Hygienization and microbial metabolic adaptation during anaerobic co-digestion of swine manure and corn stover

Abstract

This thesis is an investigation of the use of anaerobic co-digestion (AcoD) of swine manure (SM) and corn stover (CS) to produce biogas and reduce the environmental health risk of manure.Laboratory-scale mesophilic (38 °C) batch AcoD of different ratios of SM and CS were conducted to measure cumulative methane potential, organic matter reduction, hygienization efficiency, and microbial metabolic adaptation in response to increasing total solids (TS). The results revealed the highest methane potential and greatest organic matter reduction for SM mono-digestion. These same parameters were measured during long-term mesophilic AcoD in a semi-continuously fed auger plug-flow reactor (PFR), with a step-wise increase of organic loading rate (OLR) from 0.25-4.7 kg volatile solids fed (VS) m -3 d -1 . The results revealed the highest biogas potential and organic matter reduction at the lowest OLR. Hygienization efficiency was low in both experiments and lignocellulosic degradation increased in response to increased TS content.

Effect of the Inoculum-to-Substrate Ratio on Putative Pathogens and Microbial Kinetics during the Batch Anaerobic Digestion of Simulated Food Waste

“…Thus, the accumulation of VFAs which is attributable to high total solids, could have contributed to the inability of the resident E. coli to regain viability, as well as rapid coliform elimination [ 25 , 33 ]. This observation also agrees with the work of Arias et al [ 26 ] who reported more pathogen killing with higher total solids during batch AD. Although Fagbohungbe et al [ 27 ] reported an increase in E. coli and coliform inactivation only with an increase in ISR during batch AD of human faecal material, in this study, it was observed that ISR < 0.5 or ≥2, which led to high acidity or alkalinity, respectively, during the initial days of digestion would enhance E. coli and coliform inactivation during mesophilic AD.…”

“…Enterococci are very resistant to environmental stress and treatment [ 11 , 37 ]. The findings from this study agrees with the work of Arias et al [ 26 ], who observed no clear trend in Enterococcus inactivation after 75 d of batch mesophilic AD, as well as Do et al [ 38 ], who also reported the resistance of Enterococcus during a 90 d batch AD of pig slurry.…”

“…The effects of ISR on the AD process stability and biogas production have been studied [ 1 , 20 , 22 , 23 , 24 , 25 ], but there is little work that has been performed on the effect of ISR on pathogen kinetics. Although Arias et al [ 26 ] reported the effect of high total solids on pathogen inactivation during batch mesophilic AD of agricultural residue, and Fagbohungbe et al [ 27 ] investigated the effect of ISR on batch AD of human faecal material, both authors used different feedstock and pathogen detection methods and reported results for only the initial and final pathogen loadings. This research considers the effect of ISR on pathogen and microbial kinetics during batch mesophilic anaerobic digestion of simulated food waste, using culture-based and q PCR analyses respectively.…”

Application of microbial resources in biorefineries: Current trend and future prospects

“…A consortium of Clostridium , Bacteroides , Ruminococcus and Methanosarcina applied on particulated rice straw gave a maximum yield of 275 mol of hydrogen per g of substrate [ 167 ]. Members of anaerobic Clostridiales class were also able to produce methane from wheat straw, swine manure and corn stover [ 168 , 169 ].…”

Evaluation and modelling of methane production from corn stover pretreated with various physicochemical techniques

“…Corn stover refers to the residual biomass left in the field after harvesting grain, including leaves, stalks, husks, tassels and cobs. While maize grain is utilized as a substrate for ethanol production ( Schwietzke et al, 2009 ) and maize silage is used as a substrate for biogas production in Europe and North America ( Veluchamy et al, 2019 ), corn stover is currently under-utilized as a substrate for renewable energy production ( Arias et al, 2020 ).…”