| 1. |
- Bengtsson, Simon, et al.
(författare)
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Acidogenic fermentation of industrial wastewaters: Effects of chemostat retention time and pH on volatile fatty acids production
- 2008
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Ingår i: Biochemical Engineering Journal. - : Elsevier BV. - 1369-703X. ; 40:3, s. 492-499
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Tidskriftsartikel (refereegranskat)abstract
- Acidogenic fermentation of wastewater can serve as a first step in a process for mixed culture production of polyhydroxyalkanoates (PHA) since the produced volatile fatty acids (VFA) are preferred substrates for PHA production. Acidogenic fermentation of industrial wastewaters (cheese whey permeate and three pulp and paper mill effluents) was evaluated in batch and continuous experiments. From the batch experiments, it was found that for whey and one of the paper mill effluents nearly 100% of the soluble COD was readily fermentable. In continuous chemostat experiments with these two effluents, varying the retention time (RT) and pH of the reactors exhibited significant impact on the amount and composition of VFA produced. Increasing RT resulted in increased degrees of acidification up to a maximum of 0.93 g COD of VFA per g influent SCOD at RT 95 h for whey and 0.75 gCOD/gCOD at RT 24 h for the paper mill effluent. Main fermentation products were acetate, propionate and butyrate. Acetate production was rather insensitive to RT while above RT 10 h a shift from butyrate production to propionate production with increasing RT occurred for both effluents. Increasing pH from 5 to 6 resulted in increased amount of propionate. Based on these findings the possibility of regulating PHA monomer composition and associated polymer properties by controlling RT and pH during acidogenic pretreatment was discussed. (c) 2008 Elsevier B.V. All rights reserved.
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| 2. |
- Bengtsson, Simon, et al.
(författare)
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Production of polyhydroxyalkanoates by activated sludge treating a paper mill wastewater
- 2008
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Ingår i: Bioresource Technology. - : Elsevier BV. - 1873-2976 .- 0960-8524. ; 99:3, s. 509-516
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Tidskriftsartikel (refereegranskat)abstract
- Production of polyhydroxyalkanoates (PHAs) in activated sludge treating wastewater represents an economical and environmental promising alternative to pure culture fermentations. A process for production of PHA from a paper mill wastewater was examined at laboratory scale. The three stage process examined consisted of acidogenic fermentation to convert wastewater organic matter to volatile fatty acids (VFAs), an activated sludge system operating under feast/famine conditions to enrich for PHA producing organisms and accumulation of PHA in batch experiments. After fermentation of the wastewater, 74% of the soluble COD was present as VFA (acetate, propionate, butyrate and valerate) and the resulting PHA after batch accumulation consisted of 31-47 mol% hydroxybutyrate and 5369 mol% hydroxyvalerate. The maximum PHA content achieved was 48% of the sludge dry weight and the three stage process exhibited a potential to produce 0.11 kg of PHA per kg of influent COD treated. (c) 2007 Elsevier Ltd. All rights reserved.
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| 3. |
- Bengtsson, Simon, et al.
(författare)
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Production of polyhydroxyalkanoates by glycogen accumulating organisms treating a paper mill wastewater.
- 2008
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 58:2, s. 323-330
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Tidskriftsartikel (refereegranskat)abstract
- A process for production of polyhydroxyalkanoates (PHA) by activated sludge treating a paper mill wastewater was investigated. The applied strategy was to select for glycogen accumulating organisms (GAOs) by alternating anaerobic/aerobic conditions. Acidogenic fermentation was used as pretreatment to convert various organic compounds to volatile fatty acids which are preferable substrates for PHA production. Enrichment resulted in a culture dominated by GAOs related to Defluviicoccus vanus (56%) and Candidatus Competibacter phosphatis (22%). Optimization of PHA accumulation by the enriched GAO culture was performed through batch experiments. Accumulation of PHA under anaerobic conditions was limited by the intracellular glycogen stored. Under aerobic conditions significant glycogen production (to 25% of sludge dry weight) was observed alongside PHA accumulation (to 22% of sludge dry weight). By applying a subsequent anaerobic period after an initial aerobic, the produced glycogen could be utilized for further PHA accumulation and by this strategy PHA content was increased to 42% of sludge dry weight. The PHA yield over the entire process was 0.10 kg per kg of influent COD treated which is similar to what has been achieved with a process applying feast/famine enrichment strategy with the same wastewater.
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| 4. |
- Heimersson, Sara, 1984, et al.
