| 1. |
- Elhamarnah, Yousef, et al.
(author)
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Investigating the impact of stormwater fouling on polysulfone ultrafiltration membranes modified with deep eutectic solvents
- 2023
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In: Journal of Water Process Engineering. - 2214-7144. ; 56, s. 104362-104362
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Journal article (peer-reviewed)abstract
- In this study, we evaluate the performance of modified polysulfone (PSF) ultrafiltration (UF) membranes, which incorporate deep eutectic solvents (DES), in treating stormwater laden with natural organic matter e.g. chemical oxygen demand (COD) and total suspended solids (TSS). We also aim to understand how these organic substances, e.g. COD, TSS, from the water source contribute to the fouling of the synthesized membranes. PSF membranes were synthesized using a non-solvent induced phase separation technique and integrated with varying concentrations of ChCl:FR (Choline Chloride: D-(−)-Fructose) 1:1 DES. The surface and porous structures of the membranes were characterized through Fourier-transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), contact angle measurements, scanning electron microscopy (SEM), and mechanical testing. The UF performance of these membranes was assessed and compared with different commercially available UF flat sheet membranes in terms of pure water permeability and antifouling behavior against collected stormwater from a sedimentation pond. Furthermore, the study evaluated the quality of the permeate based on parameters such as COD, turbidity, TSS, pH, and conductivity and compared the permeate quality of a pilot-scale ceramic UF membrane unit. The findings indicate that the inclusion of DES in the polysulfone membrane structure enhances the membranes' antifouling properties and permeability. This research offers valuable insights into the role of DES in the formation of polysulfone UF membranes and their potential for practical use e.g. sedimented stormwater.
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| 2. |
- Hey, Tobias, et al.
(author)
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Calibration of a Dynamic Model of a Full Scale Wastewater Treatment Plant for Prediction of the Potentials of Combined In-line Hydrolysis with Predenitrification
- 2012
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In: ARGESIM Report. ; S38, s. 79-79
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Conference paper (peer-reviewed)abstract
- Abstract in UndeterminedCombining sludge hydrolysis with predenitrification is a promising method to remove nitrogen and decreased use of external carbon content in wastewater. The Klagshamn wastewater treatment plant plans to alter the primary settler into an in-line hydrolysis basin with subsequent predenitrification to reduce the nitrate load into the overstrained moving-bed biofilm reactor. A reference scenario, which included annual data from the process control system, was established and calibrated with the operational findings from the plant in 2007 to form a dynamic wastewater model. A method for generating a complete annual data set based on laboratory values was established and implemented with the model. The simulated results agreed well with Klagshamn’s actual operation. In addition, the simulated results of the proposed in-line hydrolysis basin were used to evaluate the potential for predenitrification. The results with hydrolysate showed that an additional 40 t·a-1 of nitrogen could be denitrified compared tothe reference scenario.
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| 3. |
- Hey, Tobias
(author)
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Carbon utilisation for extended nitrogen removal and resource savings
- 2013
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Licentiate thesis (other academic/artistic)abstract
- A full-scale in-line primary sludge hydrolysis experiment was conducted in one out of four primary settlers at the Klagshamn Wastewater Treatment Plant (WWTP) to test if the wastewater quality can be improved in terms of providing easily accessible carbon for possible pre-denitrification and the reduction of external carbon sources. The amount of easily accessible carbon produced, in the form of the volatile fatty acid (VFA), alkalinity and ammonium concentrations, was measured throughout the entire full-scale experiment at the outlet of the hydrolysis tank and that of the ordinary primary settler, which served as a reference line. VFA concentrations were measured in wastewater and hydrolysate samples using three analytical methods: the 5 and 8 pH point titration methods and gas chromatography. A calibrated model was established to fit data regarding the Klagshamn WWTP’s annual activated sludge operation of its secondary settler and wastewater composition. For modelling purposes and due to the small amount of data available, a linear regression method was established and used to complete the annual data set of the wastewater entering the Klagshamn WWTP. The full-scale data were incorporated into the calibrated model to simulate different scenarios of the activated sludge process with the purpose of saving energy (electricity) and resources (ethanol). Furthermore, an environmental (CO2-emissions) and economic evaluation was performed based on the data gathered from the full-scale experiment. A VFA concentration of 43 mgCODVFA∙l-1 with no release of ammonium was achieved in the full-scale hydrolysis experiment; this amount was shown, by simulation, to substitute for 50% of the concentration of ethanol currently used. The amount of ethanol saved represents an equivalent electricity saving of 19 MWh for ethanol production, and the operation of fewer nitrification zones, while still maintaining full nitrification over two summer months, could ensure an additional electricity saving of 177 MWh. The evaluation and comparison of the results obtained using the three techniques showed that the 5 pH point titrimetric method was adequate and sufficiently accurate in this context to monitor VFA concentrations below 100 mg∙l-1 at an alkalinity of 300 mgCaCO3∙l-1. The method can be easily implemented in the routine laboratory of the WWTP, and the measured VFA concentrations are equivalent to those obtained by gas chromatography. For the Klagshamn WWTP, the modelling results and further evaluations showed that in-line primary sludge hydrolysis can decrease the dependence on external carbon utilization and can thereby reduce chemical costs and carbon dioxide emissions.
