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  • 1901. Zapico, Jorge Luis
    et al.
    Katzeff, Cecilia
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Miljöstrategisk analys (fms).
    Bohne, Ulrica
    Milestad, Rebecka
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Miljöstrategisk analys (fms).
    Eco-feedback Visualization for Closing the Gap of Organic Food Consumption2016Inngår i: PROCEEDINGS OF THE NORDICHI '16: THE 9TH NORDIC CONFERENCE ON HUMAN-COMPUTER INTERACTION - GAME CHANGING DESIGN, Association for Computing Machinery , 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents the results of EcoPanel, an eco-feedback visualization created in collaboration with a Swedish food retailer. The visualization uses automatic data gathering to provide consumers with detailed information and long-term trends about their organic food consumption. The results from a five months test with 65 users show an increase in organic purchases compared to the control group, especially for the users who overestimated their percentage of organic food before the test. From the results we point out the possibilities of using visualization as a way of creating insight on behaviors such as food consumption, that are difficult to grasp from individual actions. This insight can be a way of closing the gap between attitudes and actual behavior, helping users that are already aware and willing to change, to perform more sustainable.

  • 1902.
    Zapico Lamela, Jorge Luis
    KTH, Skolan för datavetenskap och kommunikation (CSC), Medieteknik och interaktionsdesign, MID. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Industriell ekologi. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centre for Sustainable Communications, CESC.
    Hacking for Sustainability2014Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    ICT for Sustainability is a growing research area looking at the potential of information and communication technologies for contributing to sustainability. The existing work in this area can be grouped in four main categories: The optimization of existing systems using ICT, the dematerialization of cultural assets and presence, the use of technology for behavioral change, and the support of sustainability practice and research. Within this research area, this thesis focuses on exploring how new technologies and approaches of working with data, such as APIs, mashups, crowdsourcing, open data, and dynamic visualizations, can be applied to sustainability and sustainability practice.

    This thesis follows a research through design method, where applications, prototypes, and events were created and released following an iterative design process. Five different design artifacts or “hacks” are presented and analyzed together as a portfolio. This collection of artifacts is a practical exploration of the research questions and it embodies the results.

    Based on the created artifacts, this text argues that the new technologies and paradigms coming from ICT can transform how sustainability work is performed, by changing the way that sustainability data is created, shared and visualized. This new “data-driven” approach is characterized by a bottom-up way of data gathering, automatic data collection and crowdsourcing, a real time orientation, a focus on transparency and openness, dynamic and interactive visualizations, and new approaches to innovation. These characteristics create new opportunities for making sustainability practice more effective and broaden its impact, but they also create new problems and increase existing risks.

    Finally it is argued that while information and communication technologies are usually treated as tools, these innovations in ICT for Sustainability are not only technological, but also cultural. The hacker ethic values connected with computer technologies, such as an open way of sharing knowledge, the focus on creativity as a driving force, and a hands-on approach, are key for understanding this research area and an important part of the contribution from ICT to sustainability. 

  • 1903.
    Zdyrska, Aleksandra
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Evaluation of Partial Nitritation/Anammox processes operated in IFAS mode2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The main aim of the study was to optimize Partial Nitritation/Anammox process operated in pilot-scale integrated fixed film activated sludge (IFAS) mode supplied with low-temperature mainstream wastewater and efficiency evaluation based on laboratory analysis and data from online sensors. Main tasks of research work were to stabilize the ongoing process and find the optimal conditions for maximizing effects of nitrogen removal. The use of online sensors (dissolved oxygen, pH, conductivity, oxidation-reduction potential, NH4-N, NO3-N and NO2-N) has allowed continuous process monitoring.

    During research period the influent wastewater flow, recirculated sludge flow, time of aeration, set point of dissolved oxygen and temperature were changed. Flow of influent wastewater varied between 11.2 and 16.8 L/h resulting in HRT varying between 11.9 and 17.9h. Different strategies of aeration were tested: 20, 25 and 30 minutes of aeration in one-hour cycle with DO values of 1.0, 1.3 and 1.5 mg O2/L.

    The best result of nitrogen removal efficiency for IFAS reactor operated at 15°C was 46.6% (based on online data) at oxygen concentration value of 1.3 mg O2/L, with 20 minutes of aeration and 40 minutes without aeration in 1-hour cycle. After increase of temperature to 17°C higher nitrogen removal efficiency was obtained with maximum value of 48.0% (based on online data).

  • 1904. Zech, A.
    et al.
    Attinger, S.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Dagan, G.
    Dietrich, P.
    Fiori, A.
    Rubin, Y.
    Teutsch, G.
    Is unique scaling of aquifer macrodispersivity supported by field data?2015Inngår i: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 51, nr 9, s. 7662-7679Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Spreading of conservative solutes in groundwater due to aquifer heterogeneity is quantified by the macrodispersivity, which was found to be scale dependent. It increases with travel distance, stabilizing eventually at a constant value. However, the question of its asymptotic behavior at very large scale is still a matter of debate. It was surmised in the literature that macrodispersivity scales up following a unique scaling law. Attempts to define such a law were made by fitting a regression line in the log-log representation of an ensemble of macrodispersivities from multiple experiments. The functional relationships differ among the authors, based on the choice of data. Our study revisits the data basis, used for inferring unique scaling, through a detailed analysis of literature marcodispersivities. In addition, values were collected from the most recent tracer tests reported in the literature. We specified a system of criteria for reliability and reevaluated the reliability of the reported values. The final collection of reliable estimates of macrodispersivity does not support a unique scaling law relationship. On the contrary, our results indicate, that the field data can be explained as a collection of macrodispersivities of aquifers with varying degree of heterogeneity where each exhibits its own constant asymptotic value. Our investigation concludes that transport, and particularly the macrodispersivity, is formation-specific, and that modeling of transport cannot be relegated to a unique scaling law. Instead, transport requires characterization of aquifer properties, e.g., spatial distribution of hydraulic conductivity, and the use of adequate models.

  • 1905. Zech, A.
    et al.
    Attinger, S.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Dagan, G.
    Dietrich, P.
    Fiori, A.
    Rubin, Y.
    Teutsch, G.
    Reply to comment by S. Neuman on "Is unique scaling of aquifer macrodispersivity supported by field data?"2016Inngår i: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 52, nr 5, s. 4203-4205Artikkel i tidsskrift (Annet vitenskapelig)
  • 1906.
    Zech, Alraune
    et al.
    UFZ Helmholtz Ctr Environm Res, Permoserstr 15, D-04318 Leipzig, Germany..
    Attinger, Sabine
    UFZ Helmholtz Ctr Environm Res, Permoserstr 15, D-04318 Leipzig, Germany.;Univ Potsdam, Inst Earth & Environm Sci, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany..
    Bellin, Alberto
    Univ Trento, Dept Civil Environm & Mech Engn, Via Mesiano 77, I-38123 Trento, Italy..
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Dietrich, Peter
    UFZ Helmholtz Ctr Environm Res, Permoserstr 15, D-04318 Leipzig, Germany.;Univ Tubingen, Ctr Appl Geosci, Holderlinstr 12, D-72074 Tubingen, Germany..
    Fiori, Aldo
    Roma Tre Univ, Dept Engn, Via Volterra 62, I-00146 Rome, Italy..
    Teutsch, Georg
    UFZ Helmholtz Ctr Environm Res, Permoserstr 15, D-04318 Leipzig, Germany..
    Dagan, Gedeon
    Tel Aviv Univ, Sch Mech Engn, IL-69978 Ramat Aviv, Israel..
    A Critical Analysis of Transverse Dispersivity Field Data2019Inngår i: Ground Water, ISSN 0017-467X, E-ISSN 1745-6584, Vol. 57, nr 4, s. 632-639Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Transverse dispersion, or tracer spreading orthogonal to the mean flow direction, which is relevant e.g, for quantifying bio-degradation of contaminant plumes or mixing of reactive solutes, has been studied in the literature less than the longitudinal one. Inferring transverse dispersion coefficients from field experiments is a difficult and error-prone task, requiring a spatial resolution of solute plumes which is not easily achievable in applications. In absence of field data, it is a questionable common practice to set transverse dispersivities as a fraction of the longitudinal one, with the ratio 1/10 being the most prevalent. We collected estimates of field-scale transverse dispersivities from existing publications and explored possible scale relationships as guidance criteria for applications. Our investigation showed that a large number of estimates available in the literature are of low reliability and should be discarded from further analysis. The remaining reliable estimates are formation-specific, span three orders of magnitude and do not show any clear scale-dependence on the plume traveled distance. The ratios with the longitudinal dispersivity are also site specific and vary widely. The reliability of transverse dispersivities depends significantly on the type of field experiment and method of data analysis. In applications where transverse dispersion plays a significant role, inference of transverse dispersivities should be part of site characterization with the transverse dispersivity estimated as an independent parameter rather than related heuristically to longitudinal dispersivity.

  • 1907.
    Zhang, Chi
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Industriell ekologi.
    Apply on Instance of IBM Watson Cognitive Computing System2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Smart Cities concern a variety of domains such as information, data, energy, transport, health, etc. The ‘Information Age’, which shifts from the Industrial Revolution to information computerisation, accesses to large volumes of data explored by sophisticated computer based analytics. ICT solutions interconnect businesses and customers through the cloud while driving the global economy and development of Smart Cities. This MSc thesis aims to investigate connections between Smart Cities and cloud-based Cognitive Computing, then demonstrate with instances how the combination of Watson cognitive system and Pepper humanoid robot can enhance living experience. The investigation is based on literature review in the area of Smart Cities and ICT focusing on Internet of Things, Cloud Computing, and Cognitive Computing, observation of services on Bluemix, and interview with consultants and engineers of IBM. The services of Watson cognitive computing system enable Pepper to process unstructured information and interact with humans. The results also contain use cases of the functionality of Watson-powered Pepper, which could be further implemented for public services.

  • 1908. Zhang, Linus
    et al.
    Gustafsson, David
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Editorial: 'The Nordic Hydrology Model' - Linking science and practice2016Inngår i: Hydrology Research, ISSN 1998-9563, Vol. 47, nr 4, s. 671-671Artikkel i tidsskrift (Fagfellevurdert)
  • 1909.
    Zhang, Wen
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Vatten- och miljöteknik.
    An add-on filter technique to improve micropollutant removal and water quality in on-site sewage treatment facilities2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Onsite sewage treatment facilities (OSSFs) in Sweden currently release significant amounts of nitrogen (N) and phosphorus (P) into groundwater or/and receiving water bodies. Micropollutants (MPs) have been found in both surface water and groundwater, indicating insufficient removal of MPs by OSSFs. Two laboratory-scale column experiments, followed by a field experiment, were performed to study removal of a set of organic MPs by organic and inorganic sorbents. The set covered different product categories, e.g. an artificial sweetener, organophosphates, parabens, personal care products, perfluoroalkyl substances (PFASs), pesticides, pharmaceuticals, a plasticiser, a polymer impurity, stimulants and surfactants. An experiment using five organic and five inorganic sorbents showed that coal-based organic sorbents performed better than natural fibre and inorganic sorbents in removal of MPs, with 20% higher removal efficiency on average. Five sorbents were selected for a long-term column experiment examining 31 MPs. Physical properties and chemical structure of the sorbents, namely pore structure and surface functional groups, were found to be correlated to their capacity for removal of MPs. Molecular weight, solvent-accessible area, octanol-water partition coefficient and distribution-coefficient of PFASs were found to be strongly positively correlated with their removal by some sorbents. Organic sorbents with good performance in removal of MPs and a conventional sand bed showed limited ability to remove P, while calcium-rich sorbents increased P removal greatly. Two sorbents, granulated activated carbon (GAC) and xyloid lignite (Xylit), were tested for 24 weeks in an add-on filter for effluent from a soil treatment system and found to significantly improve removal of MPs. A replaceable add-on unit for removal of MPs from OSSF effluent is recommended and should contain an organic sorbent such as GAC or Xylit.

  • 1910.
    Zhang, Wen
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Removal of micropollutants and nutrients using filter beds for on-site sewage treatment – column and field experiments2017Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    On-site sewage treatment facilities (OSSFs) are widely applied in rural areas in the Nordic countries. A potential amount of phosphorus (P) and nitrogen (N) are released from these systems every year. The concerns are also about micropollutants (MPs), i.e. pharmaceuticals and synthetic organic compounds which are contaminating the environment and can affect the ecosystem and human health (Luo, 2014). About 40% of the OSSFs in Sweden use soil-based systems to treat wastewater (Olshammar, 2015) and sand is the most commonly applied media. The aim of this study was to evaluate the removal efficiencies of P, N and a number of MPs in filter beds and to find out the potential additional treatment efficiency which could be achieved by combining sand with other commercial filter materials.

    Two bench-scale column experiments were performed during 2016 (Table 1). The first experiment was operated with saturated flow conditions during two weeks. The second experiment applied unsaturated flow conditions and was operated during twelve weeks.

    The wastewater used in the experiment was spiked with a number of MPs to investigate their removal by the sand filtration. The MPs included pharmaceuticals, pesticides, biocides, plasticizers, fragrances, surfactants, UV-stabilizers, rubber additives and food additives. Weekly samples were taken for N, P and MPs analysis. Other parameters measured during the experiments included dissolved organic carbon (DOC), pH, turbidity and electric conductivity.

    A field pilot plant was constructed in 2013 (Kholoma, 2016) with three subsurface parallel filter beds. Each bed had a length and depth of 1.5 and 0.8 m, respectively, and an upper surface area of 0.75 m2. The three filter beds were filled with sand, biochar and sand, biochar and Sorbulite® (a product based on gas concrete), respectively. The system was maintained for two and a half years prior the sampling (November 2016), where 24-hour composite water samples were taken from the influent and the effluent.

    The average removal efficiencies of DOC, NH4-N and Ptot in column and field samples are presented in table 2. Compared with the sand filter, the added biochar layer improved the removal of DOC by 18% and the added Sorbulite layer increased both the DOC and total phosphorus removal efficiencies by 7%.

    The MPs in the column experiment showed different removal efficiencies: Firstly, biocides (hexachlorobenzene and triclosan), pharmaceuticals (acetaminophen and caffeine), fragrance (musk xylene) and preservative (propylparaben) have been efficiently removed with an average removal above 90%. Secondly, a few organophosphorus flame retardants such as tributylphosphate and triphenylphosphate, perfluoroaklyl substances, UV stabilizer (benzophenone) and fragrances (musk ketone and galaxolide) had lower removal efficiencies in the range 51% and 81%. The sand did not remove most of pharmaceuticals very efficiently. Seven out of the nine investigated pharmaceuticals had removal efficiencies ranging between 17% and 48%, whereas four of them (diclofenac, oxazepam, losartan and carbamazepine) had an average removal efficiency lower than 30%.

    A number of 47 MPs were identified in the field experiment samples with concentrations ranging from 0.1 ng L-1 to 46285 ng L-1. The removal efficiency varied depending on the type of filter media and MPs. The dual layer filter with biochar and sand provided a better removal of MPs (on average, 68%) than the other two filters (on average, 65% and 56% for sand and biochar + Sorbulite, respectively). In the future, to improve the removal efficiency of nutrients and MPs, the application of new filter materials to optimize the traditional filter bed is needed. The life span of sand and alternative sorbents were not considered in the column experiments, however it is one of the essential research tasks for future work.

  • 1911.
    Zhang, Wen
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Screening of different types of on-site sewage facilities - treatment function and potential for removing micropollutants2016Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    On-site sewage facilities (OSSF) in Sweden were investigated to check the treatment function and determine the potential for removing micropollutants (MPs). The 16 OSSFs studied included soil filtration systems (SFS), package treatment systems (PTS) and source separation of sewage (SSS). Two medium-sized municipal wastewater treatment plants were also included for reference. Nitrogen (N), phosphorus (P), dissolved organic carbon (DOC) and MPs were analysed. For SFS, overall removal efficiency of nitrogen and phosphorus was acceptable, but some individual facilities showed poor treatment results. This was generally attributable to lack of maintenance, which affected removal performance for most parameters tested. No-target screening for MPs, carried out in laboratories at Umeå University (UU) and the Swedish University of Agricultural Sciences (SLU), revealed average removal efficiency of 52.4% for SFS and 37.5% for PTS. Thus MPs can be removed by on-site sewage systems, but higher removal efficiency is needed.

  • 1912.
    Zhang, Wen
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Gago-Ferrero, Pablo
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Box 7050, SE-75007 Uppsala, Sweden..
    Gao, Qiuju
    Umea Univ, Dept Chem, Linnaeus Vag 6, SE-90187 Umea, Sweden..
    Ahrens, Lutz
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Box 7050, SE-75007 Uppsala, Sweden..
    Blum, Kristin
    Umea Univ, Dept Chem, Linnaeus Vag 6, SE-90187 Umea, Sweden..
    Rostvall, Ande
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Box 7050, SE-75007 Uppsala, Sweden..
    Björlenius, Berndt
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Industriell bioteknologi.
    Andersson, Patrik L.
    Umea Univ, Dept Chem, Linnaeus Vag 6, SE-90187 Umea, Sweden..
    Wiberg, Karin
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Box 7050, SE-75007 Uppsala, Sweden..
    Haglund, Peter
    Umea Univ, Dept Chem, Linnaeus Vag 6, SE-90187 Umea, Sweden..
    Renman, Gunno
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Evaluation of five filter media in column experiment on the removal of selected organic micropollutants and phosphorus from household wastewater2019Inngår i: Journal of Environmental Management, ISSN 0301-4797, E-ISSN 1095-8630, Vol. 246, s. 920-928Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A bench-scale column experiment was performed to study the removal of 31 selected organic micropollutants (MPs) and phosphorus by lignite, xyloid lignite (Xylit), granular activated carbon (GAC), Polonite (R) and sand over a period of 12 weeks. In total 29 out of the 31 MPs showed removal efficiency > 90% by GAC with an average removal of 97 +/- 6%. Xylit and lignite were less efficient with an average removal of 80 +/- 28% and 68 +/- 29%, respectively. The removal efficiency was found to be impacted by the characterization of the sorbents and physicochemical properties of the compounds, as well as the interaction between the sorbents and compounds. For instance, Xylit and lignite performed well for relatively hydrophobic (log octanol/water partition coefficient (K-ow) >= 3) MPs, while the removal efficiency of moderately hydrophilic, highly hydrophilic and negatively charged MPs were lower. The organic sorbents were found to have more functional groups at their surfaces, which might explain the higher adsorption of MPs to these sorbents. The removal of several MPs improved after four weeks in sand, Xylit, GAC and lignite which may be related to increased biological activity and biofilm development. GAC and sand had limited ability to remove phosphorus (12 +/- 27% and 14 +/- 2%, respectively), while the calcium-silicate material Polonite (R) precipitated phosphorus efficiently and increased the total phosphorus removal from 12% to 96% after the GAC filter.

