes en jämförelse mellan hoppkräftors skadeeffekter och läkemedelshalter genom att ta ut skillnaden i medelvärde mellan in- och utflöde.

Resultatet från analyserna visade att när våtmarker användes som tilläggsrening minskade mortaliteten hos hoppkräftor för koncentrationerna 11,25 % och 90 % avloppsvatten. För koncentrationerna 22,5 % och 45 % fanns däremot ingen signifikant skillnad i mortalitet. Larvutvecklingskvoten minskade efter våtmarksbehandlingen för alla koncentrationer utom 90 %. Läkemedelshalten minskade i snitt med 30 % mellan inflöde och utflöde i våtmarkerna. För läkemedlen sulfametoxazol och oxazepam kunde dock en ökning ses efter behandling med våtmark. Ingen direkt trend kunde utläsas mellan läkemedelshalt och mortalitet hos hoppkräftor. Detta berodde troligtvis på att andra faktorer och föroreningar påverkade hoppkräftornas mortalitet och larvutvecklingskvot i högre grad än läkemedelshalterna.

I studien kunde ingen slutsats dras om huruvida tilläggsvåtmarker är en effektiv reningsmetod med avseende på skadeeffekter hos hoppkräftor. Hoppkräftor är bra indikatorer på föroreningar i vattnet, dock är det svårt att bestämma vilka föroreningar som påverkar mest i detta fall. Detta medför att inga direkta samband mellan läkemedel och hoppkräftors mortalitet kunde påvisas i studien. De undersökta läkemedlen reducerades generellt. Eftersom mätningarna gjordes under vinterförhållanden då nedbrytningen i våtmarken är som minst effektiv bör resultatet ses som ett lägsta värde.

Intensified land use can disturb water quality, potentially increasing the abundance of bacterial pathogens, threatening public access to clean water. This threat involves both direct contamination of faecal bacteria as well as indirect factors, such as disturbed water chemistry and microbiota, which can lead to contamination. While direct contamination has been well described, the impact of indirect factors is less explored, despite the potential of severe downstream consequences on water supply. To assess direct and indirect downstream effects of buildings, farms, pastures and fields on potential water sources, we studied five Swedish lakes and their inflows. We analysed a total of 160 samples in a gradient of anthropogenic activity spanning four time points, including faecal and water-quality indicators. Through species distribution modelling, Random Forest and network analysis using 16S rRNA amplicon sequencing data, our findings highlight that land use indirectly impacts lakes via inflows. Land use impacted approximately one third of inflow microbiota taxa, in turn impacting ∼20–50 % of lake taxa. Indirect effects via inflows were also suggested by causal links between e.g. water colour and lake bacterial taxa, where this influenced the abundance of several freshwater bacteria, such as Polynucleobacter and Limnohabitans. However, it was not possible to identify direct effects on the lakes based on analysis of physiochemical- or microbial parameters. To avoid potential downstream consequences on water supply, it is thus important to consider possible indirect effects from upstream land use and inflows, even when no direct effects can be observed on lakes. Legionella (a genus containing bacterial pathogens) illustrated potential consequences, since the genus was particularly abundant in inflows and was shown to increase by the presence of pastures, fields, and farms. The approach presented here could be used to assess the suitability of lakes as alternative raw water sources or help to mitigate contaminations in important water catchments. Continued broad investigations of stressors on the microbial network can identify indirect effects, avoid enrichment of pathogens, and help secure water accessibility.

The effectiveness of automated treatment processes within wastewater treatment plants ultimately depend on the quality of the measurement data that is given from the installed sensors. Sensor faults affect the control of the treatment plants and are often the reason different control strategies fail. Today there is a lack of standardized guidelines for how to organize and work with online sensors at Swedish wastewater treatment plants which limits the opportunities for treatment plants to reach their effluent criteria in a resource efficient manner. Much research has been done on ways to optimize control strategies but the role of sensors in the efficiency of the treatment plants has not been given the same level of attention. The purpose of this thesis has been to examine how instrumentation at wastewater treatment plants can be organized and structured to ensure good quality measurement data and to examine how sensor faults affect the treatment process.

Within the thesis a literature study was conducted where instrumentation at wastewater treatment plants was examined. The effects of sensor faults were examined by simulating a pre-denitrification process in Benchmark Simulation Model no. 2 where off-sets (biases) and drift where added to measurements from different implemented sensors. The simulations showed that positive off-sets (0.10–0.50 mg/l) in an ammonium sensor within a cascaded feedback-loop adds to the energy consumption used for aeration by roughly 4-25%. It could further be shown that all types of faults in a DO sensor in the last aerated basin had significantly larger effect on the treatment process than the same fault in any of the other DO sensors in the preceding basins. If the last aerated basin is designed to have low DO concentrations the DO sensor in that basin is the most important DO sensor to maintain. Positive off-sets (200–1 000 mg TSS/l) in suspended solids sensors used for control of waste activated sludge flow contributed to large increases of ammonia, by 29-464%, in effluent waters. Negative drift in DO sensors showed that significant savings in aeration energy, roughly 4%, was possible to achieve with more frequent maintenance.

Whether a sensor is affected by a positive or a negative fault, be it off-set or drift, will affect how much and in what way the treatment process will be affected. The study of sensor faults showed that the effect of a positive or a negative fault varied and that the effect on the treatment process was not linear. The effect of a sensor fault on the treatment process will ultimately depend on the implemented control strategy, settings in the controllers and on the controlled process.

Arsenic is an extremely poisonous element. It has been reported to cause contamination of drinking water sources in many parts of the world. The current drinking water permissible limit for arsenic in the European Union is 10 μg/L. The World Health Organization has a general rule that no substance may have a higher lifetime risk of more than 1 in 100,000. However, several studies on toxicity of arsenic suggest that purely based on health effects the arsenic limit of 10 μg/L is not sufficient. The main goal of this research was to develop an efficient arsenic removal technology that could be able to produce drinking water with an arsenic concentration of less than 1 μg/L. For this purpose, an innovative three step technique, Advanced Oxidation - Coagulation - Filtration (AOCF), was investigated through bench-scale and pilot scale experiments in the Netherlands at the water treatment plant of Dorst. Firstly, prior to the investigations on AOCF, the existing arsenic removal at the water treatment plant was investigated. Secondly, through a series of bench-scale experiments, the optimum type of coagulant, its combination dose with the selected chemical oxidant and optimum process pH were determined. Eventually, the partially optimized technique from the bench-scale was implemented at the pilot scale physical model of water treatment plant Dorst where AOCF was evaluated for arsenic removal and its effect on the removal of other common undesirable groundwater constituents. The optimized AOCF technology consistently removed arsenic from groundwater to below 1 ug/L when implemented at pilot scale. The overall effluent quality also remained acceptable. The method is efficient with both types of filtration media tested in this research i.e., virgin sand and metal oxide coated sand, however virgin sand media showed slightly better arsenic removal efficiency.

Removal of arsenic (As) from water by co-precipitation with Fe(III) (oxyhydr)oxides is a widely used technique in water treatment. Nevertheless, As removal efficiency appears to be sensitive to the composition of the water matrix. The aim of this study was to gain a deeper understanding of the independent and combined effects of silicate (Si), phosphate (P), natural organic matter (NOM) and calcium (Ca) on arsenate [As(V)] co-precipitation efficiency and the size of Fe(III) precipitates. We found that, in complex solutions, containing multiple solutes and high levels of Ca, (variations in) Si and P concentrations reduce As(V) removal to some extent, mainly due to a decreased adsorption of As(V) onto Fe(III) precipitates. On the other hand, NOM concentrations reduced As(V) removal to a much greater extent, due to possible formation of mobile Fe(III)-NOM complexes that were difficult to remove by filtration. These findings have a great significance for predicting As(V) removal as a function of seasonal and process-related water quality changes at water treatment plants.

The co-precipitation of Fe(III) (oxyhydr)oxides with arsenic (As) is one of the most widespread approaches to treat As-contaminated groundwater in both low- and high-income settings. Fe-based co-precipitation of As occurs in a variety of conventional and decentralized treatment schemes, including aeration and sand filtration, ferric chloride addition and technologies based on controlled corrosion of Fe(0) (i.e., electrocoagulation). Despite its ease of deployment, Fe-based co-precipitation of As entails a complex series of chemical reactions that often occur simultaneously, including electron-transfer reactions, mineral nucleation, crystal growth, and As sorption. In recent years, the growing use of sophisticated synchrotron-based characterization techniques in water treatment research has generated new detailed and mechanistic insights into the reactions that govern As removal efficiency. The purpose of this critical review is to synthesize the current understanding of the molecular-scale reaction pathways of As co-precipitation with Fe(III), where the source of Fe(III) can be ferric chloride solutions or oxidized Fe(II) sourced from natural Fe(II) in groundwater, ferrous salts or controlled Fe(0) corrosion. We draw primarily on the mechanistic knowledge gained from spectroscopic and nano-scale investigations. We begin by describing the least complex reactions relevant in these conditions (Fe(II) oxidation, Fe(III) polymerization, As sorption in single-solute systems) and build to multi-solute systems containing common groundwater ions that can alter the pathways of As uptake during Fe(III) co-precipitation (Ca, Mg bivalent cations; P, Si oxyanions). We conclude the review by providing a perspective on critical knowledge gaps remaining in this field and new research directions that can further improve the understanding of As removal via Fe(III) co-precipitation.

Sweden's drinking water quality is considered to be high partly due to a high quality of the raw water and a well developed sewage infrastructure. Despite this, there is water contamination that could be prevented by installation of a sophisticated early warning system. Some of the major players in the production of drinking water have already invested in different types of early warning systems to ensure drinking water of high quality. There are various forms of early warning systems where automatic monitoring of E. Coli is an interesting alternative. Today's technology allows for this type of measurement, but it is often expensive and sometimes slow.

This work aims to investigate whether the phenomenon of Extraordinary Optical Transmission (EOT) can be used as the technology of sensors for real-time measurement of indicators of fecal contaminated water. EOT is a transmissions peak which arises due to plasmon resonance. The study was conducted by performing verification measurements by spectrophotometry to detect the EOT. After this biomeasurements where done to show that the surface of the sample can be functionalized to provide the opportunity to choose which analytes should be detected.

