| 1. |
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| 2. |
- Sylwan, Ida, 1984-, et al.
(författare)
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Heavy metal sorption by sludge-derived biochar with focus on Pb2+ sorption capacity at µg/L concentrations
- 2020
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Ingår i: Processes. - : MDPI AG. - 2227-9717. ; 8:12, s. 1-23
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Tidskriftsartikel (refereegranskat)abstract
- Municipal wastewater management causes metal exposure to humans and the environment. Targeted metal removal is suggested to reduce metal loads during sludge reuse and release of effluent to receiving waters. Biochar is considered a low-cost sorbent with high sorption capacity for heavy metals. In this study, heavy metal sorption to sludge-derived biochar (SDBC) was investigated through batch experiments and modeling and compared to that of wood-derived biochar (WDBC) and activated carbon (AC). The aim was to investigate the sorption efficiency at metal concentrations comparable to those in municipal wastewater (<1 mg/L), for which experimental data are lacking and isotherm models have not been verified in previous works. Pb2+ removal of up to 83% was demonstrated at concentrations comparable to those in municipal wastewater, at pH 2. SDBC showed superior Pb2+ sorption capacity (maximum ~2 mg/g at pH 2) compared to WDBC and AC (<0 and (3.5 ± 0.4) × 10−3 mg/g, respectively); however, at the lowest concentration investigated (0.005 mg/L), SDBC released Pb2+. The potential risk of release of other heavy metals (i.e., Ni, Cd, Cu, and Zn) needs to be further examined. The sorption capacity of SDBC over a metal concentration span of 0.005–150 mg Pb2+/L could be predicted with the Redlich– Peterson model. It was shown that experimental data at concentrations comparable to those in municipal wastewater are necessary to accurately model and predict the sorption capacity of SDBC at these concentrations.
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| 3. |
- Sylwan, Ida, et al.
(författare)
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Primary and digested sludge-derived char as a Cd sorbent : Feasibility of local utilisation
- 2023
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 88:11, s. 2917-2930
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Tidskriftsartikel (refereegranskat)abstract
- Cadmium (Cd) is a highly toxic metal, occurring in municipal wastewater and stormwater as well as in wastewater from various industries. Char derived from the pyrolysis of municipal sewage sludge has the potential to be a low-cost sorption media for the removal of Cd. However, the balance between possible local char production and demand has not been assessed previously. In this study, the Cd sorption capacities of chars derived from primary (PSC) and secondary sludge (DSC), as well as the feasibility of char production for Cd sorbent purposes, and the pyrolysis energy balance were evaluated. Results showed that the sorption capacity of PSC (9.1 mg/g; 800 C, 70 min) was superior to that of DSC (6.0 mg/g; 800 C, 70 min), and increased with a higher pyrolysis temperature. Pyrolysis of primary sludge had a more favourable energy balance compared with the pyrolysis of digested sludge; however, when accounting for loss of biogas production the energy balance of primary sludge pyrolysis was negative. Assessment of the regional demand (Västeras, Sweden) indicated that PSC or DSC may cover the local Cd sorbent demand. However, it was estimated that large char volumes would be required, thus making the use of DSC/PSC less feasible.
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| 4. |
- Sylwan, Ida, 1984-
(författare)
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Sludge-derived char : utilisation as a metal sorbent in dilute wastewaters
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Metal concentrations in soil and water have increased since the Industrial Revolution, which may have negative health and environmental effects. Metal pollution occurs, for instance, in municipal wastewater, industrial wastewater, and stormwater. Concentrations are often low, due to dilution. A common technology for metal removal is sorption. Char produced from pyrolysis of municipal sludge (SDC), has been pointed out as a potential low-cost sorbent. However, the scientific literature mainly focuses on experiments using artificial solutions at concentrations much higher than those found in said wastewaters (in a Swedish context). The goal of this study was to investigate SDC use for the removal of metals, focusing on reuse of SDC in primary treatment (PT) of municipal wastewater and with some attention to other applications. The investigation was performed through experimental laboratory studies, modelling, and literature review/assessment. The data obtained from the literature review indicated that sorption is suitable for enhancing removal of nickel (Ni), copper (Cu), cadmium (Cd), lead (Pb), and zinc (Zn) during PT. With respect to Ni and Cu; from ~7–50% and ~10–70%, respectively (no SDC), to ~65–98% and ~45–85%, respectively (with SDC). Experimental results showed that SDC could remove >95% of Pb, Cd, Cu, Cr, Ni, Hg, and Ag from artificial solution, at concentrations similar to those in raw municipal wastewater. However, sorption of Cu and Ni was inhibited in real wastewater (a decrease from >99 and 99%, respectively, to 68 and 40% respectively). The inhibition was linked to the presence of dissolved organic matter. Modelling, based on raw wastewater composition indicated that SDC addition in PT may enhance the removal of Cd and Cu (from 39% to 79% and 30 % to 43%, respectively). Experiments showed that the investigated SDC had a larger Pb sorption capacity, compared to activated carbon and wood-derived char. Experimental investigations and modelling (sorption isotherms) indicated that literature data did not give satisfactory estimations of the Pb sorption capacity onto SDC at concentrations considered; the available data was generally valid for much higher concentrations. The experimentally determined Cd sorption capacity of SDC produced from primary sludge exceeded that of SDC produced from digested sludge. However, given the loss of biogas production the theoretical energy balance of primary sludge pyrolysis was negative. Finally, the local demand for Cd-sorbent in the Västerås region could potentially be covered by the SDC generated locally.
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| 5. |
- Xie, Y., et al.
(författare)
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A critical review on production, modification and utilization of biochar
- 2022
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Ingår i: Journal of Analytical and Applied Pyrolysis. - : Elsevier B.V.. - 0165-2370 .- 1873-250X. ; 161
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Tidskriftsartikel (refereegranskat)abstract
- There has been an increased interest in the production of sustainable biochar in the past years, as biochar shows versatile physicochemical properties and, can have a wide applicability in diverse fields. Comprehensive studies have been made to characterize biochar produced from various biomass materials, using different production technologies and under different process conditions. However, research is still lacking in correlating biochar properties needed for certain applications with (i) feedstock, (ii) biochar production processes and conditions and (iii) biochar upgrading and modification strategies. To produce biochar with desired properties, there is a great need to establish and clarify such correlations, which can guide the selection of feedstock, tuning and optimization of the production process and more efficient utilization of biochar. On the other hand, further elucidation of these correlations is also important for biochar-stakeholder and end-users for predicting physiochemical properties of biochar from certain feedstock and production conditions, assessing potential effects of biochar utilization and clearly address needs towards biochar critical properties. This review summarizes a wide range of literature on the impact of feedstocks and production processes and reactions conditions on the biochar properties and the most important biochar properties required for the different potential applications. Based on collected data, recommendations are provided for mapping out biochar production for different biochar applications. Knowledge gaps and perspectives for future research have also been identified regarding the characterization and production of biochar.
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| 6. |
- Envall, Ida, et al.