  • 1913.
    Zhang, Wen
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Renman, Gunno
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Vatten- och miljöteknik.
    Removal of 31 organic micropollutants and phosphorus by filter media in a column experiment using household wastewaterManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    A bench-scale column experiment was performed to study the removal of 31 selected organic micropollutants (MPs) by lignite, xyloid lignite (Xylit), granular activated carbon (GAC), Polonite® and sand over a period of 12 weeks. The MPs analysed included an artificial sweetener, biocides, fragrances, organophosphates, perfluoroalkyl substances (PFASs), pesticides, pharmaceuticals, a plasticiser, a polymer impurity, a preservative, a rubber additive, a surfactant and UV stabilisers. The removal of several MPs improved after four weeks in sand, Xylit, GAC and lignite which may be related to increased biological activity and biofilm development. In total 29 out of the 31 MPs showed a removal efficiency of >90% by GAC with an average removal of 97 ± 6%. Xylit and lignite were less efficient with an average removal of 80 ± 28% and 68 ± 29%, respectively. However, Xylit and lignite performed well for relatively hydrophobic (log Kow ≥3) MPs (i.e. hexachlorobenzene, galaxolide and tributylphosphate) with an average removal efficiency of 90 ± 5 % and 95 ± 4 %, respectively. The removal efficiency obtained with Xylit and lignite of moderately hydrophilic MPs (i.e. tris-(2-chloroethyl)phosphate), highly hydrophilic (i.e. sucralose) and negatively charged (i.e. PFOS and diclofenac) were lower (67 ± 35% for Xylit and 49 ± 26% for lignite). The organic sorbents were found to have more functional groups at their surfaces, which might explain the higher adsorption of MPs to these sorbents. GAC and sand had limited ability to remove phosphorus (12 ± 27% and 14 ± 2%, respectively), while the calcium-silicate material Polonite® precipitated phosphorus efficiently and increased the total phosphorus removal from 12% to 96% after the GAC filter.

  • 1914.
    Zhang, Wen
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Renman, Gunno
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Vatten- och miljöteknik.
    Removal of micropollutants and nutrients in household wastewater using organic and inorganic sorbentsInngår i: Desalination and Water Treatment, ISSN 1944-3994, E-ISSN 1944-3986Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The efficiency of five organic and five inorganic sorbents in removing 19 organic micropollutants (MPs), phosphorus, nitrogen, and dissolved organic carbon (DOC) was tested in a two-week column experiment using household wastewater spiked with pharmaceuticals (n = 6), biocides/pesticides (n = 4), organophosphates (n = 3), a fragrance, a UV-stablizer, a food additive,a rubber additive, a plasticizer and a surfactant. Two types of granular activated carbon (GAC), two types of lignite, a pine bark product, and five mineral-based sorbents were tested. All the organic sorbents except pine bark achieved better removal efficiencies of DOC (on average, 70 ± 27%) and MPs (93 ± 11%) than the inorganic materials (DOC: 44 ± 7% and MPs: 66 ± 38%). However, the organic sorbents (i.e. GAC and xyloid lignite) removed less phosphorus (46 ± 18%), while sorbents with a high calcium or iron content (i.e. Polonite® and lignite) generally removed phosphorus more efficiently (93 ± 3%). Ammonium-nitrogen was well removed by sorbents with a pH between 7 and 9, with an average removal of 87%, whereas lignite (pH 4) showed the lowest removal efficiency (50%). Some MPs were well removed by all sorbents (≥97%) including biocides (hexachlorobenzene, triclosan and terbutryn), organophosphates (tributylphosphate, tris-(1,3-dichloro-2-propyl)phosphate and triphenylphosphate) and one fragrance (galaxolide). The pesticide 2,6-dichlorobenzamide and the pharmaceutical diclofenac were poorly removed by the pine bark and inorganic sorbents (on average, 4%), while organic sorbents achieved high removal of these chemicals (87%).

  • 1915.
    Zhang, Wen
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Renman, Gunno
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Vatten- och miljöteknik.
    Wastewater purification and removal of micropollutants in a soiltreatment system and by subsequent filtration through activatedcarbon and xyloid lignite – a field experimentManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Soil treatment systems (STS) are often used in rural areas to remove nutrients and microorganisms from wastewater. These and other facilities designed for on-site sewage treatment should also have the capacity to remove micropollutants (MPs), i.e. pharmaceuticals, personal care products, detergents, polymer additives, and other synthetic organic compounds. In a six-month study on a medium-scale STS with two add-on filters installed to purify the effluent, possible removal enhancement of MPs, phosphorus (Ptot) and ammonium-nitrogen (NH4-N) was examined. The filters contained granular activated carbon (GAC) and xyloid lignite (Xylit). A total of 58 compounds were detected, comprising artificial sweeteners (n = 2), organophosphates (n = 7), parabens (n = 3), personal care products (n = 7), pesticides (n = 2), perfluoroalkyl substances (PFAS) (n = 3), pharmaceuticals (n = 27), a plasticiser, a polymer impurity, a rubber additive, stimulants (n = 3) and a surfactant. The concentrations in influent water to the STS ranged from 1.3 ng L-1 (ranitidine) to 110 μg L-1 (acetaminophen). Mean removal rate of MPs by the STS was 49 ± 56 %. The add-on filters significantly improved (ANOVA, p<0.001) removal of MPs, despite treating a high hydraulic load (2350 L m-2 day-1). The GAC and Xylit filters removed 98 ± 6 % and 87 ± 28 %, respectively, demonstrating the potential of these materials to reduce MPs in STS effluent to very low concentrations. The add-on filters did not improve removal of P and NH4-N from STS effluent, but the GAC-based filter improved removal of organics (COD) by 5%. 

  • 1916.
    Zhang, Wen
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Termida, Nursitihazlin Ahmad
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Transportplanering, ekonomi och teknik.
    Susilo, Yusak O.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Systemanalys och ekonomi.
    What construct one's familiar area?: A quantitative and longitudinal study2019Inngår i: Environment and Planning B: Urban Analytics and City Science, ISSN 2399-8083, Vol. 46, nr 2, s. 322-340Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is a lack of understanding of how certain characteristics of the urban environment influence an individual's spatial cognition and familiarity with surrounding areas, and, subsequently, their travel behaviours and how these change over time. This paper aims to address this research gap in exploring the dynamics of individuals' spatial cognitions by observing the changes of respondents' familiar areas over time, and investigating the possible determinants that constitute respondents' familiar areas. Panel data, containing two-week travel diaries and maps of familiar areas, were collected in four different waves over a seven-month period for 55 individuals in Stockholm, Sweden. The reported familiar areas for each individual were digitised into quantifiable variable form and further analysed by applying dynamic binary probit and linear regression models. The results show that, while familiar area is largely influenced by one's previous knowledge of the area, it is also continuously corrected by events in between. Different land use characteristics have different impacts on different social groups' travel patterns, thus contributing to the variability in the size of one's familiar areas.

  • 1917.
    Zhang, Yizhou
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Industriell ekologi.
    Real Time Crowding Information (RTCI) Provision: Impacts and Proposed Technical Solution2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The increasing population leads to higher passenger travel demand in Stockholm. The public transport becomes more and more crowded in rush hours. However, passengers carry out decisions usually based on limited traffic information and their travel experience. Passengers cannot take the initiative to avoid crowding based on existing SL traffic information. Real time crowding information (RTCI) research aims to help passenger to have more initiative to plan their travel in metro system, and assist operator to have higher space utilization efficiency. RTCI system contains4 subsystems: projection system, communication system, speaker system and recording system. The practical test was applied in Tekniska Högskolan metro station for two weeks in May 2015 with the permission from SL.