(författare)
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Methodological issues in LCA of wastewater treatment combined with PHA biopolymer production
- 2013
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Ingår i: The proceedings of The 6th International Conference on Life Cycle Management.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Production of polyhydroxyalkanoates (PHAs) by mixed microbial cultures utilising the organic content of wastewaters is one of the technologies studied in the EU project ROUTES. When comparing the life-cycle environmental impacts of simultaneous wastewater treatment and production of PHA-rich biomass to traditional wastewater and solids treatment, the handling of this multi-functionality is critical for the results. Only one LCA of such a system has been found in the literature. The current paper identifies substitution and allocation based on chemical oxygen demand removal as two possible options to account for the multi-functionality of the system. Examples based on literature data were used to show that for global warming potential, the choice of allocation method can substantially affect the results.
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| 5. |
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| 6. |
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| 7. |
- Morgan-Sagastume, Fernando, et al.
(författare)
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Acclimation Process for Enhancing Polyhydroxyalkanoate Accumulation in Activated-Sludge Biomass
- 2019
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Ingår i: Waste and Biomass Valorization. - : Springer. - 1877-2641 .- 1877-265X. ; 10:4, s. 1065-1082
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Tidskriftsartikel (refereegranskat)abstract
- A strategy was evaluated for conditioning activated sludge biomass to a new substrate whereby the polyhydroxyalkanoate (PHA) accumulation capacity of the biomass was enhanced based on a series of aerobic feast–famine acclimation cycles applied prior to PHA accumulation. Different biomass types enriched during the treatment of municipal wastewater at laboratory, pilot, and full scales were exposed to aerobic feast–famine acclimation cycles at different feast-to-famine ratios with an acetate–propionate mixture (laboratory scale), acetate (pilot scale), and fermented waste–sludge centrate (pilot scale). A sevenfold increase in specific PHA storage rates and 20% increase in substrate utilization rates were observed during acclimation cycles (laboratory acetate–propionate). Biomass acclimation led to more than doubling of the specific substrate utilization rates, PHA storage rates, biomass PHA contents, and specific PHA productivities (per initial biomass) during PHA accumulation. The biomass PHA contents were found to increase due to acclimation from 0.19 to 0.34 (laboratory acetate–propionate), 0.39 to 0.46 (pilot acetate) and 0.19 to 0.25 gPHA/gVSS (pilot centrate). A similar bacterial community structure during acclimation indicated that a physiological rather than a genotypic adaptation occurred in the biomass. The physiological state of the biomass at the start of PHA accumulation was deemed significant in the subsequent PHA-accumulation performance. Positive acclimation trends can be monitored by measuring the relative increase in feast substrate utilization or respiration rates with respect to those of the first acclimation cycle.
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| 8. |
- Morgan-Sagastume, Fernando, et al.
(författare)
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Mixed-culture polyhydroxyalkanoate (PHA) production integrated into a food-industry effluent biological treatment: A pilot-scale evaluation
- 2020
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Ingår i: Journal of Environmental Chemical Engineering. - : Elsevier. - 2213-3437. ; 8:6
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Tidskriftsartikel (refereegranskat)abstract
- Production of a mixed microbial culture (MMC) biomass for polyhydroxyalkanoate (PHA) production was integrated into the wastewater treatment (WWT) of a potato-starch factory. A pilot-scale on-site evaluation was conducted over ten months, with inherent water quality variations including organic composition, temperature, and pH. The wastewater was rich in acetate and the organic matter content fluctuated from 50 to 90 % with respect to volatile fatty acids (VFAs). The PHA accumulation potential (PAP) of the surplus biomass, nevertheless, remained from 0.40 to 0.70 gPHA/gVSS. Biomass PAP characteristics were benchmarked at both pilot and laboratory scales using different feedstocks and accumulation methods. The resultant co-polymer type could be readily shifted by changes in feedstock VFA content. Selected polymer batches were recovered at pilot scale as commercial-quality prototype materials for development of PHA-based wood-fibre composites. WWT performance with 98 % organic contaminant removal remained consistent throughout. The good settleability of the pilot-scale biomass was in contrast to the poorly settleable biomass from the factory’s full-scale activated sludge. Metered nitrogen and phosphorus addition ensured stable WWT without major nitrification levels. Successful robust outcomes of both feast-famine selection principles and WWT can be translated and integrated into the full-scale WWT by a proposed adaptation to existing infrastructure. Analogous aerobic feast enrichment is proposed to be achievable with continuous or intermittent flow through a process selector/zone. This pilot-scale experience under actual field conditions of industrial WWT provides further evidence for the technical viability to produce biomass for PHA production while maintaining standards in effluent water quality.
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| 9. |
- Morgan-Sagastume, Fernando, et al.