The verifying measurements showed that EOT was detected for one of the five samples where the hole size was 400 nm and the hole spacing was 600 nm. This is due to the high signal strength and to the fact that the phenomenon occurred within the measurement range of the instruments. Samples where designated with the name sPa where s indicates hole size in nm and a hole spacing in nm. The signal strength of the sample 140P600 and 200P600 was too low to determine whether EOT occurred. For samples 400P1000 and 600P1000 calculations showed that EOT occurred outside the measurement range, which meant that EOT could not be measured. Sample 400P600 was chosen to implement bio-measurements wherein the surface was functionalized with biotin Bovine serum albumin (B-BSA) to later bind with fluidMAG Streptavidin. Both B-BSA and streptavidin was bound as shown by the kinetic measurements. 

Sustainable water recycling and wastewater reuse are urgent nowadays considering water scarcity and increased water consumption through human activities. In 2015, United Nations Sustainable Development Goal 6 (UN SDG6) highlighted the necessity of recycling wastewater to guarantee water availability for individuals. Currently, wastewater irrigation (WWI) of crops and agricultural land appears essential. The present work overviews the quality of treated wastewater in terms of soil microbial activities, and discusses challenges and benefits of WWI in line with wastewater reuse in agriculture and aquaculture irrigation. Combined conventional-advanced wastewater treatment processes are specifically deliberated, considering the harmful impacts on human health arising from WWI originating from reuse of contaminated water (salts, organic pollutants, toxic metals, and microbial pathogens i.e., viruses and bacteria). The comprehensive literature survey revealed that, in addition to the increased levels of pathogen and microbial threats to human wellbeing, poorly-treated wastewater results in plant and soil contamination with toxic organic/inorganic chemicals, and microbial pathogens. The impact of long-term emerging pollutants like plastic nanoparticles should also be established in further studies, with the development of standardized analytical techniques for such hazardous chemicals. Likewise, the reliable, long-term and extensive judgment on heavy metals threat to human beings's health should be explored in future investigations.

In modern times, wastewater treatment is vital due to increased water contamination arising from pollutants such as nutrients, pathogens, heavy metals, and pharmaceutical residues. Polysaccharides (PSAs) are natural, renewable, and non-toxic biopolymers used in wastewater treatment in the field of gas separation, liquid filtration, adsorption processes, pervaporation, and proton exchange membranes. Since addition of nanoparticles to PSAs improves their sustainability and strength, nanocomposite PSAs has gained significant attention for wastewater treatment in the past decade. This review presents a comprehensive analysis of PSA-based nanocomposites used for efficient wastewater treatment, focusing on adsorption, photocatalysis, and membrane-based methods. It also discusses potential future applications, challenges, and opportunities in adsorption, filtration, and photocatalysis. Recently, PSAs have shown promise as adsorbents in biological-based systems, effectively removing heavy metals that could hinder microbial activity. Cellulose-mediated adsorbents have successfully removed various pollutants from wastewater, including heavy metals, dyes, oil, organic solvents, pesticides, and pharmaceutical residues. Thus, PSA nanocomposites would support biological processes in wastewater treatment plants. A major concern is the discharge of antibiotic wastes from pharmaceutical industries, posing significant environmental and health risks. PSA-mediated bio-adsorbents, like clay polymeric nanocomposite hydrogel beads, efficiently remove antibiotics from wastewater, ensuring water quality and ecosystem balance. The successful use of PSA-mediated bio-adsorbents in wastewater treatment depends on ongoing research to optimize their application and evaluate their potential environmental impacts. Implementing these eco-friendly adsorbents on a large scale holds great promise in significantly reducing water pollution, safeguarding ecosystems, and protecting human health. 

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.

Due to its high pollutant rejection and low energy usage, the spiral wound module of reverse osmosis (RO) process is the most commonly used technology utilised in wastewater treatment. For a spiral wound module, the presence of a feed spacer is important as a key solution to mitigate the concentration polarisation phenomenon, due to disorderly fluid flow, and to improve the mass transfer coefficient. Undoubtedly, improvements in the spiral wound module design, mainly in the symmetrical shape of the feed spacer, can have a significant impact on the cost and probable use of these modules. Despite the wide interest in appraising the impact of feed spacer geometry and orientation on the performance of a spiral wound module for RO process-based water desalination, the hydrodynamics of feed spacers (pressure drop and mass transfer coefficient) and the associated influences of feed spacer design (the height of the feed spacer, the angle of the filaments, and the porosity) on the removal of pollutants from wastewater have not yet been addressed. The current investigation aims to fill this gap by studying the hydrodynamics and design parameters of the selected parallelogram feed spacer type ultrafiltration (UF−3) for the removal of dimethylphenol from wastewater. Using model-based simulation, the impacts of UF−3 feed spacer design parameters, including the height, angle between the filaments (orientation), and porosity on the pressure drop, friction factor, axial flow fluid velocity, mass transfer coefficient, water flux, dimethylphenol rejection, recovery rate, and specific energy consumption are detailed in this study. The study intends to demonstrate the optimum design features of UF−3 feed spacer that should be considered to assure the highest elimination of dimethylphenol from wastewater in addition to the lowest specific energy consumption.

In this research, an assessment was conducted for several materials to examine their efficiency for sorption phosphate and their potential use as filter media. This work focuses on seeking materials that can achieve high, rapid, and robust phosphate retention. To assess the phosphate removal efficiency, batch-mode testing was conducted. The capability of the selected materials for effectively removal the phosphate is largely influenced by their inherent properties. Therefore, this research determines the effectiveness of the material by examining its physical and chemical characteristics. The selection method for these materials was guided by the understanding that the sorbents that have the most effective behavior for phosphate tend to contain easily soluble Ca/Mg compounds or Fe/Al hydroxides. The findings of the batch experiments demonstrated that material such as Bio ash (Bio-A) exhibited superior phosphate removal performance throughout the entire duration of the experiments. In contrast, materials calcium carbonate (C-C) and conventional silica (C-S) displayed relatively poor removal performance compared to Bio-A.

Ferrihydrite in a suspension has been studied as a solution for purification of arsenic contaminated water. Many development countries, amongst them Burkina Faso, have arsenic in their groundwater and the current methods for purification are too expensive. Measurements have shown extremely high levels of arsenic in the groundwater in several places in Burkina Faso. Since the availability of surface water is limited, the groundwater is still used as drinking water.

A suspension of ferrihydrite has capacity to adsorb arsenic in water due to its chemical characteristics. Small-scale laboratory work with ferrihydrite suspensions has been performed in parallel in Uppsala, Sweden, and Ouagadougou, Burkina Faso. To purify the water with regard to the economical and practical circumstances in Burkina Faso, a column with safety filter was made out of simple materials such as plastic bottles, plastic tubes and glass wool. The contaminated water was flowing upwards through the column to prevent the filter from clogging.

In Uppsala it was discovered that a 1 L ferrihydrite suspension containing 10 g ferrihydrite can adsorb 0.7 g arsenic while it was shaken and centrifuged well. In Ouagadougou it was possible, in the setup, to clean 2 L arsenic contaminated water with the concentration of 100 µg/L. The conclusions from the experiments in this project are that ferrihydrite can adsorb arsenic in contaminated water but that the setup used needs to be further evaluated and developed

In recent years, the microalgal–bacterial process has been considered to be a very attractive engineering solution for wastewater treatment. However, it has not been widely studied in the context of conventional wastewater treatment design under Swedish conditions. The technology holds several advantages: as a CO₂ sink, ability to withstand cold conditions, ability to grow under low light, fast settling without chemical precipitation, and reducing the loss of valuable nutrients (CO₂, N₂, N₂O, PO₄). The process also provides the option to be operated either as mainstream (treatment of municipal wastewater) or side stream (treatment of centrate from anaerobic digesters) to reduce the nutrient load of the wastewater. Furthermore, the application is not only limited to wastewater treatment; the biomass can be used to synthesise platform chemicals or biofuels and can be followed by recovery of ammonium and phosphate for use in agriculture.

In the present study, the feasibility of applying the process in Swedish temperature and light conditions was investigated by implementing microalgae within the activated sludge process. In this context, the supporting operational and performance indicators (hydraulic retention time (HRT), sludge retention time (SRT) and nutrients removal) were evaluated to support naturally occurring consortia in photo-sequencing and continuous bioreactor configuration. Furthermore, CO₂ uptake and light spectrum-mediated nutrient removal were investigated to reduce the impact on climate and the technical challenges associated with this type of system.

The results identified effective retention times of 6 and 4 days (HRT = SRT) under limited lighting to reduce the electrical consumption. From the perspective of nitrogen removal, the process demands effective CO₂ input either in the mainstream or side stream treatment. The incorporation of a vertical absorption column demonstrated effective CO₂ mass transfer to support efficient nitrogen and phosphorus removal as a side stream treatment. However, the investigation of a continuous single-stage process as the mainstream showed a requirement for a lower SRT in comparison to semi-continuous operation due to faster settlability, regardless of inorganic carbon. Furthermore, the process showed an effective reduction of influent phosphorus and organic compounds (i.e. COD/TOC) load in the wastewater as a result of photosynthetic aeration. Most importantly, the operation was stable at the temperature equivalent of wastewater (12 and 13 ˚C), under different lighting (white, and red-blue wavelengths) and retention times (6 and 1.5 d HRT) with complete nitrification. Additionally, the biomass production was stable with faster settling properties without any physiochemical separation.

The outcomes of this thesis on microalgal–bacterial nutrient removal demonstrates that (1) photosynthesis-based aeration at existing wastewater conditions under photo-sequential and continuous photobioreactor setup, (2) flocs with rapid settling characteristics at all studied retention times, (3) the possibility of increasing carbon supplementation to achieve higher carbon to nitrogen balance in the photobioreactor, and (4) most importantly, nitrification-based microalgal biomass uptake occurred at all spectral distributions, lower photosynthetic active radiation and existing wastewater conditions.

The municipal wastewater is mainly composed of water containing anthropogenic wastes that are rich in nutrients such as carbon, nitrogen and phosphorous. The cost for biological treatment of wastewater is increasing globally due to the population growth in urban cities. In general, the activated sludge (AS) process is a biological nutrient removal process used in wastewater treatment plants (WWTPs). The AS is composed of different microorganisms in which bacteria play a crucial role in wastewater treatment (WWT). During the process, air is bubbled to supply oxygen and methanol is added to improve nitrogen removal, which is released as a gas. Phosphorous is removed in the expense of precipitation chemicals. Altogether, the current process requires electrical energy, precipitation chemicals, handling of excess sludge and it emits carbon dioxide (CO₂) as a by-product. This process is still in practise in the WWTPs since 1914 although numerous modifications are implemented to meet the stringent regulations in the European Union and globally.

