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- PostHow can corrosion damages be estimated based on surface observations?(2024) Vafaeizadeh, Mojtaba; Uqla, Ahmad; Chalmers tekniska högskola / Institutionen för arkitektur och samhällsbyggnadsteknik (ACE); Chalmers tekniska högskola / Institutionen för arkitektur och samhällsbyggnadsteknik (ACE); Lundgren, Karin; Lundgren, KarinReinforced concrete structures are widely used, but their lifespan is often shortened by reinforcing bar corrosion. Since concrete and steel production is resource-intensive and contributes to carbon emissions, enhancing the durability of existing structures can reduce material demand and environmental impact. Visual inspections are largely based on surface observations. As corrosion progresses, the expansion of corrosion products increases the stress within the concrete, this stress leads to the formation of longitudinal cracks that run parallel to the bars. These cracks are a common and visible indicator of ongoing corrosion, signaling the need for further investigation. Several parameters affect the level of corrosion, including concrete cover thickness, bar diameter, concrete quality, and the ratio of concrete cover thickness to bar diameter. This project focuses on investigating the relationship between the width of longitudinal cracks and the underlying factors influencing bar corrosion. Specifically, it analyzes the correlation between crack width and parameters such as concrete cover thickness, bar diameter, and concrete quality. Establishing these relationships is crucial for improving the accuracy of corrosion assessments and enhancing the ability to predict the remaining service life of reinforced concrete structures.
- PostContext shapes structure: Exploring a non-extractive home with what is at hand(2024) Fogde Eriksson, Kristin; Chalmers tekniska högskola / Institutionen för arkitektur och samhällsbyggnadsteknik (ACE); Chalmers tekniska högskola / Institutionen för arkitektur och samhällsbyggnadsteknik (ACE); Norell, Daniel; Christensson, Peter
- PostImpact of High Flow on Phosphorus Treatment Performance(2024) Aboobacker Siddique, Mohammed Shareef; Chalmers tekniska högskola / Institutionen för arkitektur och samhällsbyggnadsteknik (ACE); Chalmers tekniska högskola / Institutionen för arkitektur och samhällsbyggnadsteknik (ACE); Modin, Oskar; Ohlin Saletti, AnnaThis thesis assesses the impact of high flow conditions on the performance of five wastewater treatment plants (WWTPs) in Sweden in terms of phosphorus (P) removal, focusing specifically on effluent P mass flow. Predictive models were developed for each WWTP using actual flow and effluent P concentration data to estimate the effluent P mass flow outcomes under varying flow rates. These estimates provide stakeholders with valuable insights into current performance and potential opportunities for optimisation. The research involved the collection and analysis of three years of flow, influent, and effluent P concentration data for each plant. Statistical analyses were conducted to identify flow rate patterns, and regression models were developed to predict effluent P concentration which is then used to estimate effluent P mass flow under different flow conditions. Key findings indicate that as flow increases, effluent P mass flow also rises. When a WWTP’s capacity is exceeded, bypass scenarios occur, resulting in a significant increase in effluent P mass flow. The effectiveness of P removal at each WWTP is closely related to the plant's overall treatment capacity and the inflow it receives. The study also examined the performance of WWTPs under two scenarios: swapping of catchments and swapping of WWTPs within municipalities, revealing additional opportunities for optimisation. For most municipalities, improving catchment area management could help reduce inflow peaks, and for all of them, upgrading design capacities, techniques, or WWTP operations could significantly enhance P removal performance. In conclusion, this thesis provides important insights for optimising WWTP performance in P treatment under high flow conditions, contributing to improved environmental protection and regulatory compliance in Sweden.
