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  • 1.
    Anbalagan, Anbarasan
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    A passage to wastewater nutrient recovery units: Microalgal-Bacterial bioreactors2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    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.

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  • 2.
    Anbalagan, Anbarasan
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Indigenous microalgae-activated sludge cultivation system for wastewater treatment2016Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Avloppsvatten innehåller allt det ni spolar ner i avloppet, med höga halter av viktiga näringsämnen som fosfor, kväve och kol. Kostnaden för att rena avloppsvatten ökar i världen på grund av ökad urbanisering och ökade krav på reningen.

    Reningsprocessen domineras av aktivslamprocessen, i vilken mikroorganismer (främst bakterier) renar vattnet från kol och kväve medan det mesta av fosforn fälls ut med kemikalier. Processen är mycket energikrävande på grund av den stora mängden luft som pumpas in för att förse bakterierna med syre. Tillsammans utgör alla de här funktionerna en energi- och resurskrävande process som dessutom kräver tillskott av mer kol, oftast som ren alkohol, för att kvävereningen ska fungera.

    I den här avhandlingen har ett alternativ till konventionell, bakteriell avloppsvattenrening studerats; mikroalgbaserad aktivslamprocess (MAAS). Bakgrunden är att gröna mikroalger i likhet med växter utnyttjar fotosyntesen. Genom i fotosyntesen kan algerna snabbt föröka sig om det finns näringsämnen, ljus och koldioxid. Eftersom avloppsvattnet innehåller alla nödvändiga näringsämnen kan det räcka med att tillsätta koldioxid under rätt ljusförhållanden för att en livskraftig algkultur ska växa till. Algerna producerar även syre i processen som i sin tur kan användas av bakterierna i MAAS processen i en intressant symbios. Mest intressant är mikroalgbaserad vattenrening ur ett resursutvinningsperspektiv eftersom näringsämnena assimileras i algerna och därmed förblir i slammet och kan sedan utvinnas som en gödselprodukt.

    Målet med MAAS-forskningen har varit att använda koldioxid, näringsämnen och en algkultur från svenska förhållanden, i det här fallet Mälaren, för att bygga upp en effektiv kultur för vattenrening. Samtidigt vill vi i forskningen optimera processen utifrån hur mycket ljus som behöver tillföras, hur snabbt mikroorganismerna kan rena vattnet och vilka andra ämnen som kan störa processen.

    I den här avhandlingen har olika ljuskällor undersökts, med särskilt fokus på effektiva LED-lampor. Därefter har målet varit att optimera processen så att uppehållstiden, dvs den tid det tar för en viss volym vatten att renas, skulle kunna sänkas från 6 dagar (vilket anses vara internationell standard) till 4 eller till och med 2 dagars uppehållstid. Slutligen studerades effekterna av fällningskemikalier i mikroalgkulturen med slutsatsen att mikroalger blir begränsade av fällningskemikalier men att mikroalgerna däremot har goda förutsättningar att rena vattnet från betydande mängder fosfor och därmed minska mängderna fällningskemikalier som måste till sättas.

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  • 3.
    Anbalagan, Anbarasan
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Jeanette Castro, Cynthia
    University of Massachusetts Amherst, US.
    Schwede, Sebastian
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lindberg, Carl-Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB AB Corporate Research, Sweden.
    Nehrenheim, Emma
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Northvolt AB, Sweden.
    Butler, Caitlyn
    University of Massachusetts Amherst, US.
    Influence of environmental stress on the microalgal-bacterial process during nitrogen removalManuskript (preprint) (Övrigt vetenskapligt)
  • 4.
    Anbalagan, Anbarasan
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lindberg, Carl-Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Nehrenheim, Emma
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Influence of light intensity and phosphorous on microalgae activated sludge in phosphate precipitated conditionManuskript (preprint) (Övrigt vetenskapligt)
  • 5.
    Anbalagan, Anbarasan
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. University of Valladolid, Dr. Mergelina s/n, Valladolid, Spain.
    Toledo-Cervantes, A.
    University of Valladolid, Dr. Mergelina s/n, Valladolid, Spain.
    Posadas, E.
    University of Valladolid, Dr. Mergelina s/n, Valladolid, Spain.
    Rojo, E. M.
    University of Valladolid, Dr. Mergelina s/n, Valladolid, Spain.
    Lebrero, R.
    University of Valladolid, Dr. Mergelina s/n, Valladolid, Spain.
    González-Sánchez, A.
    University of Valladolid, Dr. Mergelina s/n, Valladolid, Spain.
    Nehrenheim, Emma
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Muñoz, R.
    University of Valladolid, Dr. Mergelina s/n, Valladolid, Spain.
    Continuous photosynthetic abatement of CO2 and volatile organic compounds from exhaust gas coupled to wastewater treatment: Evaluation of tubular algal-bacterial photobioreactor2017Ingår i: Journal of CO2 Utilization, ISSN 2212-9820, E-ISSN 2212-9839, Vol. 21, s. 353-359Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    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. 