Microalgae are microorganisms that perform photosynthesis like plants. They are green and reproduce fast using available nutrients (nitrogen and phosphorous) and CO₂ from their environment in the presence of light. As a result of photosynthesis, oxygen is released as waste gas. The synthesised oxygen during this process can be implemented to support the AS bacteria that leads to the microalgae activated sludge (MAAS) process. The main advantage is combined removal of nutrients.

The vision of the research is to implement the indigenous microalgae cultivation in activated sludge process to consume CO₂ and recover the nutrients from wastewater. This study is performed to improve the understanding of the process such as: light utilisation, nutrient removal and recovery of the biomass from wastewater in closed photo-bioreactors. Photo-bioreactors are vessels where the cultivation is carried out in the presence of light. At first, the influence of the light spectrum on micro-algal cultivation is investigated for photosynthetic growth. This is followed by operational challenges of the microalgae cultivation during the AS process. The process is experimentally performed in the photo-bioreactors with different treatment time of the raw wastewater. The results showed that 2 - 6 days of treatment time can be used for reducing nutrients in wastewater if the process is optimised further. Also, nutrient ratio is analysed for the availability of the micro-algal growth. Furthermore, the biogas potential of MAAS showed a biogas yield of about 60-80% within 5 to 9 days.

At last, the experimental verification of chemically precipitated wastewater showed limitation of phosphorous for micro-algal growth. Additionally, the optimal oxygen supply through light response is verified for photo-bioreactors. The outcome of this study shows that knowing the right conditions can lower the treatment time. By doing so, a stable nutrient removal and reduction of precipitation chemicals can be established as well as a better recovery of valuable nutrients as phosphorous and nitrogen.

The continuous abatement of CO2 and toluene from the exhaust gas by an indigenous microalgal-bacterial consortium was investigated in a pilot tubular photobioreactor interconnected to an absorption column using diluted centrate in seawater as a free nutrient source. The removal efficiency of CO2 and toluene was maximised in the vertical absorption column by identifying an optimum liquid to gas (L/G) ratio of 15. The photobioreactor supported steady-state nitrogen and phosphorus removals of 91 ± 2% and 95 ± 4% using 15% diluted centrate at 14 and 7 d of hydraulic retention time (HRT), respectively. A decrease in the removal efficiencies of nitrogen (36 ± 5%) and phosphorus (58 ± 10%) was recorded when using 30% diluted centrate at 7 d of HRT. The volumetric biomass productivities obtained at an HRT of 7 d accounted for 42 ± 11 and 80 ± 3 mg TSS L-1 d-1 using 15 and 30% centrate, respectively. Stable CO2 (76 ± 7%) and toluene removals (89 ± 5%) were achieved at an L/G ratio of 15 regardless of the HRT or centrate dilution. Hence, this study demonstrated the potential of algal-bacterial systems for the continuous removal of CO2 and volatile organic compounds from exhaust gas coupled with the simultaneous treatment of centrate. 

Disinfection by-products (DBPs) are potentially toxic compounds formed when drinking water is treated with disinfectants, such as chlorine or chloramine. A large proportion of the exposure to DBPs is still unknown and the health risks observed through epidemiological studies cannot be explained by DBPs known today. In this thesis, a part of the unknown DBP fraction is investigated, covering a wide range of non-volatile, chlorine/bromine-containing DBPs. The goals were to investigate how the compositions of these DBPs differ between water treatment plants, how their occurrence changes in the distribution system until reaching consumers and how new treatment techniques can reduce their formation and toxicity. To analyze unknown DBPs, a non-targeted approach adopting ultra-high-resolution mass spectrometry, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), was used, where the mass of molecules is measured with such accuracy that the elemental composition of individual DBPs can be calculated. A panel of bioassays was used to assess the combined toxic effects from these DBP mixtures. 

The results show that the formation of these DBPs to a large extent was specific to each water treatment plant and that local conditions influenced DBP formation, based on e.g., the abundance of organic material with certain chemical structures, bromide and disinfection procedure and agent (chlorine or chloramine). The DBPs were detected in both chlorinated and chloraminated water and in all tap water samples, demonstrating that they are part of human exposure. The number of DBP formulae decreased and the DBP composition changed between drinking water treatment and consumer taps, suggesting that DBP exposure to consumers is not necessarily resembling measurements at the treatment plants. Evaluation of new treatment techniques showed that suspended ion exchange and ozonation have potential to decrease the formation and toxic effects of DBPs and that the removal of organic matter can influence qualitative aspects of DBP formation, such as the proportions of chlorine-containing (less toxic) versus bromine-containing (more toxic) DBPs. Through increased knowledge about the role and relevance of non-volatile DBPs, this work can contribute to future monitoring and actions to reduce the health risks associated with DBPs in chlorinated or chloraminated drinking water. 

Disinfection by-products (DBPs) are potentially toxic compounds formed upon chemical disinfection of drinking water. Controlling the levels and characteristics of dissolved organic matter (DOM) as precursor material for DBPs is a major target to reduce DBP formation. A pilot-scale treatment including suspended ion exchange (SIX (R)), a ceramic microfilter (CeraMac (R)) with in-line coagulation and optional pre-ozonation followed by granular activated carbon (GAC) filtration was compared with a conventional full-scale treatment based on DOM removal and DBP formation using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), rapid fractionation, liquid chromatography organic carbon detection (LC-OCD), adsorbable organic halogens (AOX) and trihalomethane (THM) analysis. The new treatment combination showed different selectivity for DOM removal, compared to the conventional, leading to changes in composition of the DBPs formed. SIX (R) and GAC had the largest impacts on reducing AOX and THM formation potentials but the high adsorptive capacity of GAC affected the diversity of detected DBPs most. Chlorination and chloramination of pilot treated water with doses normally used in Sweden produced low levels of AOX compared to the full-scale treatment, but FT-ICR MS revealed an abundance of brominated DBP species in contrast with the conventional treatment, which were dominated by chlorinated DBPs. This finding was largely linked to the high DOM removal by the pilot treatment, causing an increased Br-/C ratio and a higher formation of HOBr. Potential increases in Br-DBPs are important to consider in minimizing health risks associated with DBPs, because of the supposed higher toxicity of Br-DBPs compared to Cl-DBPs.

Energy efficient processes and the use of fossil free fuels play an important role in order to reduce the impact of climate change. Anaerobic digestion is a common way for stabilizing sewage sludge at wastewater treatment plants (WWTP). One of the benefits with anaerobic digestion is that it also produces biogas, a fossil free fuel with low greenhouse gas emissions. An operational temperature within the mesophilic range has proven to give a stable process with an unfluctuating production of gas. The mesophilic temperature range between 25-40°C but most processes are operated between 35-40°C. This study investigates the opportunity to lower the temperature within the mesophilic range in order to reduce energy consumption. It is important to maintain the production of biogas with a lower temperature. Therefore, the reduction in VS-content (VS-volatile solids), methane yield and time for degradation was determined by a BMP-experiment (BMP-Biochemical Methane Potential) in three different temperatures (32, 34.5 and 37.5°C). In order to quantify the reduction in heat consumption with lower operational temperatures the change in heat balance for a full-scale WWTP in Uppsala was calculated. A major part of the operational cost is dewatering of sludge and it is therefore important that it does not deteriorate with a lower temperature. The effect on the dewaterability at different temperatures was examined by a filterability test measuring CST (capillary suction time). The results from the study showed no significant difference in methane yield between 37.5°C and 34.5°C. The methane yield at 32°C was 11 % lower compared to 37.5°C but the degradation kinetic was not affected by a temperature change. The reduction in heat consumption was 14 % when the temperature was reduced to 34.5°C and 27 % when it was reduced to 32°C. The filterability test did not show a deterioration with lower temperatures. The study showed that it is possible to reduce the operational temperature for anaerobic digestion at the WWTP in Uppsala in order to reduce the energy consumption. To confirm these results a continuously experiment should be done, but this study shows that it is possible to get a successful degradation in a lower mesophilic temperature. This leads the way for further investigations within the mesophilic range and could lead to optimizing anaerobic digestion and the opportunity to get an energy efficient production of biogas.

The availability to clean drinking water is something a lot of people take for granted today. Daily, there are about 1.8 billion people around the world that drinks water from a contaminated water source. Unfortunately, the deficiency is a fact, and about 361 000 children under the age of five die each year because of diarrheal disease (WHO, 2016a). 

Earlier studies show that a biosand filter is an easy and efficient water purification method that cleans the water both physically, biologically and chemically. A biosand filter is often built using local material and is filled with sand, which makes the construction cheap and easy to repair is needed. Earlier studies have shown that this purification method can reduce waterborne disease by 99,9% with the help of a biofilm layer which develop in the top layer of the sand if the conditions are meet (CAWST, 2009).

The purpose with this study was to build and evaluate a biosand filter as a water treatment method in Ghana. In total, three biosand filters was built with local material, each with different sand heights. The evaluation was done by studying the waters physical, biological and chemical properties before and after the filtration, which then was compared to the water quality standards from the World Health Organization (WHO) and Sweden. The results show that none of the three filters could produce water which met the standards for drinking water, which might be caused by the high flow of water through the filter which prevented the biofilm to grow. With the help from the results in Ghana, a new design of a water filter has been made to reduce the flow of water through the filter. Which gave a new biosand filter design with a diameter of 42 cm that, sand height of 80 cm and gravel height of 15 cm.  

Denna rapport sammanställer erfarenheter och resultat från pilotskaleförsök med stripping och kristallisation för kväveåtervinning från avloppsvatten. Projektet har varit ett samarbete mellan EkoBalans och IVL Svenska Miljöinstitutet, där EkoBalans anläggning eco:N testats under sommaren 2020 på IVLs test- och demonstrationsanläggning Hammarby Sjöstadsverk.

Försöken har visat att det i anläggningen är möjligt att behandla ett rejektvatten från avvattning av rötat slam med ammoniumhalt från 500 till 2000 mg NH4-N/L med en ammoniumreduktion överstigande 95 % över själva strippern.

