%0 Journal Article
%T Improving Anaerobic Digestion of Wheat Straw by Plasma-Assisted Pretreatment
%A Stefan Heiske
%A Nadja Schultz-Jensen
%A Frank Leipold
%A Jens Ejbye Schmidt
%J Journal of Atomic and Molecular Physics
%D 2013
%R 10.1155/2013/791353
%X Plasma-assisted pretreatment (PAP) of lignocellulosic biomass has been shown to be an efficient method to decompose lignin and consequently facilitate microbial access to cellulose and hemicellulose. In the present study, PAP was tested for its suitability to enhance bioconversion of wheat straw to methane. In thermophilic batch experiments, methane yields of up to 366£żmL/g volatile solids (VSs) were achieved, accounting for a yield increase of 45%. Common lignin-derived inhibitors like 5-hydroxymethylfurfural (5-HMF) and furfural were not detected after PAP, but toxicity test resulted in lower methane yields at higher substrate concentrations, indicating the presence of other unidentified inhibitors. However, in a continuous lab-scale biogas reactor experiment, stable codigestion of cattle manure with 20% PAP wheat straw was demonstrated, while no signs of adverse effects on the anaerobic digestion process were observed. After the introduction of the pretreated wheat straw to the reactor, volatile fatty acid concentrations remained low and stable, while gas production increased. In co-digestion, the PAP wheat straw was converted at an average yield of 343£żmL CH4/gVS. 1. Introduction Anaerobic digestion (AD) is a widely applied method of managing agricultural byproducts such as animal manure and crop residues with multiple benefits. Treating organic material in biogas plants can produce renewable energy in the form of biogas, reduce land-use related environmental impacts, and improve the fertilizer quality of manure. These benefits have increased the interest in biogas technology worldwide. At present, the economic benefits of AD of agricultural residues are, however, limited because manure has a low energy density and many fibrous residues are only poorly degraded. This results in a low biogas yield which is a barrier to the expansion of biogas technology for energy production purposes. However, manure and crop residues hold the potential for a more efficient conversion to biogas as a considerable fraction of the organic material remains undigested in currently applied biogas processes. The main reason for the low yields lies in the structure of the biomass. Crop residues and fibers contained in manure mainly consist of lignocellulose, which is poorly degraded in biogas reactors as lignin is not degradable under anaerobic conditions and prevents microbial access to cellulose and hemicelluloses [1, 2]. Hence, removing lignin can facilitate anaerobic degradation of the fibers and thereby increase the biogas yield of manure and crop residues
%U http://www.hindawi.com/journals/jamp/2013/791353/