| 1. |
- Milovanovic, Ivan, 1990-, et al.
(författare)
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Zeolitfilter för avrinning från koppartak
- 2024
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Koppar används ibland som takmaterial i städer, men det medför problem för miljön. Avrinningen från koppartak är svår att behandla i stadsmiljöer. En ny studie har tittat på hur effektivt ett filtersystem med zeolit som filtermedium kan vara för att minska kopparhalten. Resultaten visar att filtret lyckades minska total och löst koppar med 52–82 % respektive 48–85 %. Trots detta var kopparhalterna i avrinningen fortfarande höga, mellan 350–600 μg/l. Detta överstiger rekommenderade nivåer och indikerar behovet av fortsatt forskning för att förbättra behandlingsmetoderna och minimera miljöpåverkan från koppartak.
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| 2. |
- Okwori, Emmanuel, 1988-
(författare)
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Analytics-driven approaches supporting asset management of sanitary sewer networks
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sewer blockages can cause overflows and flooding, with consequences such as damage to property and environmental pollution, risks to public health and economic loss. Despite the causes being understood, blockages in sewer networks may occur unpredictably. The responsible staff for sewer networks at water utilities need to efficiently determine the most effective action (what), the specific network location needing attention (where), the optimal timing for intervention (when), and the appropriate remedial task (how), especially given the unpredictability of blockages. Today a reactive approach to asset management and maintenance is often adopted. Additionally, data availability, quality and interoperability between systems are not always at levels that can support decided objectives, proactive maintenance planning and asset management of pipe networks. Thus, the aim of this thesis is to propose and evaluate approaches that can support analytics-driven maintenance planning and asset management for sewer networks. These approaches aim to contribute to mitigating the impact of siloed data structures and enhance the understanding of blockage root causes from a spatial perspective.In this thesis, the challenges of data management in the asset management of pipe networks were investigated through focus group workshops and questionnaire surveys. A conceptual framework was developed based on findings from focus group workshops and surveys. The framework combines data quality assessments, interoperability evaluations between asset management tools, data collection, and informational benefits analysis. This framework aimed to identify the presence of data silos and plausible pathways towards more data-driven data management strategies. A performance assessment combining performance indicators associated with blockages and partial least squares regression (PLS) was conducted to draw inferences that could be useful at a strategic level. Furthermore, a spatial heterogeneity assessment of blockages and factors affecting blockages was carried out. This approach combined network kernel density estimation (NKDE), network k-function, and geographically weighted Poisson regression (GWPR). Lastly, a vulnerability assessment was carried out that combined topological analysis using edge-based centrality measures and network cross-k-function. These approaches were applied to three sewer networks.The focus group workshops and questionnaire surveys identified several challenges affecting data management in the context of pipe network asset management. Many of the challenges could be ascribed to issues related to data quality and interoperability. Results from the preliminary application of the conceptual framework showed how it could be applied for identifying data silos and pathways to data-driven decision-making towards proactive management blockages in sewers. The observed spatial trends and patterns from network k-function analysis and network kernel density estimation showed spatial variability in the occurrence of blockages (single occurring and recurring). Geographically-weighted Poisson regression analysis showed spatial heterogeneity in factors influencing blockage propensity. The network cross-k-function analysis demonstrated that pipes with historical blockage incidents tend to be clustered around critical pipes with higher centrality values. These results could support vulnerability assessments in sewer networks and the development of targeted maintenance strategies. These approaches together could aid data-informed maintenance planning and asset management at the strategic, tactical and operational levels.
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| 3. |
- Okwori, Emmanuel, 1988-, et al.
(författare)
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Data integration in asset management of municipal pipe networks in Sweden: Challenges, gaps, and potential drivers
- 2024
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Ingår i: Utilities Policy. - : Elsevier. - 0957-1787 .- 1878-4356. ; 86
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Tidskriftsartikel (refereegranskat)abstract
- This study involved a survey of Swedish water utilities to evaluate their pipe-network data-collection objectives, usage, storage, and exchange routines. Factors impacting data integration (and the associated benefits) were also identified. Results showed that current data storage and exchange routines can be augmented to support commonly identified objectives and data utilisation needs, especially in larger water utilities. Levels of awareness of the opportunities for and benefits gained through asset management processes and data integration varied between utilities. Further research on the benefits of data integration in pipe network asset management is required to develop an evidence base on benefits accrued in practice, especially considering metadata, the diversity of legacy systems still in operation, costs and policy use.
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| 4. |
- Okwori, Emmanuel Jenkeri, 1988-, et al.
(författare)
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Edge-based graph centrality measures with spatial analytics to support vulnerability assessment and maintenance planning in sewer networks
- 2024
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the spatial relationship between critical pipes identified using edge-based centrality measures and pipes with higher failure probability-based vulnerability indicators were analysed in sanitary sewer networks. By analysing two sub-networks, one residential and the other a central network, significant spatial associations between pipes with high centrality values and those exhibiting adverse conditions (poor CCTV grades, previous blockages, and low self-cleaning capabilities) were identified. Path-based centrality measures, particularly edge betweenness and K-path edge centrality were less influenced by weights when identifying critical pipes. In contrast, non-path-based measures like nearest neighbour edge centrality could identify localised spatial patterns between critical pipes and pipes in adverse conditions within the sewer networks investigated. The results showed that the spatial patterns between critical pipes and pipes in adverse conditions were not random and could support proactive maintenance planning and the development of more resilient networks. Additionally, the impact of network structure, connectivity, and differences in the composition of pipe attributes could contribute to variations in the strength of observable spatial associations.
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| 5. |
- Sami, Mashreki, et al.
(författare)
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Treatment of greywater and presence of microplastics in on-site systems
- 2024
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Ingår i: Journal of Environmental Management. - : Elsevier. - 0301-4797 .- 1095-8630. ; 366
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Tidskriftsartikel (refereegranskat)abstract
- Eight on-site greywater treatment facilities of four different types (A, B, C and D) were investigated. Three were commercially available package plants (A–C) and one was a conventional sand filter (D). The treatment unit of Type A consisted of a geotextile-fitted trickling filter and a sand filter bottom layer, the Type B consisted of packs of fibrous mineral wool filter materials, and the Type C consisted of a fine-meshed plastic filter. The treatment systems were assessed in terms of their removal efficiency for organic matter (e.g. BOD, COD, TOC), nutrients (nitrogen and phosphorus), surfactants, indicator bacteria (E. coli and enterococci) as well as microplastics. Systems A and D effectively reduced organic matter by >96% BOD, >94% COD and >90% TOC. Their effluent BOD was <29 mg/l. The BOD reduction in the treatment facilities of types B and C was in the range of 70–95%. Removal of anionic surfactants was >90% with effluent concentration <1 mg/l in all facilities. In general, the treatment systems were ineffective in removing E. coli and enterococci; the most efficient was the sand filter (type D), achieving 1.4–3.8 log10 for E. coli and 2.3–3.3 log10 for enterococci. Due to the high E. coli in the effluents, all the on-site systems were classified as Poor (score: 0–44) according to the water quality index (WQI) assessment. In two of the studied facilities, nine microplastic polymers were targeted (i.e. PVC, PS, PET, PE, PC, NG, PMMA, PP and PA6) and analyzed using the thermal extraction desorption gas chromatography-mass spectrometry (TED-GCMS) technique. PVC, PS, PET and PA6 were commonly detected in the influent and effluent. The effluent quality from type A and D systems was found to comply with the European Commission’s guideline for the reuse of reclaimed water except for the indicator bacteria concentration.
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