Pilotförsöken har också visat att kristalliserad ammoniumsulfat kunde utvinnas, även om begränsningar i tillgänglighet till försöksanläggningen och substrat som gjorde att kontinuerlig drift inte var möjlig.

Inom projektet har även många praktiska erfarenheter genererats vilket bidragit till fortsatt utveckling av anläggningen.

During 2013–2022, the membrane bioreactor technology (MBR) has been evaluated through pilot tests at the Hammarby Sjöstadsverk research facility, in preparation for full-scale implementation at the Henriksdal wastewater treatment plant. This report summarizes specific experiences, challenges, and opportunities identified. The pilot consists of pre- and post-denitrification with the addition of an external carbon source for nitrogen removal. Phosphorus is removed through pre- and simultaneous precipitation at three dosing points. The pilot has generally achieved stable treatment efficiency, even under high load conditions, with effluent concentrations far below the discharge requirements. This even with less consumption of chemicals compared to design values. The report includes results from various control strategies and a comparison of  different external carbon sources. The membrane operation was generally stable, with permeability ranging from 600 to 200 lmh/bar. Optimization of resource consumption has been a focus in the pilot project since 2018. Attempts to reduce membrane fouling and the amount of chemicals used for membrane cleaning have been conducted, showing, for example, a reduction of membrane cleaning chemical requirements to 30–40% of the design. This finding has partially been confirmed in the full-scale line. Tests with reduced sludge  recirculation to decrease energy consumption indicated no negative effects on membrane performance. Tests with a flux enhancer showed no apparent positive or negative changes in membrane permeability. However, tests with an antifoaming agent were effective in reducing and controlling foaming. An assessment of micropollutants such as pharmaceutical residues, microplastics and PFAS, showed comparable levels between the MBR pilot and the conventional activated sludge process at Henriksdal WWTP. Emissions of chlorinated compounds were measured during several recovery cleanings with sodium hypochlorite, indicating potential harm throughout the cleaning process from an exposure perspective. Measurements of greenhouse gas emissions showed varied emissions between different measurements. In addition to these and other results and aspects, experiences from other MBR plants in Sweden and internationally are also presented.The MBR pilot was also used for several other activities outlined in the report, including: ● Testing and comparing different carbon sources for post-denitrification, including sodium acetate, Brenntaplus, methanol, acetic acid, glycerol, ethanol, and internally produced VFA (volatile fatty acids). ● Biological phosphorus removal, although the process was not specifically designed for this purpose. This resulted in significantly lower consumption of precipitation chemicals than expected. ● Tests with advanced treatment techniques such as ozonation, activated carbon, and others for the removal of micropollutants. Experiences from other Swedish and international MBR plants are also described. ● Use of the MBR pilot as part of a direct potable reuse (DPR) system, which involves treating the purified wastewater for direct use as drinking water. Finally, the report discusses various aspects including decommissioning and management of spent membranes, general operational experiences, pilot to full-scale feedback, and future potential and challenges for MBR technology.

Henriksdal wastewater treatment plant (WWTP) in Stockholm is currently being extended and rebuilt for increased capacity (from 0.8 to 1.6 million PE) and enhanced treatment efficiency (6 mg TN/L, 0.20 mg TP/L, 5 mg BOD7/L).

The reconstruction includes retrofitting of the existing conventional activated sludge (CAS) tanks with a new membrane bioreactor (MBR) process containing 1.6 million m2 of membrane area. It also includes extended pretreatment and a new treatment step for thickening of primary sludge. Digestion of thick sludge (~6 % TS) will be done at thermophilic conditions, unlike today’s mesophilic operation, with high organic load and relatively short retention time.

To increase the knowledge of MBRs in Nordic conditions, Stockholm Vatten och Avfall (SVOA) and IVL Swedish Environmental Research Institute have conducted long-term MBR studies in pilot scale at the R&D-facility Hammarby Sjöstadsverk, located on the premises of the Henriksdal WWTP. The MBR-pilot was taken into operation in 2013 and was reconstructed to its current configuration in 2016. In 2017 the MBR pilot was supplemented with a sludge treatment line to study different aspects of sludge digestion. 

During 2021, the MBR-pilot was operated at a fixed inflow of 4.1 m3/h, which is 37 % higher than the design average flow, with externally provided glycerol as well as internally produced VFA as carbon source for post-denitrification. Aluminum (PAX) was used instead of Ferric (PIX) as complement to Ferrous (FeSO4) for phosphorous precipitation. This was done to test the operational strategy for the first MBR line in Henriksdal WWTP. The average effluent concentration of nitrogen and phosphorus was 3.9 mg TN/L and 0.07 mg TP/L, respectively, which means that the effluent requirements were met also this year. To achieve this, 8.6 g Fe2+/m3 and 0.9 g Al3+/m3 was required.

During flux enhancer trials a total of 17.8 g iron (Fe2+ + Fe3+)/m3 was added. The glycerol dose was equivalent to 17.3 g COD/m3 and for internally produced VFA the dose equivalent was 15.5 g COD/m3. The slightly higher consumption of phosphorus precipitation chemicals compared to 2020, 1.29 mole metal per mole of phosphorus removed, was mainly due to a lower enhanced biological phospho¬rus removal (EBPR) activity in 2021. In 2021 the phosphorous release rates were low during the spring and showed < 1 g PO4-P/kg VSS,h in June but recovered in the summer with 5.5 g PO4-P/kg VSS,h in July after the defoaming agent dosing was stopped.

The iron and aluminum content in the activated sludge was 6.2 and 0.7 %, respectively. Average total sludge age during 2021 was 17.2 days and average aerated sludge age was 7 days. Nitrification was always complete with ammonia concentrations below 2 mg/L except week 25. Test with use of internally produced VFA as carbon source showed that the specific COD consumption was almost the same as for glycerol when comparing the yearly average from 2021 and 2020. Effluent nitrate and total nitrogen removal was similar during the trial with VFA as the rest of the year, when glycerol was used.

 Like previous years, the membranes in membrane tank 1 (MT1) was cleaned with oxalic acid and the membranes in MT2 with citric acid. Both membranes were also cleaned with sodium hypochlorite. The membranes were operated with an average net flux around 21 to 25 L/(m2·h) but starting from week 25, the flux was increased to 30 L/(m2·h) which is the design net max flux of the full scale MBR in Henriksdal and was tested in the pilot for 25 weeks.

The net TMP varied between 49 and 218 mbar for MT1 and between 51 and 146 mbar for MT2. TMP was reduced after each recovery cleaning (RC) with hypochlorite, but the effect did not last long. The permeability was generally above 200 L/(m2·h·bar) throughout 2021-2022 for both membranes. Recovery cleanings were done twice with hypochlorite and once with acids during 2021. During 2022 a final RC, first with hypochlorite then with acids was carried out.

The first RC for MT1 resulted in a clear increase in permeability after cleaning. For MT2 the major increase in permeability was the result of a citric acid MC (one week after the hypochlorite RC). The RCs at the end of 2021 and in March 2022 had clear but smaller positive impact on permeability. Prior to the first RCs, permeability was higher for MT1 (cleaned with oxalic acid) compared to MT2 (cleaned with citric acid). After the first RCs, both membranes had similar permeability. As a result of the tough operational strategy from week 25 2021, permeability decreased quite quickly after RCs. MT2 reached a stable level around 250-300 L/(m2·h·bar) while MT1 decreased even more, to as low as around 200 L/(m2·h·bar). 

Emission of chlorinated compounds in the off-gas ventilation were measured during the final sodium hypochlorite recovery cleaning. The emission process was slower than expected and generally no clear sign of attenuation of emissions was observed during the 21 hours of sampling. Although composite samples of several hours during the night are not providing enough details, it was concluded that the emissions can be harmful during the entire RC process from an exposure perspective. Trichloramine peaked at 36 times the recommended limit, chlorine gas at 73 % of the short-term exposure limit (15 min exposure), and chloroform at 9 % of the occupational exposure limit (8-hour workday average).To follow up previous measurements of greenhouse gases nitrous oxide (N2O) and methane (CH4), a new campaign was performed during several months in 2021. Generally, emissions observed in 2021 were significantly higher than in previous campaigns in the pilot and especially high N2O-emissions from the membrane-tank could be identified.

No clear reason could be identified but the increased incoming load with a maintained effluent quality and a “better” sampling setup may partly be an explanation.In collaboration with Kemira, tests with a flux enhancer product were performed in 2021. However, no obvious positive or negative change in permeability due to dosing of flux enhancer was possible to identify based on continuously monitored process parameters and commonly observed variations in permeability and effect of membrane cleaning.  As the formation of foam is a common phenomenon in MBR plants, tests with an antifoaming agent were done by dosing in batches and continuously to the biological treatment during the period of heavy foaming (March-June).

Even if foaming was not avoided, a good reduction and control of foaming could be achieved. An optimal effect was achieved with continuous dosages of > 10 ppm. However, even though the product has shown to have a positive effect in the MBR-pilot, a permanent use in full-scale may not be economically feasible due to the high consumption.Test with a reduced RAS flow from the design value of 4×Qin to 2×Qin was done with the aim to reduce energy consumption for pumping. A reduced RAS flow would however imply an increased sludge concentration in the membrane tanks, which may have negative effects on the membrane performance with more clogging and consequently increased aeration for membrane scouring and need for more frequent membrane cleaning.

However, no negative effects of the reduced RAS-flow could be seen on the membrane performance.    During 2021, tests with a transition from mesophilic to thermophilic anaerobic digestion, dewatering of digested sludge after mesophilic and thermophilic digestion, and thermophilic digestion at high organic loading rate (OLR) and low hydraulic retention time (HRT) were performed in the sludge pilot. Results show that the transition from mesophilic to thermophilic digestion can be done without any major problems if the load was reduced during the most critical temperatures and that stable operation was achieved after 10-12 days. Evaluating the dewatering of mesophilically and thermophilically digested sludge was more difficult and no clear differences could be observed. However, it was concluded that used methods for determining dewaterability or optimal polymer dose are not reliable.

