High solids co-digestion of food and landscape waste and the potential for ammonia toxicity.
A pilot-scale study was completed to determine the feasibility of high-solids anaerobic digestion (HSAD) of a mixture of food and landscape wastes at a university in central Pennsylvania (USA). HSAD was stable at low loadings (2g COD/L-day), but developed inhibitory ammonia concentrations at high loadings (15 g COD/L-day). At low loadings, methane yields were 232 L CH4/kg COD fed and 229 L CH4/kg VS fed, and at high loadings yields were 211 L CH4/kg COD fed and 272 L CH4/kg VS fed. Based on characterization and biodegradability studies, food waste appears to be a good candidate for HSAD at low organic loading rates; however, the development of ammonia inhibition at high loading rates suggests that the C:N ratio is too low for use as a single substrate. The relatively low biodegradability of landscape waste as reported herein made it an unsuitable substrate to increase the C:N ratio. Codigestion of food waste with a substrate high in bioavailable carbon is recommended to increase the C:N ratio sufficiently to allow HSAD at loading rates of 15 g COD/L-day.
Department of Civil & Environmental Engineering, Bucknell University, Lewisburg, PA 17837, USA.
Margaret F
MF
Drennan
Department of Civil & Environmental Engineering, Bucknell University, Lewisburg, PA 17837, USA. Electronic address: thomas.distefano@bucknell.edu.
Thomas D
TD
DiStefano
D000641:Ammonia / Q000032:analysis* / Q000633:toxicity; D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D019149:Bioreactors; D004785:Environmental Pollutants / Q000032:analysis*; D005504:Food Analysis; D008697:Methane / Q000032:analysis; D010414:Pennsylvania; D010865:Pilot Projects; D012037:Refuse Disposal / Q000379:methods*; D014866:Waste Products / Q000032:analysis*
D004785:Environmental Pollutants; D014866:Waste Products; D000641:Ammonia; D008697:Methane
Ammonia inhibition; Food waste; High-solids anaerobic co-digestion; Landscape waste; Waste biodegradability