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| 4. |
- Hey, Tobias, et al.
(author)
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Direct membrane filtration of municipal wastewater in Norway
- 2019
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Conference paper (other academic/artistic)abstract
- Real raw municipal wastewater is treated abiotic in combination of chemical and mechanical treatment with microfiltration as the final treatment step. This rather new treatment concept is described as direct membrane filtration and has been tested in a smaller scale in Sweden. The presented concept in this study is significantly larger (386 times) and is built in Norway to compare both studies performed in Sweden and Norway. The expected outcome is high carbon and phosphorus removal which makes it very interesting for wastewater treatment in the Norwegian but also European (< 10 000 PE) perspective. Furthermore, the concepts potential is to treat wastewater energy neutral due to high carbon rejection and a Finish study showed high >99 % removal of microplastics which is a world-wide hot topic. The presented direct membrane filtration concept is claimed to be the largest tested concept within Scandinavia.
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| 5. |
- Hey, Tobias, et al.
(author)
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Evaluation of direct membrane filtration and direct forward osmosis as concepts for compact and energy-positive municipal wastewater treatment
- 2018
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In: Environmental Technology. - : Informa UK Limited. - 0959-3330 .- 1479-487X. ; 39:3, s. 264-276
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Journal article (peer-reviewed)abstract
- Municipal wastewater treatment commonly involves mechanical, biological and chemical treatment steps to protect humans and the environment from adverse effects. Membrane technology has gained increasing attention as an alternative to conventional wastewater treatment due to increased urbanization. Among the available membrane technologies, microfiltration (MF) and forward osmosis (FO) have been selected for this study due to their specific characteristics, such as compactness and efficient removal of particles. In this study, two treatment concepts were evaluated with regard to their specific electricity, energy and area demands. Both concepts would fulfil the Swedish discharge demands for small- and medium-sized wastewater treatment plants at full scale: (1) direct MF and (2) direct FO with seawater as the draw solution. The framework of this study is based on a combination of data obtained from bench- and pilot-scale experiments applying direct MF and FO, respectively. Additionally, available complementary data from a Swedish full-scale wastewater treatment plant and the literature were used to evaluate the concepts in depth. The results of this study indicate that both concepts are net positive with respect to electricity and energy, as more biogas can be produced compared to that using conventional wastewater treatment. Furthermore, the specific area demand is significantly reduced. This study demonstrates that municipal wastewater could be treated in a more energy- and area-efficient manner with techniques that are already commercially available and with future membrane technology.
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| 6. |
- Hey, Tobias, et al.
(author)
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Full-scale in-line hydrolysis and simulation for potential energy and resource savings in activated sludge – a case study
- 2012
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In: Environmental Technology. - : Informa UK Limited. - 1479-487X .- 0959-3330. ; 33:15, s. 1819-1825
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Journal article (peer-reviewed)abstract
- The potential effects of altering primary settlers during biological in-line hydrolysis and converting a nitrifying activated sludge process into a partial pre-denitrification process for the purpose of resource conservation were evaluated. A full-scale primary sludge hydrolysis experiment was performed at a wastewater treatment plant and implemented in a dynamic modelling tool based on ASM2d. The full-scale hydrolysis experiment achieved a volatile fatty acid (VFA) production of 43 g CODHAc·m−3 with no release of ammonium. Additional nitrogen removal of 44 t N·a−1 was simulated, and the produced hydrolysate was able to replace 50% of the annual ethanol usage. Furthermore, 196 MWh of electricity per annum could be saved through the reduction of ethanol production and the optimization of the operation strategy of the activated sludge tank by operating a different number of anoxic zones.
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| 7. |
- Hey, Tobias, et al.
(author)
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Influences of mechanical pretreatment on the non-biological treatment of municipal wastewater by forward osmosis
- 2017
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In: Environmental Technology. - : Informa UK Limited. - 0959-3330 .- 1479-487X. ; 38:18, s. 2295-2304
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Journal article (peer-reviewed)abstract
- Municipal wastewater treatment involves mechanical, biological and chemical treatment steps for protecting the environment from adverse effects. The biological treatment step consumes the most energy and can create greenhouse gases. This study investigates municipal wastewater treatment without the biological treatment step, including the effects of different pretreatment configurations, for example, direct membrane filtration before forward osmosis. Forward osmosis was tested using raw wastewater and wastewater subjected to different types of mechanical pretreatment, for example, microsieving and microfiltration permeation, as a potential technology for municipal wastewater treatment. Forward osmosis was performed using Aquaporin Inside™ and Hydration Technologies Inc. (HTI) membranes with NaCl as the draw solution. Both types of forward osmosis membranes were tested in parallel for the different types of pretreated feed and evaluated in terms of water flux and solute rejection, that is, biochemical oxygen demand (BOD7) and total and soluble phosphorus contents. The Aquaporin and HTI membranes achieved a stable water flux with rejection rates of more than 96% for BOD7 and total and soluble phosphorus, regardless of the type of mechanical pretreated wastewater considered. This result indicates that forward osmosis membranes can tolerate exposure to municipal waste water and that the permeate can fulfil the Swedish discharge limits.
