Evaluating the Effects of Electroporation Pre-treatment on the Biogas Yield from Ley Crop Silage

Abstract

Exploiting the full biogas potential of some types of biomass is challenging. The complex structures of lignocellulosic biomass are difficult to break down and thus require longer retention times for the nutrients to become biologically available. It is possible to increase the digestibility of the substrate by pre-treating the material before digestion. This paper explores a pre-treatment of ley crop silage that uses electrical fields, known as electroporation (EP). Different settings of the EP equipment were tested, and the results were analyzed using a batch digestion setup. The results show that it is possible to increase the biogas yield with 16 % by subjecting the substrates to 65 pulses at a field strength of 96 kV/cm corresponding to a total energy input of 259 Wh/kg volatile solid (VS). However, at 100 pulses, a lower field strength of 48 kV/cm and the same total energy input, no effects of the treatment were observed. The energy balance of the EP treatment suggests that the yield, in the form of methane, can be up to double the electrical energy input of the process.

Application of Pulsed Electric Energy for Lignocellulosic Biorefinery

“…It was concluded that permeabilization of switch grass and wood chip species using the PEF can be utilized to improve the cellulose hydrolysis to sugar. Electroporation of lignocellulosic biomass (ley crop silage) under the PEF treatment (at E = 48-96 kV/cm) has been investigated (Lindmark et al 2014). Ley crop (a mixture that consists mainly of grass and clover) is commonly used in a crop rotation to fertilize a soil with nitrogen.…”

Perspectives on using pulsed electric field to enhance biogas yield in anaerobic digestion

“…Moreover, strong shockwaves generated by methods such as sparking are able to crack conglomerates (plant debris, lignocellulose, manure, soil), making carbon sources better available 8 . Although postulated in earlier days, there is no evidence that shockwaves are able to crack lignin, but electrical treatment can enhance digestion of ligno-cellulose rich material 48 .…”

Performance optimization of the Växtkraft biogas production plant

“…The results from the previous studies by the authors on pre-treatment and membrane filtration of the process water [5,6,16] presented in Table 1 and 2 were used to estimate what it would mean for the full-scale biogas plant if these measures are taken. The results of the studies were also converted to the same form to be able to compare them.…”

“…Therefore pre-treatment of the ley crop silage to increase the digestion rate is of interest to improve the performance of the plant. Mechanical pre-treatment and pre-treatment by electroporation of ley crop silage has previously been studied by the authors [5,6]. In the mechanical pre-treatment tests two commercial available grinding machines for recovering of fibres from recycled paper were used, GLD 360 HW and KD 450 from Cellwood Machinery AB.…”