Assessment of Anaerobic Co-Digestion Effects of Maize Cob and Poultry Manure on Biogas Yields and Their Digestate Characteristics

Aim: The aim of the study was to assess the effects of anaerobic co-digestion of maize cob and poultry manure on biogas yields and their digestate characteristics.

Place and Duration of Study: Department of Forestry Technology, Federal College of Forestry, Jos between March and April, 2018.

Methodology: Slurries of five co-substrate treatment ratios viz 0:1(T1), 1:3(T2), 1:1(T3), 3:1(T4) and 1:0(T5) of these wastes (in three replicates) were separately fed to 13.6L locally made batch-digesters. The anaerobic reactors were monitored for a 56 day retention period. Weekly biogas yields and some digestate characteristics were measured by standard methods.

Results: The cumulative biogas yields was in the order of T3(2481.3 mL/kg) >TI(2197.9 mL/kg) > T4(2163.0 mL/kg) > T2(2116.3 mL/kg) >T5(1713.2 mL/kg), in favor of the mixed substrates. While the percentage C:N reductions ranged from (12.94% - 81.80%), with T5 and T1 recording the highest and lowest values respectively. The chemical oxygen demand removal was in the order of T3(80.70%) > T4(58.00%) >T5(46.81%) >T1(34.15%) >T2(13.16%). The anaerobic digestion (AD) effected reductions in Mg, C, Ca, P, Mn, Zn, Fe, Pb and increase in Cu contents of the digestates across treatments. While the K contents increased in T2(36.72%), T3(229.79%) and T4(220.51%); %N in T3(9.94%), T4(113.19%) and T5(291.84%) and Na increased only in T4(4.55%). The Cu contents indicated % increase in the order of T5(487.5%) >T3(270.97%) >T2(268.10%) >T4(43.66%) >T1(35.82%).

Conclusion: The anaerobic co-digestion of these organic wastes had unlocked the alternative energy potentials, enhanced the bioremediation tendency, while promoting sustainable public health and environmental management.