Designing pre-treatment and anaerobic digestion of biowastes for higher crop nutrient utilisation

ESR 3 - Jared Nyang'Au

Aarhus University (AU)

To improve the fertiliser value of biowastes for higher crop nutrient utilisation, AU researchers are testing innovative pre-treatment techniques such as ultrasonication and high voltage (electrokinetic) techniques to treat biowastes before anaerobic digestion. First, the biowastes from the primary digestion step are pre-treated, followed by a subsequent secondary anaerobic digestion step.

The treated and non-treated digestates were applied to established winter wheat by surface banding and by direct injection to a spring barley crop to study the effects of the pre-treatment techniques and anaerobic digestion on nitrogen availability. Jared hypothesised that the pre-treatment techniques would enhance accessibility for enzymes and microbes to degrade the organic matter in the digester, thus increasing nutrient solubilisation. Jared also hypothesised that the modifications of the biowastes might improve the nitrogen use efficiency through better infiltration in soil and thereby reduced ammonia volatilisation after application. These pre-treatment techniques would also potentially increase biogas production and biogas yields are measured in the experiments.