Improving the Anaerobic Digestion of Swine Manure through an Optimized Ammonia Treatment: Process Performance, Digestate and Techno-Economic Aspects

Abstract

Swine manure mono-digestion results in relatively low methane productivity due to the low degradation rate of its solid fraction (manure fibers), and due to the high ammonia and water content. The aqueous ammonia soaking (AAS) pretreatment of manure fibers has been proposed for overcoming these limitations. In this study, continuous anaerobic digestion (AD) of manure mixed with optimally AAS-treated manure fibers was compared to the AD of manure mixed with untreated manure fibers. Due to lab-scale pumping restrictions, the ratio of AAS-optimally treated manure fibers to manure was only 1/3 on a total solids (TS) basis. However, the biogas productivity and methane yield were improved by 17% and 38%, respectively, also confirming the predictions from a simplified 1st order hydrolysis model based on batch experiments. Furthermore, an improved reduction efficiency of major organic components was observed for the digester processing AAS-treated manure fibers compared to the non-treated one (e.g., 42% increased reduction for cellulose fraction). A preliminary techno-economic analysis of the proposed process showed that mixing raw manure with AAS manure fibers in large-scale digesters could result in a 72% increase of revenue compared to the AD of manure mixed with untreated fibers and 135% increase compared to that of solely manure.

Prediction of methane yield and pretreatment efficiency of lignocellulosic biomass based on composition

“…The AD of chicken manure is a topic that has attracted a lot of research due to its high N content and tendency to cause NH 3 inhibition (Bayrakdar et al, 2017). Our findings (negative ultimate CH 4 yield increase and limited hydrolysis rate increase) imply that this biomass would not benefit from an ammonia pretreatment process, however the AD may be improved if the biomass undergoes only the NH 3 recovery step that would be associated to ammonia pretreatment application in an industrial setup (Lymperatou et al, 2021).…”

“…slaughterhouse waste) in previous studies (Harris et al, 2017;Mouneimne et al, 2003). Moreover, an improved reduction of lipids during AD of ammonia-treated manure fibers has been reported recently in continuous AD (Lymperatou et al, 2021). However, the strong negative correlation found between the biodegradation extent after the ammonia pretreatment and the lipid content indicates that the pretreatment may be harsh on biomass with a high lipids share, resulting to a loss of fatty material easily convertible to CH 4 .…”

“…For this purpose, a simple ammonia pretreatment at room temperature was selected as a case study and partial least square (PLS) regression was used for model generation. This pretreatment has so far been tested on some types of biomass with a variable efficiency (Antonopoulou et al, 2015;Jurado et al, 2013bJurado et al, , 2013aMirtsou-Xanthopoulou et al, 2014), and has recently been reported to be promising for industrial application given the mild conditions and possibility for ammonia recovery (Lymperatou et al, 2021). The developed models are valuable tools for estimating the ultimate methane yield of lignocellulosic biomass and for evaluating the suitability of the ammonia pretreatment based on the initial composition of the biomass.…”

Effects of different treatments of manure on mitigating methane emissions during storage and preserving the methane potential for anaerobic digestion

“…The kinetics of the CH 4 production from the solid fraction of untreated and pasteurized manure was compared by fitting the data to a 1st order kinetic model following the assumption that hydrolysis is the limitation step of biomass AD (Jensen et al, 2011;Lymperatou et al, 2021):…”

Feeding coproducts to pigs to reduce feed cost and reach sustainable food production

“…For example, bacterial denitrification of manure can reduce N 2 O emissions ( Wang et al, 2013 ; Luo et al, 2020 ). Finally, manure slurry with high organic matter content can be biodigested so that produced methane can be captured and used as energy source ( Lymperatou et al, 2021 ).…”