AUTHOR=Eduok Samuel , John Ofonime , Ita Basil , Inyang Edidiong , Coulon Frédéric 

TITLE=Enhanced Biogas Production From Anaerobic Co-digestion of Lignocellulosic Biomass and Poultry Feces Using Source Separated Human Urine as Buffering Agent

JOURNAL=Frontiers in Environmental Science

VOLUME=6

YEAR=2018

URL=https://www.frontiersin.org/journals/environmental-science/articles/10.3389/fenvs.2018.00067

DOI=10.3389/fenvs.2018.00067

ISSN=2296-665X

ABSTRACT=<p>Effect of source separated human urine as buffering agent compared to sodium bicarbonate and water in anaerobic co-digestion of lignocellulosic biomass and poultry feces was evaluated in laboratory scale reactor for 180 days at 37 ± 2°C. Mean biogas volume ranged from 37 ± 8 to 101 ± 18 mL gVS<sup>−1</sup> in the urine buffered reactors which was 1–5 times higher than the bicarbonate and water buffered reactors and the difference was significant at <italic>p</italic> = 0. 05. Total volatile fatty acids (VFA) concentration ranged between 396 and 1,400 mg L<sup>−1</sup> with a pH of 6.9 ± 0.3 and 7.8 ± 0.1, respectively. In contrast, VFA concentration ranged between 386 and 3,109 mg L<sup>−1</sup> (pH 7.6 ± 0.2 and 4.8 ± 0.4) in sodium bicarbonate buffered digestate and control (water) respectively. The result indicates buffering capacity of urine on anaerobic co-digestion with positive effect on biogas production. The Archaeal isoprenoids included markers of aceticlastic and hydrogenotrophic methanogens with a relative abundance that ranged between 0.71–18, 3–55, and 2–59 μg g<sup>−1</sup> dry matter in the water (control), bicarbonate and urine buffered digestate, respectively. The Archaeal abundance was 1.12 and 6 times higher in the combined female/male urine than the bicarbonate buffered digestate and the control, and the difference was significant at <italic>p</italic> = 0.05. Overall, this study demonstrates that human urine with no pharmaceutical loadings as a wetting and buffering agent is a promising option for anaerobic co-digestion with competitive edge over sodium bicarbonate on lignocellulosic biomass saccharification for enhanced biogas production.</p><p><bold>HIGHLIGHTS</bold><list list-type="simple"><list-item><p>- Source separated human urine served as buffer in anaerobic co-digestion process.</p></list-item><list-item><p>- Combined female/male urine exerted an additive effect on biogas production.</p></list-item><list-item><p>- Competitive edge offered by the combined female/male urine over sodiumbicarbonate buffer in relation to biogas produced.</p></list-item><list-item><p>- Evidence of synergy for enhanced biogas production fromhigh C/N ratio lignocellulosic biomass combined with low C/N ratio poultry feces.</p></list-item></list></p>