Due to climate change and increasing pollution of the environment, freshwater has become an increasingly valuable resource. Hot summers and drought make saving water resources in summertime crucial also in the Baltic Sea Region. Freshwater should be recognized as being a labor intense product, which despite extensive initial treatment, is still often discharged after single use in many countries. This practice wastes money, energy, and human labor, which could be reduced with water recovery from wastewater. Water recovered from wastewater is also called reclaimed water.

However, reclaiming water has its challenges, which are related to specific requirements for reclaimed water quality. The goal of research into reclaimed water is to reduce the risk of the potentially harmful impact of reclaimed water on the environment and human health. The key is to develop solutions for the recovery of safe water, free of pathogens and micropollutants, with the right amount of nutrients. Overcoming potential societal hesitation is also crucial. ReNutriWater researchers are well aware of the perception people have of what constitutes clean and dirty water. Which is why, in ReNutriWater, we aim to start by researching mainly non-potable uses of reclaimed water.

In ReNutriWater we aim to preserve nutrients in the reclaimed water, to combat the eutrophication of the Baltic Sea and reduce the need for artificial fertilizers. In the process of reclaiming water, nutrients can be preserved. The amount of them can be adjusted and the water then used for irrigation. This decreases the need for artificial fertilizers and creates beneficial usage of nutrients instead of having them aggregate in the residue of the water treatment process. This mitigates eutrophication of the Baltic Sea, which is caused by the excess of nutrients. In the pilot cases in ReNutriWater, we are testing how nutrient-rich reclaimed water could be produced and used, and thus, would create circular economy business models in the water sector.

Among the beneficiaries of reclaimed water use we count both local authorities and private entities. Reclaimed water can be used by local authorities and private entities for various purposes, such as street cleaning, car washes, fountains and pond recharge, irrigation of recreational areas, plant breeding.

ReNutriWater is structured with 3 pilots:

• Pilot 1: Testing out efficient methods of disinfection of reclaimed water. Pilot 1 activities will be carried out by partners: Warsaw water utility and at the University of Savonia.
• Pilot 2: Testing methods of selecting the composition of reclaimed water, in order to tailor it to specific needs, such as irrigation of plants. Pilot 2 activities will be carried out by partners: Schwander Polska in Poland and Jurmala water utility in Latvia.
• Pilot 3: Test methods to ensure the safe use of reclaimed water, including testing of reclaimed water in greenhouses. Pilot 3 activities will be carried out by partners: Samsø wastewater utility in Denmark, the University of Savonia in Finland, VNK Serviss in Latvia and Schwander Polska in Poland.

Once pilot testing is completed ReNutriWater will communicate results to target groups and help them assess the feasibility of implementing selected water reuse technologies in their own operations. ReNutriWater aims to present cost-benefit analyses on which business models for reclaimed water can be built.

This project is intended to address all these challenges to accelerate policymaking, facilitating the implementation of water reuse in the cities of Europe. The good practice of reclaiming water promotes a circular economy and addresses SDG #6 “Clean water and sanitation for all”.