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The thesis investigates how anaerobic digestion could be utilized to improve wastewater management,specifically in regards to future expected regulation on sludge management in Sweden.Two possible paths of applying anaerobic digestion are investigated. First, the usage of thermophilic anaerobicdigestion of sludge in order to achieve pathogen hygienization. Second, the usage of anaerobic digestion totreat wastewaters at decreased temperature. The evaluation of each path was made through practical labscale experiments. Additionally, the benefits of each path was compared through desk top environmentalimpact studies and economic analysis.The results for the first path showed that thermophilic anaerobic digestion renders high pathogen hygienizationeven at relative short exposure times. However no additional beneficial impact on biogas production or thereduction of organic micropollutants was found. The results for the second path showed that the difficulty ofoperating the sensitive anaerobic digestion process at low temperatures can be partly overcome by simpleengineering batch tests. Furthermore, the dissolved methane in the effluent wastewaters can be extractedusing membrane contactors. Finally, the environmental impact assessment showed that increased resourcerecovery from wastewater, as well as decreased climate impact, can be achieved by applying anaerobicdigestion on source separated domestic wastewaster.The economic evaluation of the two paths showed that the implementation of source separation systems isexpensive compared to implementing the needed thermophilic hygienization. However, source separationsystems would greatly boost nutrient recovery from cities to agriculture which complies well with the goals ofthe Swedish Environmental Protection Agency.

Owners of stables and owners of zoos have difficulty finding an economically sustainable deposition of their produced manure. More than two million tons of horse manure are produced in urban environments in Sweden every year. If the manure cannot be used as fertilizer on farm land it is classified as a waste fraction and should be handled according to current regulations. The manure is a valuable waste fraction that contains both energy and nutrients. If the manure cannot be spread on farm land more applications need to be identified, where the energy and nutrients in the manure can be used. The focus in this study is to investigate possible applications for the usage of horse and zoo manure within Borås municipality where, among other things, a waste water treatment plant and a combined heat and power plant are available. Horse and zoo manure have been investigated in the following applications: co-digestion with sewage sludge at a waste water treatment plant (lab experiments), co-digestion with food waste (theoretical), co-incineration with waste (full scale) and co-incineration with biomass (theoretical). Potential quantity of manure and economical and legal aspects have been studied as well. There is no compilation of the number of horses in the country which makes it hard to estimate the true quantity of manure. The quantity of manure from the zoos are somewhat easier to estimate since the zoo owners are fewer and have knowledge of their manure production. The co-digestions experiments in this study showed that addition of horse manure to digestion can be of interest in many ways, among other things it can give a more stable biogas production and a possible decrease in the Cd/P-ratio in the end product. Horse manure turned out to have a faster degradation rate compared to zoo manure, however the degradation rate was lower than that of sewage sludge. Zoo manure gave a relatively low biogas production compared to horse manure at thermophilic conditions. The co-incineration trial with waste and manure gave no negative effect with regard to emissions and operation. However, the amount of manure added to the incineration trial was low. The theoretical studies regarding the co-incineration with biomass, showed two potential alternatives that need to be investigated further. Interesting aspects to look further upon, based on this study, are for example: • Laws and regulations in the EU regarding manure. • Co-digestion of manure and sewage sludge in a larger scale. • Laws and regulations and costs regarding incineration of manure with biomass.

The study evaluated effect of anaerobic digestion (35, 55 and 60 °C ) at different minimum exposure times as well as from pasteurization on hygienization of pathogens, biogas production and removal of pharmaceutical substances and PAH. The study evaluated effect of anaerobic digestion (35, 55 and 60 °C ) at different minimum exposure times as well as from pasteurization on hygienization of pathogens, biogas production and removal of pharmaceutical substances and PAH.

Author-generated pre-print of the paper "Integrated nutrient recovery from source-separated domestic wastewaters for application as fertilisers" published in August 2019 in the journal Current Opinion in Environmental Sustainability. Full reference: Bisschops I., Kjerstadius H., Meulman B., van Eekert M. (2019) Integrated nutrient recovery from source-separated domestic wastewaters for application as fertilisers. Current Opinion in Environmental Sustainability 40, 7-13. https://doi.org/10.1016/j.cosust.2019.06.010.