Trials with high organic loading rate at thermophilic digestion showed that the digester performance could be maintained up to an OLR of around 4 kg VS/m3, d and an HRT of 12 d. When the load is further increased and HRT decreased, the performance in terms of VS reduction and biogas-/methane production decreased although the reactor operation was still stable.   The overall resource consumption in the pilot showed that the consumption of glycerol was the same as for the future Henriksdal design, even though the nitrogen load in the pilot was 21 % higher and the average effluent total nitrogen concentration was 3.9 mg TN/L compared to the design of 6 mg TN/L.

Also, the iron/metal consumption was 73 % of the future Henriksdal design, although the phosphorus load to the pilot was about 50 % higher compared to design values and effluent phosphate concentrations were below the target concentration. This is mainly explained by the EBPR activity in the pilot. Also, the consumption of cleaning chemicals was lower than the future Henriksdal design although the inflow to the pilot was 30 % higher than design.

Chitosan biopolymer with a deacetylation degree of 85%, was assessed for its capability to adsorb As(V) from drinking water by batch experiments. To characterize the chitosan biopolymer, chitosan was analyzed by FTIR and SEM. The results showed that chitosan is an effective and promising sorbent for As(V) from drinking water. From the batch tests, results showed a maximum adsorption of 355 μg/L of As(V) with 1.18 μg g-1 adsorption capacity at pH 6. The kinetic data, obtained at pH 6 could be fitted with pseudo-second order equation (adsorption capacity: 0.923 μg g-1) and the process was suitably described by a Freundlich (R2 = 0.9933) model than by a Langmuir model (R2 = 0.9741). The results above indicated that chitosan is a very favorable sorbent for As(V) removal from aqueous solution.

Plastic production and use of plastic are increasing every year throughout the world and this is one of the world's biggest problems. Plastic is a persistent substance, and its biodegradation process can take hundreds of years. This in turn leads to the accumulation of plastic causing harmful effects on the climate, the environment, and people. One of the alternatives that has great potential when it comes to dealing with this problem is to reduce the use of plastics and instead increase the production and use of bioplastics or biopolymers that are biodegradable.

Bioplastics have a shorter biodegradation time than plastics and therefore bioplastics are a good alternative instead of using ordinary plastic. There are three different groups of bioplastics, namely those that are bio-based, those that are biodegradable and those that are both bio-based and biodegradable.

One type of bioplastic that is biodegradable and bio-based is Polyhydroxyalkanoates (PHA) which are used in various industries as PHA is one of the biopolymers that shows the greatest potential to replace plastic in the future.

Research is underway at the University of Borås with the goal of developing a new process for the production and recycling of PHAs. The process is based on the production of PHAs from volatile fatty acids produced from acidogenic fermentation. Acid fermentation is a modified process of anaerobic digestion; the latter is used nowadays to produce biogas from waste and can be the right process for recycling PHA-based waste and for producing a cheap substrate, namely volatile fatty acids for PHA's production. This project is about a part of the process, namely the production of PHAs with bacteria. The research group at the University of Borås has a bacterial strain that has not been yet investigated for the production of PHAs. Before this bacterium can be studied for the production of PHAs from volatile fatty acids the compositionoptimization of the cultivation medium for bacterial growth is needed.

The purpose of this work is to investigate the effect of different glucose concentrations as a source of carbon and different amounts of ammonium sulphate in the growth of the bacterium Bacillus megaterium and the production of polyhydroxyalkanoates. A comparison between the defined medium under development in this project with nutrient broth, a complex medium normally used to grow bacteria, was also carried out in order to evaluate the suitability of the defined medium to support bacterial growth. During this work several different analytical techniques have been used such as pH measurement, High-Performance Liquid Chromatography (HPLC), Spectrometer (for optical density (OD) measurement), and Fourier-Transform Infrared Spectroscopy (FTIR) to evaluate bacterial growth and production of PHA as well as PHAs composition.

The amount of ammonium sulphate affected glucose consumption rate, where concentrations of 3 g/L and 7 g/L were shown to lead to a faster glucose consumption compared to that at 5 g/L. Therefore, 3 g/L ammonium sulphate was chosen as it represents less chemical consumption while not affecting cell growth negatively. During bacterial cultivation in a medium containing 3 g/L ammonium sulphate, 10 g/L glucose, among other compounds, glucose was completely consumed after 72 hours of bacterial growth and the maximum PHA production was 13-14% based on cell dry weight. The cultivation medium developed in this project was shown to be suitable for bacterial growth since the use of nutrient broth, normally used for bacterial growth, led to slower glucose consumption.

Initial glucose concentration (5, 10 and 20 g/L) did not affect glucose consumption rate and should be further studied to increase cell concentration and consequently the production of PHA. One of the most studied polymers in the PHA family is polyhydroxybutyrate (PHB). During this work, it was found, through the use of FTIR, that PHB was produced.

Gravimetric sedimentation is known as a relatively simple method of determining density of spherical particles. When the method is applied to water-swollen starch microparticles of about submillimeter sizes, it becomes evident that a careful selection of the experimental setup parameters is needed for producing accurate testing results. The main reason for this is that the mean particle density is very close to the density of water, and therefore, a dynamic model accounting for the so-called Bassett history force should be employed for describing the unsteady accelerating particle settling. A main novelty of this study consists in deriving a priori estimates for the settling time and distance.

Lack of safe drinking water is one of the biggest humanitarian problems in the world today. Over one billion people in developing countries have no access to good quality drinking water, and subsequently, diarrhoea caused by unclean water leads to 1.8 million deaths of children under the age of five. That corresponds to 90 per cent of all deaths among children in that age group. However, by improving water and sanitation management, one tenth of all worldwide cases of disease can be prevented. In relation to this, the United Nations has launched the seventh millennium goal, which is to half the proportion of people lacking access to safe drinking water by year 2015 (compared with the proportion of year 2000). Therefore, it is important to both improve and develop water treatment techniques in order to achieve a sustainable development, especially in the third world.

Kofi Ansah and Edumafa are two villages on the Ghanaian countryside. Here, as in the rest of Ghana, it is common to drink water from throwaway plastic containers. This is because the water quality is poor in the stationary water sources such as tanks and wells etc. The plastic containers contribute to a big waste problem and it´s therefore desirable to improve the water quality in stationary water sources in order to reduce the waste problem that now is occurring.

Solar Disinfection, or SODIS, is a water treatment technique that is based on solar radiation. Water containers (usually PET bottles) are filled with water and then exposed to the sun for about six hours. The germicidal effect can be derived to thermal heating in combination with the sun’s ultraviolet radiation. The technique is suitable in the third world since the treatment procedure is both simple and inexpensive. The purpose of this study was to estimate the possible waste reduction regarding the small plastic containers by the implementation of SODIS as a water treatment technique, and evaluate if SODIS is an adequate way to improve the quality of water collected from stationary water distribution systems in Ghana.

The study has shown that SODIS is an adequate method for producing low health risk water at a household level in Ghana. A solar exposure of six hours is enough to reach a safe bacterial content within the treated water. It is also clear that SODIS could reduce the present waste problem regarding the throwaway plastic containers by more than 1600 plastic bags per person and year, and that the Ghanaians attitude to start performing SODIS is positive.

Further work should be aimed at implementing SODIS as a water treatment technique by teaching the Ghanaian people, especially in the rural areas, the importance of water and sanitation issues. The implementation of SODIS is a long term project that cannot be accomplished singlehandedly. It can be achieved by instructing certain people in the villages as to how the procedure is done. For this to be effective, these individuals should preferably be well educated and speak both English and the local language. These people can in turn educate and instruct the other villagers in how SODIS is executed and by doing so complete and secure a sustainable use of the technique.

Disinfection by-products (DBPs) are unwanted, potentially toxic compounds formed when drinking water is disinfected with chemical disinfectants such as chlorine or chloramine. The levels of DBPs produced depends on parameters, such as levels of natural organic matter (NOM) and the nature and concentration of chemical disinfectant used. In this thesis, the effects of two different types of chemical disinfectants, chlorine and chloramine, are investigated in terms of levels of DBP production. The goal was to investigate if chlorine disinfection produces similar levels and types of DBPs as in case of chloramination.

Within the thesis work was also tested a method based on a gas chromatograph coupled with halogen selective detector (GC-XSD) to determine the known DBPs in the drinking water.

The results show that the formation of DBPs at chlorine or chloramine disinfection were similar. Still, chloramine is preferably used because it produces less legally regulated DBPs.

The GC-XSD worked well for the determination of DBPs in drinking water. Since XSD is very selective and specific towards halogens and easy to operate, therefore this setup not only a potential tool for routine DBPs monitoring at drinking water facilities, but it could also be used for the determination of unknow halogenated compounds.

Through increased knowledge in the formation of DBPs and their determination with GC-XSD can contribute to the development of better methods to quantify known and identify unknow halogenated organic compounds in treated drinking water and reduce public exposure to potentially toxic halogenated organic compounds.

Fluoride contamination in water is a key problem facing the world, leading to health problems such as dental and skeletal fluorosis. So, we used low-cost multifunctional tea biochar (TBC) and magnetic tea biochar (MTBC) prepared by facile one-step pyrolysis of waste tea leaves. The TBC and MTBC were characterized by XRD, SEM, FTIR, and VSM. Both TBC and MTBC contain high carbon contents of 63.45 and 63.75%, respectively. The surface area of MTBC (115.65 m2/g) was higher than TBC (81.64 m2/g). The modified biochar MTBC was further used to remediate the fluoride-contaminated water. The fluoride adsorption testing was conducted using the batch method at 298, 308, and 318 K. The maximum fluoride removal efficiency (E%) using MTBC was 98% when the adsorbent dosage was 0.5 g/L and the fluoride concentration was 50 mg/L. The experiment data for fluoride adsorption on MTBC best fit the pseudo 2nd order, rather than the pseudo 1st order. In addition, the intraparticle diffusion model predicts the boundary diffusion. Langmuir, Freundlich, Temkin, and Dubnin–Radushkevich isotherm models were fitted to explain the fluoride adsorption on MTBC. The Langmuir adsorption capacity of MTBC = 18.78 mg/g was recorded at 298 K and decreased as the temperature increased. The MTBC biochar was reused in ten cycles, and the E% was still 85%. The obtained biochar with a large pore size and high removal efficiency may be an effective and low-cost adsorbent for treating fluoride-containing water.

