Solid-State Anaerobic Digestion of Dairy Manure from a Sawdust-Bedded Pack Barn: Moisture Responses

Abstract

Abstract:Bedded pack manure has long been considered an unsuitable feedstock for conventional anaerobic digestion systems due to its high solids content. However, solid-state anaerobic digestion (SS-AD) provides an opportunity to generate methane from such high-solids feedstocks. This study was conducted to determine the influence of moisture content on the digestion of bedded pack dairy manure using SS-AD. Mixtures of sawdust bedding and dairy manure were prepared with moisture contents (MCs) of 70%, 76% and 83% and digested at 37 • C for 85 days. The performance of digesters containing manure at 83% MC was 1.3 to 1.4-fold higher than that of digesters containing 70% MC manure in terms of volatile solids (VS) reduction and biogas production. VS reduction rates were 55 to 75% and cumulative methane yield ranged from 64 to 90 NmL g VS −1 . These values are lower than those from SS-AD of fresh manure and this is likely due to the partial decomposition of biodegradable materials during the two to three-month period before the manure was removed from the barn. However, in terms of efficient management of farm odors and providing a renewable energy source for heating, SS-AD of bedded pack manure offers a potential alternative to the conventional composting systems currently in use.

Fermentation characteristics of bedded pack barn dairy cattle manure on methane yield, carbon, and nitrogen content in solid-state anaerobic digestion

“…(3) ) presented by Shin (2002) : where, C CH 4 (R) is the calibrated methane concentration (%), C CH 4 is the measured methane concentration (%), and C CO 2 is the measured carbon dioxide concentration (%). The volatile solid reduction rate was determined by the equation described by Kim et al (2018) .…”

“…(4) – (6) . The ultimate biodegradability was calculated by plotting the ratio of TVS e and initial TVS before degradation (TVS 0 ) on the Y -axis and reciprocal of the operating time (1/time) on the X -axis according to the method described by Kim et al (2018) . …”

“…The daily methane yield rate from BDCM during SSAD was simulated using the modified Gaussian and Gomperz equations ( Kim et al, 2018 ). This model describes the daily methane yield in batch AD assuming that the kinetic growth of microbes including methanogens follows a normal distribution during the process.…”

“…The mixing of sawdust and cattle manure may affect the characteristics of SSAD. Previous studies have assessed the effect of moisture content and substrate-to-inoculum ratio on methane production from a mixture of cattle manure and sawdust using SSAD ( SeungHun et al, 2017 ; Kim et al, 2018 ). However, studies on carbon and nitrogen of cattle manure mixed with sawdust are rare during SSAD.…”

High-Solid Anaerobic Digestion: Reviewing Strategies for Increasing Reactor Performance

“…Kim et al [79] studied the effect of moisture content in SS-AD using a bedding material composed of sawdust collected after 2-3 months of being used as cattle bedding. These authors evaluated this material as a substrate, which had a solid content between 17% and 30%.…”