    The triangle analysis was applied to analyze the impacts of RTCI. The analysiscontains three analysis methods: passenger load data analysis, video record analysis and interview result analysis. The interview result shows RTCI increased round nine tenth of passengers ‘satisfaction and 43% of interviewees thought it was very useful for them. The calculation based on video record and interview result shows that 25% of passengers consulted this information and changed their behaviors on platform. According to the video record, the path became wider and passenger flow became smoother while RTCI system was activated. Passenger distribution was more even in metro based on passenger load data. The number of passengers who got into last unit train increased 8%, and the number in first and second unit train decreased 4% during RTCI practical test.

    The thesis mainly focused to analyze the impacts of RTCI instead of solving technical challenges. But the technical solution for RTCI system was proposed in thesis. The concept - “Smart Travel” was discussed in chapter11 which mainly considers travel time, crowding information and travel cost as most important factors to passenger. 

  • 1918.
    Zhang, Zizhu
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    An eco-city indicator system for the city of Changsha.2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    With rapid urban development in China, many cities are still concerned about the quantity of the economy growth while ignoring the quality of the growth; ecological systems face a challenging situation. How to evaluate and guide a sustainable devel-opment is a vitally important question to the government of China. The study was partly performed in cooperation with the Institute of Building Research (IBR), who was entrusted by Changsha government of the Hunan Province. To evaluate the sus-tainability of urban development, a comprehensive indicator system was developed and applied, which was consistent to the policy of the so called "Two oriented socie-ty", which means Resource conservation and Environment friendly society. This pa-per shows a logic methodology to develop an indicator system – through the re-search, from literature review to modern concept; it shows clearly the factors that are important to build a sustainable city.

    The indicator system was derived and compared with other existing systems. The comparison showed that the indicator system we developed for the city is operational and integrated with a consistent hierarchy. Thereafter, the established indicator sys-tem was evaluated using an Analytical Hierarchy Process methodology. Indictors of ecological aspects were evaluated using the data collected, including the Changsha green field map, wetland map and ecological control maps. The indicator system was applied and the result was used as decision support in urban planning for 2020. How-ever, a main limitation lied in data collection: since the data we collected was not completely the data we expected. Besides, the indicator system was developed on the base of the policy called the "Two oriented society",which has its preference and limi-tation itself. Still, in sum, the indicator system we built through the research provided a satisfactory framework to the government to guide the development of the society in a macro scale. It needs future involvement to improve the data collection and standardization.

  • 1919. Zhao, Z.
    et al.
    Liu, Longcheng
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Neretnieks, Ivars
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Solute transport in a single fracture with time-dependent aperture due to chemically medicated changes2014Inngår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 66, s. 69-75Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In addition to mechanical loading, the transport properties of rock fractures are also affected by chemically mediated changes, such as pressure solution, stress corrosion and free-face dissolution, among others. Based on a time-dependent model of fracture closure under constant normal stresses, the transport behavior of contaminants in a slowly closing fracture is studied using a finite difference scheme. The results show that the contaminant penetrating along the fracture plane gradually becomes slow or almost negligible during the process of fracture closure induced by chemical processes, whereas the matrix diffusion of contaminants is active all the time. This finding indicates that diffusion into the rock matrix perpendicular to the advective flow direction always plays an important role in determining the fate of contaminant in rock fractures. The smaller the fluid flow due to fracture closure and the larger impact the matrix diffusion can further delay the solute transport.

  • 1920.
    Zhao, Zhihong
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Neretnieks, Ivars
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Moreno, Luis
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    A new numerical method of considering local longitudinal dispersion in single fractures2014Inngår i: International journal for numerical and analytical methods in geomechanics (Print), ISSN 0363-9061, E-ISSN 1096-9853, Vol. 38, nr 1, s. 20-36Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The solutions of advection-dispersion equation in single fractures were carefully reviewed, and their relationships were addressed. The classic solution, which represents the resident or flux concentration within the semi-infinite fractures under constant concentration or flux boundary conditions, respectively, describes the effluent concentration for a finite fracture. In addition, it also predicts the cumulative distribution of solute particle residence time passing through a single fracture under pulse injection condition, based on which a particle tracking approach was developed to simulate the local advection-dispersion in single fractures. We applied the proposed method to investigate the influence of local dispersion in single fractures on the macrodispersion in different fracture systems with relatively high fracture density. The results show that the effects of local dispersion on macrodispersion are dependent on the heterogeneity of fracture system, but generally the local dispersion plays limited roles on marodispersion at least in dense fracture network. This trend was in agreement with the macrodispersion in heterogeneous porous media.

  • 1921.
    Zhou, Guanghong
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Industriell ekologi.
    Low-Carbon City Initiatives in China: Planning Approaches, Dilemmas and Opportunities2015Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In order to reduce greenhouse gas (GHG) emissions, tackle climate change and move toward sustainable development, the central government in China has proposed low-carbon city development as the national strategy and relevant initiatives have been taken by local governments. This thesis analyses current low-carbon city programmes and planning approaches in China, identifies limitations and proposes a metabolic approach that could be used to account for physical resources, monitor GHG emissions and involve stakeholders in the planning process.

    There are currently two parallel programmes for low-carbon initiatives in China: the “Low-Carbon City” programme and the “Low-Carbon Eco-City” programme. Around thirty cities in the Coastal, Central and Western regions of China have been selected as the national pilot areas for these programmes. This widespread distribution marks a change the previous priority set on development in the Coastal region, meaning that more cities have opportunities to explore low-carbon pathways and obtain support from the state. The large number of cities involved shows China’s determination to transition to low-carbon development in different city contexts. The selected cities have set up local administrative groups to manage low-carbon development and have established integrated approaches to reduce GHG emissions from urban sectors such as energy, transportation, buildings and waste. Some plans have been developed by the cities themselves, while others have involved international cooperation. However, because of limited knowledge on low-carbon city development, an absence of established standards and procedures and the Chinese top-down planning system, low-carbon planning faces specific challenges, such as lack of information about GHG flows, GHG monitoring and stakeholder involvement.

    To overcome these challenges and improve low-carbon city approaches in China, this thesis proposes a holistic approach to low-carbon city development, by integrating Industrial Ecology into urban planning. Such work would benefit greatly from adopting a metabolic approach, within which a metabolic approach-based standard is used to understand low-carbon city from GHG flows; a DPSIR framework is used to address root causes of GHG emissions; and an Eco-Cycle Model is used to describe urban metabolism and account for physical resources, monitor GHG emissions and involve stakeholders in the planning process.

    The thesis also recommends better collaboration between relevant government departments and stakeholders. Moreover, instead of simply transferring approaches developed elsewhere, international cooperation needs to combine the local context and knowledge in China with international knowledge and experience. In return, experiences from China can help improve low-carbon city approaches in other parts of the world.

  • 1922.
    Zhou, Guanghong
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Industriell ekologi.
    Liu, Hongling
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Industriell ekologi.
    Yin, Ying
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Urbana och regionala studier.
    Frostell, Björn
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Industriell ekologi.
    Towards low-carbon cities in China: integrating greenhouse gas management in urban planning2014Inngår i: Resilience – The New Research Frontier, Trondheim: Norwegian University of Science and Technology , 2014, s. 150-164Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Low-carbon development has been proposed as one of the key national environmental strategies by the central government of China. There are hundreds of Chinese cities that have set low-carbon goals and there are many types of plan within the urban planning system. However, these plans face great challenges. For example, the current urban planning approach focuses on spatial arrangements while it has difficulties in recognising the complexity of GHG metabolism. As another example, urban planning lacks stakeholder involvement and cooperation which contributes to the failure to monitor GHG emissions. This study compares the situation in China with that experienced in Stockholm, Sweden and proposes an approach to improve low-carbon planning. This approach involves integrating GHG accounting into urban planning based on Industrial Ecology knowledge. Using lessons learnt from the Eco-Cycle Model 2.0 in Stockholm, the study highlights the intimate relationship between energy consumption and GHG emissions in Chinese cities, which requires integrating energy systems thinking and GHG thinking into the urban planning process. A life cycle perspective is needed in urban planning to integrate parallel energy consumption and GHG emissions budgeting in different urban sectors. Furthermore, a GHG metabolic approach may become a broad platform for communicating low-carbon development among different stakeholders in a city.

  • 1923.
    Zhou, Guanghong
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Industriell ekologi.
    Singh, Jagdeep
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Industriell ekologi.
    Wu, Jiechen
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Industriell ekologi.
    Sinha, Rajib
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Industriell ekologi.
    Laurenti, Rafael
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Industriell ekologi.
    Frostell, Björn
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Industriell ekologi.
    Evaluating low-carbon city initiatives from the DPSIR framework perspective2015Inngår i: Habitat International, ISSN 0197-3975, E-ISSN 1873-5428, Vol. 50, s. 289-299Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Current low-carbon city initiatives were evaluated using the DPSIR (Drivingforces-Pressures-State-Impacts-Responses) causal-effect framework for investigating interactions between environmental issues and human activities. For effective management towards achieving a low-carbon city, integrating the pressure-based, driver-oriented DPSIR approach could help decision makers examine whether greenhouse gas (GHG) reduction approaches deal with the root causes of GHG emissions and work to-wards low-carbon city development goals. The DPSIR framework was used on 36 global cities to analyse the socio-economic dynamics of GHG emissions and their pressures on the environment, the state of the environment, related climate change impacts and responses from society. The results indicated that numerous cities have awareness of low-car bon plans and that most of these plans are pressure-based and driver-oriented. Most city plans recognise energy, transportation and building as the main driving forces for GHG emissions, which cause environmental pressures, and highlight technical responses to reduce GHG emissions pressures from these root causes. Inaddition, most plans recognise institutional and cognitional responses to low-carbon city development, such as: policies and legislation; departmental planning and cooperation; measuring, monitoring and reporting performance; capital invest-ment; community education and outreach; and stakeholder involvement.

