Fed Batch Enzymatic Hydrolysis of Cotton and Viscose Waste Fibers to Produce Ethanol

Kolsum Safartalab,Farzaneh Vahabzadeh,Fatemeh Dadashian

doi:10.13189/ujc.2014.020103

Abstract

The main effort of this study was to enhance the enzymatic hydrolysis yields of cotton and viscose waste fibers via fed batch enzymatic hydrolysis. To do so, enzymes fed into slurries at two steps in fed batch mode. Also, the batch mode with the same amount of enzymes was implemented in order to be compared with the fed batch mode. The results showed that the released sugar contents from fed batch hydrolysis of cotton and viscose waste fibers were 29.0 and 32.3 g/l, respectively, but batch process released 25.0 and 30.3 g/l from cotton and viscose waste fibers, respectively, which confirms the increasing effect of fed batch process on the hydrolysis of both waste fibers. In addition, the morphological studies and enzymatic hydrolysis yields from pretreated cotton and untreated viscose waste fibers showed that alkali pretreatment for viscose waste fibers is not necessary, but has significant effect on enzymatic hydrolysis of cotton waste fibers; also, the differences in microcrystalline structures of viscose and cotton waste fibers have resulted in more enzymatic hydrolysis and then fermentation yields of viscose waste fibers. The amount of ethanol produced from cotton and viscose waste fibers were 6.9 and 8.1g/l, respectively.

Highlights

Cellulose is a biocompatible and biodegradable polymer which is widely used in textile industry
According to Fig. 2&3, using fresh enzymes in fed batch mode could make up the reduced rates for both fibers, and resulted into higher hydrolysis yield (Table 2) which is in accordance with Howell’s finding [21] which says that if the initial enzyme-to-substrate ratio was low, resuspension of substrate in fresh enzyme or addition of fresh enzyme resulted into further high rate hydrolysis [21]
This study proved that fed batch enzymatic hydrolysis of cotton and viscose waste fibers improved the release of sugars and subsequently ethanol yields

Summary

Introduction

Cellulose is a biocompatible and biodegradable polymer which is widely used in textile industry. A sort of cellulosic fibers, have the highest percentage of cellulose among various cellulosic sources [1], and with annual production of more than 23 million tons per year stands for about one third of the global market of textile fibers [2].Viscose fibers, are another cellulose rich fibers, and are commonly used in today’s textile industry [3]. These fibers become wasted during the manufacturing and final uses, creating difficulties in the safe disposal of the waste generated [3, 4]. Cotton and viscose wastes fibers due to lack of lignin in their cellulosic structure [1] won’t face with such problems, and are suitable substrates for bioethanol production

Methods

Results

Conclusion