Unveiling the synergy of Chlorella sp. and cattle manure co-digestion under high feeding load

The synergy in anaerobic co-digestion (AcoD) of cattle manure (CM) and Chlorella sp. (Ch) Under high feeding loads (50 g VS/L) was investigated with different mixing gradients in terms of organic constitute, process pa-rameters, and microbial community structure. AcoD enhanced the methane yield of CM by 9.3%-22.8% and Ch by 3.9%-16.7%, compared with their mono-digestion. The suitable protein/carbohydrates ratio was the important reason for having such a synergetic effect between carbohydrates-rich and protein-rich feedstock. AcoD of CM and Ch at the ratio of 8:2 showed a high methane yield enhanced, the fastest methane production rate, and a high relative abundance of Methanosaeta, which may be an available matching strategy for further application. The relative abundance of acetoclastic methanogen decreased with the increase of total ammonia nitrogen (TAN), and the fast methane production rate is associated with the syntrophism and high relative abundance of Syner-01 and Methanosaeta.