  • 1924. Zivkovic, Marija
    et al.
    Pereverza, Kateryna
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Industriell ekologi.
    Pasichnyi, Oleksii
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Industriell ekologi.
    Madzarevic, Aleksandar
    Ivezic, Dejan
    Kordas, Olga
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Industriell ekologi.
    Exploring scenarios for more sustainable heating: The case of Nis, Serbia2016Inngår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 115, s. 1758-1770Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sustainability transformation of the heating sector is recognised as being essential for reaching climate and environmental targets while improving the quality of life in cities worldwide. Participatory strategic planning enabled by scenario methods can be an important tool to guide this transformation, but methods for qualitative scenario analysis supporting stakeholder participation must be further developed and tested in the context of different cities. This paper presents results from integration of urban energy system modelling into the participatory strategic planning process implemented in the city of NE, which suffers problems typical of the heating sector in Serbia and the Western Balkans. The aim was to explore how the scenarios developed by local stakeholders could transform the NB heating system by 2030. Five scenarios developed within participatory backcasting project and a BAU scenario were analysed in terms of decarbonisation, energy security and energy efficiency using Long-range Energy Alternatives Planning System (LEAP). A final scenario "Efficiency for the green future" designed by the stakeholders for implementation in the city included high standards of energy efficiency in buildings, increased share of renewables in the heating energy mix, expanding the district heating system, deploying smart technologies and green architecture. The LEAP model demonstrated that this final scenario could lead to achievement of the desirable future vision developed by stakeholders for NB, through substantial improvements in energy efficiency and energy security, and to considerable emissions decreases by 2030 in comparison with the base year (2010) and the BAU scenario.

  • 1925. Zou, L.
    et al.
    Frampton, A.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Impacts of dead-ends on flow and transport in fractured rocks2018Inngår i: 2nd International Discrete Fracture Network Engineering Conference, DFNE 2018, American Rock Mechanics Association (ARMA) , 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Detailed simulation of flow and transport through a rough-walled fracture-matrix system with fracture dead-ends is performed. The analysis demonstrates a significant impact of fracture dead-ends on fluid flow and solute transport processes in the modelled system. Two 2D representative rock fracture-matrix models with and without fracture dead-ends are constructed based on high-resolution laser-scanned measurements of a granite rock fracture surface. Simulations of flow and transport with three Péclet numbers (Pe) ranging from 0.1 to 10 are conducted using a code implementing the finite volume method (FVM) to solve the Navier-Stokes equations (NSE) for water flow in the fracture, and the advection-diffusion equation (ADE) is adopted to solve for transport in the whole fracture-matrix system, also accounting for matrix diffusion. The features of the velocity fields and evolution of concentration distributions as well as breakthrough curves of the two modelled cases are presented and analyzed, with results showing that fracture dead-ends significantly affect solute transport processes and cause important retardation of transport in the fracture. This indicates that overly conservative assessments of solute mass arrivals may be made when fracture dead-ends are ignored in discrete fracture network modelling.

  • 1926.
    Zou, Liangchao
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Numerical modeling of fluid flow and solute transport in rock fractures2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This study focuses on numerical modeling of fluid flow and solute transport in rough-walled rock fractures and fracture-matrix systems, with the main aim to investigate the impacts of fracture surface roughness on flow and transport processes in rock fractures. Both 2D and 3D fracture models were built from laser-scanned surface tomography of a real granite rock sample, to consider realistic features of surface tomography and potential asperity contacts. The flow was simulated by directly solving the Navier-Stokes equations (NSE) and the transport was modeled by solving the advection-dispersion equation (ADE) in the entire domain of fracture-matrix system, including matrix diffusion process. Such direct simulations provided detailed flow and concentration fields for quantitatively analysis of flow and transport behavior. The detailed analysis of surface roughness decomposition, complex flow patterns (i.e., channeling, transverse and eddy flows), effective advective flow apertures, effective transmissivity, effective dispersivity, residence time, transport resistance and specific surface area demonstrated significant impacts of realistic fracture surface roughness on fluid flow and solute transport processes in rock fractures. The results show that the surface roughness and shear displacement caused asperity contacts significantly enhance nonlinearity and complexity of flow and transport processes in rough-walled fractures and fracture-matrix systems. The surface roughness also causes invasion flows in intersected fractures which enhance solute mixing at fracture intersections. Therefore, the fracture surface roughness is an important source of uncertainty in application of such simplified models like cubic law (CL) for fluid flow and analytical solutions for solute transport in rock fractures. The research conducted advances our understanding of realistic flow and transport processes in natural fractured rocks. The results are useful for model validation/extension, uncertainty analysis/quantification and laboratory experiments design in the context of various applications related to fracture flow and transport.

  • 1927.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik. KTH.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik. KTH.
    Modeling of advection-dominated transport in rough-walled rock fractures: a comparison of Reynolds and Navier-Stokes equationsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Statistical analysis of flow-dependent specific surface areas of a 3D rough-walled fracture-matrix system were presented in this paper, based on numerical simulations of fluid flow and advective particle transport. The aim is to investigate the flow-dependent solute transport quantities in natural fracture-matrix systems, and identify the potential uncertainty lie in the common used flow model (i.e., Reynolds equation) by comparing with the more realistic flow model(i.e., Navier-Stokes equations). The rough-walled fracture model was built from laser-scanned surface tomography of a real rock sample, by considering realistic features of surfaces roughness and asperity contacts. Based on the flow fields simulated by solving the Reynolds and Navier-Stokes equations, the advective transport was modeled through Lagrangian particle tracking. The controlling quantities of advective transport in fracture-matrix systems (i.e., residence time, transport resistance and specific surface area) were statistically analyzed and compared. The results generally show that fracture surface roughness and associated spatially variable apertures as well as shear caused asperity contacts significantly increase the heterogeneity of flow field in rough-walled fractures, which consequently affects the flow-dependent transport process. By comparison, the simplified flow model (i.e., Reynolds equation) may cause uncertainty in quantifying of the specific surface area for the realistic rough-walled fracture-matrix systems. To identify such uncertainty, it is important to obtain the more reliable flow fields by solving the NSE. The presented results are helpful in uncertainty quantification and risk assessment of solute transport in natural fractured rocks.

  • 1928.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Roughness decomposition and effects on fluid flow in single rock fractures2014Inngår i: ISRM International Symposium - 8th Asian Rock Mechanics Symposium, ARMS 2014, International Society for Rock Mechanics , 2014, s. 457-465Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The rock fractures usually consist of surfaces with different orders or scales of roughness, which have critical effects on the fluid flow behavior inside the fractures. In this paper, a two dimensional representative single rock fracture model was built, based on a laser scanned data of rock surface of granite. The surfaces roughness of the fracture was then quantitively decomposed into several levels of surface roughness by applying the wavelet analysis. A self-developed Finite Volume Method solver was then applied to solve the Navier-Stokes equations for numerical modelling of fluid flow in the fracture models formatted with four levels of decomposed roughness, respectively, with different Reynolds numbers varying from 0.001 to 1000.0. Then, the features of velocity profiles and the effective hydraulic apertures at each level of rough fractures decomposition and Reynolds numbers were calculated and analyzed. The results show that when the Reynolds number is small (less than 10.0), the effective hydraulic aperture slightly increase nearly linearly with the decomposed roughness levels. When the Reynolds number is large, the effective hydraulic apertures decrease dramatically, and the non-linear flow behaviors represented by expansion of the eddy flow regions caused by roughness: The larger extent of high-frequency roughness, the more obvious and complicate eddy flow regions yielded.

  • 1929.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Ivars, Diego Mas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Impact of Normal Stress Caused Closure on Fluid Flow and Solute Retention in Rock Fractures2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Modeling of coupled hydro-mechanical and chemical (HMC) processes in fractured rocks is an important topic for many geoengineering projects.  Over the past decades, many efforts have been devoted to study the flow and transport in single fractures with consideration of mechanical effects. It is generally known that the mechanical effects, i.e. normal and shear deformation, significantly affect fluid flow and solute transport processes in rough-walled rock fractures since the deformation may largely alter the structure of fracture apertures that directly controls transmissivity. Due to complicated physical processes combined with complexity of geometry structures, many issues remain open questions, such as fracture surface roughness characterization, deformation dependence of transmissivity and advective transport in natural rock fractures. In this work, we attempt to investigate the impact of stress caused closure on fluid flow and solute advective transport in a rough-walled fracture through numerical modeling.  A rough-walled fracture model is created based on a laser-scanned rock surface. The Bandis’s model is used to describe the fracture closure subject to normal stress. The flow is modeled by solving Reynolds equation and the advective transport is simulated through Lagrangian particle tracking. The results show that the normal stress caused fracture closure creates asperity contacts and reduces the mean aperture, which significantly reduces transmissivity, and affects the travel time and transport resistance. With increases of normal stress, the specific surface area reduces nonlinearly due to the nonlinear closure. In practice, especially for important hydrogeological projects, e.g. nuclear waste disposal, it is important to consider the coupled HMC processes in design and risk assessment.