(författare)
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Existing evidence related to soil retention of phosphorus from on-site wastewater treatment systems in boreal and temperate climate zones : a systematic map
- 2023
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Ingår i: Environmental Evidence. - : Springer Nature. - 2047-2382. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: In Sweden there are nearly one million soil-based on-site wastewater treatment systems (OWTSs). OWTSs may contribute to eutrophication of surface waters, due to the discharge of phosphorus (P). Hence, in certain cases, a high P removal rate (up to 90%) of OWTSs is required by Swedish authorities. Since these requirements may have costly consequences to property owners, it is debated whether they are too strict. In this debate, it is often claimed that the soil retention of P occurring in the natural environments may be underestimated by authorities. Soil retention is the inhibition of the transport of P through the ground, due to different chemical, physical and biological processes occurring there. These processes make the P transport slower, which may reduce the unwanted impact on receiving water bodies. However, the efficiency of soil retention of P remains unclear. The objective of this systematic map was to collect, code, organise and elucidate the relevant evidence related to the topic, to be able to guide stakeholders through the evidence base, and to support future research synthesising, commissioning, and funding. The systematic map was carried out in response to needs declared by the Swedish Agency for Marine and Water Management but the conclusions should be valid for a wider range of countries across boreo-temperate regions.Methods: Searches were made for peer-reviewed and grey literature using bibliographic databases, search engines, specialist websites, and stakeholder contacts. The references were screened for relevance according to a predefined set of eligibility criteria. A detailed database of the relevant studies was compiled. Data and metadata that enable evaluation and discussion of the character and quality of the evidence base were extracted and coded. Special focus was placed on assessing if existing evidence could contribute to policy and practice decision making. Descriptive information about the evidence base was presented in tables and figures. An interactive evidence atlas and a choropleth were created, displaying the locations of all studies.Review findings: 234 articles out of 10,797 screened records fulfilled the eligibility criteria. These articles contain 256 studies, performed in the field or in the laboratory. Six different study types were identified, based on where the measurements were conducted. Most studies, including laboratory studies, lack replicates. Most field studies are observational case studies.Conclusions: It is not possible to derive valid generic measures of the efficiency of soil retention of P occurring in the natural soil environment from available research. Neither does the evidence base allow for answering the question of the magnitude of the potential impact of OWTSs on the P concentration in recipients on a general basis, or under what conditions OWTSs generally have such an impact. A compilation of groundwater studies may provide examples of how far the P may reach in x years, but the number of groundwater studies is insufficient to draw any general conclusions, given the complexity and variability of the systems. Future research should strive for replicated study designs, more elaborate reporting, and the establishment of a reporting standard.
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| 7. |
- Envall, Ida, et al.
(författare)
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What evidence exists related to soil retention of phosphorus from on-site wastewater treatment systems in boreal and temperate climate zones? : A systematic map protocol
- 2020
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Ingår i: Environmental Evidence. - : BMC. - 2047-2382. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Background Soil-based on-site wastewater treatment systems (OWSs) are suspected to contribute to eutrophication of surface waters, due to the discharge of phosphorus (P). However, along the flow path between the facilities and surface waters, different processes contribute to delay the transport of phosphorus through the ground. This may reduce the unwanted impact on receiving water bodies. However, the strength and significance of this so-called soil retention remains unclear. In Sweden, there are nearly one million OWSs. To protect surface waters, a high P removal rate (up to 90%) is often required by the local municipalities. However, since these requirements may have costly consequences to property owners, it is debated as to whether they are too strict. In this debate, it is often claimed that the retention of P occurring in natural environments may be underestimated by authorities. Accordingly, there is a need for a scrutiny of the available evidence related to soil retention of phosphorus from OWSs. This is the objective of the planned systematic map. Focus will be on boreal and temperate climate zones. Methods Searches will be made for peer-reviewed articles and grey literature using bibliographic databases, search engines, specialist websites and stakeholder contacts. The references will be screened for relevance according to a predefined set of eligibility criteria. At stage one, after testing and clarifying the eligibility criteria, the references will be single-screened based on title and abstract. At stage two, potentially relevant references will be screened in full-text independently by two reviewers. We will compile a detailed database of the relevant studies. Moreover, a narrative report will be produced, describing the research landscape in general terms. This will be carried out with a conceptual model, describing the processes involved in P retention in natural environments, as a foundation. It will be discussed where the respective studies/study types fit into the conceptual model, and also evaluated how each study/study type can be related to the overarching question of eutrophication. Moreover, we will describe identified knowledge gaps that warrant further primary research effort, as well as identified knowledge clusters that could be suitable for systematic reviews.
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| 11. |
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| 13. |
- Johansson Westholm, Lena, 1967-, et al.