  • 6.
    Chaudhary, R.
    et al.
    Indian Inst Technol, Ctr Environm Sci & Engn, Maharashtra, India.
    Tong, Y. W.
    Natl Univ Singapore, Dept Chem & Biomol Engn, Singapore..
    Dikshit, Anil Kumar
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. IndianInst Technol, Ctr Environm Sci & Engn, Maharashtra, India; Asian Inst Technol, Sch Environm Resources & Dev, Pathumthani,Thailand.
    CO2-assisted removal of nutrients from municipal wastewater by microalgae Chlorella vulgaris and Scenedesmus obliquus2018Ingår i: International Journal of Environmental Science and Technology, ISSN 1735-1472, E-ISSN 1735-2630, Vol. 15, nr 10, s. 2183-2192Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Axenic culture of microalgae Chlorella vulgaris ATCC((R)) 13482 and Scenedesmus obliquus FACHB 417 was used for phycoremediation of primary municipal wastewater. The main aim of this study was to measure the effects of normal air and CO2-augmented air on the removal efficacy of nutrients (ammonia N and phosphate P) from municipal wastewater by the two microalgae. Batch experiments were carried out in cylindrical glass bottles of 1L working volume at 25 degrees C and cool fluorescent light of 6500lux maintaining 14/10h of light/dark cycle with normal air supplied at 0.2Lmin(-1) per liter of the liquid for both algal strains for the experimental period. In the next set of experiments, the treatment process was enhanced by using 1, 2 and 5% CO2/air (vol./vol.) supply into microalgal cultures. The enrichment of inlet air with CO2 was found to be beneficial. The maximum removal of 76.3 and 76% COD, 94.2 and 92.6% ammonia, and 94.8 and 93.1% phosphate after a period of 10days was reported for C. vulgaris and S. obliquus, respectively, with 5% CO2/air supply. Comparing the two microalgae, maximum removal rates of ammonia and phosphate by C. vulgaris were 4.12 and 1.75mgL(-1)day(-1), respectively, at 5% CO2/air supply. From kinetic study data, it was found that the specific rates of phosphate utilization (q(phsophate)) by C. vulgaris and S. obliquus at 5% CO2/air supply were 1.98 and 2.11day(-1), respectively. Scale-up estimation of a reactor removing phosphate (the criteria pollutant) from 50 MLD wastewater influent was also done.

  • 7.
    Chusova, Olga
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Nolvak, H.
    Institute of Ecology and Earth Sciences, University of Tartu, Vanemuise 46, Tartu 51014, Estonia.
    Nehrenheim, Emma
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Truu, J.
    University of Tartu, Estonia.
    Odlare, Monica
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Oopkaup, K.
    University of Tartu, Estonia.
    Truu, M.
    University of Tartu, Estonia.
    Effect of pine bark on the biotransformation of trinitrotoluene and on the bacterial community structure in a batch experiment2014Ingår i: Environmental technology, ISSN 0959-3330, E-ISSN 1479-487X, Vol. 35, nr 19, s. 2456-2465Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pine bark, a low-cost industrial residue, has been suggested as a promising substitute for granular activated carbon in the on-site treatment of water contaminated with 2,4,6-trinitrotoluene (TNT). However, the complex organic structure and indigenous microbial community of pine bark have thus far not been thoroughly described in the context of TNT-contaminated water treatment. This two-week batch study examined the removal efficiency of TNT from water by (1) adsorption on pine bark and (2) simultaneous adsorption on pine bark and biotransformation by specialized TNT-biotransforming microbial inocula. The bacterial community composition of experimental batches, inocula and pine bark, was profiled by Illumina sequencing of the V6 region ofthe 16S rRNA gene. The results revealed that the inocula and experimental batches were dominated by phylotypes belonging to the Enterobacteriaceae family and that the tested inocula had good potential for TNT biotransformation. The type of applied inocula had the most profound effect on the TNT-transforming bacterial community structure in the experimental batches. The indigenous microbial community of pine bark harboured phylotypes that also have a potential to degrade TNT. Altogether, the combination of a specialized inoculum and pine bark proved to be the most efficient treatment option for TNT-contaminated water.

