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  • 1.
    Renman, Agnieszka
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    Renman, Gunno
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    Kholoma, Ezekiel
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    Zhang, Wen
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    Leachability and plant -availability of phosphorus in post-sorption wastewater filters fortified with biochar2018In: Environmental technology, ISSN 0959-3330, E-ISSN 1479-487XArticle in journal (Refereed)
    Abstract [en]

    Sand and gravel are widely applied for filtering pre- or primary-treated wastewater in small-scale wastewater treatment (SWT) systems. However, ecological materials continue to attract increasing interest in use as retrofits for achieving better performance in removing dissolved contaminants and recovering nutrients from wastewater. In this study, we assessed the plant availability and leachability of phosphorus (P) from sand (Sa) and gas concrete (GC) media previously fortified with biochar (BC) and used for phosphorus (P) removal in laboratory-scale packed bed reactors and field-scale constructed filter beds. Batch and leaching experiments were conducted, with distilled water and ammonium lactate (AL) solutions (1:20 solid–liquid (w/v) ratio) applied as extractants. In the findings, reference (Sa) and fortified (Sa-BC) sand filters leached 11.2 and 20.5 mg P kg−1 respectively, to percolating water while the P seemed less likely to leach from GC systems. Extraction with AL showed that P retained in GC was plant-available and that GC could release up to 90 mg kg−1 of the bound mass. These findings highlight the need to evaluate risks of nutrient leaching from filter media for SWT systems especially where groundwater and surface water are final recipients of such effluents. For greater sustainability of use of the media, the weakly bound P in media such as Sa and BC and strongly bound in media such as GC types of materials may be recovered by recycling the spent material to agriculture. However, this may require re-design of the treatment system especially with respect to particle size to make recycling technically feasible.

  • 2.
    Rostvall, Ande
    et al.
    Dept. of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
    Zhang, Wen
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Dürig, W.
    Dept. of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
    Renman, Gunno
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    Wiberg, Karin
    Dept. of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
    Ahrens, Lutz
    Dept. of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
    Gago-Ferrero, Pablo
    Dept. of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
    Removal of pharmaceuticals, perfluoroalkyl substances and other micropollutants from wastewater using lignite, Xylit, sand, granular activated carbon (GAC) and GAC+Polonite® in column tests – Role of physicochemical properties2018In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 137, p. 97-106Article in journal (Refereed)
    Abstract [en]

    This study evaluated the performance of five different sorbents (granular activated carbon (GAC), GAC + Polonite® (GAC + P), Xylit, lignite and sand) for a set of 83 micropollutants (MPs) (pharmaceuticals, perfluoroalkyl substances (PFASs), personal care products, artificial sweeteners, parabens, pesticide, stimulants), together representing a wide range of physicochemical properties. Treatment with GAC and GAC + P provided the highest removal efficiencies, with average values above 97%. Removal rates were generally lower for Xylit (on average 74%) and lignite (on average 68%), although they proved to be highly efficient for a few individual MPs. The average removal efficiency for sand was only 47%. It was observed that the MPs behaved differently depending on their physicochemical properties. The physicochemical properties of PFASs (i.e. molecular weight, topological molecular surface area, log octanol water partition coefficient (Kow) and distribution coefficient between octanol and water (log D)) were positively correlated to observed removal efficiency for the sorbents Xylit, lignite and sand (p < 0.05), indicating a strong influence of perfluorocarbon chain length and associated hydrophobic characteristics. In contrast, for the other MPs the ratio between apolar and polar surface area (SA/SP) was positively correlated with the removal efficiency, indicating that hydrophobic adsorption may be a key feature of their sorption mechanisms. GAC showed to be the most promising filter medium to improve the removal of MPs in on-site sewage treatment facilities. However, more studies are needed to evaluate the removal of MPs in field trials.

  • 3.
    Zhang, Wen
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    An add-on filter technique to improve micropollutant removal and water quality in on-site sewage treatment facilities2018Doctoral thesis, comprehensive summary (Other academic)
    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.

  • 4.
    Zhang, Wen
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Removal of micropollutants and nutrients using filter beds for on-site sewage treatment – column and field experiments2017Conference paper (Other academic)
    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.

  • 5.
    Zhang, Wen
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Screening of different types of on-site sewage facilities - treatment function and potential for removing micropollutants2016Conference paper (Other academic)
    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.

  • 6.
    Zhang, Wen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    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, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Industrial Biotechnology.
    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, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Evaluation of five filter media in column experiment on the removal of selected organic micropollutants and phosphorus from household wastewater2019In: Journal of Environmental Management, ISSN 0301-4797, E-ISSN 1095-8630, Vol. 246, p. 920-928Article in journal (Refereed)
    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.

  • 7.
    Zhang, Wen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Renman, Gunno
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    Removal of 31 organic micropollutants and phosphorus by filter media in a column experiment using household wastewaterManuscript (preprint) (Other academic)
    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.

  • 8.
    Zhang, Wen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Renman, Gunno
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    Removal of micropollutants and nutrients in household wastewater using organic and inorganic sorbentsIn: Desalination and Water Treatment, ISSN 1944-3994, E-ISSN 1944-3986Article in journal (Refereed)
    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%).

  • 9.
    Zhang, Wen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Renman, Gunno
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    Wastewater purification and removal of micropollutants in a soiltreatment system and by subsequent filtration through activatedcarbon and xyloid lignite – a field experimentManuscript (preprint) (Other academic)
    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%. 

  • 10.
    Zhang, Wen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Termida, Nursitihazlin Ahmad
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport Planning, Economics and Engineering.
    Susilo, Yusak O.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, System Analysis and Economics.
    What construct one's familiar area?: A quantitative and longitudinal study2019In: Environment and Planning B: Urban Analytics and City Science, ISSN 2399-8083, Vol. 46, no 2, p. 322-340Article in journal (Refereed)
    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.

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