(författare)
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Promoting Good Research Practices—Taking Responsibility for the Researchers of Tomorrow
- 2022
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Ingår i: Teaching Ethics: The Journal of the Society for Ethics Across the Curriculum. - : Society for Ethics Across the Curriculum. - 1544-4031 .- 2154-0551. ; 22:1, s. 149-165
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Tidskriftsartikel (refereegranskat)abstract
- In respect to the increased number of cases of research misconduct in Sweden, especially the Macchiarini case, a new national ethics legislation has been adopted. Following the previous and new legal acts and the Higher Ordinance for studies, Swedish universities have established qualitative measures to make sure that PhD students have knowledge about research ethics when graduating, for instance through offering third-cycle courses in research ethics. In this article, we describe how a Swedish university has been working with such a course to promote good research practice and ethical integrity to the researchers of tomorrow. We are doing this by describing the course structure and content, its outcome in relation to the legislation concerning misconduct in research and ethics within research, as a conscious reflection on research and its consequences. The results indicate that the course is in alignment with other scientists and/or rules and regulations.
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| 14. |
- Johansson Westholm, Lena, 1967-
(författare)
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Substrates for phosphorus removal - potential benefits for on-site wastewater treatment?
- 2006
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Ingår i: Water Research. - : Elsevier Science. - 0043-1354 .- 1879-2448. ; 40:1, s. 23-26
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Tidskriftsartikel (refereegranskat)abstract
- A large number of substrates potential for removal of phosphorus (P) in wastewater has been reviewed. The substrates consist of natural materials, industrial by-products and man-made products. Most substrates have been investigated in batch and column studies in the laboratory; others have also been tested in field trials. The results from these investigations vary, but a few substrates, e.g. wollastonite, slag material and, to some extent, light weight aggregate products, have demonstrated promising properties with regard to P-sorption capacity and hydraulics. The problems of normalisation of data are discussed, as well as the substrates potential benefits for on-site wastewater treatment.
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| 15. |
- Johansson Westholm, Lena, 1967-, et al.
(författare)
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The use of blast furnace and electric arc furnace steel slag in water pollution control
- 2011
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Ingår i: Proceedings of the 6th European Slag Conference, 20-22 October, Madrid, Spain. - Duisburg : The European Slag Association. ; , s. 103-113, s. 103-113
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Konferensbidrag (refereegranskat)abstract
- Filter technology has proved to be successful with regard to removal of pollutants from varying wastewater streams. A large number of filter materials have been investigated with promising results, among them several steel and iron slag materials. However, despite significant scientific evidence over the past 15 years on the efficiency of steel slag in P removal in particular from a variety of wastewaters around the world, currently there are very few full-scale steel slag filters in operation. In this paper we will present research efforts and experiences in using blast furnace slag in Sweden and electric arc furnace steel slag in Vermont, USA and hindrances faced in obtaining regulatory approvals for this innovative technology.
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| 16. |
- Johansson Westholm, Lena, 1967-
(författare)
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The Use of Blast Furnace Slag for Removal of Phosphorus from Wastewater in Sweden—A Review
- 2010
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Ingår i: Water. - MPDI : MPDI Publishing, Switzerland. - 2073-4441. ; 2:4, s. 826-837
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Tidskriftsartikel (refereegranskat)abstract
- Research on Phosphorus (P) removal capacity by blast furnace slags (BFS) has been undertaken in Sweden for the last decade. Both laboratory experiments and field trials have been carried out. While laboratory investigations revealed that BFS has a high P-sorption capacity (95–100%), P removal in field trials was much lower, ranging from 40 to 53%. In addition, a number of problems have been observed in BFS field testing including clogging, sulfuric odor and environmental (regulatory) concerns about possible leaching of heavy metals from the slag. In spite of these problems, and questioning by the environmental regulatory authorities, research continues to provide evidence that BFS can be regarded as a suitable filter media, and attempts have also been undertaken in order to further improve the P-removal capacity of this adsorbing material.
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| 18. |
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| 19. |
- Khokhotva, O. P., et al.
