An Economical Method for Simultaneously Improving Pretreatment and Anaerobic Fermentation Effects on Corn Straw Using Ultra-Low Concentration FeCl2

Yina Qiao,Zehao Zhi,Shuting Zhang,Xuebin Lu

doi:10.3390/en13071779

Abstract

Low pollution, slight corrosion, and low cost are the main challenges in the conversion of biomass to biogas. In this work, based on the whole process optimization of biomass conversion, an effective method using an ultra-low concentration of FeCl2 was proposed to simultaneously promote the biochemical reaction and improve the pretreatment effect. The concentration of FeCl2 in the pretreatment was determined according to the requirements of the minimum amount which led to the optimal performance of the anaerobic system and had economical importance. The effects of FeCl2 in the pretreatment and anaerobic fermentation were evaluated by comparing with that of distilled water in the production of hydrolysis products and organic acids. The optimal condition was obtained at 180 °C and 10 min with 1 × 10−5 mol/L FeCl2 pretreatment. At that condition, hemicellulose achieved a high conversion of 97.6%, and the released xylose reached nearly 95%. At least 77.5% of the organic matter in the solution can be utilized for subsequent fermentation. FeCl2 pretreatment also accelerated the anaerobic acidification fermentation process and promoted organic acid yields. The work provided a meaningful and economical choice for the conversion technology of biomass to biogas.

Highlights

Lignocellulose materials draw a lot of attention because they are abundant, low-priced, and renewable
The main goal of the work was to investigate the influence of an ultra-low concentration FeCl2 on both pretreatment and anaerobic fermentation in view of the whole process optimization
Biomass is subjected to autohydrolysis at certain temperature conditions, such as 150–240 ◦ C [46]

Summary

Introduction

Lignocellulose materials draw a lot of attention because they are abundant, low-priced, and renewable. They play a significant role in the utilization of alternative energy sources in the future which can be used to produce biofuels, such as biogas or bioethanol. The conversion process is generally considered to have three steps: pretreatment, enzymatic hydrolysis, and fermentation to produce biofuel [4]. Pretreatment is considered the most important and efficient step for the degradation of lignocellulose [5]. It can break the lignin envelope and liberate its crystalline structure to be used more in the subsequent hydrolysis process [6]

Objectives

Methods

Results