  • 8.
    Kanders, Linda
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Purac AB.
    Start-up and operational strategies for deammonification plants: - a study with one-stage moving bed biofilm reactors treating reject water2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    To limit eutrophication, wastewater treatment plants use biological methods to convert degraded nitrogen to nitrogen gas. Deammonification, or partial nitritation in combination with anammox, has been shown to be an energy efficient process. This process is currently implemented in approximately 150 full-scale plants, and mainly on reject waters, the liquid fraction after dewatering of anaerobic digestion at municipal wastewater treatment plants. Implementation has been impeded by the slow growth of anammox bacteria, and 99% of the full-scale plants using the process have been using different methods to inoculate the process with anammox bacteria from elsewhere. Separate reject water installations, however, have shown high nitrous oxide emissions, which could increase the total carbon footprint.

    The objective of this thesis was to develop and validate a start-up concept using the moving bed biofilm reactor (MBBR) technique applied to reject water, and to investigate how the operational strategies could be optimized to limit potential nitrous oxide emissions. The results show that a one-stage deammonification process based on the MBBR technology with indigenous anammox bacteria originating from the reject water can be set up within a applicable time frame (<100 days). This was validated in two laboratory reactors and in two full-scale studies. Reject water originating from both mesophilic and thermophilic digested sludge was used. Anammox growth and nitrogen reduction were detected with fluorescence in situ hybridization (FISH) and chemical analysis, respectively. The start-up time was 72 days in the laboratory and 120 days in full-scale. In laboratory scale, there was no improvement in start-up time when adding external anammox inoculum. Results from a screening study of seven reject waters and their content of anammox bacteria using qPCR indicated the presence of 104–105 genome units anammox per mL in reject water, which could be sufficient for starting up deammonification plants within an applicable time frame.

    A final case study shows the potential of decreasing nitrous oxide emissions when a full-scale plant treating reject water was modified from nitrification/denitrification using a Sequencing Batch Reactor (SBR) to a deammonification process using the MBBR technique. The nitrous oxide emissions decreased from 10% to 0.1–0.7% of total nitrogen load with the change of operation mode. Further optimization by pH set point led to lower emission values. This effect is thought to be linked to the lower aeration ratio and increase in complete denitrification of dissolved nitrous oxide at higher pH.

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  • 9.
    Kanders, Linda
    Purac AB, Sweden.
    Swedish Experience of the Deammonification Process in a Biofilm System2011Ingår i: Swedish experience with deammonification process in biofilm system, 2011, s. 1333-1345Konferensbidrag (Refereegranskat)
    Abstract [en]

    Based on results from many years of pilot plant experiments a one-stage deammonification

    process for treatment of supernatant from dewatering of digested sludge has been applied in a

    full scale at the Himmerfjärden wastewater treatment plant in the Stockholm region. The plant

    was designed for nitrogen load of 480 kg d-1 and is based on the Moving Bed Biofilm Reactor

    (MBBR), with about 32% of its volume filled with suspended carriers (K1H, Kaldnes®). An

    outer biofilm layer performs nitritation while an inner layer the anammox reaction.

    Experience gained from more than 2 years of operation of the plant is presented in the paper. After an

    effective start–up period of about 6-7 months (totally 10 months) over 80% nitrogen removal

    efficiency was obtained and nitrogen removal rates reached almost 2g m-2 d at a temperature of

    28 oC. The nitrite production was the limiting step for the anammox reaction. Intermittent

    aeration was used to secure a suitable ratio of aerobic and anaerobic conditions in the biofilm.

    Inhibition of the ammonia oxidizers was observed at concentrations over 15 mg l-1 of free

    ammonia as NH3. The free ammonia was controlled by a combination of different strategies

    including aeration time, influent load and effluent recirculation. Conductivity proved to be a

    suitable tool for the process monitoring.

