Abstract

Residual biosolids from wastewater treatment facilities and the organic fraction of municipal solid waste (OFMSW), such as food and yard wastes (FW and YW), are difficult to manage due to increased waste generation and recent stringent regulations. This study investigated the effect of substrate to inoculum ratio (S/I) on biochemical transformation mechanisms and biomethane production during high solids anaerobic digestion of FW, YW, and biosolids. Biochemical methane potential (BMP) assays were set up under mesophilic conditions at S/I of 1.0, 2.0, and 3.0 g OFMSW total solids (TS)/g inoculum TS. BMP with the lowest S/I (1.0) produced the highest cumulative CH4 yield of 126 mL CH4/(g VSadded ), with 90% of its maximum yield by day 37, and a hydrolysis rate constant (Khyd) of (0.06 day-1 ). S/Is 2.0 and 3.0 resulted in higher volatile fatty acid release than S/I 1.0. This led to pH-induced inhibition of methanogenesis, longer lag phases (S/I 2.0 = 12 days and S/I 3.0 = 26 days)], and lower cumulative CH4 yields [S/I = 2.0 at 45.6-mL CH4/(g VSadded ); S/I = 3.0 at 6.75-mL CH4/(g VSadded). The results show that accumulation of inhibitory intermediates can cause system failure due to mass transfer limitation under low moisture conditions when S/I > 1.0 based on TS. Results from this work assist in developing best solid waste management practices for OFMSW and resource recovery.

Document Type

Article

Publication Date

12-2019

Notes/Citation Information

© Mary Ann Liebert, Inc.

Digital Object Identifier (DOI)

https://doi.org/10.1089/ees.2019.0078

Funding Information

This material is based upon work supported by the Hinkley Center for Solid and Hazardous Waste Management and the National Science Foundation under Grant No. 1243510.

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