SOS_AQUAE focuses on promoting sustainable agricultural practices by utilising renewable fertilisers derived from slurry and digestate treatment. The aim is to optimise nutrient usage on farms while reducing reliance on synthetic mineral fertilisers. Specifically, the OG has developed a system to utilise the liquid fraction of digestate efficiently by mixing it with water for fertigation, thereby saving on mineral fertiliser input.

Three innovative agricultural systems were evaluated:

1. Non-tillage system with alternating crops fertigated with ammonium sulphate from digestate treatment.
2. Minimal tillage system with double crops, one for food and one for biogas, fertigated with microfiltered digestate.
3. Conventional system for food and non-food crops, fertigated with microfiltered digestate.

Microfiltration and subsurface drip irrigation were developed and implemented, resulting in a technically and economically feasible solution with low filtration costs. The process involves common solid-liquid separation followed by microfiltration at 50 μm, producing microfiltered digestate suitable for fertigation. This treated digestate is mixed with water and injected into a Subsurface Drip Irrigation system for efficient nutrient utilisation in growing crops.