  • 10.
    Kanders, Linda
    et al.
    Purac AB, Sweden.
    Areskoug, Therese
    Lunds universitet, Sweden.
    Schneider, Yvonne
    Leibniz Universitaet Hannover, Geramany.
    Ling, Daniel
    Purac AB, Sweden.
    Punzi, Marisa
    Lunds universitet, Sweden.
    Beier, Maike
    Leibniz Universitaet Hannover, Geramany.
    Impact of seeding on the start-up of one-stage deammonification MBBRs2014Ingår i: Environmental technology, ISSN 0959-3330, E-ISSN 1479-487X, Vol. 35, nr 22, s. 2767-2773Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Treating nitrogen-rich reject water from anaerobically digested sludge with deammonification has become a very beneficial side stream process. One common technique is the one-stage moving bed bioreactors (MBBRs), which in comparison with the other deammonification techniques can be started up without seeding anammox bacteria. This study investigated the impact of biofilm seeding on the start-up of one-stage deammonification MBBRs. Two lab-scale reactors were run in parallel with partial nitritation for 56 days until 11% of the carrier area in one reactor was replaced with fully developed deammonification biofilm to work as the seeding material. The seeded reactor started nitrogen reduction immediately up to a plateau of 1.3gNm−2 d−1; after another 54 days on day 110, the reduction significantly increased. At the same time, the non-seeded reactor also started to reduce nitrogen due to deammonification. The development was followed with both nitrogen analyses and fluorescence in situ hybridization analyses. On day 134, the biofilm in both reactors contained >90% anammox bacteria and reached maximum nitrogen removal rates of 7.5 and 5.6gNm−2 d−1 in the seeded and non-seeded reactor, respectively. Over 80% of the inorganic nitrogen was reduced. In conclusion, the seeding did not contribute to a shorter start-up time or the achieved anammox enrichment, although it did contribute to a partial, immediate nitrogen reduction. The boundary conditions are the most important factors for a successful start-up in a deammonification MBBR system.

  • 11.
    Kanders, Linda
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Purac AB, Sweden.
    Yang, Jing-jing
    IVL Swedish Environmental Research Institute, Sweden.
    Baresel, Christian
    IVL Swedish Environmental Research Institute, Sweden.
    Zambrano, Jesus
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Full-scale comparison of N2O emissions from SBR N/DN operation versus one-stage deammonification MBBR treating reject water: - and optimization with pHset-point2019Ingår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 79, nr 8, s. 1616-1625Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To be able to fulfill the Paris agreement regarding anthropogenic greenhouse gases, all potential 12 emissions must be mitigated. Wastewater treatment plants should aim to eliminate emissions of the 13 most potent greenhouse gas, nitrous oxide. In this study, these emissions were measured at a full-scale 14 reject water treatment tank during two different operation modes: nitrification/denitrification (N/DN) 15 operating as a sequencing batch reactor (SBR), and deammonification (nitritation/anammox) as a moving 16 bed biofilm reactor (MBBR). Nitrous oxide was measured both in the water phase and in the off-gas. The 17 treatment process emitted significantly less nitrous oxide in deammonification mode 0.14-0.7 %, 18 compared to 10 % of Total Nitrogen in N/DN mode. The decrease can be linked to the change feeding 19 strategy, concentration in nitrite, load of ammonia oxidized, shorter aeration time, no ethanol dosage 20 and the introduction of biofilm. Further, evaluation was done how the operational pH set point 21 influenced the emissions in deammonification mode. Lower concentrations of nitrous oxide was 22 measured in water phase at higher pH (7.5-7.6) than at lower pH (6.6-7.1). This is believed to be mainly 23 because of the lower aeration ratio and increased complete denitrification at the higher pH set point.

  • 12.
    Krustok, Ivo
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Communities of microalgae and bacteria in photobioreactors treating municipal wastewater2015Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Everyone who uses water produces wastewater. This inevitability creates several problems that increase with the growth of the population and industry. What to do with the wastewater, how to purify it and how to design the infrastructure are all important questions that each municipality has to deal with, taking into account ever growing demands to reduce environmental impact. In these conditions scientists and engineers have turned to biological processes to help treat the water. Currently the most commonly used wastewater treatment method known as the activated sludge process involves bacteria that help break down the pollutants. While it has been used successfully for around 100 years now, it has many limitations when faced with modern demands. As an alternative, microalgae reactors, commonly known as photobioreactors, have been suggested.