- PostAssessing Pretreatment Methods to Mitigate Nanofiltration Fouling(2024) hallset, Beate; Jakobsson, Emma; Chalmers tekniska högskola / Institutionen för arkitektur och samhällsbyggnadsteknik (ACE); Chalmers tekniska högskola / Institutionen för arkitektur och samhällsbyggnadsteknik (ACE); Modin, Oskar; Modin, OskarGlobally, water scarcity is a critical issue affecting millions of people, exacerbated by increasing population and climate change. In countries like Sweden, where water availability is sufficient, this vital resource is often taken for granted. However, the extensive reliance on centralised water infrastructure in Sweden has its limitations. To address these challenges, modular drinking water treatment systems (MDWTS) offer a viable solution. These systems can serve as a complement to, or in the ab sence of, centralised water infrastructure, ensuring sustainable water management and availability. Membrane filtration is a compact treatment method applicable for various raw water qualities, which makes it suitable to implement in a MDWTS. However, membrane modules face an obstacle due to the risk of fouling caused by organic and inorganic compounds in the raw water. Fouling results in a reduc tion of treatment efficiency, while increasing the need of operational and economic resources. The aim of this thesis is to suggest suitable pretreatment methods for raw water to mitigate membrane fouling in a MDWTS, where nanofiltration acts as the main treatment step. The issue was investigated through a study of litera ture, identifying key foulants and possible pretreatment methods. The key foulants identified in the study of literature are particles, natural organic matter, iron, man ganese, calcium, magnesium, aluminium and silica. In addition, bench studies on a biological activated carbon filter, an alkaline filter and a charged sieve followed by a disc filter were performed to evaluate their potential to operate as pretreatment. Further, the findings were applied to three water types representing water qualities from three water sources in Sweden, aiming to suggest pretreatment chains to re duce key foulants. The pretreatment chains suggested in the result for the three water types are all spatially manageable in a MDWTS. Although, for one of the water types, the pretreatment may be challenging to implement due to operational complexity. To include additional water qualities, a general procedure connecting key foulants to suitable pretreatment methods is presented. Due to the complexity of nanofiltration fouling and the possible interactions between key foulants and the different steps in the pretreatment chain, pilot studies are necessary to evaluate the fouling mitigation. By validating the framework through pilot testing, this work can contribute to enhancing nanofiltration performance and further the development of MDWTS
- PostAssessment of pluvial flooding at Mossen(2024) Börjesson, Hanna; Pettersson, Elin; Chalmers tekniska högskola / Institutionen för arkitektur och samhällsbyggnadsteknik (ACE); Chalmers tekniska högskola / Institutionen för arkitektur och samhällsbyggnadsteknik (ACE); Bondelind, Mia; rauch, SebastienWith the increased severeness of urban pluvial flooding due to climate change, cities have to increase their resilience against heavy cloudbursts. As a response to the upcoming challenges an interim target for all Swedish municipalities is to investigate and integrate sustainable stormwater management when planning new construction as well as existing stock. The city of Gothenburg is no exception, and in the structural plan the municipality presents several potential cloudburst surfaces, with the football field Mossens IP being one of them. The aim of this thesis was to investigate the resilience of the football field against a 100-year rain, and whether it is possible to mitigate the consequences at site through Nature-based solutions simultaneously as the area benefits socially and environmentally through increased recreational value and eco-system services. Further, the potential effect of flooding on the possibility for sport associations to utilize the field was investigated. The thesis was scenario-based and applied three different scenarios. Scenario 1 was used as a baseline scenario, thus representing the current flooding situation during a 100-year rain at Mossen football field if no changes were made, whereas Scenario 2 involved Nature-based solutions e.g. rain gardens, green roofs, blue-green roofs and permeable paving within the catchment area. Lastly, Scenario 3 involved storage focused solutions, e.g. retention ponds and detention basins within the catchment area. Modelling was conducted in SCALGO Live and thereafter analyzed with the decision making framework MCDA. The study concluded that the nature-based solutions implemented in Scenario 2 are not preferred in this case from a strictly quantitative stormwater management point of view, as no notable reduction in flooding of the field was found. In this case study, the most beneficial stormwater solutions proved to be the detention basins in Scenario 3 with a total reduction of 23 cm. However, both scenarios performed well regarding increasing recreational values and eco-system services. Rain gardens and a multi-functional detention basin were found to be the most optimal ones