(författare)
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Techno-environmental assessment of integrating polyhydroxyalkanoate (PHA) production with services of municipal wastewater treatment
- 2016
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Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526. ; 137, s. 1368-1381
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Tidskriftsartikel (refereegranskat)abstract
- © 2016 Elsevier Ltd In this paper, the potential impacts in the techno-environmental performance of a municipal wastewater treatment plant with integrated mixed-microbial-culture polyhydroxyalkanoate (PHA) production are presented for the first time. A life cycle assessment was conducted based on mass and energy balances. The techno-environmental performance was evaluated for five wastewater treatment configurations: a reference case and four alternative processes producing PHA-rich biomass using influent municipal wastewater as the only organic carbon source. The integration of PHA-rich biomass production into a municipal wastewater treatment plant with sludge digestion sustains the overall conversion yield for total products of biogas and PHA-rich biomass (around 0.26 gCOD products per influent gCOD treated). PHA production integration has the potential to improve the overall environmental performance with respect to the reference case. Even when no benefits were accounted for substitutions related to the biogas and PHA-rich biomass, similar or improved environmental performances were estimated for all four alternatives for global warming potential, acidification potential, terrestrial e utrophication potential, and photo-oxidant formation potential. When benefits were accounted from substitutions of electricity and heat co-generated from biogas and of PHA-rich biomass by pure-culture PHA-rich biomass from sugar fermentation, gains were even higher due to the diversion of carbon from biogas to PHA-rich biomass. Freshwater and marine eutrophication potentials were dependent on effluent specifications. Case-by-case process configurations influence the mass and energy balance and trade-offs of process integration. The production and export of PHA-rich biomass decreased the aeration requirements for COD and nitrogen removal; however, increased demands for heat, power and chemicals were incurred for the generation of volatile fatty acids from primary solids fermentation. The choice of nitrogen-removal approach (nitrification-denitrification vs. anammox) also impacted energy consumption. Using influent wastewater as the sole carbon supply, the energy balance and PHA production were sensitive to the efficiency of primary treatment and available flux of volatile fatty acids into PHA production. Other regional inputs of organic residuals may improve carbon recovery in the treatment facility. The improved environmental performance of the treatment configurations motivates the idea that individual municipal wastewater treatment plants may become suppliers of renewable raw materials of higher value than that of biogas and/or energy and heat today.
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| 10. |
- Pawar, Sudhanshu S., et al.
(författare)
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MultiBio: Environmental services from a multipurpose biorefinery
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- MultiBio project aimed to establish and demonstrate a novel multipurpose biorefinery cascade concept, producing three renewable biobased products: 1) biohydrogen, 2) biopolymers and 3) protein rich meal ingredients for fish farming. The cascade concept exploits the ability of a bacterium (Caldicellulosiruptor saccharolyticus) to transform nutrients present in low-value waste process waters of the pulp and paper industry, to high-value products hydrogen gas, organic acids and microbial biomass. The organic acid rich effluent will then be managed in an open culture microbial process used to achieve discharge water quality objectives and to produce polyhydroxyalkanoate (PHA) biopolymers. Moreover, since C. saccharolyticus protein content is more than 63% of cell dry weight, their potential in formulation of fish feed was evaluated. A fiber sludge containing, CTMP residual stream was found to be a possible feedstock for the MultiBio process concept. Due to safety risks the demo-scale experiments of biohydrogen gas technology were moved from Biorefinery demo plant (Örnsköldsvik) of 40 m3 capacity to ATEX classified pilot-scale facility with 0.4 m3 capacity. Hence, bacterial biomass enough for the large-scale fish feed ingredient could not be produced. Lab-scale experiments with Caldicellulosiruptor cells as fish feed ingredient showed promising results as a protein-rich, sustainable fish feed ingredient. In addition, PHA biopolymer also showed favourable results as fish food ingredient for experiments at Gårdsfisk AB. Lab-scale experimental tests showed that the surplus activated sludge from the mills wastewater treatment could currently accumulate PHA to about 20 % of its dry weight. Mass balance evaluations based on realistically achievable expectations indicated a PHA biopolymer production potential of 3 600 tons of PHA per year from available organic residuals and for the two evaluated mills combined. The MultiBio concept has a positive climate impact in comparison with current treatment and moves developments in a positive direction to achieve 7 of the 10 Swedish environmental goals. Through a detailed feasibility analysis, a natural progression in next steps in scenarios were suggested for PHA production. The MultiBio cascade process can be implemented with further necessary development with good business potential and a positive effect on climate change. However, biohydrogen technology needs further developments before this cascade process concept can be implemented. Alternatively, a scenario with only biopolymer technology shows already a significant business potential and even larger positive effect on climate change. A successful next step in demonstration of the PHA biopolymer production scenario may lead to it being implemented within the next few years. Furthermore, MultiBio has attracted a lot of attention regionally and nationally but also internationally with a total of 65 media listings. A licentiate thesis and three university degree projects linked to the project have been completed. Overall, the MultiBio project has successfully achieved its goals and objectives.
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