(författare)
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The impact of surface properties of modified pine bark on the mechanism of sorption of heavy metals from aqueous media
- 2017
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Ingår i: Journal of Water Chemistry and Technology. - : Allerton Press Incorporation. - 1063-455X. ; 39:3, s. 148-154
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Tidskriftsartikel (refereegranskat)abstract
- The surface properties of pine bark before and after the treatment with urea solution and the adsorption of Cu(II), Ni(II) and Zn(II) from aqueous solutions at different pH values have been studied. Types of active sorption sites, their surface concentration and change after the bark treatment with urea solution were determined. The results of potentiometric titration were processed by using ProtoFit and FITEQL software programs. The data obtained make it possible to conclude that in the extraction mechanism of heavy metals from water the share of ion exchange decreases and the share of complexation increases. The impact of alkaline and alkaline earth metals in the range of their concentrations up to 3000 mg/dm3 on Cu(II) extraction from model aqueous solutions was also investigated.
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| 20. |
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| 21. |
- Nehrenheim, Emma, 1979-, et al.
(författare)
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Treatment of Landfill Leachate Using Filter Substrates
- 2005
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Ingår i: Sardinia 2005. - Cagliari : CISA, Environmental Sanitary Engineering Centre.
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Konferensbidrag (refereegranskat)abstract
- Three by-products from the steel and paper manufacturing industries have been tested as filter materials for removal of heavy metals in metal solution and in landfill leachate. Laboratory experiments were used to determine the capacity of the materials to remove heavy metals. A column set-up at a landfill site examined the field application possibilities of pine bark, amorphous and crystalline blast furnace slag. All three materials have shown large potential for removal of heavy metals inmetal solution also when the concentrations are low. On-site treatment however was distrurbed by factors not present in batch experiments. Physical parameters such as pH and electric conductivity of the water stream were not significantly affected by the treatment.
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| 22. |
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| 23. |
- Nilsson, Charlotte, 1985-, et al.
(författare)
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Effect of organic load on phosphorus and bacteria removal from wastewater using alkaline filter materials
- 2013
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 47:16, s. 6289-6297
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Tidskriftsartikel (refereegranskat)abstract
- The organic matter released from septic tanks can disturb the subsequent step in on-site wastewater treatment such as the innovative filters for phosphorus removal. This study investigated the effect of organic load on phosphorus (P) and bacteria removal by reactive filter materials under real-life treatment conditions. Two long-term column experiments were conducted at very short hydraulic residence times (average similar to 5.5 h), using wastewater with high (mean similar to 120 mg L-1) and low (mean similar to 20 mg L-1) BOD7 values. Two alkaline filter materials, the calcium-silicate material Polonite and blast furnace slag (BFS), were tested for the removal capacity of total P, total organic carbon (TOC) and Enterococci. Both experiments showed that Polonite removed P significantly ( p < 0.01) better than BFS. An increase in P removal efficiency of 29.3% was observed for the Polonite filter at the lower concentration of BOD7 ( p < 0.05). Polonite was also better than BFS with regard to removal of TOC, but there were no significant differences between the two filter materials with regard to removal of Enterococci. The reduction in Enterococci was greater in the experiment using wastewater with high BOD7, an effect attributable to the higher concentration of bacteria in that wastewater. Overall, the results demonstrate the importance of extensive pre-treatment of wastewater to achieve good phosphorus removal in reactive bed filters and prolonged filter life.
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| 24. |
- Westholm, Lena Johansson, 1967-
(författare)
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Filter media for storm water treatment in sustainable cities : A review
- 2023
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Ingår i: Frontiers in Chemical Engineering. - : Frontiers Media S.A.. - 2673-2718. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Storm water treatment and management will be more important in the future due to climate changes, e.g., more frequent, and intense rain events that might cause flooding. To meet these challenges, low impact development (LID) technologies such as paved surfaces, green roofs and various bioretention systems have been suggested in urban areas. Various filter media, natural and engineered materials, have been used to amend the LID solutions in field experiments enhancing the removal of different contaminants present in storm water of different kinds. Researchers suggest locally available low-cost media having high capacity to remove pollutants. Other parameters to take into consideration when selecting filter media are clogging, hydraulic parameters. Climatic conditions in different regions, e.g., temperate, or cold climatic zones, do not seem to have a large impact on performance on LID solutions.
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