Figure 6: Single (X) 20 ml/L digestate supplementation from C/N 26 and two stage feeding (Y-Z) Two-stage feeding. (Y) Addition of high (C/N 30) and low (C/N 26) nitrogen digestates at 0-120 h (initial-exponential) and 120-180 h (stationary phase), respectively. (Z) Addition of only C/N 26 digestate at 12 hourly (0-120 h) by 12 ml/L and 3 ml/L at 0-120 and 120-180, respectively.