Production of biogas from poultry litter mixed with the co-substrate cow dung

Peer review under responsibility of Taibah University.

Figures & data

Fig. 1 Outline of the experimental setup for biogas generation.

Table 1 Characterization of raw materials used in the biogas digester.

Constituents	Poultry litter	Poultry dropping	Cow dung	Inoculums
pH (6% of slurry)	8.5	7.0	6.3	6.43
Moisture content (%)	27.68	77.5	83	96
TS (%)	72.32	22.5	17	6
VS (%)	83.95	66.72	89	88.66
COD (g/l)	76.5	65.3	–	–
C/N ratio	7.5	6.5	24	–
Calorific value (kcal/kg)	4519.77	3980.75	4658.07	–

DS, desulfurized slag; WQS, water-quenched slag; AAR, arsenic–alkali residue; BFD, blast furnace dust.

Fig. 2 Cumulative gas production with time at different reactors.

Fig. 3 Observed peak gas generation time with initial volatile solid conc. (g/l).

Fig. 4 Cumulative destruction of volatile solid (VS) and cumulative gas production with time for reactors R1, R2, R3 and R4.

Table 4 Yield of gas generation with % of VS destruction among four reactors.

Reactors	VS (g/l)		VS reduction (%)	Yield of gas generation with VS destruction (l/g)
	Initial	Final
R1	50.37	27.14	46	0.57
R2	51.15	24.56	51.99	0.902
R3	51.9	24.94	51.96	0.808
R4	47.24	26.93	43	0.52

Fig. 5 COD reduction and cumulative gas production with time in R2 reactor.

Fig. 6 Effect of cow dung on gas production.

Fig. 7 Effect of C/N ratio against the yield of biogas.

Fig. 8 Refractory fraction in four different reactors R1, R2, R3 and R4.

Table 2 Refractory fraction, biodegradable fraction and total VS destruction observed in different reactors.

Reactor	Refractory fraction of VS (%)	% of VS destruction based on refractory fraction of VS	% of VS destruction based on total of VS
R1	52.6	47.4	46
R2	45.2	54.8	51.99
R3	44.2	55.8	51.96
R4	55.7	44.3	43

Fig. 9 Logarithmic plot of gas production with time for different reactors experimented.

Table 3 Yield constant, rate constant, correlation coefficient, predicted and observed lag time for various reactors.

Reactor	Yield constant, l/g	Rate constant, k	Correlation coefficient, R^2	Lag time, t0 days (predicted)	Lag time, t0 days (observed)
R1	0.57	0.013	0.998	7.8	4
R2	0.902	0.015	0.999	2.3	2
R3	0.808	0.015	0.997	2.1	2
R4	0.52	0.012	0.995	7.6	5

R1 = 100% poultry litter; R2 = 75% poultry litter and 25% cow dung; R3 = 50% poultry litter and 50% cow dung; and R4 = 70% poultry litter and 30% poultry dropping.