Sustainable Urban Water Management: A Case Study on Rainwater Recovery and Grey Water Recycling Installation.

^AUTHORS:

¹⁾Marzena Smol, ¹⁾Dominika Szołdrowska, ²⁾Beata Szatkowska, ²⁾Renata  Tomczak-Wandzel, ³⁾Dariusz Włóka

1. Mineral and Energy Economy Research Institute The Polish Academy of Sciences, Poland, smol@meeri.pl;
2. Aquateam COWI, Norway;
3. GreenBack sp. Z o.o., Poland, lab@greenback.net.pl 

ABSTRACT:

This article explores a case-study of water management system, designed to realize both the rainwater recovery and grey water recycling. The system's operational mechanisms, environmental benefits, and potential drawbacks are examined to provide a comprehensive understanding of its impact and efficiency of proposed solution. Thanks to provided innovations, system demonstrated in this article can execute a effective water distribution to plants watering systems. Such an design can find wide range of of applications in urban development and industrial purposes.

 

1. Introduction

Water management is an increasingly critical field of study as the global population grows and climate patterns shift unpredictably. Among the various strategies implemented to safeguard water resources, rainwater recovery and grey water reuse stand out as crucial techniques in the drive towards sustainable water use [1, 2].

Rainwater recovery involves capturing, storing, and utilizing rainwater. This practice not only provides an alternative water source but also reduces the demand on conventional water supplies such as rivers and groundwater, which are under increasing stress from overexploitation and contamination. Additionally, effective rainwater management can mitigate the risk of flooding and erosion during peak precipitation events, thereby preserving natural landscapes and urban infrastructure [3].

Grey water reuse, is also commonly highlighted among the process that starting to be important within water management strategies. This type of resource may come from baths, showers, laundry or even technical installations used on gardens. By treating and reusing grey water for non-potable purposes such as irrigation of plants or tools/surface cleaning, significant reductions in the total water consumption of a community can be achieved. This not only extends the lifecycle of freshwater resources but also decreases the energy and costs associated with water purification and distribution [4].

The significance of these water management strategies is magnified by the challenges posed by climate change. Increased variability in rainfall patterns and the intensification of droughts and floods demand adaptive management strategies that enhance water resilience and security. Furthermore, the integration of rainwater recovery and grey water systems can be a pivotal element in urban planning, contributing to greener cities and improved public health [5].

The aim of this article is to demonstrate the case-study of installation that has been designed to provide both rainwater and gray water recovery. Obtained resources in presented system, after collection and storage was subjected to utilization as a main source of water for plants in garden and greenhouses systems.

2. System Design and Installation

The focus is on a specific installation within a complex that includes two buildings and a garden area. The system consists of a rainwater collection setup on the rooftops, which channels water through two pre-storage tanks (each with a capacity of 3 cubic meters), a filtration station, and a water utilization system comprising two greenhouses and a garden area. Additionally, the system includes a gray water recirculation system designed to serve as a backup for the garden tools cleaning station. The water filtration process employs both mechanical filters and UV lamps to ensure the purity of the recovered water resources. The purified water is then stored in dedicated tanks.

Within the filtration station, innovative solutions have been implemented involving water purification in an in-pipe system. The uniqueness of this approach is based on a novel form of mineral bed that contains active particles. These particles are characterized by their capacity to bind phosphorus compounds and adsorb organic matter. Thanks to this type of filtration mixture, the developed bed demonstrates high efficiency in reducing the level of biogens in the treated water and significantly enhances water clarity.

The schematic of the developed solution is presented in the figure below - Fig. 1.

Fig. 1. The scheme of the new filtration device concept based on CEwater project.

3. Challenges and Limitations

While the system offers numerous advantages, several challenges persist. These include the initial high costs of installation, maintenance requirements, and the potential for reduced water quality due to airborne pollutants in rainwater.

The initial challenge discussed is the high cost of constructing facilities that enable the recovery and efficient storage of rainwater. These costs primarily arise from the need to purchase watertight tanks that are responsible for the safe storage of the collected resource. Such tanks should provide appropriate conditions for water storage. Primarily, they should be shielded from the impact of sunlight and should be thermally insulated to limit the heating effect on the stored resource. The simplest method to achieve both objectives is the underground installation of tanks. Unfortunately, this type of endeavor generates additional costs and entails the need to use additional equipment to provide the water with working pressure, thus enabling its later use.

The second challenge discussed pertains to the quality of stored water and the impact of pollutants on the system's operation. Firstly, rainwater may become contaminated at the point of precipitation itself by capturing airborne pollutants. This factor is particularly significant in highly urbanized locations, where air pollution is considered a common issue. Another source of rainwater contamination may be pollutants accumulated on the surface of the infrastructure from which the rainwater is collected. The large surface area of roofs or other surfaces commonly used for rainwater collection can increase the risk level of water contamination directed for recovery. The pollutants in both instances may originate from both anthropogenic and natural sources. The specific contamination profile present in the collected water will thus depend on the individual location where the installation is mounted. Facilities located in industrial areas will be more significantly burdened with petroleum-based pollutants and compounds emitted by transportation, industry, and the energy sector. Conversely, rural and less urbanized locations may be exposed to the deposition of plant dust, fungal spores, and even parts of plants or seeds from trees and shrubs.

4. Conclusions.

The article concludes with a discussion on the future potential of such systems in urban water management, including technological advancements that could enhance efficiency and scalability. Recommendations for policymakers and urban planners are also provided.

References

1. Deksissa, T., Trobman, H., Zendehdel, K., & Azam, H. (2021). Integrating urban agriculture and stormwater management in a circular economy to enhance ecosystem services: Connecting the dots. Sustainability, 13(15), 8293.

2. Martins Vaz, I. C., Istchuk, R. N., Oneda, T. M. S., & Ghisi, E. (2023). Sustainable Rainwater Management and Life Cycle Assessment: Challenges and Perspectives. Sustainability, 15(16), 12133.

3. Villarreal, E. L., & Dixon, A. (2005). Analysis of a rainwater collection system for domestic water supply in Ringdansen, Norrköping, Sweden. Building and Environment, 40(9), 1174-1184.

4. Bocanegra-Martínez, A., Ponce-Ortega, J. M., Nápoles-Rivera, F., Serna-González, M., Castro-Montoya, A. J., & El-Halwagi, M. M. (2014). Optimal design of rainwater collecting systems for domestic use into a residential development. Resources, Conservation and Recycling, 84, 44-56.

5. Slanina, J., Möls, J. J., Baard, J. H., Van der Sloot, H. A., Van Raaphorst, J. G., & Aaman, W. (1979). Collection and analysis of rainwater; experimental problems and the interpretation of results. International Journal of Environmental Analytical Chemistry, 7(2), 161-176.

Project "waterCEmanagement in practice - developing comprehensive solutions for water reuse and raising awareness of the key role of water in the transformation process towards a circular economy (CE)” uses funding worth 323 549,34 euro received from Iceland, Liechtenstein and Norway under the EEA Funds. The aim of the project is to strengthen the transformation towards a circular economy in the field of circular water resources management.