Effect of Liquid Hot Water Pretreatment on Hydrolysates Composition and Methane Yield of Rice Processing Residue

Lisbet Mailin López González,Monika Heiermann

doi:10.3390/en14113254

Abstract

Lignocellulosic rice processing residue was pretreated in liquid hot water (LHW) at three different temperatures (140, 160, and 180 °C) and two pretreatment times (10 and 20 min) in order to assess its effects on hydrolysates composition, matrix structural changes and methane yield. The concentrations of acetic acid, 5-hydroxymethylfurfural and furfural increased with pretreatment severity (log Ro). The maximum methane yield (276 L kg−1 VS) was achieved under pretreatment conditions of 180 °C for 20 min, with a 63% increase compared to untreated biomass. Structural changes resulted in a slight removal of silica on the upper portion of rice husks, visible predominantly at maximum severity. However, the outer epidermis was kept well organized. The results indicate, at severities 2.48 ≤ log Ro ≤ 3.66, a significant potential for the use of LHW to improve methane production from rice processing residue.

Highlights

Leibniz Institute for Agricultural Engineering and Bioeconomy, Department Technology Assessment and Substance Cycles, Max-Eyth-Allee 100, 14469 Potsdam, Germany
Lignocellulosic rice processing residue was pretreated in liquid hot water (LHW) at three different temperatures (140, 160, and 180 ◦ C) and two pretreatment times (10 and 20 min) in order to assess its effects on hydrolysates composition, matrix structural changes and methane yield
This study provides data to adjust the pretreatment conditions of locally available RD considered as a feedstock for methane production as a renewable energy carrier

Summary

Introduction

Lignocellulosic rice processing residue was pretreated in liquid hot water (LHW) at three different temperatures (140, 160, and 180 ◦ C) and two pretreatment times (10 and 20 min) in order to assess its effects on hydrolysates composition, matrix structural changes and methane yield. The maximum methane yield (276 L kg−1 VS) was achieved under pretreatment conditions of 180 ◦ C for 20 min, with a 63% increase compared to untreated biomass. The results indicate, at severities 2.48 ≤ log Ro ≤ 3.66, a significant potential for the use of LHW to improve methane production from rice processing residue. 439.9 million tonnes of millet-equivalent rice [1] This is considered the third agricultural crop of global importance in terms of total cultivated area and production. RS, comprising leaves and stems, is a by-product accruing when harvesting paddy

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