    Microalgae are microscopic water organisms that can use photosynthesis to form sugars from CO2 and water. To do this they require energy from light, hence the photo part of the photobioreactor. In addition to taking up CO2 from their environment, they take up nutrients such as nitrogen and phosphorous compounds. This is a reason why microalgae have great potential for use in wastewater treatment. When grown in wastewater together with the microorganisms already present, they are able to reduce the amount of pollutants by taking them up into their cells, effectively purifying the water.

    Since wastewater has its own microbial community, the biological processes taking place in a wastewater treating photobioreactor are more complex compared to growing a single species of algae in a sterile medium. With the work presented in this licentiate, we characterized the algae and bacterial communities present in photobioreactors treating wastewater in addition to finding the most optimal ways to grow algae originating from a local lake in a wastewater medium. We looked at the species found, most important metabolic pathways, growth dynamics for both algae and bacteria and water purification dynamics.

    Overall, we were successful in inoculating municipal wastewater from Västerås wastewater treatment plant with algae from Lake Mälaren. The dominant algae growing in our systems belonged to the genera Scenedesmus, Desmodesmus and Chlorella. We also saw that the bacterial community was involved in synthesis of vitamins essential for algae growth. The information presented in this thesis is another step towards a better design of control and monitoring systems in full-scale photobioreactor plants.

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  • 13.
    Krustok, Ivo
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Microbiological analysis of municipal wastewater treating photobioreactors2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    I takt med att världens befolkning ökar, så produceras dagligen allt mer avfall. Detta kan orsaka stora problem för miljön. När det byggs nya system för vattenrening behöver vi även ta hänsyn till kravet att minska energiåtgången. Dagens vattenreningssystem har vissa tillkortakommanden när det gäller reningsnivåer och energianvändning. Ett alternativ till dagens system, kan vara fotobioreaktorer, dvs. vattenrening med hjälp av mikroalger. Dessa system använder mikroalger och bakterier för att rena vattnet från föroreningar, kväve och fosfor.

    Vattenrening med fotobioreaktorer är en relativt ny teknik. Flera aspekter gällande biologin i dessa system har ännu inte studerats i detalj. Den här avhandlingen presenterar en översikt av de alger och bakterier som är aktiva i fotobioreaktorer. Andra viktiga aspekter som tillväxt, arter samt vattenreningsförmåga har också studerats.

    Ett antal försök genomfördes där alger från Mälaren tillsattes i vatten från Västerås kommunala vattenreningsanläggning. Storleken på försöken varierade mellan 250 ml och 20 liter. Det visade sig att algerna hade en bra tillväxt samt att mängden ammonium och fosfor minskade i vattnet under försöksperioden.

    De alger som tillväxte mest i studien tillhörde Scenedesmus, Desmodesmus och Chlorella. Förutom alger tillväxte även ett stort antal bakterier från grupperna Proteobacteria and Bacteroidetes. Dessa bakterier visade sig syntetisera viktiga vitaminer, t.ex. vitamin B12, som algerna normalt inte kan syntetisera själva.

    Sammanfattningsvis, så presenterar denna avhandling viktig information gällande alger och bakterier i en fotobioreaktor. Informationen kan vara ett viktigt bidrag till framtida utveckling av storskaliga fotobioreaktorer för vattenrening.

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  • 14.
    Krustok, Ivo
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Nehrenheim, Emma
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Odlare, Monica
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    M.A., Shabiimam
    Indian Institute of Technology, Bombay, India..
    Truu, Jaak
    University of Tartu, Estonia.
    Ligi, Teele
    University of Tartu, Estonia.
    Truu, Marika
    University of Tartu, Estonia.
    Characterization of algal and microbial community dynamics in a wastewater photo-bioreactor using indigenous algae from lake mälaren2014Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Microalgae grown in photo-bioreactors can be a valuable source for biomass especially when combined with the treatment of wastewater. While most published research has been studying pure cultures, consortia of algae and bacteria from the wastewater have more complex dynamics affecting both the biomass production and pollutant removal. In this paper we investigate dynamics of algal and bacterial communities in mixed culture photo-bioreactors using chlorophyll and real-time PCR analysis. Wastewater photo-bioreactors were inoculated with water from a nearby lake to add native algae species. The results indicated a decline in bacterial 16S rDNA copy numbers before algae started to multiply. The photo-bioreactors inoculated with lake algae produced more biomass and grew faster than the algae originating only from wastewater. The reactors were effective in removing ammonia from the wastewater which seemed work to mostly through nitrification thus causing an increase in nitrate concentration. There was also an increase in Cr, Co and Ni ion concentrations during the experiment suggesting they may have moved from organic complexes to the water phase as free ions.

