News Project Update

Operations start at the Belgium-based WalNUT pilot site!

Published on 15 Sep 2023

Located in Aartselaar near Antwerp, the pilot works on the recovery of urban wastewater and sewage sludge.

Be smart with water. The WalNUT project distinguishes itself for its wide perspective and coverage of the entire supply chain. By doing this, hopefully, we can offer an answer to current and future resource scarcity.”
– Lennert Dockx, Researcher at Aquafin

In the pilot led by Aquafin, raw municipal  wastewater (1 m³/day) will be treated through a novel 2-stage technology:

  1. In the first stage, high-rate activated sludge (HRAS) will focus on the removal of organic matter. Almost no nutrient (nitrogen and phosphorus) removal will occur due to the low sludge retention time.
  2. In the second stage, nitrogen will be recovered by using zeolites as adsorption material. Furthermore, the regeneration of the saturated adsorption material will be investigated.

Subsequently, the optimal resource recovery can be selected: straight use of the adsorbent as fertiliser, regeneration and production of a mineral fertiliser, or a combination thereof.

The work of the pilot is not without its challenges: since the connected area of the wastewater treatment plant (WWTP) of Aartselaar is characterised by many rainwater connections on the sewer system, in case of rainy weather, the incoming load would be strongly diluted. By operating the installation on this (quite often diluted) wastewater, the robustness of the investigated technology can be further explored. Therefore, it can be determined what the minimum incoming load should be in order to obtain a stable process.

Furthermore, the Belgian pilot is fully automated, meaning that based on continuous sensor data (e.g., NH4-N) the process is controlled in order to obtain/retain the optimal conditions.

WalNUT partners expect the pilot to showcase the use of recovered nitrogen as part of a circular economy as well as the reduction of nitrous oxide emissions related to the urban wastewater treatment process.

Photo in the text & Gallery: technology allowing the two-stage treatment of raw municipal wastewater (courtesy of Aquafin)

Featured photo: Amritanshu Sikdar via Unsplash

Share the news: