(S) The global transition to a carbon-neutral economy increasingly relies on alternatives such as hydrogen as a clean energy carrier. However, hydrogen production through electrolysis requires ultrapure water, which places additional stress on freshwater resources that are already under pressure due to population growth, urbanisation, and climate change. Over 2.7 billion people are affected by water scarcity yearly and this poses major challenges to human health, socio-economic development, and environmental stability.
Desalination of seawater is a promising solution to produce the required water. However, water desalination also produces a high-salinity byproduct called brine. Consequently, traditional discharge methods threaten marine ecosystems with brine disposal. New desalination approaches such as Zero Liquid Discharge (ZLD) and Minimal Liquid Discharge (MLD) technologies offer a potential to mitigate environmental harms with brine by reducing or even eliminating the liquid waste. However, these systems require a lot of technologies placed in series with energy demand which makes the new approach expensive. This leads to concerns about the economic feasibility of MLD and ZLD technologies. (C) Most studies evaluating MLD and ZLD systems rely on Techno-Economic Analysis (TEA). TEA methods focus on capital expenditures (CAPEX) and operational expenditures (OPEX). The downside of TEA is that it often fails to capture broader societal and environmental externalities such as marine degradation from brine discharge or benefits of freshwater recovery in water-stressed regions. Furthermore, the choice between ZLD and MLD is also very complicated. ZLD achieves higher recovery rates than MLD and single water desalinations but at the same its technological complexity and high energy consumption make it a difficult application. In contrast, MLD systems offer lower recovery rates but may present a more cost-effective and feasible solution. Despite this, the literature lacks a more societal and environmental application such as a Cost-Benefit Analysis (CBA) to assess whether the broader societal value of MLD systems justifies their higher costs. This absence represents a significant knowledge gap in the literature and policy evaluation. (Q) To address this knowledge gap, the following research question is formulated which focuses on Nanofiltration (NF) and Multi-Effect Distillation (MED) as the core technologies for MLD, in order to keep the research feasible within the 21-week timeframe of this study: "What are the societal costs and benefits of Minimal Liquid Discharge (MLD) technologies, with a focus on Nanofiltration (NF) and Multi-Effect Distillation (MED), for hydrogen production?" (A) This thesis applies a CBA framework to assess the economic and societal viability of two MLD configurations. The first MLD is a stand-alone MED system and the second MLD a hybrid NF-MED system. The research uses a mixed-methods approach by combining a structured literature review with expert interviews to identify and validate cost elements, operational parameters, and environmental impacts. All cost elements of the CBA including CAPEX, OPEX, and environmental externalities were monetised, so the Net Present Value (NPV) of the two MLDs can be calculated. The CBA demonstrates that while both systems carry significant upfront and operational costs, the standalone MED and the hybrid NF-MED result in positive NPVs. The hybrid NF-MED MLD results in higher water recovery at reduced steam cost per unit of ultrapure water because of the opportunity to operate at higher temperatures. The COSEM Master Thesis Minimal Liquid Discharge for Hydrogen Production results show that wider benefits, such as protecting ecosystems and saving freshwater, can make up for the high upfront costs. Especially if certain conditions are met such as access to green electricity or free waste heat. However, this is dependent on which individuals have standing in the CBA and how they value the wider benefits. The study also shows that using only a TEA gives an incomplete picture, because it leaves out these important environmental and social benefits. (R) This research recommends the adoption of CBA as a complementary tool to TEA in evaluating MLD systems, especially in sustainability sectors like hydrogen production. Policymakers should consider regulatory frameworks that internalise the environmental impact of brine discharge, making MLD systems financially more competitive. For project developers and investors, the hybrid NF-MED system represents a promising solution between conventional water desalination brine discharge and the more expensive ZLD. Further research should focus on scaling the pilot project with additional pre- and posttreatment, and exploring the integration of entirely renewable energy sources and alternative waste heat to further reduce OPEX.

Kaumera is a material made from wastewater treatment and has shown promising characteristic as a flame retardant. In this research report we aimed to bridge the gap between academia and commerce by analysing the potential of Kaumera using a generalised framework of Sustainable Business Model Innovation and the Lean Startup Methodology. The named models were researched through the method of research through design. Using the SBMI framework of Bocken (2019) a startup was proposed and compared to the Lean Startup Methodology. As defined by the SBMI framework, the symbiotic dependencies were identified to be the producers of Kaumera, the clients of the company, the IP owners, academics involved and potential partners. The neutral dependency is related to legislation and legislative bodies, and the competitive dependency are competitors. Furthermore, it was analysed how the assumptions could be validated by the company for the early-stage, scaling and diversification and internationalisation phases of the company.
The results found that Kaumera is a feasible flame retardant both in a commercial and sustainability perspective. It was found that the SMBI framework focusses too much on the sustainability aspect to be truly a viable Business Model approach for startups and does not allow for flexible and adjustable business strategies. For this reason, a combination with the Lean methodology can be applied to overcome the shortcomings of the SBMI framework. This research report shows that the Lean methodology complements the aspects of SBMI which are not suited for startups. This research report therefore suggests the use of a framework based on Lean incorporating generalised aspects of SBMI as an effective and flexible sustainable business model for startups.

There is a rising concern on the sustainability of Zero Liquid Discharge (ZLD) desalination. In this study, Multi-criteria Decision-making (MCDM) is applied to compare the sustainability performance of various ZLD scenarios, which is part of a Strong Sustainability (SS) assessment of desalination. ZLD desalination systems are considered to be complex and have intricate interdependence among various factors, which were seldom recognized in previous research. The purpose of this study is to explore the impact of interdependence among criteria on the MCDM process, with a desalination case study from Water Mining project used for demonstration. A transparent MCDM methodology is proposed in this study, which consists of Best Worst Method – Decision Making Trial and Evaluation Laboratory (BWM-DEMATEL), hierarchical clustering, and Preference Ranking Organization Method for Enrichment Evaluations (PROMETHEE).
In the desalination case study, the use of hierarchical clustering allows for the identification and preservation of both majority and minority opinions, based on which, the same ranking of desalination scenarios is produced through PROMETHEE. Concerning the interdependence among criteria, the results reveal that it can help identify the crucial factors for improvement of sustainability performance of the alternatives. In addition, by considering it, the understanding of criteria is enhanced, which leads to more concentrated opinions of stakeholders in the desalination case. However, the findings indicate that the influence of incorporating the criteria independency on the final decisions is restricted in cases insensitive to weight variation.
The application of BWM-DEMATEL method is a complex and time-consuming activity. Considering the effectiveness and the cost of implementation, BWM-DEMATEL might be not as worthy of application in this case study. Inspired by this, it is meaningful to develop an approach to estimate the impact of the interdependence among criteria on the alternatives ranking in a certain decision problem in the future.