Shifting the concept of municipal wastewater treatment to recover resources is one of the key factors contributing to a sustainable society. A novel concept based on research is proposed to recover four main bio-based products from mu-nicipal wastewater while reaching the necessary regulatory standards. The main resource recovery units of the pro-posed system include upflow anaerobic sludge blanket reactor for the recovery of biogas (as product 1) from mainstream municipal wastewater after primary sedimentation. Sewage sludge is co-fermented with external organic waste such as food waste for volatile fatty acids (VFAs) production as precursors for other bio-based production. A por-tion of the VFA mixture (product 2) is used as carbon sources in the denitrification step of the nitrification/denitrifica-ti on process as an alternative for nitrogen removal. The other alternative for nitrogen removal is the partial nitrification/anammx process. The VFA mixture is separated with nanofiltration/reverse osmosis membrane technol-ogy into low-carbon VFAs and high-carbon VFAs. Polyhydroxyalkanoate (as product 3) is produced from the low -carbon VFAs. Using membrane contactor-based processes and ion-exchange techniques, high-carbon VFAs are recovered as one-type VFA (pure VFA) and in ester forms (product 4). The nutrient-rich fermented and dewatered bio-solid is applied as a fertilizer. The proposed units are seen as individual resource recovery systems as well as a concept of an integrated system. A qualitative environmental assessment of the proposed resource recovery units confirms the positive environmental impacts of the proposed system.

Wastewater-based epidemiology (WBE) can be used to track the spread of SARS-CoV-2 in a population. This study pre-sents the learning outcomes from over two-year long monitoring of SARS-CoV-2 in Stockholm, Sweden. The three main wastewater treatment plants in Stockholm, with a total of six inlets, were monitored from April 2020 until June 2022 (in total 600 samples). This spans five major SARS-CoV-2 waves, where WBE data provided early warning signals for each wave. Further, the measured SARS-CoV-2 content in the wastewater correlated significantly with the level of positive COVID-19 tests (r = 0.86; p << 0.0001) measured by widespread testing of the population. Moreover, as a proof-of-concept, six SARS-CoV-2 variants of concern were monitored using hpPCR assay, demonstrating that var-iants can be traced through wastewater monitoring.During this long-term surveillance, two sampling protocols, two RNA concentration/extraction methods, two calcula-tion approaches, and normalization to the RNA virus Pepper mild mottle virus (PMMoV) were evaluated. In addition, a study of storage conditions was performed, demonstrating that the decay of viral RNA was significantly reduced upon the addition of glycerol to the wastewater before storage at -80 degrees C. Our results provide valuable information that can facilitate the incorporation of WBE as a prediction tool for possible future outbreaks of SARS-CoV-2 and preparations for future pandemics.

Burgeoning concerns on the adverse environmental impacts of fossil-derived products are propelling the pursuit of material production from sustainable resources. Resource recovery from waste is a key component of meeting the environmental sustainability agendas set by the United Nations. Municipal organic wastes present a significant opportunity for resource recovery due to their inherent organic content. Volatile fatty acids (VFAs), the intermediary products of anaerobic digestion of waste streams, can serve as building block chemicals with a wide range of applications. Meanwhile, microbiologically produced biopolymers called polyhydroxyalkanoates (PHAs) hold an enormous potential as an alternative to petrochemical-based plastics, given their comparable physiochemical properties, biodegradability and biocompatibility. In view of this, the focus of this thesis was on bio-based VFA production from food waste (FW) and PHA production from municipal organic waste by exploring process optimization and microbial community dynamics of mono and co-cultures as well as mixed microbial cultures (MMCs).

The link between different inocula, retention time and pH on VFA production from FW was elucidated. This part of the study employed three distinct inocula under initial acidic (pH 5) and alkaline (pH 10) conditions for a period of 30 days. 

Waste-derived VFAs were employed for mono and co-culture PHA biosynthesis with bacteria, Cupriavidus necator, Burkholderia cepacia and Bacillus megaterium. The highest PHA yields of 78 ± 5.7% of cell dried weight (CDW) was obtained with C. necator and a PHA yield of 55 ± 3.7% of CDW was achieved with B. cepacia. 

In the next part of the study, activated sludge MMC was enriched over short (3 and 5 days) periods in combination with bioaugmentation of C. necator and B. cepacia in both mono and co-culture modes. While bioaugmentation did not increase the total PHA accumulation capacity, the microbial composition of the different bioreactors was modified. 

