and their industrial by-products (potato stillage and potato peels)
with pig manure. Sunflower seed hulls and chicken manure were
researched by Demirel et al. [19]. According to Parawira et al. [20],
the methane yield of the co-digestion of potato wastes with sugar
beet leaves was 31e62% higher than that of potato wastes alone.
Anaerobic co-digestion also improves the nutrient balance in the
biogas digester and improves fertilizer quality [19] and [21].