PPS project Closing the cycle of nutrients from wastewater and process water (KNAP)

The development and implementation of systems that return nutrients to the (food) cycle face several barriers at the intersection of technology, knowledge, regulation, cooperation and economics. For this reason, this research focuses on the integrated closure of nutrient cycles from municipal and industrial wastewater systems, closing nutrient cycles both in concept development and in practice. The aim is to take nutrient recovery and reuse from wastewater to agriculture (or beyond) to a higher level through four related work packages:

1. Development of a quality system for recycled fertilisers from municipal and industrial wastewater, including system and scenario analysis for (macro)nutrients;
2. Realisation of cases regarding municipal wastewater, where the recovery of nutrient-rich products (centralised and decentralised recovery) is combined with the development of the quality system;
3. Realisation of cases concerning industrial waste water (process water), where the recovery of nutrient-rich products from the agri-food industry and SMEs is combined with the development of the quality system;
4. Project management, stakeholder consultation and dissemination of the quality system and cases, involving relevant companies, governments (national, provincial, municipal, water boards) and other parties in the development of the quality system and the implementation of the cases.

The municipal waste-water cases are:

• Valorisation of concentrated liquid fertilisers containing nitrogen;
• Valorisation of solid mineral/phosphate fertilisers from municipal wastewater;
• Valorisation of dewatered sludge and digestate from treated black water;
• Valorisation of source separated decentralised sanitation (urine, possibly black water and organic waste);
• Circular agriculture with recycled fertiliser from wastewater in the Flevoland region.

The cases for industrial wastewater are:

• Sustainable use of valuable nutrients from the agri-food industry;
• Valorisation of digestate from processed food waste;
• Circular greenhouse horticulture with fertiliser from wastewater;
• Valorisation of valuable nutrients from brewery and dairy effluent wastewater.

The outcome of this project consists of the following components:

• An elaborated quality system for recycled products and fertilisers from municipal and industrial wastewater, with special attention to challenges in legislation and regulations at Dutch and EU level [Work Package 1];
• Up-to-date insight into the largest leakages of (macro)nutrients from the Dutch nutrient system [WP1];
• A variety of cases where nutrients from municipal and industrial wastewater are recovered and reused in a centralised and decentralised way, in interaction with the development of quality systems [WP2, WP3];
• Detailed information on the agricultural value, quality and safety of individual recycled fertilisers [WP1, WP2, WP3];
• Support of relevant parties for the quality system and implementation of cases during and after the project with regard to authorities, companies and knowledge institutions [WP4];
• Listing of existing barriers in legislation and regulations that prevent optimal valorisation of nutrient-rich residue streams [WP1, WP2, WP3, WP4].

The project fills the gap to achieve the ambitions and goals of reusing nutrients from the wastewater system, using (locally) available raw materials as much as possible. The underlying objectives are:

• Reduce as much as possible the input of 'fossil' nutrients, including feed and fertiliser imports;
• To create added value by recycling and valorising nutrients from wastewater;
• Reduce/shorten nutrient loops in the food system as much as possible and close them as locally as possible;
• Remove and control contaminants in the closed-loop wastewater system to enable safe reuse of products;
• Reduce emissions to land, water and air at source.