This Ph.D. project provided insights on recovery of biobased materials from waste. Manipulation of the microbial communities in the MMCs can be a critical parameter to enhance the overall efficacy as well as to tailor the composition of the end products. 

En växande oro för de negativa miljöeffekterna av fossilbaserade produkter driver strävan efter materialproduktion från hållbara resurser. Resursåtervinning från avfall är en nyckelkomponent för att uppfylla FN:s miljöpolitiska hållbarhetsagendor. Kommunalt organiskt avfall utgör en betydande möjlighet till resursåtervinning på grund av sitt inneboende organiska innehåll. Flyktiga fettsyror (VFA), mellanprodukter från anaerob rötning av avfallsströmmar, kan fungera som byggstenskemikalier med ett brett spektrum av tillämpningar. Samtidigt har mikrobiologiskt framställda biopolymerer som kallas polyhydroxialkanoater (PHA) en enorm potential som ett alternativ till petrokemiskt baserad plast, med tanke på deras jämförbara fysiokemiska egenskaper, biologiska nedbrytbarhet och biokompatibilitet. Mot bakgrund av detta låg fokus för denna avhandling på biobaserad VFA-produktion från matavfall (FW) och PHA-produktion från kommunalt organiskt avfall genom att utforska processoptimering och mikrobiell gemenskapsdynamik hos mono- och samkulturer samt blandade mikrobiella kulturer (MMC).Kopplingen mellan olika inokula, retentionstid och pH på VFA-produktion från FW klargjordes. Denna del av studien använde tre distinkta inokula under initiala sura (pH 5) och alkaliska (pH 10) betingelser under en period av 30 dagar.Avfallshärledda VFAs användes för mono- och samodling av PHA-biosyntes med bakterier, Cupriavidus necator, Burkholderia cepacia och Bacillus megaterium. De högsta PHA-utbytena på 78  5,7 % av celltorkad vikt (CDW) erhölls med C. necator och ett PHA-utbyte på 55  3,7 % av CDW uppnåddes med B. cepacia.I nästa del av studien berikades aktivt slam MMC under korta (3 och 5 dagar) perioder i kombination med bioaugmentation av C. necator och B. cepacia i både mono- och samodling. Även om bioaugmentering inte ökade den totala PHA-ackumuleringskapaciteten, modifierades den mikrobiella sammansättningen av de olika bioreaktorerna.Denna Ph.D. projektet gav insikter om återvinning av biobaserat material från avfall. Manipulering av de mikrobiella samhällena i MMC:erna kan vara en kritisk parameter för att förbättra den totala effektiviteten samt för att skräddarsy sammansättningen av slutprodukterna.

Polyhydroxyalkanoates (PHAs), as bio-based plastics, promise a transition from petroleum products to green and sustainable alternatives. However, their commercial production is yet impeded by high production costs. In this study, we assessed synthetic culture in mono and co-culture modes for bacterial PHA production. It was demonstrated that volatile fatty acids (VFAs) derived from food waste and primary sludge are cheap carbon sources for maintaining high production yields in the synthetic cultures. The maximum obtained PHA was 77.54 ± 5.67% of cell dried weight (CDW) (1.723 g/L) from Cupriavidus necator and 54.9 ± 3.66% of CDW (1.088 g/L) from Burkholderia cepacia. The acquired results are comparable to those in literature using sugar substrates. Comparatively, lower PHA productions were obtained from the co-cultivations ranging between 36-45 CDW% (0.39–0.48 g/L). Meanwhile, the 3-hydroxyvalerate content in the biopolymers were increased up to 21%.

Wastewater-based epidemiology offers a cost-effective alternative to testing large populations for SARS-CoV-2 virus, and may potentially be used as an early warning system for SARS-CoV-2 pandemic spread. However, viruses are highly diluted in wastewater, and a validated method for their concentration and further processing, and suitable reference viruses, are the main needs to be established for reliable SARS-CoV-2 municipal wastewater detection. For this purpose, we collected wastewater from two European cities during the Covid-19 pandemic and evaluated the sensitivity of RT-qPCR detection of viral RNA after four concentration methods (two variants of ultrafiltration-based method and two adsorption and extraction-based methods). Further, we evaluated one external (bovine corona virus) and one internal (pepper mild mottle virus) reference virus. We found a consistently higher recovery of spiked virus using the modified ultrafiltration-based method. This method also had a significantly higher efficiency (p-value <0.01) for wastewater SARS-CoV-2 detection. The ultracentrifugation method was the only method that detected SARS-CoV-2 in the wastewater of both cities. The pepper mild mottle virus was found to function as a potentially suitable internal reference standard.

