The Second Life of Water: Harnessing Trade-offs and Synergies

  • 2020/05/15     Dresden, Germany

    By Shuvojit Nath

    Sustainable development – defined as promoting prosperity while also protecting the environment – can be achieved by moving away from the traditional linear economy towards a circular economy, thus, maximising resource efficiency. In this regard, solid wastes and wastewater are being considered in new ways to identify them as resources from which we can extract value.

    In Nexus Seminar No. 43 titled “The Second Life of Water: Harnessing Trade-offs and Synergies” held on 27 April 2020 by Dr Serena Caucci, Senior Research Associate at UNU-FLORES, highlighted the relevance of water reuse in the circular economy globally with a focus on agriculture, industrial settings, and aquifer recharge. It was the first Nexus Seminar to be held completely online due to the current pandemic circumstances.

    Dr Caucci began the seminar introducing the concepts of sustainable development and the Nexus Approach. The nexus perspective emphasises interconnections and interdependencies of compartments and their transitions and fluxes across spatial scales and between compartments.

    Dr Caucci started her discussion concerning the reuse of wastewater in agriculture with an interesting video to capture the attention of the audience. She highlighted the relevance of her research in the present-day context due to intensifying water scarcity and climate change. Almost 70 per cent of water consumed worldwide is in the agricultural sector (FAO, AQUASTAT). So, sustainable management of wastewater in agriculture across all three dimensions of society, economy, and environment is essential. To address this, a systematic literature review was done. Several indicators and indicator factors were found out and they were categorised on the dimensions of sustainability they assessed. In the study on Sustainability Assessment, environmental factors are found to be substantially weighted greater over society and economy.

    In this regard, Dr Caucci introduced the case study in Mezquital Valley, Mexico. This poor agricultural region is situated in the north of Mexico City. It receives untreated wastewater from Mexico City through channels used by farmers in agriculture. The potential benefit of using wastewater is its richness in nutrients and it acts as a substitute for inorganic fertiliser. It also has an unintended result of aquifer recharge; however, its volume and quality are not properly monitored. UNU-FLORES’s projects such as the Safe Use of Wastewater in Agriculture (SUWA) and Sludgetec set a blueprint for good practice towards assessing and developing tailor-made wastewater treatment and management systems for small to medium-sized cities.

    Dr Caucci explained that the arbitrary approach of sustainability assessment left no room for comparability. Therefore, to reduce the bias a Sustainability Index was created to allow comparisons. The Index is designed in such a way that it is most suitable for policymaking. In this, the socioeconomic dimension is also equally represented with the environmental dimension. The Sustainable Index consists of a cascade of different environmental and socioeconomic indices, relatively rated to form a single indicator. The Index is now in development and testing phase. Results would be discussed further in a separate seminar after completion of the pilot testing. This indicator addressed the issues of inter-relativity of social and economic dimensions, exclusion of factors measuring the same aspect, and exclusion of those which are hard to measure.

    Dr Caucci advocated another approach to water reuse: as a sustainable practice for aquifer recharge. In this regard, she presented the study UNU-FLORES has conducted in Korba, North Tunisia with the support of the Ministry of Environment in Tunisia and INGREF. This technique was applied in this region due to high salinity in groundwater because of saltwater intrusion from the sea and severe water scarcity in the region due to intensive agriculture practices and climate change. Dr Caucci emphasised wastewater-managed aquifer technique (MAR) as a potential solution to water scarcity but if wastewater is not of adequate quality, it can become a source of emerging pollutants, which are not monitored presently in Tunisia. The study concluded that MAR, despite being proofed as a sustainable nature-based solution, the scale of MAR application to the region was not sufficient to reach sustainability but it could prevent saltwater intrusion. Macro contaminants like Nitrogen and salt are still a major source of pollution from wastewater into aquifers. Contaminants of emerging concern like pharmaceuticals are instead not in elevated concentration into groundwaters but their presence should be carefully monitored due to the high risk for health and environment carried by such pollutants. The study calls for policymakers to take concrete actions against the increasing water quality deterioration which will negatively impact agriculture in the region. Upscaling of MAR size and the improvement of wastewater treatment plant performance were recommended. Further studies and appropriate monitoring of pollutants was also recommended.

    Dr Caucci concluded the seminar with the mention of a new project she will be leading in the field of water reuse in industrial settings. Together with the Technical University of Dresden, UNU-IAS and with multiple other International Partners, the SMART-WaterDomain (EIG-JAPAN) project will be providing a framework for organisational decision-making processes for companies and utilities to facilitate the uptake of water reuse practices in their operation. The project will test assumptions regarding technical feasibility, legal provisions, political assessments and sustainability benefits for the environment, economy and society. Project’s innovation is to serve as a technology and know-how bridge among the IT, the industry and the community addressing the gap between theoretical technical capabilities and actual application in socio-political and cultural environments. SMART-WaterDomain will join forces in supporting the strategy of UNU-FLORES toward the implementation of the Nexus Approach to environmental resources management.

    Further Reading

    Avellán, Tamara, Lucía Benavides, Serena Caucci, Angela Hahn, Sabrina Kirschke, and Andrea Müller. 2019. Towards Sustainable Wastewater Treatment Systems: Implementing a Nexus Approach in Two Cases in Latin America. Dresden: United Nations University Institute for Integrated Management of Material Fluxes and of Resources (UNU-FLORES).

    Georgiou, Isabella, Hiroshan Hettiarachchi, and Serena Caucci. 2020. Towards a Unified Index for Assessing the Sustainability of Wastewater Irrigation. Working Paper. Dresden: United Nations University Institute for Integrated Management of Material Fluxes and of Resources (UNU-FLORES).

    Hettiarachchi, Hiroshan, Serena Caucci, and Reza Ardakanian. 2018. “Safe Use of Wastewater in Agriculture: The Golden Example of Nexus Approach” in Safe Use of Wastewater in Agriculture: From Concept to Implementation, ed. Hettiarachchi, Hiroshan and Reza Ardakanian, 1–11. Cham: Springer Nature.