## 4 Ways to Intensify Dry AD of Chicken Manure
### Dry Anaerobic co-Fermentation of Chicken Manure
[PERSON] [55] investigated batch anaerobic poultry manure co-fermentation and corn production waste at a TS concentration between 25 and 35%, at 35 \({}^{\circ}\)C. A ratio of 2.5:1 of manure to maize waste was used. The author showed the positive effect of increasing the TS concentration on the process. Thus, the maximal methane yield was 42.95 mL/g of VS, with a methane concentration of 59% at a TS concentration equal to 35%. The ammonium concentration was about 20 g/L. [PERSON] [23] was able to achieve an increase in biogas output by 22% and 44% while applying chicken manure co-fermentation with silage corn at the ratios of 5:1 and 1.35:1 of grease, respectively, at a TS concentration equal to 20%. The studies were carried out at a temperature of 35 \({}^{\circ}\)C. Thus, biogas yield of fermentation with maize silage was 473 mL/g of VS (methane concentration was 246 ml/g VS), and with oil waste, it was 560 mL/g of VS (methane concentration was 270 of mL/g of VS) [23]. A study by [PERSON] et al. indicated the negative effect of increased glycerin concentration obtained after biodiesel production, on chicken manure co-fermentation at 35 to 55 \({}^{\circ}\)C. The substrate with the ratios of chicken manure to glycerol of 9:1, 8:2, and 7:3 at TS contents equal to 26, 22, and 18%, respectively, were used to provide fermentation. Methane production occurred only when the ratio of chicken manure to glycerol was 9:1 at all moisture content values. Moreover, the results in thermophilic conditions were much worse than in mesophilic conditions. The maximum methane and biogas outputs were observed at a TS concentration of 22%. Thus, the maximum methane output in the mesophilic conditions was 6.34 mL/g of VS with a methane concentration in the biogas of 13.3%, and in thermophilic ones, it was 1 mL/g of VS with 10% of methane. Probably, inhibition was due to substances after biodiesel synthesis [99]. In the works of [PERSON] [100], the positive effect of glycerin after biodiesel production was achieved on the compatible fermentation with wastewater from poultry farms. [PERSON] et al. [101] researched chicken manure co-fermentation with straw at a TS concentration equal to 22.29%, at a C/N ratio of 16.8:1, at 37 \({}^{\circ}\)C. They found that the optimum loading rate was 4.2 g of TS/(L*day). Under such a loading rate, the methane yield was 163 mL/g of TS with a methane content of 65.1%. Ammonium concentration was in the range from 1.35 to 2 g/L, and there was no VFA accumulation. The VFA accumulation took place for cases with higher loading rates. However, they found that the limiting factor of manure co-fermentation with straw was the cellulose hydrolysis [102]. [PERSON] [97] provided semi-continuous fermentation of chicken manure and kitchen waste at a ratio of 1:4 with a TS concentration of 26.5%, at a temperature of 35 \({}^{\circ}\)C. However, the chicken manure and kitchen waste ratio changed to 1:31.5 with a TS concentration of 18.24%, due to a possible ammonium accumulation. Methane production was stable at a loading rate from 1 to 3 g VS/(L*day). Ammonium and total nitrogen concentrations were 1.3 g/L and 3.3 g/L, respectively, under the loading rate of 3 g VS/(L*day). Methane yield was 388 mL/g VS, which corresponded to 98% of the theoretical value [97]. Chicken manure co-fermentation regularly has better results than chicken manure fermentation as a monosubstrate. The low methane yield was observed only for studies that used switchgrass (2 mL/g VS) [95], straw (4.34 mL/g VS) [96], and glycerol after biodiesel production (6.34 mL/g VS) [99]. In general, methane output in co-fermentation was in the range from 2 to 406 mL/g VS, and ammonia concentration was in the range from 0.935 to 20 g/L. The largest methane yield was 406 mL/g VS, which was demonstrated in the [PERSON]'s et al. study [67]. The results of the dry anaerobic co-fermentation of chicken manure with other wastes are presented in Table 4.