Non-sewered sanitation systems have emerged as a valuable complement to sewered systems over the past two decades. Their importance is pronounced in urban areas of low- and middle-income countries, where they could prevent ~600,000 deaths annually by supplementing inadequate sanitation infrastructure. Additionally, in high-income countries, non-sewered systems are gaining traction due to sewer capacity limits and the growing emphasis on resource recovery.

Despite these advantages, the treatment and reclamation of blackwater (toilet wastewater) in non-sewered systems remains challenging. Approximately 20,000 liters/year of freshwater are used per person for toilet flushing, equivalent to an individual's drinking water needs for 15 years. Blackwater reclamation offers a promising solution to reduce freshwater extraction and prevent environmental pollution. However, research in this area has gained prominence recently, and there remains a gap in designing treatment trains. Current research focuses on individual technologies rather than proposing holistic frameworks that could aid urban planners and researchers in selecting technologies along the treatment train. Furthermore, the carbon footprint of complete non-sewered systems has not been quantified.

Addressing this, the thesis aims to: (1) develop a methodology to select technologies along the treatment train, (2) quantify the carbon footprint of a non-sewered system, and (3) assess the relevance of blackwater reuse in urban communities worldwide. The NEST building in Switzerland serves as a case study to demonstrate the application of the proposed approaches.

The methodology involves collecting data on blackwater quality and quantity, compiling a list of suitable technologies through literature review, and refining this list using pre-selection criteria. A pre-selection matrix groups technologies according to these criteria, assisting researchers in selecting context-specific technologies. Configured treatment trains are evaluated using 14 decision-making criteria to ensure social, technical, economic, and environmental sustainability. Applying this methodology, the most suitable treatment train for non-potable reuse (e.g., toilet flushing) includes a moving bed biofilm reactor, chemical precipitation, ultrafiltration, granular activated carbon, and UV disinfection. For indirect potable reuse (e.g., recharge of drinking water reservoirs), nanofiltration should be included.

Process designs are developed for the treatment trains using BioWin and used for the carbon footprint analysis. Indirect emissions from electricity consumption, particularly in the urine concentration unit, are identified as the largest contributors. Transitioning to renewable energy could significantly reduce the carbon footprint, emphasizing the need for comprehensive life cycle cost and benefit evaluations.

Finally, the thesis assesses the feasibility of applying the developed methods and results in urban communities across various income levels. For low-income countries, the selection of simple, robust technologies is emphasized due to frequent power cuts and high maintenance costs. Middle-income countries require a balance between efficiency and operational ease, while high-income countries benefit from resource recovery, necessitating legislative support for non-sewered systems.

In conclusion, this thesis establishes a framework for designing safe, reliable, and sustainable non-sewered sanitation systems for urban blackwater treatment and reuse, addressing a critical gap in current literature. It calls for pilot testing to validate these theoretical frameworks, advancing the operational knowledge of non-sewered sanitation to match the maturity level of traditional sewered systems.

Since its production concentrations of the manmade chemical compounds PFAS found in the environment has increased significantly. The properties created by incorporating these chemicals, make them attractive for industrial usage and for many consumer products. These chemicals bioaccumulate and are very persistent. With known adverse health effects, its treatment to prevent release in the environment has become more and more important. To remediate PFAS in aquatic environments, such as groundwater and surface water helps protect our drinking water sources and reduces exposure to these harmful compounds. With this in mind the treatment technology, electrochemical oxidation of PFAS is applied here in various water matrices to study the destruction of these compounds. Through galvanostatic EC experiments, water types in 10L continuously stirred reactor tanks, where pumped through an electrochemical cell consisting of boron-doped diamond electrodes at a constant current of either 30 or 40 A for a duration of either 3 or 6 hours. Samples were processed and then analysed for 29 PFAS through HPLC-MS/MS. Remediation of these compounds proved to be less efficient than in other studies.

Environmental guidelines (EU WFD) impose a strict effluent phosphate target on wastewater treatment plants (WWTP). An abundance of phosphate (and other nutrients) in a water body is called eutrophication. Eutrophication can lead to algal blooms which result in very low oxygen concentrations in the water. Other species, like fish and aquatic plants, can die because of the lack of oxygen. Most WWTPs in the Netherlands are performing well and reach phosphate effluent concentrations below 1 mg/l. Nevertheless, Dutch water authorities are looking for ways to improve nutrient removal to perform even better then the WDF guidelines. At the same time they are anticipating on the expectation of more strict phosphate effluent targets in the future.

This research is focusing on VFA production from the sieved fraction of activated sludge. Sieves with a mesh size of 0.5 mm were used to sieve cellulose fibers from the sludge. Microbial conversion processes are stimulated in the VFA production reactors. A pilot plant that was performed resulted in very high phosphate concentrations in the reactor. The first phase of this research was devoted to identifying the source of the high phosphate concentration. The second phase was focused on phosphate removal and recovery strategies.

It was found that 20% of the sievings consisted of PAO sludge. The conditions in the VFA production pilot lead to extreme phosphate release by PAO. This resulted in high phosphate levels ranging up to 200 mg/l.

The released phosphate potentiates recovery methods. It was not able to precipitate struvite at the low pH levels at which the VFA production reactor was operated. Calcium carbonate addition could decrease phosphate levels (50%) and can be used to control pH in the reactor. The applied method does not allow for easy recovery because the precipitate ends up in the sievings. Finally vivianite precipitation was achieved by adding FeCl2. 90% phosphate removal was achieved. The para-magnetic property of vivianite allows for easy recovery with a magnetic separator. This results in the production of 2 valuable streams from a waste stream: VFA and vivianite.