This paper presents the feasibility study of installation of a solar-driven integrated MD desalination system for simultaneous production of pure drinking water and solar domestic hot water in United Arab Emirates (UAE) for a single-family villa comprising of 4-5 persons. In order to satisfy the current and future demand of water for domestic purposes, the desalination of seawater is considered to be one of the most effective and strategic technique in UAE. The stress on the underground water aquifers, rapid industrial growth, and increase in urban population in UAE results in the tremendous increase in fresh water demand during the past few decades. Since the local municipalities also provide the desalinated fresh water to the people but they mostly rely on bottled water for drinking purpose. In this paper, the pilot setup plant is designed, commissioned, and installed on site in UAE using air gap membrane distillation desalination process to fulfill the demand of 15-25 L/d of pure drinking water and 250 L/d of domestic hot water for a single-family villa. Experimental analyses have been performed on this setup during summer on flat plate solar collectors having different aperture areas (Experiments have been performed for aperture area of 11.9 m(2) in this research study for feasibility purpose). The average hot-side temperature ranges from 50 to 70 degrees C and average cold-side temperature of 35 degrees C.

En av de viktigaste miljöaspekterna när det gäller deponering av avfall är utsläpp till vatten. Tidigare leddes lakvatten från de flesta deponier till kommunala reningsverk, men på senare tid har trenden gått mot allt mer lokala lösningar i mark- växtbaserade system.

Vid Häradsuddens deponi i Norrköpings kommun har Econova mellan åren 2007 och 2011, i etapper, anlagt ett kombinerat system med lakvattenrecirkulering, luftad damm, intermittent översilning samt våtmark för rening av lakvattnet. Syftet med denna studie var att klarlägga vattenbalans och reningsfunktion för Häradsuddens reningssystem samt ge förslag på eventuella förbättringar.

Resultaten i undersökningen tyder på en avsevärt högre belastning på våtmarken än de kända flöden som pumpas till lakvattensystemet, vilket tyder på utläckage av lakvatten från deponin. Reningssystemet klarade dock med god marginal reningskraven avseende halt för NH₄-N och P_tot. Begränsande för möjligheten att släppa vattnet till recipient är halten TOC. Med anledning av lakvattnets sammansättning samt de förhållandevis höga halterna i tillrinnande vatten kan det bli svårt att komma ner i TOC-halter som säkrar möjlighet till utsläpp av behandlat lakvatten.

Den areaspecifika reningen varierade beroende på om hänsyn togs till förmodat inläckage. Den areaspecifika reningen avseende NH₄-N och N_tot var i princip obefintlig om ingen hänsyn togs till inläckage av lakvatten medan den var 80 respektive 50 g/m²·år om en beräkning av möjligt inläckage räknades med. När det gäller P_tot ökade avskiljningen från 1 till 2 g/m²·år vid hänsyn tagen till inläckage. Avskiljningen var något låg jämfört med etablerade våtmarker, men borde kunna öka med tiden.

Analysunderlag för den luftade lakvattendammen och översilningen är otillräckligt och osäkert för att det ska kunna gå att dra några långtgående slutsatser avseende reningseffekt för dessa delar. De bedöms dock kunna ha potential för att öka avskiljningen, varför en noggrann utredning av reningseffekt och olika driftstrategier för lakvattendammen och översilningen rekommenderas.

The aim of this study is to propose appropriate solutions that can complete Hemlingbys existing stormwater treatment systems. The solutions presented in this study has been developed with regards to the current situation, which includes water drainage systems and ponds. The study includes a survey of the current stormwater management within the district, as a result, the authors have localized two problem areas that should be investigated, i.e. are Hemlingbybäcken and Kryddstigen. The stormwater recipient i.e. Hemlingbybäcken is affected by human activities. Contaminates that affect the stream consist mainly of copper, lead and zinc. Due to the lack of stormwater storage capacity problems associated with stormwater flooding occurred from nearby buildings and industrial areas. Kryddstigen is an area in the district where business in technology and trade are located, these activities contribute to pollution that degrades groundwater and recipient conditions. The northern part of Hemlingby consist mostly of hard surfaces, which reduces the possibility of a natural infiltration of rain water, this in turn has caused an increased risk of flooding in the area. Gävle municipality have through earlier investigations identified some of the problems and tried to prevent them by implementing ponds that can delay incoming stormwater. Follow-up works proves that the ponds serve a larger catchment area than previously estimated, which adverse the ponds efficiency. Capacity problems have therefore arisen, for instance wetland ponds are sized to handle 10-yearsrain from a catchment area of 19 hectares. However, the existing wetland ponds can only handle a 2-yearsrain from a catchment area of 2400m3. This study presents open stormwater management as alternative solution, this has been proposed based on existing sewerage systems and ponds. Open stormwater solutions are applied mostly in urban environment to delay and locally dispose stormwater. This is done by vegetation which makes it possible to achieve a natural infiltration. The public can also take use of open stormwater solutions by turning an unattractive city to a beautiful one. It can also be beneficial to the community because open stormwater solutions contribute with an aesthetically pleasing environment and increasing biodiversity. The alternatives are described as follows: Green roofs, permeable ground surfaces, ditch with macadam basin and, rain gardens. These solutions are then assessed together with the existing solutions based on internal and external aspects concerning stormwater management. External aspects include legislation and stormwater policy, internal aspects take into account factors such as economy, technology, social and environment conditions. Assessment methodology that are presented in this study aims to evaluate and prepare documentation that is relevant for decision- making and the development of technical solutions based on the current situation. The evaluation method used in this study is inspired by PESTEL- analysis model. This method has been adapted to assess stormwater solutions. An overall description of what a PESTEL- analysis is given in this study as well as the interpretation and application of the assessment method. The result for single alternatives is presented and discussed with respect to existing solutions in the area of this study.

The current study involves a synthesis of a composite of nickel oxide nanoparticles (NiONPs) with a chromium dopant to yield (Cr/NiONPs). Synthesis of nickel oxide was performed by the co-precipitation method. The synthesis of the composite was conducted by the impregnation method. FTIR, EDX, SEM, and XRD were used to characterize the synthesized materials. The synthesised materials’ point zero charges (PZC) were performed using the potentiometric titration method. The obtained results show that the PZC for neat nickel oxide was around 5, and it was around 8 for Cr/NiONPs. The adsorption action of the prepared materials was examined by applying them to remove Reactive Red 2 (RR2) and Crystal Violate (CV) dyes from solutions. The outcomes demonstrated that Cr/NiONPs were stronger in the removal of dyes than NiONPs. Cr/NiONPs achieved 99.9% removal of dyes after 1 h. Adsorption isotherms involving Freundlich and Langmuir adsorption isotherms were also conducted, and the outcomes indicated that the most accurate representation of the adsorption data was offered by Langmuir adsorption isotherms. Additionally, it was discovered that the adsorption characteristics of the NiONPs and Cr/NiONPs correspond well with the pseudo-second-order kinetic model. Each of the NiONPs and Cr/NiONPs was reused five times, and the results display that the effectiveness of the removal of RR2 dye slightly declined with the increase in reuse cycles; it lost only 5% of its original efficiency after the 5 cycles. Generally, Cr/NiONPs showed better reusability than NiONPs under the same conditions.

Due to resource scarcity, current industrial systems are switching from waste treatment, such as wastewater treatment and biomass, to resource recovery (RR). Biofuels, manure, pesticides, organic acids, and other bioproducts with a great market value can be produced from wastewater and activated sludge (AS). This will not only help in the transition from a linear economy to a circular economy, but also contribute to sustainable development. However, the cost of recovering resources from wastewater and AS to produce value-added products is quite high as compared to conventional treatment methods. In addition, most antioxidant technologies remain at the laboratory scale that have not yet reached the level at industrial scale. In order to promote the innovation of resource recovery technology, the various methods of treating wastewater and AS to produce biofuels, nutrients and energy are reviewed, including biochemistry, thermochemistry and chemical stabilization. The limitations of wastewater and AS treatment methods are prospected from biochemical characteristics, economic and environmental factors. The biofuels derived from third generation feedstocks, such as wastewater are more sustainable. Microalgal biomass are being used to produce biodiesel, bioethanol, biohydrogen, biogas, biooils, bioplastics, biofertilizers, biochar and biopesticides. New technologies and policies can promote a circular economy based on biological materials.

The pine weevil, Hylobius abietis, is a severe forest pest insect as it feeds on newly planted conifer seedlings. To identify and develop an antifeedant could be one step towards the protection of seedlings from feeding damage by the pine weevil. With the aim to trace the origin of the antifeedants previously found in feces of the pine weevil, we investigated the culturable bacteria associated with the gut and identified the volatiles they produced. Bacterial isolates were identified by 16S ribosomal RNA gene analysis. The volatile emissions of selected bacteria, cultivated on NB media or on the grated phloem of Scots pine twigs dispersed in water, were collected and analyzed by solid-phase microextraction gas chromatography-mass spectrometry. The bacterial isolates released a variety of compounds, among others 2-methoxyphenol, 2-phenylethanol, 3-methyl-1-butanol, 1-octen-3-ol, 3-octanone, dimethyl disulfide, and dimethyl trisulfide. A strong antifeedant effect was observed by 2-phenylethanol, which could thus be a good candidate for use to protect planted conifer seedlings against feeding damage caused by H. abietis.

This study presents the synthesis of activated orange peel, derived from bio-waste (orange peel) and its doping with selenium nano-particles to enhance the adsorption capacity. The synthesized nanocomposite orange peel/Selenium (OP/Se) was applied as adsorbents for the removal of Lead (Pb) and Chromium (Cr) from synthetic waste water as an economical water cleaning technology. Orange peel/Selenium nanocomposite was characterized by X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and Scanning electron microscopy (SEM). Scanning electron microscopy results showed the porous structure of OP/Se nanocomposite and distinct peaks observed in XRD and FTIR spectra depicted the successful synthesis of nanocomposite. Batch experiments were conducted to figure out the effect of different parameters on adsorption of Pb and Cr by using Atomic Absorption Spectroscopy. The maximum adsorption capacity of 99.9% was achieved for both lead and chromium at acidic pH. While at temperature of 60°C the maximum adsorption of 98.3 and 95.9% was found for Pb and Cr respectively. Furthermore the experimental data was examined with Pseudo-first order, first-order and Pseudo-second order kinetic model, as well as Morris Intraparticle diffusion model where the pseudo second order was best fitted which indicated the chemisorption mechanism in adsorption process. The adsorption process followed the Langmuir isotherm model verified that OP/Se nanocomposite was found to be favorable for the process of adsorption. The adsorption thermodynamics indicate that adsorption of heavy metals ions is spontaneous (ΔG° < 0) and the adsorption increases with increase in temperature which means that reaction was endothermic in nature. This study revealed that the synthesized bio-activated nanocomposite was an efficient adsorbent material for the removal of heavy metals from waste water.

