The combined nitrogen losses from the separated fractions were significantly greater than those from the respective unseparated digestates. Nitrogen losses in the form of N2 are expected to be low: using the model developed by Harper et al. (2014), which relates N2 emissions to CH4 emissions, the N2 emissions would be 2.8–2.6 g t1 d1. During the storage period, P_TR and C_TR lost 41% and 43%, respectively, of their initial TAN content while P_UN and C_UN lost 35% and 20%, respectively (Table 2).