  • 15.
    Krustok, Ivo
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Odlare, Monica
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    M.A., Shabiimam
    Indian Institute of Technology, Bombay, India..
    Truu, Jaak
    University of Tartu, Estonia.
    Truu, Marika
    University of Tartu, Estonia.
    Ligi, Teele
    University of Tartu, Estonia.
    Nehrenheim, Emma
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Characterization of algal and microbial community growth in a wastewater treating batch photo-bioreactor inoculated with lake water2015Ingår i: Algal Research, ISSN 2211-9264, Vol. 11, nr Sept, s. 421-427Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Microalgae grown in photo-bioreactors can be a valuable source of biomass, especially when combined with wastewater treatment. While most published research has studied pure cultures, the consortia of algae and bacteria from wastewater have more complex community dynamics which affect both the biomass production and pollutant removal. In this paper we investigate the dynamics of algal and bacterial growth in wastewater treating batch photo-bioreactors. The photo-bioreactors were inoculated with water from a nearby lake. Lake water was obtained in August, November and December in order to add native algal species and study the effects of the season. The photo-bioreactors inoculated with lake water obtained in August and November produced more biomass and grew faster than those that only contained the algae from wastewater. The results indicated a rapid decline in bacterial abundance before algae began to multiply in reactors supplemented with lake water in November and December. The reactors were also successful in removing nitrogen and phosphorous from wastewater.

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  • 16.
    Krustok, Ivo
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Odlare, Monica
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Truu, Jaak
    University of Tartu, Estonia.
    Nehrenheim, Emma
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Inhibition of nitrification in municipal wastewater treating photobioreactors: effect on algal growth and nutrient uptake2016Ingår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 202, s. 238-243Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of inhibiting nitrification on algal growth and nutrient uptake was studied in photobioreactors treating municipal wastewater. As previous studies have indicated that algae prefer certain nitrogen species to others, and because nitrifying bacteria are inhibited by microalgae, it is important to shed more light on these interactions. In this study allylthiourea (ATU) was used to inhibit nitrification in wastewater-treating photobioreactors. The nitrification-inhibited reactors were compared to control reactors with no ATU added.

    Microalgae had higher growth in the inhibited reactors, resulting in a higher chlorophyll a concentration. The species mix also differed, with Chlorella and Scenedesmus being the dominant genera in the control reactors and Cryptomonas and Chlorella dominating in the inhibited reactors. The nitrogen speciation in the reactors after 8 days incubation was also different in the two setups, with N existing mostly as NH4-N in the inhibited reactors and as NO3-N in the control reactors.

  • 17.
    Krustok, Ivo
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Oopkaup, Kristjan
    University of Tartu, Estonia.
    Truu, Jaak
    University of Tartu, Estonia.
    Odlare, Monica
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Nehrenheim, Emma
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Comparative analysis of the metagenomes extracted from wastewater treating photobioreactorsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The metagenomes of lab-scale municipal wastewater treating batch photobioreactors were studied with a focus on nitrogen metabolism, pathogen abundance and antibiotic resistance genes. Previous studies based on the dataset showed that in general, as algae growth in the reactors increased, nitrogen metabolism and virulence genes decreased. With this study, a more detailed view of these gene groups is presented.

