Fig. 1. Changes of gas productivity (a) and methane concentration (b) during the anaerobic digestion of pig and dairy manure slurries
Note: mean±standard errors (n=3)

Fig. 2. Changes of DOM content in the raw and digested pig and dairy manure slurries
Note: Different capital and small letters indicate the significant (p<0.05) differences between the treatments in raw and digested materials, respectively; *** indicate significant (p<0.001) differences between the raw and digested materials. The same below.

Fig. 3. 3DEEM changes of DOM in the raw and digested pig of (a) PM1; (b) PM2; (c) DM1; (d): DM2

Fig. 4. PARAFAC fluorescence components (a) and F_max (b) of DOM in the raw and digested pig and dairy manure slurries

Fig. 5. Changes of DOM humification index in the raw and digested pig and dairy manure slurries
Note: ** and *** indicate significant (p<0.01, p<0.001) differences between the raw and digested pig and dairy manure slurries, respectively