This is an author-generated post-print of the paper: Bisschops I., Kjerstadius H., Meulman B., van Eekert M. (2019) Integrated nutrient recovery from source-separated domestic wastewaters for application as fertilisers. Current Opinion in Environmental Sustainability 40, 7-13. Under embargo until 22 August 2021. The version published by Elsevier can be found at https://doi.org/10.1016/j.cosust.2019.06.010

Author-generated pre-print of the paper "Integrated nutrient recovery from source-separated domestic wastewaters for application as fertilisers" published in August 2019 in the journal Current Opinion in Environmental Sustainability. Full reference: Bisschops I., Kjerstadius H., Meulman B., van Eekert M. (2019) Integrated nutrient recovery from source-separated domestic wastewaters for application as fertilisers. Current Opinion in Environmental Sustainability 40, 7-13. https://doi.org/10.1016/j.cosust.2019.06.010.

of the poster presentation held by Marinette Hagman at the 2018 IWA World Water Congress & Exhibition in Tokyo, Japan, 16-21 September 2018.

of the poster presentation held by Marinette Hagman at the 2018 IWA World Water Congress & Exhibition in Tokyo, Japan, 16-21 September 2018.

This is an author-generated post-print of the paper: Bisschops I., Kjerstadius H., Meulman B., van Eekert M. (2019) Integrated nutrient recovery from source-separated domestic wastewaters for application as fertilisers. Current Opinion in Environmental Sustainability 40, 7-13. Under embargo until 22 August 2021. The version published by Elsevier can be found at https://doi.org/10.1016/j.cosust.2019.06.010 &nbsp

Brochure (in English) about the RecoLab treatment plant and test bed facility that is integrated in the Oceanhamnen project in Helsingborg.

Brochure (in Swedish) about the RecoLab treatment plant and test bed facility that is integrated in the Oceanhamnen project in Helsingborg.

There has been an increasing interest in wastewater treatment in last decades to reduce human footprint. Primarily, anaerobic technology focused on treatment and stabilization of sludge, but now the tendency is to give it a major role in low cost treatment of high/low strength wastewaters, since anaerobic digestion offers energy generation through gas production. Anaerobic membrane bioreactors (AnMBR) combine anaerobic digestion with membrane filtration. They are becoming a feasible option for treating previous unsuitable low-strength wastewaters, decoupling hydraulic and solid retention times, and providing successful treatment with the benefits of biogas production. However, the digestion process is optimal at mesophilic or termophilic (35-37 ºC), requiring heating of reactors. The more inexpensive option to treat the wastewater at its ambient temperature is feasible using AnMBR since this type of reactor can offer long sludge retention times. On the other hand, the digestion equilibrium turns out more sensible and delicate, and performing a proper and robust start-up of AnMBR in ambient temperatures is still challenging. The aim of the thesis was the successful startup and stabilization of AnMBR systems at ambient temperature (25 ºC) and low organic loading rate (OLR). Reactor operation was monitored, and the most relevant process parameters were considered for the aim. Two pilot-scale AnMBR’s (120L) were used with an external membrane configuration. The experiment was carried out in 100 days. Substrate feeding consisted of synthetic dairy wastewater with added nutrients solution. The inoculum was provided from a full-scale anaerobic plant at a digester of BV dairy (UK) treating dairy wastewater at 30ºC. Main operation parameters were monitored every day, along with gas production and methane yield. Laboratory tests were performed twice a week with samples of the reactors and effluent. A number of parameters were analyzed, the most important of which were total solids content (TSS), alkalinity, fatty acids, biogas content and chemical oxygen demand (COD). The startup of the two AnMBR’s differed greatly. In System 1, stable conditions were acquired in one month of operation. System 2 failed after 20 days of function, and did not achieve successful startup. It was not possible to fully recover it during the days of study due to dramatically slow growth of microorganisms and low stability of the process. Thus, satisfactory system performance could be achieved but the ambient anaerobic process was vulnerable to inhibitory conditions. Both systems showed that the delicate process operation required fast corrective measures to prevent digestion failure. Causes of instability and failure were: washout of biomass, high content of VFA, low buffering capacity and poor performance of technical equipment and low pH. However, the digestion could stand a lower pH range than found in literature. In conclusion, the best parameters to control the startup were pH, alkalinity, methane content, biomass content and organic removal. In this sense, low buffering capacity of a reactor makes it vulnerable to inhibition by sudden pH changes, easily solved by systematic addition of a buffering compound. Finally, the use of simple and fast alkalimetric methodologies can give satisfactory process overview compared to complex and more precise techniques for alkalinity measurement. Outgoing