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| 8. |
- HEY, TOBIAS
(author)
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Municipal wastewater treatment by microsieving, microfiltration and forward osmosis : Concepts and potentials
- 2016
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Doctoral thesis (other academic/artistic)abstract
- Conventional wastewater treatment plants are designed for treating manmade wastewater (e.g., from households and industries) and to protect the environment (e.g., receiving water bodies) and humans from adverse effects.The objective of this work was to investigate the feasibility of treating municipal wastewater without a biological treatment step by applying different separation processes, such as microsieving, microfiltration and forward osmosis. The scope of this work was to treat municipal wastewater with a lower area demand while meeting the Swedish wastewater discharge requirements and allowing for the integration of the new separation techniques with existing full-scale wastewater treatment plants. To achieve these goals, pilot-plant and bench scale studies were conducted using raw municipal wastewater on-site at a full-scale wastewater treatment plant.Two different treatment concepts were identified to be feasible for municipal wastewater treatment based on the experimental findings. The first concept comprised coagulation and anionic flocculation before microsieving with subsequent microfiltration. The second concept only included microsieving and forward osmosis. Both concepts were evaluated for their specific electricity, energy and area demands, including sludge treatment, and were compared with five existing conventional wastewater treatment plants.Both concepts complied with the Swedish wastewater discharge demands for only small- and medium-sized wastewater treatment plants because up to only 65% of the nitrogen was retained. Nevertheless, both concepts achieved high retentions, with ≥96% for biochemical oxygen demand, ≥94% for chemical oxygen demand, and ≥99% for total phosphorus. Furthermore, the evaluation of both concepts showed that the specific electricity demand was 30% lower than the average specific electricity demand for 105 traditional Swedish wastewater treatment plants with population sizes of 1 500-10 000. In addition, the specific area demand could be reduced by at least 73% for existing wastewater treatment plants supporting the same population or a population of equivalent magnitude. Moreover, the results indicated that the new method had positive effects on electricity and energy due to the increased biogas potential compared to conventional wastewater treatment.
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| 9. |
- Hey, Tobias, et al.
(author)
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Potential of combining mechanical and physicochemical municipal wastewater pre-treatment with direct membrane filtration
- 2017
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In: Environmental Technology. - : Informa UK Limited. - 0959-3330 .- 1479-487X. ; 38:1, s. 108-115
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Journal article (peer-reviewed)abstract
- At a full-scale wastewater treatment plant, raw municipal wastewater from the sand trap outlet was mechanically and physicochemically pre-treated before microfiltration (MF) in a large pilot-scale study. MF was performed using a low transmembrane pressure (0.03 bar) without backflushing for up to 159 h (∼6.6 d). Pre-filtration ensured stable MF operation compared with the direct application of raw wastewater on the membrane. The combination of physicochemical pre-treatment, such as coagulation, flocculation, and microsieving, with MF meets the European and Swedish discharge limits for small- and medium-sized wastewater treatment plants (WWTPs). The specific electricity footprint was 0.3–0.4 kWh·m−3, which is an improvement compared to the median footprint of 0.75 kWh·m−3 found in 105 traditional Swedish WWTPs with sizes of 1500–10,000 person equivalents. Furthermore, the biological treatment step can be omitted, and the risk of releasing greenhouse gases was eliminated. The investigated wastewater treatment process required less space than conventional wastewater treatment processes, and more carbon was made available for biogas production.
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| 10. |
- Hey, Tobias, et al.
(author)
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The effects of physicochemical wastewater treatment operations on forward osmosis
- 2017
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In: Environmental Technology. - : Informa UK Limited. - 0959-3330 .- 1479-487X. ; 38:17, s. 2130-2142
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Journal article (peer-reviewed)abstract
- Raw municipal wastewater from a full-scale wastewater treatment plant was physicochemically pretreated in a large pilot-scale system comprising coagulation, flocculation, microsieve and microfiltration operated in various configurations. The produced microsieve filtrates and microfiltration permeates were then concentrated using forward osmosis (FO). Aquaporin InsideTM FO membranes were used for both the microsieve filtrate and microfiltration permeates, and Hydration Technologies Inc.–thin-film composite membranes for the microfiltration permeate using only NaCl as the draw solution. The FO performance was evaluated in terms of the water flux, water flux decline and solute rejections of biochemical oxygen demand, and total and soluble phosphorus. The obtained results were compared with the results of FO after only mechanical pretreatment. The FO permeates satisfied the Swedish discharge demands for small and medium-sized wastewater treatment plants. The study demonstrates that physicochemical pretreatment can improve the FO water flux by up to 20%. In contrast, the solute rejection decreases significantly compared to the FO-treated wastewater with mechanical pretreatment.
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