Additional drinking water sources and circular economy

Moderator of this session: Luuk Rietvald (Department of water management, TU Delft)

This session will include the speakers: Badrul Hasan (Copernicus Institute of Sustainable Development, Utrecht University, Netherlands), Gertjan Zwolsman (Dunea Duin & Water) and Mehdi Khoury (University of Exeter)

Take a look at the abstracts below:

A Community Management Plus Model for the Governance of Community Drinking Water Systems: A Comparative Case Study of Pond Sand Filter Systems in Bangladesh 

Presenting author: Badrul Hasan

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Community drinking water systems (CDWS) in Bangladesh and elsewhere of the global south often fail to perform optimally. It is acknowledged that pure community management approach will not reverse this trend. The CDWS end-users need support from the external entities regarding organization of collective action that some have labeled as community management plus (CM+) approach. In order to understand what this support could look like; we particularly zoom in on the role of public agencies. We ask firstly, what conditions explain variation in collective action among the beneficiaries of CDWS? And secondly, what conditions explain variation in collaboration between CDWS end-users and a public agency? We lean on the concepts and insights drawn from the commons’ literature. After all, community drinking water system can be framed as a common poor resource (CPR). Its users frequently face appropriation and provision dilemmas, that have to be solved to avoid its failure. Based on this literature, we develop a list of enabling conditions for (i) collective action among CDWS end-users, and (ii) collaboration between the CDWS users and public agency. We applied this list to study the governance of thirty pond sand filter systems (PSF)-community drinking water systems in the Southwestern coastal area of Bangladesh. Computing correlation, the we find that large group size, interdependency among the group members, heterogeneity of endowments, a high level of dependence on PSF system, locally devised access and management rules, and well-working collaboration between PSF users and public agency officials are significantly associated with the occurrence of collective action among the PSF users. We also find that collaboration between PSF users and the public agency) is positively influenced by transparency and inclusive decision-making procedures, but mostly by a relation that is characterized by trust. The study findings have practical implication as it would help the policy makers and practitioners to optimize the implementation strategy of CDWS and thereby helps to avoid the failure of the CDWS in Bangladesh and elsewhere of the similar contexts.  

The LIFE-Freshman project: Feasibility of brackish groundwater as additional drinking water source in the Dutch coastal zone 

Presenting author: Gertjan Zwolsman

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Dunea supplies drinking water to 1.3 million customers in The Hague and surroundings (southwest Netherlands), using a managed aquifer recharge (MAR) scheme installed in the coastal dunes in the 1950s. Pre-treated river water is infiltrated in the coastal dunes to replenish the natural freshwater lens and balance the freshwater extraction for the production of drinking water. The system is effective in maintaining the volume of the freshwater lens, yet further expansion is restricted by the natural hydrogeological conditions, i.e. the presence of brackish groundwater below the lens. Population is growing and thus water demands are increasing, urging Dunea to develop alternative water resources. 

One of the options is the use of brackish groundwater for drinking water production. Brackish groundwater is an excellent feed water for (low-pressure) reverse osmosis membranes, and can be desalinated at acceptable (energy) costs. Extracting brackish groundwater below the freshwater lens in the coastal dunes has a second advantage: deep-well extraction causes hydraulic (groundwater) heads to decrease, resulting in a downward shift of the fresh-brackish groundwater interface and an effective growth of the freshwater lens (Zuurbier et al., 2016). Brackish groundwater may thus provide an additional water source and extraction may result in an effective increase in Dunea’s strategic fresh groundwater reserves. These combined benefits of brackish water abstraction are referred to as the Freshman concept (see Figure). 

To investigate the potential and optimization of the Freshman concept, a field pilot has been set up at Dunea’s primary drinking water production site in the coastal dunes of The Hague. For the pilot, a multi-screened abstraction well for brackish groundwater has been installed, along with an additional abstraction well for fresh groundwater, multiple monitoring wells, and a facility for collection and desalination of the abstracted brackish groundwater. The pilot will run for three years (2022-2024). The pilot will be used to better characterize the hydrogeology, increase our understanding of fresh-brackish groundwater interactions, validate model results, and to gain operational experience with brackish water desalination. Based on the results of the field test and follow-up modelling studies, Dunea will decide whether brackish groundwater indeed is a feasible drinking water source for the near future. If proven successful, the Freshman concept may be replicated in other coastal areas, where freshwater availability is limited and under increasing pressure due to sea level rise and increasing water demand. 

The NEXTGEN Serious Game : learning about Circular Economy of water in an urban catchment.

Presenting author: Mehdi Khoury

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Serious Games are games developed for a purpose other than mere entertainment. In the context of the NEXTGEN European research project, an educational Serious Game standing at the intersection between decision support system, interactive visualization, and learning sandbox has been developed. The Serious Game allows participants to watch over “ToyTown”, a virtual urban catchment with a population of around 300 000 inhabitants. The objective of the game is to maximise the benefits of Circular Economy in a water system.

Players can change settings in the game to observe the interactions between different components in the urban water cycle and their effects on water availability, energy use, material recovery, environmental health, and costs.

The result is an online browser-based single player Serious Game that tells “stories”, showing different ways the urban water cycle can be affected by enabling various water technologies inside households and at the infrastructural level. The effects of the change initiated by the player are immediately analysed in the background via a System Dynamic Model. This model is specifically developed using the Julia programming language, showing simulation results over 20 years in under a second. Participants can explore how their choices change the water quality and environmental flow in a river and impact on the health of the ecosystem. Similarly, the energy footprint resulting from their choices can be visualised, including an emphasis on wastewater treatment with options to recycle not just nutrients but also metals. The decision can lead to surprising savings in both energy and carbon emissions. Actions have multiple consequences, for example, enabling a nature based solution for urban drainage to lower the volume of water going to wastewater treatment plants after a heavy rainfall, will decrease the amount of energy used for treatment and the number of untreated discharges in the river, but will also increase installation and operational costs.

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