Valorisation of the digestate from pig manure as new fertilizers with an organic / mineral base and gradual release.
LIFE MIX_FERTILIZER is a project funded by the EU through the LIFE + call with a budget of more than € 1.2 M. Leaded by CARTIF Technology Centre, the rest of the consortium partners were the Soria provincial Centre of young farmers (ASAJA –Soria), and the companies Pural SL and Servimed SL.
This project has aimed to develop an innovative system for the treatment of the waste from the anaerobic digestion of pig manure (digestate) and its subsequent agricultural recovery. Project activities started in September 2013 and lasted for 3 years to result in a new type of fertilizers with an organic / mineral base and gradual release of the nitrogen.
The actions were developed mainly in the province of Soria (Spain). The solid fraction of the digestate obtained at the biogas plant owned by Pural in Almazan (Soria, Spain) was composted with other organic wastes such as chicken manure and vegetable biomass.
On the other hand, the liquid fraction of the digestate was treated in a stripping prototype for the recovery of the nitrogen as ammonium sulphate. Treated effluent has been used for the fertirrigation of sunflower in 4 controlled trials.
Servimed has produced a new type of fertilizers by the combination of the organic fraction and the ammonium sulphate previously obtained and a nitrification inhibitor to control the nitrogen release. In a subsequent stage, ASAJA-Soria evaluated the effectiveness of these new fertilizers in controlled barley rainfed trials. Because of their dual nature, the new fertilizers have shown a number of environmental and economic benefits over currently marketed products such as soil quality improvement, minimization of nitrogen losses through nitrate leaching, GHG emissions reduction, agricultural yields increase and cost reduction by a single application. Finally, CARTIF has evaluated the Carbon Footprint of the process and has carried out the Life Cycle Assessment of these new products.