  • 1930.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Håkansson, U.
    KTH.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Impacts of elastic jacking on rock grouting2018Inngår i: ISRM International Symposium - 10th Asian Rock Mechanics Symposium, ARMS 2018, International Society for Rock Mechanics , 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The injection pressure is an important design and operational parameter in rock grouting since it controls the grout penetration length and may cause harmful mechanical deformation of the rock mass, such as opening/dilation of the fractures, referred to as jacking. At present, modeling of rock grouting mainly relies on analytical models where the impact of jacking on the grout penetration in rock fractures is not considered. In this study, we present a hydro-mechanical coupled model for rock grouting in a single one-dimensional rock fracture, with consideration of jacking and two-phase flow, i.e. cement grout and groundwater. It assumes that the cement grouts are Bingham fluids and that the rock matrix is an elastic material. The fracture is simplified as a pair of smooth parallel plates. A finite element method (FEM) code is developed to iteratively solve the two-phase flow in the fracture and the elastic deformation of the rock matrix. Two cases with and without consideration of jacking are simulated and compared. The results generally show that jacking of fractures significantly affects the grout penetration in the fracture, which should be properly considered in modeling of rock grouting. This numerical model is able to describe more realistic physical processes in rock grouting, which can be used to estimate the optimal injection pressure in practice. 

  • 1931.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Håkansson, Ulf
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik. Skanska AB, Stockholm.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Cement grout propagation in 2D fracture networks: impact of rheology2019Inngår i: Proceedings in Earth and Geosciences: Rock Mechanics for Natural Resources and Infrastructure Development / [ed] Sergio A.B. da Fontoura, Ricardo Jose Rocca, José Pavón Mendoza, CRC Press, 2019, Vol. 6, s. 2486-2493Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Cement grouts propagation into a two-dimensional water-saturated fracture networks with different values of rheological properties are simulated by using an extended two-phase flow model. The cement grouts are typical non-Newtonian fluids that contain yield stress, which are often assumed as Bingham fluids. The aim of this study is to investigate the impact of Bingham rheological properties, i.e. yield stress and plastic viscosity, on cement gouts propagation in two-dimensional fracture networks. The results generally show that the rheological properties of cement grouts, i.e. yield stress and plastic viscosity, significantly affect cement grouts propagation in the fracture network. The propagation rate in the fracture networks reduces with the increase of the yield stress and the plastic viscosity of the cement grouts.

  • 1932.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Håkansson, Ulf
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Cement grout propagation in two-dimensional fracture networks: Impact of structure and hydraulic variability2019Inngår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 115, s. 1-10Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Analysis of cement grout propagation in water-saturated two-dimensional discrete fracture networks is presented in this study. A two-phase flow model for Bingham fluids flow in a single saturated fracture is extended to simulate cement grouts propagation in saturated networks. Using this extended model, the impacts of network structure and hydraulic variability, i.e., network geometry and aperture distribution, on the propagation process are investigated through numerical simulations. Cement grout propagation in 50 realizations of a two-dimensional discrete fracture network (2D DFN) are simulated with different cases of aperture variability, i.e. constant aperture, uncorrelated and length-correlated heterogeneous apertures following a truncated lognormal distribution. The results indicate that network structure and hydraulic variability significantly affect the grout propagation in 2D DFN systems. The randomized network structure and uncorrelated heterogeneous apertures significantly delay the propagation rate and largely increase the variability range of the propagation volume fraction. In contrast, in the case with length-correlated heterogeneous apertures, the propagation rate increases, while the variability range and rate of change of the propagation volume fraction decreases. The extended two-phase flow model for fracture networks and the simulation results presented in this work are useful for basic understanding of the processes relevant for design, monitoring and execution of rock grouting.

  • 1933.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Håkansson, Ulf
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap. Skanska AB, Stockholm.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Characterization of effective transmissivity for cement grout flow in rock fractures2019Inngår i: Proceedings of Nordic Grouting Symposium 2019, 2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Cement grouting has been widely used in rock engineering. Proper characterization of the effective transmissivity for cement grout flow in rock fractures is primarily important for the design of rock grouting. In practice, the hydraulic transmissivity of groundwater flow in rock fractures characterized by hydraulic tests, i.e., pumping or slug test, is often used for the design of rock grouting. However, cement grouts used in rock grouting practice are typical non-Newtonian fluids contain yield stress, which has different effective transmissivity from the Newtonian groundwater. Therefore, using the groundwater transmissivity characterized by hydraulic tests may cause significant uncertainty in modeling and design of cement rock grouting. In this study, we focus on the effective transmissivity of non-Newtonian cement grout flow in a single fracture, aiming to illustrate the difference between the effective transmissivity of non-Newtonian cement grouts and the hydraulic transmissivity of the Newtonian groundwater. The cement grout is assumed as a Bingham fluid. The theoretical solution for the effective transmissivity of Bingham grout for homogeneous fractures is presented. This solution is compared with the theoretical hydraulic transmissivity, i.e., the cubic law. The results generally illustrate the significant differences between the effective transmissivity of non-Newtonian cement grouts and the hydraulic transmissivity of groundwater. The effective transmissivity of non-Newtonian cement grout is nonlinear which a function of injection pressure. Using the hydraulic transmissivity for rock grouting may underestimate the propagation length of the cement grout in rock fractures. The obtained result is helpful for rock grouting design in practice to reduce the potential uncertainties caused by using the hydraulic transmissivity.

  • 1934.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Håkansson, Ulf
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Modeling of rock grouting in saturated variable aperture fractures2018Inngår i: Proceedings of Bergdagarna 2018., 2018, s. 79-87, artikkel-id 10Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Modeling and analysis of cement grouts flow in rock fractures is important in the design, execution and monitoring of grouting in fractured rocks. At present, modeling of rock grouting mainly relies on analytical models, e.g., the real time grouting control (RTGC) method. In the RTGC method, it is assumed that the rock fractures are consisting of smooth parallel plates or disks and water flow is neglected. However, in reality, the natural rock fractures are commonly consisting of complex rough-walled surfaces and are filled with groundwater; therefore, grouting is actually a multiphase (non-Newtonian grouts and groundwater) flow process in rough-walled rock fractures with variable apertures. In this study, we present an efficient one-dimensional (1D) numerical model for modeling of rock grouting in a single rock fracture with consideration of multiphase flow and variable apertures. It is assumed that the cement grouts are Bingham fluids and that the analytical solution for flowrate with a given pressure gradient in a pair of smooth parallel plates is locally applicable. A time-dependent advection equation is used to describe the interface (between the grout and groundwater) propagation. A finite element method (FEM) code is developed to iteratively solve the mass balance and the interface advection equations. The numerical simulations are compared with the RTGC method. It generally shows that water flow significantly affect grouts penetration in the fracture, especially for the grouts with relatively lower viscosity. The variable aperture significantly postpones the penetration process compared with that of constant aperture. This numerical model is able to describe more realistic physical processes and geometry conditions in rock grouting, which can be readily used in practice to reduce the potential uncertainties in application of simplified analytical models.

  • 1935.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Håkansson, Ulf
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Non-Newtonian fluid flow in 2D fracture networks2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Modeling of non-Newtonian fluid (e.g., drilling fluids and cement grouts) flow in fractured rocks is of interest in many geophysical and industrial practices, such as drilling operations, enhanced oil recovery and rock grouting. In fractured rock masses, the flow paths are dominated by fractures, which are often represented as discrete fracture networks (DFN). In the literature, many studies have been devoted to Newtonian fluid (e.g., groundwater) flow in fractured rock using the DFN concept, but few works are dedicated to non-Newtonian fluids.In this study, a generalized flow equation for common non-Newtonian fluids (such as Bingham, power-law and Herschel-Bulkley) in a single fracture is obtained from the analytical solutions for non-Newtonian fluid discharge between smooth parallel plates. Using Monte Carlo sampling based on site characterization data for the distribution of geometrical features (e.g., density, length, aperture and orientations) in crystalline fractured rock, a two dimensional (2D) DFN model is constructed for generic flow simulations. Due to complex properties of non-Newtonian fluids, the relationship between fluid discharge and the pressure gradient is nonlinear. A Galerkin finite element method solver is developed to iteratively solve the obtained nonlinear governing equations for the 2D DFN model. Using DFN realizations, simulation results for different geometrical distributions of the fracture network and different non-Newtonian fluid properties are presented to illustrate the spatial discharge distributions. The impact of geometrical structures and the fluid properties on the non-Newtonian fluid flow in 2D DFN is examined statistically. The results generally show that modeling non-Newtonian fluid flow in fractured rock as a DFN is feasible, and that the discharge distribution may be significantly affected by the geometrical structures as well as by the fluid constitutive properties.

  • 1936.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Håkansson, Ulf
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik. Skanska AB .
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Non-Newtonian grout flow in single rough-walled rock fractures2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Modeling of cement grout flow in rock fractures plays an important role in the design of rock grouting. Cement grouts used in rock grouting practice are typical non-Newtonian fluids containing yield stress, and are often assumed as Bingham fluids. Natural rock fractures typically consist of rough surfaces. Therefore, in reality, rock grouting process actually involves non-Newtonian fluid flow in rough-walled fractures, which is rarely studied in the literature. In this work, we focus on the impact of surface roughness and present direct numerical simulations of non-Newtonian grouts flow in single rough-walled fractures, using a regularized method to approximate the yield-stress. The rough-walled rock fracture models are created from a laser-scanned surface of a granite rock sample, to represent realistic features of natural rock fractures. The numerical results generally show nonlinear behaviors of non-Newtonian fluid flow in rough-walled fractures. The surface roughness significantly reduces the effective transmissivity when Reynolds number is relatively large. The obtained result can be used for upscaling analysis in practice, in order to reduce the potential uncertainties caused by the surface roughness of the rock fractures.

    Fulltekst tilgjengelig fra 2020-01-01 23:22
  • 1937.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Håkansson, Ulf
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Two-phase cement grout propagation in homogeneous water-saturated rock fractures2018Inngår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 106, s. 243-249Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Modeling of cement grout flow in rock fractures is important for the design, monitoring and execution of rock grouting that is widely used in a variety of rock engineering applications. This study presents a mathematical model based on the Reynolds flow equation for cement grout flow in a homogeneous water-saturated rock fracture. The model is based on two-phase flow, i.e. grout as a Bingham fluid and groundwater as a Newtonian fluid, and is used for investigating the importance of the water phase in rock grouting. The modeling results for the two-phase flow generally show the importance of the water phase that can significantly affect the pressure distribution and grout penetration in the fracture, especially under the condition of grout hardening. Such effects depend on the viscosity ratio between the grout and groundwater, which becomes increasingly important for cases with smaller values of the viscosity ratio. The grout density also affects the grout penetration length. Applying an analytical solution based on single-phase flow, i.e. neglecting the impact of groundwater flow, for modeling grout injection, will generally overestimate the penetration length.

  • 1938.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Smoothed particle hydrodynamics simulation of fluid flow in rock fractures2013Inngår i: Rock Characterisation, Modelling and Engineering Design Methods: Proceedings of the 3rd ISRM SINOROCK 2013 Symposium, 2013, s. 437-443Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The process of fluid flow in rock fractures involves complicated dynamical behavior of fluids,and its modeling is a challenge to numerical methods. In this paper, the Smoothed Particle Hydrodynamics(SPH), a particle method based on Lagrangian formulation, is employed to simulate the fluid flow in rockfractures by solving the Navier-Stokes equations directly. Firstly, the SPH method and the boundary treatmentmethod used in this simulation were introduced and the computer code of SPH was developed and validated bya series of numerical benchmark tests with analytical solutions. Then simulations were carried out to investigatethe fluid flow both in single fractures and intersected fractures, with and without considering effects of surfaceroughness. The results of the simulations are discussed and compared with the analytical solution by using theCubic law derived from the Reynolds equation. The results show that in both of rough single fractures andfracture intersections, although the relationship between mean velocity and the Reynolds number is still linear,the solutions by using Cubic law overestimated the mean fluid velocity with increasing the Reynolds number,indicating possible underestimate of travel time of mass transport in the fracture network models.

  • 1939.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Assumptions of the analytical solution for solute transport in a fracture-matrix system2016Inngår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 83, s. 211-217Artikkel i tidsskrift (Fagfellevurdert)
  • 1940.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Effect of sorption on solute transport in a single rough rock fracture2017Inngår i: 13th ISRM International Congress of Rock Mechanics, International Society for Rock Mechanics , 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Sorption process plays a significant role for solute retardation in rock fractures. In this paper, for the aim to investigate the effect of sorption on solute transport in a single rough fracture, a 2D model of representative single rock fracture was built and its roughness was statistically characterized based on the measured data of rock surface topography by laser scanning. A Finite Volume Method (FVM) code was developed to solve the Navier-Stokes (NS) equations and transport equation for numerical modelling the process of fluid flow and solute transport in the rock fracture model. Two groups of simulations were conducted: with and without the consideration of the sorption process with different average flow velocities. The results show that the surface roughness increased the complexities of flow fields, and the non-linear sorption process plays a significant role in the retardation of solute transport through rock fractures. The sorption process caused an obvious lagging time in both the solute concentration fields (plumes) and corresponding breakthrough curves. This lagging time increases with the distance from the inlet boundary, and relatively decreases with the increase of mean velocities.

  • 1941.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Effects of multi-level surface roughness on solute transport in single rock fractures2016Inngår i: The proceeding of International Symposium on Reducing Risks in Site Investigation, Modeling and Construction for Rock Engineering, 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Natural rock fractures are consisted of complicate rough surfaces with multi-level surface roughness which causes significant uncertainties in fluid flow and solute transport be-haviors through fractured rocks. In this study, for the aim of investigation the effects of multi-level surface roughness on fluid flow and solute transport in rock fractures, a single rough-walled fracture model was built from a scanned granite rock surface, which was then gradually decomposed and characterized by wavelet analysis and statistics. A verified finite volume method (FVM) code was used to simulate fluid flow and solute transport in the rough fracture models by solving the Navier-Stokes equations (NSE) and advection-dispersion equation (ADE). The simulation results of nonlinear flow and solute breakthrough curves (BTCs) showed that the multi-level surface roughness strongly correlated with the Eddy flows and the solute non-Fickian transport behaviors, represented by the changes of effective advective flow apertures and an empirical function of the BTCs. The results would improve our understanding of solute transport in fractured rocks and may help to reduce the uncertainties and risks in related engi-neering practices.

  • 1942.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Effects of Sorption on Solute Transport in a Single Rough Rock Fracture2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The sorption process plays a significant role in the retardation of solute transport through the fractures. In this paper, based on the measured data of rock surfaces by laser scanning, a 2D geometry model of a representative single rock fracture was built and its roughness was statistically characterized, and a Finite Volume Method (FVM) code was developed and applied to solve the NS equation and transport equation for numerical modelling the process of fluid flow and solute transport. Two groups of simulation were then calculated: with and without the consideration of the sorption process, with different average flow velocities. The effects of sorption on the solute transport process were then analyzed, discussed and followed by concluding remarks on the sorption impact on the understanding of mass transport process in fractured rock masses.

  • 1943.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik. KTH.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik. KTH.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik. KTH.
    Invasion flow enhanced solute mixing at rough-walled rock fracture intersectionsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The processes of fluid flow and solute transport through rock fractures are of primary importance in environmental engineering and geosciences. This study presented numerical modeling results of fluid flow and solute transport in a 3D rock fracture-matrix system with an orthogonal intersection of two rough-walled rock fractures. The rough-walled fracture geometry models were built from laser-scanned data of a real rock surface, for a realistic representation of natural rock fracture surface roughness. The fluid flow in the two intersected fractures and solute transport in the fracture-matrix system were simulated by solving the Navier-Stokes equations (NSE) and transport equation in the entire system. The dependence of mixing on Péclet number (Pe), flow directionality and interaction with matrix diffusion were analyzed. The results showed important invasion flow patterns that significantly enhanced the solute mixing process, which cannot be described by traditional complete mixing and streamline routing models. It also cannot be simulated by simplified 2D geometry models ignoring the surface roughness as widely used in previous published studies. The finding of invasion flow and associated impacts on mixing in this study is particularly important in prediction of solute transport in natural fractured rocks, especially when discrete fracture network (DFN) approach is applied.

  • 1944.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Modeling of flow and mixing in 3D rough-walled rock fracture intersections2017Inngår i: Advances in Water Resources, ISSN 0309-1708, E-ISSN 1872-9657, Vol. 107, s. 1-9Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The processes of fluid flow and solute transport through rock fractures are of primary importance in environmental engineering and geosciences. This study presented numerical modeling results of fluid flow and solute transport in a 3D rock fracture-matrix system with an orthogonal intersection of two rough-walled rock fractures. The rough-walled fracture geometry models were built from laser-scanned data of a real rock surface, for a realistic representation of natural rock fracture surface roughness. The fluid flow in the two intersected fractures and solute transport in the fracture-matrix system were simulated by solving the Navier–Stokes equations (NSE) and transport equation in the entire system. The dependence of mixing on Péclet number (Pe) and flow directionality features were analyzed. The results directly visualized important channeling flow patterns that significantly enhanced the solute mixing process at the rough-walled fracture intersection. The illustrated channeling flow and associated impacts on mixing are particularly important in the prediction of solute transport in natural fractured rocks, especially when discrete fracture network (DFN) approach is applied.

