AquaNL Trade Fair: Day 2

Concentrate flows & Circular phosphate adsorbent for treatment of surface water and wastewater

door Luuk de Waal

Within KWR’s research programme Water in the Circular Economy (WiCE), KWR is currently running the ‘Opportunities for Concentrate’ project. This project has produced a proof-of-principle lab-scale purification method that could almost completely utilise water and salt from brackish groundwater. This (purification) technical result offers a nice perspective in itself, but was elaborated in collaboration with Glastuinbouw Nederland in a social value analysis for a specific practical location. Factors such as preventing/reducing subsidence (through lower groundwater abstraction) and the discharge-free operation of a brackish water source can – in time – be decisive arguments to move towards zero-liquid-discharge treatment of brackish groundwater, especially for locations that do not have a saltwater body close at hand.

Within the Top Sector (TKI) Water Technology, KWR is working together with Aquaminerals, drinking water companies and waste water companies on the development and production of a phosphate-adsorbing filter pellet made from iron sludge. This TKI project ‘Polishing Pellets’ has produced a patented recipe for a pellet that is mechanically strong enough to be used as a filter/adsorbent material and that does not release any undesirable substances. The Water Framework Directive (for surface water) and Urban Wastewater Directive (sewage effluent) set concrete requirements for, among other things, the total phosphate content in these waters. A 9-month endurance test with the granules on a tertiary treated WWTP effluent shows the potency of the granules; both total phosphate and free phosphate experienced during the pilot test well below the set standard. Within a follow-up study, i) how the phosphate-laden pellets can be reused and phosphate recovered, ii) the functioning of the pellets will be validated more extensively on a practical scale at multiple locations and iii) all preparations will be made to rapidly scale up the production of this phosphate-adsorption pellet together with a commercial party, given the urgency in the market.

Closing Nutrient Cycles from Municipal and Industrial Wastewater

by Jorn Baan Hofman

The KNAP-project (the Dutch acronym for Closing nutrient cycles from municipal and industrial wastewater) has been in operation for two years and so it has gone past the halfway mark. We told the participants at AquaNL why we are working on this project, what we have already done and what they can expect. In some places, we have a shortage of nutrients such as phosphate and nitrogen; in others, we have too much. We have eutrophication but we also need fertilisers in our fields. Closing the nutrient cycle helps solve this dilemma. Not only can we extract nutrients from wastewater and process water, we can also use them as fertiliser. We are studying this area in the KNAP project in collaboration with 46 consortium partners. We are looking at different flows from municipal and industrial wastewater, and whether they can be used as fertiliser. When do you know if that is safe and appropriate? Can you develop an appropriate assessment framework? In addition, are these fertilisers also suitable for agricultural application? What is their agronomic value? Are they legally permitted? Or is additional support needed for their authorisation? Follow the KNAP-project for answers to these questions.

Image 1: KWR-stand

Image 2: Luuk de Waal

Image 3: Jorn Baan Hofman

Image 4: Heleen Sombekke (Uppwater)

Image 5: Piet van Erp

Image 6: Joep van den Broeke