Production of polyhydroxyalkanoates is an important field in the biorefinery as bio-alternative to conventional plastics. However, its commercialization is still limited by high production cost. In this study, a process with the potential to reduce the production cost of polyhydroxyalkanoates was proposed. Mixed cultures accumulated polyhydroxyalkanoates using volatile fatty acid-rich effluents from waste streams, without pH and temperature control. In addition, the impact of two types of carbon sources was investigated by analyzing the microbial community as well as the polyhydroxyalkanoate accumulation capacity. Mixed cultures successfully adapted to different substrates, consuming the volatile fatty acids in their totality. The phyla Proteobacteria, Bacteroidetes and Firmicutes dominated the bacterial community. The highest polyhydroxyalkanoate content was 43.5% w/w, which is comparable to contents reported from mixed cultures using synthetic carbon sources. The biopolymer consisted of (R)-3-hydroxybutyrate 94.8 ± 1.7% w/w and (R)-3-hydroxyvaletare 5.2 ± 1.7% w/w.

Bio-based production of materials from waste streams is a pivotal aspect in a circular economy. This study aimed to investigate the influence of inoculum (three different sludge taken from anaerobic digestors), pH (5 & 10) and retention time on production of total volatile fatty acids (VFAs), VFA composition as well as the microbial community during anaerobic digestion of food waste. The highest VFA production was ∼22000 ± 1036 mg COD/L and 12927 ± 1029 mg COD/L on day 15 using the inoculum acclimated to food waste at pH 10 and pH 5, respectively. Acetic acid was the dominant VFA in the batch reactors with initial alkaline conditions, whereas both propionic and acetic acids were the dominant products in the acidic condition. Firmicutes, Chloroflexi and Bacteroidetes had the highest relative abundance in the reactors. VFA generation was positively correlated to the relative abundance of Firmicutes.

The key factor for promoting bioeconomy and circularity in the cities is to examine waste streams such as municipal wastewater, sludge, solid waste, food waste, bakery industry waste, and pulp and paper industry waste as raw materials rather than wastes to be disposed. In this regard, biorefinery concept is promising for converting biomass into valuable products. Biomethane, high market value volatile fatty acids, and polyhydroxyalkanoates are some of the main outstanding products for waste biorefineries. Algal biorefinery concept is also promising as serving as a multiple product factory that can also be integrated with municipal wastewater systems. Phosphorus recovery is also essential to control eutrophication in the receiving water bodies and reversing phosphorus back to the market. Therefore, future management of cities should include these specified approaches to support circularity and minimize possible environmental problems.

Increased awareness of environmental sustainability with associated strict environmental regulations has incentivized the pursuit of novel materials to replace conventional petroleum-derived plastics. Polyhydroxyalkanoates (PHAs) are appealing intracellular biopolymers and have drawn significant attention as a viable alternative to petrochemical based plastics not only due to their comparable physiochemical properties but also, their outstanding characteristics such as biodegradability and biocompatibility. This review provides a comprehensive overview of the recent developments on the involved PHA producer microorganisms, production process from different waste streams by both pure and mixed microbial cultures (MMCs). Bio-based PHA production, particularly using cheap carbon sources with MMCs, is getting more attention. The main bottlenecks are the low production yield and the inconsistency of the biopolymers. Bioaugmentation and metabolic engineering together with cost effective downstream processing are promising approaches to overcome the hurdles of commercial PHA production from waste streams.

The aim of this study has been to investigate the environmental impacts of an innovative food waste management system and compare it with landfilling as a conventional waste management option. The investigated system is still in the laboratory research and development phase. Therefore, inventory data of the laboratory scale food waste management system was collected and then up-scaled for life cycle assessment purposes. The proposed system consists of a hygenization reactor followed by a fermenter and then a centrifuge. The system converts food waste into volatile fatty acid-rich supernatant. Functional unit is management of 1 ton food waste. The results indicate that the proposed system is a better option than landfilling in terms of all impact categories. The produced VFA-rich supernatant is supposed to be used as a replacement for methanol in the denitrification process. In one of the impact categories (ozone depletion potential) the avoided burdens are higher than the burdens and the system provides net gain (-2.82E-07 kg R11 eq.). Majority of the environmental burdens in the proposed system are due to heat consumption for hygenization. Including sludge disposal in the investigated system boundary increases the environmental burdens but the burdens are still lower compared to landfilling option.