  • 1945.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Modeling of Solute Transport in a 3D Rough-Walled Fracture-Matrix System2017Inngår i: Transport in Porous Media, ISSN 0169-3913, E-ISSN 1573-1634, Vol. 116, nr 3, s. 1005-1029Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fluid flow and solute transport in a 3D rough-walled fracture-matrix system were simulated by directly solving the Navier-Stokes equations for fracture flow and solving the transport equation for the whole domain of fracture and matrix with considering matrix diffusion. The rough-walled fracture-matrix model was built from laser-scanned surface tomography of a real rock sample, by considering realistic features of surfaces roughness and asperity contacts. The numerical modeling results were compared with both analytical solutions based on simplified fracture surface geometry and numerical results by particle tracking based on the Reynolds equation. The aim is to investigate impacts of surface roughness on solute transport in natural fracture-matrix systems and to quantify the uncertainties in application of simplified models. The results show that fracture surface roughness significantly increases heterogeneity of velocity field in the rough-walled fractures, which consequently cause complex transport behavior, especially the dispersive distributions of solute concentration in the fracture and complex concentration profiles in the matrix. Such complex transport behaviors caused by surface roughness are important sources of uncertainty that needs to be considered for modeling of solute transport processes in fractured rocks. The presented direct numerical simulations of fluid flow and solute transport serve as efficient numerical experiments that provide reliable results for the analysis of effective transmissivity as well as effective dispersion coefficient in rough-walled fracture-matrix systems. Such analysis is helpful in model verifications, uncertainty quantifications and design of laboratorial experiments.

  • 1946.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik. KTH.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik. KTH.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik. KTH.
    Modeling of solute transport in a 3D rough-walled fracture-matrix systemManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Fluid flow and solute transport in a 3D rough-walled fracture-matrix system was simulated by directly solving the Navier-Stokes equations for fracture flow and solving the transport equation for the whole domain of fracture and matrix with considering matrix diffusion. The rough-walled fracture-matrix model was built from laser-scanned surface tomography of a real rock sample, by considering realistic features of surfaces roughness and asperity contacts. The numerical modeling results were compared with both analytical solutions based on simplified fracture surface geometry and numerical results by particle tracking based on the Reynolds equation. The aim is to investigate impacts of surface roughness on solute transport in natural fracture-matrix systems, and to quantify the uncertainties in application of simplified models. The results show that fracture surface roughness significantly increases heterogeneity of velocity field in the rough-walled fractures, which consequently cause complex transport behavior, especially the dispersive distributions of solute concentration in the fracture and complex concentration profiles in the matrix. Such complex transport behavior caused by surface roughness are important sources of uncertainty that needs to be considered for modeling of solute transport processes in fractured rocks. The presented direct numerical simulations of fluid flow and solute transport serve as efficient numerical experiments that provide reliable results for the analysis of effective transmissivity as well as effective dispersion coefficient in rough-walled fracture-matrix systems. Such analyses are helpful in model verifications, uncertainty quantifications and design of laboratorial experiments.

  • 1947.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Roughness decomposition and nonlinear fluid flow in a single rock fracture2015Inngår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 75, s. 102-118Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objective of this paper is to investigate the effects of wall surface roughness on fluid flow through rock fractures. A wavelet analysis technique was developed to define a mathematical criterion for decomposing the original wall surface roughness profiles of a fracture into a high-frequency (secondary roughness) profile and a low-frequency (primary roughness) profile, in order to examine their impacts on fluid flow, by solving the Navier-Stokes equations (NSE) without linearization, using a self-developed 2D finite volume method (FVM) code. The results indicate that the high-frequency secondary roughness is the main cause for dynamic evolution of Eddy flow regions in the fracture flow field, besides the Reynolds number (Re). In the original fracture model with the high-frequency secondary roughness, our results show that fluid flow fields are not only generally non-linear, but also with non-stop generation and motions of eddies in the boundary layer regions of rough fractures when the Re = 1000 in this study, which will affect the solute transport processes in fractured rock masses. The complete NSE were solved without removing acceleration and inertial terms, so that the impacts of surface roughness on the nonlinear and dynamic flow behavior of rock fractures were calculated and visualized more accurately, which is important for modeling mass and energy transport processes in fractures and fractured rock masses.

  • 1948.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik. KTH.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Shear enhanced nonlinear flow in rough-walled rock fracturesManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Nonlinear flow in 3D rough-walled rock fracture models are simulated by solving the Navier-Stokes equations in this paper. The emphasis is on the impacts of shear caused aperture changes (variable apertures and asperity contacts) and flow conditions (inertial term) upon nonlinear flow behaviors in 3D rough-walled rock fractures. In order to compare shear effects, two 3D fracture models, with and without shear process, were established with the identical initial rough-walled surfaces tomography of a realistic rock sample. Five groups of simulations with different inflow boundary conditions of flowrates/Reynolds numbers (Re) were conducted to demonstrate shear enhanced nonlinearity of flow fields and limitations of local cubic law (LCL) approach. The flow results clearly show channeling flow along the preferential fluid paths, transverse flow around the contact spots and eddy flows behind contact spots with increasing Re numbers, which cannot be observed in 2D models. The effective transmissivity of the 3D fracture model was calculated from the modeling results of velocity and pressure fields. The results showed that the effective transmissivity is a function of local apertures with important uncertainties even when Re is small (i.e. Re = 0.4 in this study), thus the validity of the transmissivity evaluation using LCL approach for nonlinear flow in 3D rough-walled rock fractures is questionable. The mechanical effects, i.e. stress and shear caused aperture space changes and asperity contacts should be considered for modeling flow and mass/energy transport processes in rough-walled fractures in 3D.

  • 1949.
    Zou, Liangchao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Resurser, energi och infrastruktur.
    Shear-enhanced nonlinear flow in rough-walled rock fractures2017Inngår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 97, s. 33-45Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nonlinear flow in 3D rough-walled rock fractures is simulated by solving the Navier-Stokes equations. The emphasis is on the impact of shear-caused aperture changes (variable apertures and asperity contacts) and flow conditions (inertial term) upon nonlinear flow behavior. In order to compare shear effects, two 3D fracture models, with and without shear, were established with identical initial rough-walled surfaces topographies of a realistic rock sample. Five groups of simulations with different inflow boundary conditions of flowrates/Reynolds numbers (Re) were conducted to demonstrate shear-enhanced nonlinearity of flow fields and limitations of local cubic law (LCL) approach. The flow results clearly show channeling flow along the preferential paths, transverse flow around the contact spots, and eddy flows behind contact spots with increasing Re, which cannot be observed in 2D models. The effective transmissivity of the 3D fracture model was calculated from the modeling results of velocity and pressure fields. The results showed that the effective transmissivity is a function of local apertures with important uncertainties even when Re is small (i.e. Re = 0.4 in this study), thus the validity of the transmissivity evaluation using LCL approach for nonlinear flow in 3D rough-walled rock fractures is questionable.

  • 1950.
    Zuo, Minyu
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Enhanced phosphorus removal from wastewater using virgin and modified slags: performance, speciation and mechanisms2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Argon oxygen decarburization slag (AOD) was tested in batch and column experiments to investigate its phosphorus (P) removal performance. The effects of factors such as AOD dose, initial P concentration of the feeding solution, and aging on the P removal ability of the slags were analyzed. In a column experiment, electric arc furnace slag (EAF), blast furnace slag (BFS) and AOD were combined in five different ways to determine optimal conditions for P removal. In another column experiment, the three types of slag were modified with polyethylene glycol (PEG) and NaOH to adjust their dissolution properties and the effect on P removal performance was examined. In the batch experiments, AOD exhibited very promising P removal ability. It removed 94.8% of P from 6.5 mg P L-1 synthetic solution in 4 hours with a dose of 5 g L-1. Maximum P removal capacity of 27.5 mg P g-1 was achieved. In the dual-filter column experiment, the column packed with only EAF had the best P removal performance (consistently above 93%). Amorphous calcium phosphate (ACP) was identified as the main P species in the five slag samples collected from the outlet chambers. The contributions from crystalline calcium phosphate (Ca-P) and P adsorbed on iron/aluminum (hydr)oxides were greater in samples from the inlet chambers. The P speciation results revealed that P was predominantly removed by the slags through formation of ACP. The second column experiment showed that modification with PEG and NaOH solution only enhanced short-term P removal by the slags. However, exhaustion of the modified slags occurred much earlier, indicating that the modification process had shortened the lifespan of the slags. Untreated AOD showed better P removal than untreated EAF until pore volume 244, probably due to faster dissolution rate of gamma dicalcium silicate (dominating in AOD according to the XRD results) than of beta dicalcium silicate (dominating in EAF).

3637383940 1901 - 1950 of 1965
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