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. 

The pulp and paper (P&P) industry holds significant global importance. However, the industry’s processes substantially demand water and energy resources. Consequently, there is a pressing need for the industry to adopt more sustainable production practices, aiming to trim environmental impact and strengthen resilience against climate change. Recent research has highlighted the potential for substantial increases in Swedish biogas production using anaerobic wastewater (WW) treatment methods within P&P mills. The P&P sector traditionally relies on aerobic biological WW treatment, overlooking the valuable opportunity for WW resource recovery. This study aims to evaluate anaerobic moving bed biofilm reactors (AnMBBR) to enhance energy recovery while enabling treatment capacity for the P&P industry’s anaerobic WW treatment. The results of this study showed the resilience of the AnMBBR system. It proved capable of recovering from overload conditions and operating even during prolonged periods at low pH levels. However, the system removes mainly soluble COD, suggesting higher capabilities on P&P WW with a high fraction of soluble COD. Its ability to produce methane-rich biogas demonstrates efficient gas production while maintaining simple operational procedures.

Utsläpp av lustgas (N2O) utgör en betydande andel av klimatpåverkan från avloppsreningsverk (ARV). Medan de genomsnittliga utsläppen av lustgas från avloppsreningsverk med kväverening bedöms generellt ligga på ca 1,6 % av inkommande kväve förväntas inga lustgasemissioner i avloppsreningsverk utan kväverenande aktivitet. Detta eftersom lustgas bildas via processer som alla ingår i den biologiska kväveavskiljningen i avloppsvattenreningen. Dock kan det förekomma spontan och okontrollerad nitrifikation som kan leda till mycket höga lustgasutsläpp. Relativt ringa lustgasemissioner kan vara betydande för avloppsreningsverkens klimatavtryck eftersom lustgas är en mycket kraftig växthusgas, ca 273 gånger kraftigare än koldioxid. 

Trots den ökande kunskapen om lustgasutsläppens betydelse i avloppsreningsverkens klimatarbete utförs det fortfarande relativt få mätningar av lustgasutsläpp vid svenska ARV. Detta gör att det finns flera kunskapsluckor om och förståelse för lustgasutsläpp för att aktivt kunna vidta åtgärder för att minska dessa utsläpp. En anledning till att få mätningar genomförs är att det i dag inte finns krav på sådana mätningar och inte heller enkla metoder för lustgasmätning tillgängliga för VA-aktörer. 

Projektet har därför syftat till att öka kunskapen om lustgasutsläpp från avloppsrening i kallt klimat, med eller utan kontrollerad nitrifikation. Kallt klimat refererar till avloppsvatten som har minimitemperaturer ner till 4–5 grader. I samarbete med teknikleverantörer har dessutom nya lustgassensorer, anpassat för mätningar vid avloppsreningsverk, testats. För att kunna genomföra projektet med tilldelade medel och för att åstadkomma synergieffekter kopplades projektet till ett pågående pilotprojekt för kväverening i kall klimat vid Fillan avloppsreningsverk i Sundsvall, som även SVU medverkar i. 

Lustgasmätningar vid Fillan ARV som representerar en biologisk reningsprocess i kallt klimat utan kväverening är som förväntat låga. De uppmätta emissionerna uppgick till ca 0,17 % N2O-N/TN trots att en spontan och okontrollerad nitrifikation inte kunde observeras. Även om lustgasemissioner är låga så visar emissionsberäkningar att lustgasavgången ändå inte är försumbar och utgör ett avsevärt bidrag till klimatpåverkan.  

Lustgasmätningar i pilotanläggningen som representerar biologiska reningsprocesser med kväverening i kallt klimat indikerar att emissionerna kan antas vara i samma storleksordning eller högre som vid avloppsreningsverk med kväverening som inte har ett kallt inkommande avloppsvatten som regel. Ingen signifikant skillnad i lustgasemissioner kunde observeras mellan pilotens två linjer, varav den ena linjen värmdes med +4 °C mot referenslinjen. 

Utvärdering av de två nya sensorer från Unisense och Senseair har visat en mycket bra överensstämmelse mellan kalibrerade sensordata och referensmätningarna. Båda sensorer har därför en potential att användas för en kontinuerlig mätning av lustgas i gasfas ifall en kommersiell produktutveckling sker. Resultaten från kalibreringen indikerar dock vikten av en regelbunden kalibrering av sensorerna för att säkerställa korrekta mätningar, så som för sensorer i allmänhet. Kalibreringsmetoden som tillämpades inom projektet bedöms som rimlig men är inte den mest robusta eller noggranna metoden för en fullskaleimplementering.

Även utifrån andra implementeringsaspekter framstår de två testade sensorerna som ett tänkbart alternativ till andra mättekniker. Dock är dessa sensorer ännu inte kommersiellt tillgängliga och kompletterande långtidstester av sensorerna bör genomföras för en utvärdering som även kan ta hänsyn till aspekter relaterat till mätstabilitet och underhållsbehov vid långtidsdrift. 

En annan aspekt som projektet vill lyfta fram är vikten av att korrekta luftflödesmätningar utförs samtidigt som haltmätningarna. Endast en bra haltmätning i kombination med en korrekt luftflödesmätning vid mätpunkten kan ge ett korrekt underlag för emissionsberäkningar. Tyvärr kan det konstateras att enkla, robusta och ekonomiskt överkomliga sensorer för kontinuerlig luftflödesmätning inte finns idag och att det krävs en teknikutveckling även inom detta område.

Hydrothermal carbonization (HTC) of municipal sewage sludge has the potential to become one of the techniques for future sludge management at Swedish municipal wastewater treatment plants (WWTPs).

Some expected benefits of the HTC technology are a more sustainable sludge management and return of nutrients via the produced hydrochar, as well as other positive effects such as less greenhouse gas emissions and nutrient leakage into the environment.

At the same time, certain challenges such as the handling of process water and uncertainties about the properties of the produced hydrochar need to be investigated. In order to answer these questions and gather practical experience for HTC as a sludge management alternative, pilot trials with C-Green's OxyPower HTC™ have been carried out at Roslagsvattens WWTP in Margretelund, Åkersberga, Sweden.

Undigested sludge was treated to produce hydrochar and the produced HTC water was used at KTH/IVL's pilot plant Hammarby Sjöstadsverk in various side- or mainstream bench- and pilot-scale tests for biological treatment.Hydrochar and sludge from Roslagsvattens WWTP in Margretelund were characterized and tested in growth trials with soil and peat.

The formation of carbon dioxide in soil was also evaluated. In these studies, the results were also compared with hydrochar from four other substrates (digested food waste, stable manure, biosludge from treatment of process water from a pulp/paper mill and digested mixed sludge from municipal WWTPs).The project has shown that C-Green's OxyPower HTC™ is a possible technical alternative for treating Margretelund’s undigested sewage sludge. Various tests have illustrated that the technol¬ogy can reduce the sludge volume through an increase in TS to about 65 %, not only for sewage sludge but also for several other investigated substrates.

Although the HTC pilot plant could not be run continuously as a full-scale plant, still a process stability could be demonstrated. Even though the process is basically exothermic and a net production of energy over the entire process can be observed, the process needs high-quality electrical energy for operation.

An efficient utilization of the surplus heat that is produced thus becomes an important aspect to achieve resource efficiency. C-Green's OxyPower HTC™ is a compact process with relatively little surface area and costs for the process are judged to be dominated by operating costs in the form of energy and operating personnel.Tests with biological treatment of HTC water showed that a mixture with only reject water from sludge dewatering is not sufficient to achieve an effective purification to avoid an increased internal load on the mainstream process.

Although an effective reduction of organic pollutants measured as COD could be achieved, both short-term bench-scale and long-term pilot-scale tests indicated a clear inhibition of nitrification. While no complete inhibition was observed, long-term tests clearly showed that an adaptation of the microbial community over time cannot be expected. At the same time, supplementary long-term pilot tests with biological treatment of both HTC-water and reject water in the mainstream process showed an effective reduction of both organic pollutants such as COD and ammonium. No inhibitory effects were indicated, which is due to the very strong dilution of any inhibitory substances in the HTC water.

A return to the main treatment, however, means a greatly increased internal load, mainly with respect to organic pollutants and ammonium, which require extra process volumes if the effluent levels are not to be compromised.The HTC technology thus constitutes an interesting alternative for sludge management at Swedish WWTPs, which, however, requires consideration of several aspects: the facility's fitness to handle an increased internal load, today's sludge quality for producing good quality hydrochar, and a good integration into existing processes for optimal resource utilization.

Dagens reningsverk står inför flera utmaningar såsom ökad belastning, skärpta reningskrav, ett förändrat klimat, krav på ökad resurseffektivitet, en mer hållbar slamhantering och minskad miljöpåverkan från verksamheten.

I en strävan att nå mer hållbara lösningar för avloppsvattenrening och slamhantering har IVL Svenska Miljöinstitutet och Syvab haft ett långsiktigt forskningssamarbete. Under 2022 har olika aktiviteter inom områdena resursförbrukning, miljöpåverkan, slamhantering och processoptimering genomförts. Några av de aktiviteter som redovisas i denna rapport är fortfarande under genomförande och fortsätter även under 2023.  Några resultat från 2022 års arbete är följande:

Långtidspilottester med teknikkombinationen av Syvabs framtida MBR-process och två parallella 2-stegs filter med granulerat aktivt kol (GAK) för rening av läkemedelsrester och PFAS visar en fortsatt bra reningseffektivitet även om en förväntat avtagande effekt med ökade antal behandlade bäddvolymer observerats. tt kolbyte har fortfarande inte behövts efter ca 2,5 år av drift (vid ca 70 000 behandlade bäddvolymer i de enstaka GAK-filtren). Jämfört med det befintliga principförslaget så visar pilottesterna att signifikanta resurs- och kostnadsbesparingar kan åstadkommas om resultaten från pilotförsöken läggs till grund för en framtida fullskaleimplementering.Utvärderingen av övervaknings- och styrningsmöjligheter av GAK-filtren med hjälp av UVA eller DOC indikerar att en övervakning av reningen baserat på endast dessa parameter inte kommer räcka till.

