The main research question of this project was:
"How effective is the integration of a foam fractionation system in an activated sludge water treatment plant, on the removal of Per- and Polyfluoroalkyl Substances?"
To determine how foam and activated sludge can have an influence on PFAS removal, a controlled environment was created by building a bench-scale reactor that tries to mimics the full scale activated sludge WWTP of landfill Zeeasterweg. By doing this the effect on the biological performance was tried to be determined. Furthermore, a representative sample of the landfill leachate from the landfill, was used as the influent for the bench scale reactor. This leachate predominant PFAS compounds were: MeFBSAA (13.5 μg/L) and PFBS (8.8 μg/L) accounting for 70 % of total PFAS levels. To answer the main research question, two mass balances for a selected group of target PFAS compounds were develop for two experiments. The fist experiment was focusing on the PFAS removal efficiency without any foam production at all. To achieve this, antifoam was dosed on top of the nitrification zone so that no foam could be produced. The second experiment was called the "Foam Fractionation". In this experiment anfoam fractionation system was added to the nitrification zone of the bench scale reactor. This was done to determine the effect of collecting and removing the foam that was being produced inside the reactor.

The main research question of this project was:
"How effective is the integration of a foam fractionation system in an activated sludge water treatment plant, on the removal of Per- and Polyfluoroalkyl Substances?"
To determine how foam and activated sludge can have an influence on PFAS removal, a controlled environment was created by building a bench-scale reactor that tries to mimics the full scale activated sludge WWTP of landfill Zeeasterweg. By doing this the effect on the biological performance was tried to be determined. Furthermore, a representative sample of the landfill leachate from the landfill, was used as the influent for the bench scale reactor. This leachate predominant PFAS compounds were: MeFBSAA (13.5 μg/L) and PFBS (8.8 μg/L) accounting for 70 % of total PFAS levels. To answer the main research question, two mass balances for a selected group of target PFAS compounds were develop for two experiments. The fist experiment was focusing on the PFAS removal efficiency without any foam production at all. To achieve this, antifoam was dosed on top of the nitrification zone so that no foam could be produced. The second experiment was called the "Foam Fractionation". In this experiment anfoam fractionation system was added to the nitrification zone of the bench scale reactor. This was done to determine the effect of collecting and removing the foam that was being produced inside the reactor.

With population increases, the traditional linear economy has become increasingly unsustainable creating environmental pressures such as climate change and resource scarcity. The Dutch government has set lofty goals to create a circular economy by 2050. The agricultural sector in the Netherlands is vulnerable to climate pressures but is also highly profitable at the cost of sustainability making circular models difficult to implement. The world's first Floating Farm in Rotterdam, NL was created to bring food production into urban areas to increase the resilience of food supply chains. The Floating Farm has worked to implement a more circular dairy farming model by reducing land use and using recycled feed.

In this study, the circularity performance of the Floating Farm (FF) dairy production process was quantified using an indicator-based circularity assessment method. Indicators were derived from the FF's self-proclaimed circular actions and calculated using derived water, nutrient, and energy balances. A typical baseline farm was identified and used to compare indicator performance for which data was available and a comparison was relevant. From the mass and energy balances and indicator calculations, gaps in circularity were identified. To help close the gaps, scenarios to improve the farm's circularity were identified and assessed for feasibility. Each scenario was added to the indicator calculations to quantify the impact on indicator performance.

The results revealed several gaps in circularity, particularly concerning water and waste management. Once through cooling is currently used in the milk processing step leading to a very high water usage and wastewater production. In waste management, the entire liquid fraction of manure ends up in the sewer leading to significant nutrient and water losses. Generally, the farming model involves a trade-off that results in a loss of self-sufficiency, particularly regarding feed, water use, and electricity consumption. This is because no feed crops are grown, and there is no space for large-scale rainwater collection or solar energy production.

The scenario investigation revealed that switching the water source of once-through cooling water from the tap to river water is feasible, greatly impacts indicator calculations, and should be the priority for the farm to improve. The other three scenarios had several pros and cons but may be better suited for future versions of the farm due to the farm's current scale and lack of operational expertise in water treatment.

Despite the farm's efforts and enthusiasm, the indicator performance for most of the farm's circular actions have room for improvement. The farm has put effort into creating a circular economy but still must make significant strides to meet its goals. On top of the scenario recommendations, it was recommended that the farm install more measurement devices to increase the accuracy of future analyses and have a clearer view of process flows to more accurately identify losses.

Per- and polyfluoroalkyl substances (PFAS) have remained persistent environmental contaminants since the 1950s, despite ongoing efforts to curb their production and find alternatives. Most health studies have focused on Perfluorooctanoic acid (PFOA) and Perfluorooctane sulphonic acid (PFOS), leaving limited data on other PFAS compounds in water. The European Union, particularly the Netherlands, has implemented stringent measures to control PFAS in drinking water due to their uncertain health impacts on
humans. Recently, the Dutch Institute for Public Health and Environment (RIVM) proposed a new guideline of 4.4 ng PFOA equivalent (PEQ) per litre for PFAS in drinking water, a substantial reduction from the current European Drinking Water Directive standards of 100 ng/L for the sum of PFAS and 500 ng/L for total PFAS.

While improving drinking water quality is expected to have positive health outcomes, the advanced treatment technologies required to meet this new guideline can be harsh, potentially releasing emissions that may cause negative health effects. This research, centred on the Leiduin drinking water treatment plant operated by Waternet in the Netherlands, investigates whether the health benefits of the new guideline outweigh the potential harms caused by the treatment processes necessary to achieve it.

To explore this, the study first calculated the Disability-Adjusted Life Years (DALYs) lost due to PFAS exposure from drinking water at the current concentrations, exceeding the 4.4 ng PEQ/L guideline, using a literature review to link guidelines with PFAS health effects. The second step involved conducting a Life Cycle Assessment (LCA) of the treatment system at the Leiduin plant, focusing on the treatment steps necessary to meet the new guideline, and calculating the DALYs lost due to the environmental impact of achieving the 4.4 ng PEQ/L standard. These DALYs were then compared to assess whether adhering to the new guideline is justified in terms of health impacts.

The results indicate that the DALYs associated with the current and proposed guidelines fall within similar ranges, showing limited health benefits. Specifically, the health benefits (in DALYs) gained from implementing the new guideline range from 0.4 to 4 per year, while the DALYs lost due to the treatment technologies required at the Leiduin plant range from 1.55 to 3.25 per year for the population receiving drinking water from the Leiduin site, depending on the type of activated carbon used in the treatment process.

These findings suggest that the potential health benefits of stricter PFAS regulations in drinking water maybe counterbalanced by the negative health impacts of the treatment technologies required to achieve
these lower concentrations