  • 18.
    Mara, Grube
    et al.
    Latvia University, Latvia.
    Olga, Chusova
    Marita, Gavare
    Latvia University, Latvia.
    Karlis, Shvirksts
    Latvia University, Latvia.
    Nehrenheim, Emma
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Odlare, Monica
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Application of FT-IR Spectroscopy for Investigation of Pink Water Remediation by Pine Bark2015Ingår i: Open Biotechnology Journal, ISSN 1874-0707, Vol. 9Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study demonstrates the application of FT-IR spectroscopy for investigating the remediation of pink water with the low cost adsorbent pine bark. The removal of 2,4,6-trinitrotoluene (TNT) from pink water by adsorption to pine bark was accompanied by a reduction in intensities of peaks at 1544 and 1347 cm-1 in the spectra of acetonitrile extracts of the pine bark. Hierarchial cluster analysis differentiated samples with high (30-180 mg/L) and low (0-4 mg/L) TNT concentrations, demonstrating the potential of this approach as a quick screening method for the control of the removal of TNT from pink water. The amount of lignin in pine bark was inversely proportional to the size of the pine bark particles, while the concentration of phenolic hydroxyl groups increases with increasing size of pine bark particles. FT-IR spectra showed that as well as TNT, pine bark can also adsorb nitramine explosives such as RDX and HMX.

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  • 19.
    Nehrenheim, Emma
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Muter, Olga
    Latvia University.
    Odlare, Monica
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Rodriguez, Adrian
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Institute for Catalan Water Research.
    Cepurnieks, Guntis
    National Diagnostic Centre, Latvia.
    Bartkevics, Vadims
    National Diagnostic Centre, Latvia.
    Toxicity assessment and biodegradation potential of water-soluble sludge containing 2,4,6-trinitrotoluen2013Ingår i: Water Science & Technology, ISSN 0273-1223, Vol. 68, nr 8, s. 1707-1714Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    he water-soluble phase of trinitrotoluene-containing sludge (SLP) was characterized with regard to trinitrotoluene (TNT) concentration, ecotoxicity, and a model biodegradation experiment as evaluation criteria for further development of appropriate treatment technologies. SLP contained 67.8 mg TNT/l. The results of germination and root-elongation tests indicated that SLP had a species-specific phytotoxic effect. The results of a 21 day degradation experiment demonstrated TNT conversion to 4-amino-2,6-DNT and 2-amino-4,6-DNT, with a simultaneous reduction in the total concentration of nitroaromatics. Addition of inoculum stimulated the TNT degradation process. The presence of the sludge solid phase inhibited microbial activity. Measurement of microbial enzyme activity was used to assess changes in the microbial community during the biodegradation process.

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  • 20.
    Olsson, Jesper
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Co-digestion of microalgae and sewage sludge - A feasibility study for municipal wastewater treatment plants2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The increased emissions of anthropogenic greenhouse gases over the last 100 years is the reason for the acceleration in the greenhouse effect, which has led to an increase of the globally averaged combined land and ocean surface temperature of 0.85 °C between 1880 and 2012. A small fraction of the increased anthropogenic greenhouse gases originates from municipal wastewater treatment plants (WWTPs).

    This doctoral thesis was part of a larger investigation of using an alternative biological treatment based on the symbiosis of microalgae and bacteria (MAAS-process (microalgae and activated sludge)). This solution could be more energy efficient and potentially consume carbon dioxide from fossil combustion processes and also directly capture carbon dioxide from the atmosphere and thereby reduce the addition of anthropogenic greenhouse gases to the air.

     The objective of the thesis was to explore the effects when the microalgae-derived biomass from the biological treatment were co-digested with sewage sludge. The results from these experimental studies were then used to evaluate the effects on a system level when implementing microalgae in municipal WWTP.

     Microalgae grown from a synthetic medium improved the methane yield with up to 23% in mesophilic conditions when part of the sewage sludge was replaced by the microalgae. The microalgae grown from municipal wastewater showed no synergetic effect.

     In the semi-continuous experiments the methane yield was slightly reduced when implementing the microalgae. Furthermore the digestibility of the co-digestion between sewage sludge and microalgae were lower compared to the digestion of sewage sludge.

     The digestates containing microalgal substrate had higher heavy metals content than digestates containing only sewage sludge. This could have a negative effect on the potential to use this digestate on arable land in future, due to strict limits from the authorities.  Filterability measurements indicated that the addition of microalgae enhanced the dewaterability of the digested sludge and lowered the demand for polyelectrolyte significantly.

     When a hypothetical MAAS-process replaced a conventional ASP-process the amount of feedstock of biomass increased significantly due to the increased production from the autotrophic microalgae. This increased the biogas production by 66-210% and reduced the heavy metal concentration in the digestate due to a dilution effect from the increased biomass production.