Pilottester med en kombination av pulveriserat aktivt kol (PAK) och MBR-processen visar en mycket effektiv borttagning av studerade läkemedelsrester med >80 % redan vid en PAK-dos på ca 15 mg/l. Även PFOS renas bort effektivt med en avskiljning >98 %. Jämfört med teknikkombinationen MBR-GAK kan PAK-MBR alternativet ge ytterligare resursbesparingar samtidigt som andra utmaningar som slampåverkan p.g.a. PAK-tillsats behöver beaktas.

En implementering av SIMBA#-processmodellen för MBR-piloten och utvärdering av återkommande nitrifikationshämningar i fullskaleanläggningen med hjälp av dataanalys visar potential för dessa verktyg som möjlig användning i framtiden.

Mellan 2020 och 2023 har Vivab i samarbete med IVL Svenska Miljöinstitutet genomfört en förstudie om avancerad rening vid Getteröverket i Varberg. Förstudien genomfördes med bidrag från Naturvårdsverket i två olika etapper. Den första etappen omfattade en påverkansanalys av vattenmiljön, en behovsutredning och initiering av pilottester medan den andra etappen handlade främst om en fortsättning och komplettering av pilottester samt framtagandet av beslutsunderlag. Denna rapport redovisar etapp nummer två och kompletterar redan utfört arbete från etapp ett. Den första rapporten som avser etapp ett skickades till Naturvårdsverket i slutet av 2021.

Syftet med den förstudien var att utreda förutsättningarna för en fullskaleinstallation av lämplig teknik för rening av organiska mikroföroreningar såsom läkemedelsrester vid Getteröverket. Målet med studien var att ge ett väl underbyggt underlag för aktuella beslutsfattare för en eventuell implementering av en fullskaleanläggning inom befintligt verksamhetsområde.

För att uppnå ovan nämnda mål genomfördes kompletterande screeningar av organiska mikroföroreningar i föreliggande rapport. Provtagning har genomförts över avloppsreningsverket, potentiella punktkällor uppströms och i mottagande ytvatten som utgör Getteröverkets recipient. De tidigare startade långtidsförsöken från etapp 1 fortsatte under etapp 2. Försöken har utvärderat teknikkombinationen ultrafiltrering och granulerat aktiv kol (UF-GAK) och inkluderade även kompletterande pilottester med teknikkombinationen ozonering efterföljt av GAK (O3-GAK).Resultaten för den genomförda och kompletterande kartläggningen av i) mikroföroreningar över Getteröverket, ii) bidragande källor till inkommande avloppsvatten och iii) olika recipientpunkter, visade tydligt att Getteröverket är den dominerande transportvägen för läkemedelsrester till mottagande recipient inklusive Inre Farehammarsviken, som är ett känsligt och skyddat naturområde. För andra mikroföroreningar såsom PFAS (per- och polyfluorerade alkylsubstanser) och fenoler, finns även andra källor än Getteröverket. Vid undersökningar av lakvattnet från Bösarp deponi, konstaterades att det endast bidrar med en mindre del av den totala PFAS-belastningen till Getteröverket.De genomförda pilottesterna med de olika teknikkombinationerna UF-GAK och O3-GAK visade att en mycket bra reduktion av läkemedelsrester och andra organiska mikroföroreningar kunde åstadkommas.

Långtidsförsöken som pågick i ca 30 månader visade också att reduktionen kan åstadkommas med en signifikant mindre kolförbrukning i UF-GAK-lösningen jämfört med en traditionell design av kolfilter. Principförslaget som inkluderar dimensionering och tekniskt utförande för UF-GAK visar hur en fullskaleimplementering kan utföras. Projektgruppen valde att fokusera på teknikkombinationen UF-GAK i principförslaget, eftersom denna tekniklösning utvärderades under en längre tid och utifrån flera aspekter. En annan anledning till ett ökat fokus för kombinationen UF-GAK, var att den även ger ökade möjligheter för en återanvändning av vatten. För alternativet med O3-GAK gjordes endast en förenklad bedömning av resursbehovet. Utifrån den genomförda kostnadsbedömningen skulle en implementering av avancerad rening med UF-GAK vid Getteröverket generera en specifik reningskostnad på ca 2,3 kr/m3.Utöver analyser av olika organiska mikroföroreningar för pilotprocesserna genomfördes det även ett antal olika aktiviteter såsom aktivitetstester av vattenprover över olika reningssteg, flödescytometri, karakterisering av den mikrobiella sammansättningen i GAK-filter, antibiotikaresistens med mera, vilket återfinns i rapporten.

Per- and Polyfluoroalkyl Substances (PFAS) are everywhere around us in society, found in commercial and industrial products, the atmosphere, waste, water (waste, surface, drinking, and ground), soil, plants, animals, and even in our bodies. The use and spread of PFAS is a global societal challenge, affecting even the most remote places on Earth. One of the reasons why PFAS has been an attractive component in many products and industrial applications is their extreme chemical and thermal stability. However, these same properties allow for the persistence of PFAS in the environment, whereby even low PFAS emissions over time can be accumulated and pose a high risk of negative health and environmental effects. Today there are thousands of known and unknown PFAS with widely varying properties and toxicity, which makes both risk assessments and management of this growing environmental problem difficult. According to a national mass balance for PFAS emissions from products and atmospheric deposition are the major sources of PFAS in Sweden.

The amount of PFAS which are environmentally dispersed via wastewater and sewage sludge can be considered a minor part. However, due to the persistence of PFAS, measures to minimize their addition via these pathways may be necessary to reduce the total environmental load. Due to their toxicity and persistence, PFAS have recently become heavily regulated, with many regulatory agencies lowering the accepted PFAS environmental level ranges. Many PFAS have already been banned in Sweden or the EU and assessment grounds or action limits have been defined for various PFAS (e.g., surface water bodies, groundwater and drinking water) to initiate measures to reduce the spread of the substances. Already announced and stricter regulations will further increase the need for measures to minimize human exposure to PFAS and their dispersal in the environment.

Regardless of which measures are implemented, PFAS will remain in the environment for a long time, even if a global ban of the chemicals is implemented. Long-term management of PFAS is thus necessary to removal from the cycle gradually. The focus of mitigation actions should primarily be on heavily contaminated land and landfill leachate. The review of existing data from Swedish wastewater treatment plants WWTP and receiving recipients shows that today’s treatment processes do not remove PFAS. At some WWTP, however, an effective separation of certain PFAS is observed, which should be investigated further. Perfluorooctanoic sulfonic acid (PFOS) levels in many of the investigated inland surface waters receiving effluent from treatment plants and PFAS from other sources/pathways exceed existing limits. In many cases, however, analysis limitations prevent an assessment.

Ongoing activities around various treatment and destruction techniques for PFAS show that there are currently no techniques that achieve a far-reaching PFAS removal from municipal wastewater without significant resource consumption and related costs. For the continued use of sludge as a fertilizer, upstream mitigation is needed, with e.g., disconnection or treatment of PFAS-contaminated leachate. However, several ongoing projects indicate that a certain part of PFAS in wastewater can be removed as a side-effect of advanced treatment for pharmaceutical removal. This report provides guidance to stakeholders on how the PFAS problem can be tackled. It also demonstrates the need to improve and spread PFAS knowledge, particularly those involved with PFAS measurement data, treatment techniques and PFAS in sludge. 

PFAS (Per- and Polyfluoroalkyl Substances) are everywhere around us in society; in products, the atmosphere, waste, wastewater, surface water, drinking water, groundwater, soil, plants, animals and in our bodies. The use and spread of PFAS is a global societal challenge and even the most remote places on earth are no longer unaffected by PFAS substances. One of the reasons why PFAS has been attractive in many products and industrial applications is the substances' extreme chemical and thermal stability. However, the same properties create challenges in the environment as the persistence of PFAS implies that even low emissions over time can be accumulated in different environments with a high risk of negative health and environmental effects. Today there are thousands of known and unknown PFAS with widely varying properties and toxicity, which makes both risk assessments and management of this growing environmental problem difficult.

A national mass balance for PFAS shows that emissions from products and atmospheric deposition are the major sources of PFAS to Sweden. The PFAS-amounts that are spread to the environment via wastewater and sewage sludge can be considered a minor part. However, due to the persistence of PFAS substances, measures to minimize the addition via these pathways may be relevant in order to reduce the total environmental load.

Considering the toxicity and persistence of PFAS, their use has been heavily regulated in recent times and the levels that are considered acceptable in the environment have been lowered. Many PFAS have already been banned in Sweden or the EU and assessment grounds or action limits have been defined for various PFAS in e.g. surface water bodies, groundwater and drinking water to initiate measures to reduce the spread of the substances. Already announced and upcoming stricter regulations will further increase the need for measures to minimize human exposure to PFAS and their dispersal in the environment. Regardless of which measures that are implemented, PFAS will remain in the environment for a long time, even if a global ban of the chemicals is implemented. A long-term management of PFAS is thus necessary with a gradual removal from the cycle. The focus of mitigation actions should primarily be on heavily contaminated land and landfill leachate.The review of existing data at Swedish sewage treatment plants and receiving recipients shows that today's treatment processes do not remove PFAS even of some PFAS are removed and end up in the sludge. At some sewage treatment plants, however, an effective separation of certain PFAS is observed, which should be investigated further. PFOS levels in many of the investigated inland surface waters receiving effluent from treatment plants and PFAS from other sources/pathways exceed existing limits. In many cases, however, analysis limitations prevent an assessment.

Ongoing activities around various treatment and destruction techniques for PFAS show that there are currently no techniques that achieve a far-reaching PFAS removal from municipal wastewater without significant resource consumption and related costs. For a continued use of sludge as a fertilizer, upstream mitigation is needed, with e.g. disconnection or treatment of PFAS-contaminated leachate. However, several ongoing projects indicate that a certain part of PFAS in wastewater can be removed as a side-effect of advanced treatment for pharmaceutical removal.The report also provides guidance to stakeholders on how the PFAS problem can be tackled. In addition, the report shows a great need to improve and spread knowledge about PFAS with, above all, measurement data and knowledge about treatment techniques and PFAS in sludge in order to be able to meet the PFAS challenge.