     The thesis demonstrates that microalgae in combination with bacteria from a MAAS-process can be a realistic alternative feedstock to WAS in the anaerobic digestion at a municipal WWTP. A few drawbacks need to be considered when choosing a MAAS-process as biological treatment.

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  • 21.
    Olsson, Jesper
    et al.
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Ma, Shabiimam
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Nehrenheim, Emma
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Thorin, Eva
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Co-digestion of cultivated microalgae and sewage sludge from municipal waste water treatmentManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    One way to meet the increased demand for biogas in the society is to use microalgae as substrate. These algae would be cultivated in a treatment step of photobioreactors for reject water from sludge dewatering facilities. In the present study, a co-digestion experiment was established where sludge from a municipal wastewater treatment plant was fermented with harvested microalgae cultivated in lake water from lake Mälaren. The experiment was carried out as a BMP-test (Biochemical Methane Potential) under mesophilic condition (37°C) with fermentation bottles, where 0, 12, 25 and 37%, of the sludge was replaced with harvested microalgae. The results showed that the biogas production was improved with 12% for the bottles with 12% microalgae compared with the bottles with only sludge as a substrate. In the bottles with 25% and 37% microalgaes the gas production was slightly reduced compared with the bottles where only sludge was used.

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    Co-digestion of cultivated microalgae and sewage sludge from municipal waste water treatment
  • 22.
    Pierong, Rasmus
    et al.
    Uppsala University.
    Nehrenheim, Emma
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Carlsson, Bengt
    Uppsala University.
    Zambrano, Jesús
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Algae Based Wastewater Treatment Model Using The RWQM12016Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we propose a model describing the dynamics of an algae based wastewater treatment process in an activated sludge environment. As the basis for the process modelling, the River Water Quality Model no. 1 (RWQM1) is chosen. In order to evaluate the applicability of the model to an activated sludge process, the proposed model is compared to the Activated Sludge Model no. 1 (ASM1).

  • 23.
    Rodriguez Caballero, Adrian
    et al.
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Odlare, Monica
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Ramond., J-B
    Cape Peninsula University of Technology .
    Welz, P.J
    Cape Peninsula University of Technology .
    Cowan, D.A.,
    Cape Peninsula University of Technology .
    Treatment of high ethanol concentration wastewater by constructed wetlands: enhanced COD removal and bacterial community dynamics.2010Ingår i: Microbes in Wastewater & Waste Treatment, Bioremediation and Energy Production, 2010Konferensbidrag (Refereegranskat)
  • 24.
    Schwede, Sebastian
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Anbalagan, Anbarasan
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Krustok, Ivo
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lindberg, Carl-Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB AB Corporate Research, Västerås, Sweden.
    Nehrenheim, Emma
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Evaluation of the microalgae-based activated sludge (MAAS) process for municipal wastewater treatment on pilot scale2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    The microalgae-based activated sludge (MAAS) process was evaluated regarding the removal efficiency of organic matter and nitrogen from physiochemically pretreated municipal wastewater at different hydraulic retention time (HRT) on pilot scale. Additionally, the interplay between the algal and bacterial consortium was evaluated regarding the ability of the algal consortium to provide oxygen for bacterial oxidation processes. The results showed in general high organic matter (COD removal 75-90%) and total nitrogen (40-50%) removal at all HRTs (6, 4 and 2 days). The dissolved oxygen (DO) concentration was maintained stable at 6 days (6.04±0.47 mg L-1) and 4 days (4.24±0.62 mg L-1) HRT. However, the DO significantly declined at 2 days HRT due to loss of biomass at the high influent flow in the sedimentation unit. Nevertheless, the MAAS process functioned as a symbiotic algal-bacterial system with bacterial organic matter oxidation and nitrification and algal nutrient removal.

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  • 25.
    Zambrano, Jesús
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Nehrenheim, Emma
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Microalgae Activated Sludge: Process Modelling and Optimization2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    This work deals with steady-state optimization of a process formed by an algae-bacteria photo-bioreactor (PBR) in an activated sludge configuration. The optimization is done by considering the total PBR volume as two volumes in series, and aiming for the minimal nitrogen concentration in the effluent, for a given external light and carbon dioxide (CO2) injection. Results suggest that it is possible to obtain an optimum volume distribution that gives a lower effluent substrate concentration compared to a single volume, and this optimum volume depends on the CO2 applied.

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