Waste Textiles Bioprocessing to Ethanol and Biogas

................................................................................................................................... iii List of publications .................................................................................................................. iv List of publications not included in this thesis ....................................................................... v Table of contents ...................................................................................................................... vi Chapter 1: Introduction ........................................................................................................... 1 Chapter 2: Textiles: Production, consumption, and disposal .............................................. 3 2.1. Fiber classification ..................................................................................................... 3 2.1.1. Cellulosic fibers ............................................................................................. 5 2.2. Fiber production statistics .......................................................................................... 7 2.3. Environmental impact of textile production and its disposal .................................... 7 2.4. Waste management strategies for textile waste ......................................................... 9 2.4.1 Reuse ............................................................................................................ 10 2.4.2. Recycling ..................................................................................................... 11 Chapter 3: Cellulose: Structure, pretreatment, and bioconversion .................................. 15 3.1. Cellulose structure ................................................................................................... 15 3.1.1. Cellulose polymorphs .................................................................................. 18 3.1.2. Cotton fiber structure ................................................................................... 18 3.2. Hydrolysis of cellulose ............................................................................................ 20 3.2.1. Concentrated acid hydrolysis ...................................................................... 20 3.2.2. Dilute acid hydrolysis .................................................................................. 20 3.2.3. Enzymatic hydrolysis .................................................................................. 22 3.2.4. Enzymatic hydrolysis of waste textiles ....................................................... 24 3.3. Bacterial hydrolysis of cellulose .............................................................................. 24 3.3.1 Uptake, phosphorylization, and fermentative catabolism of cellulose degradation products ............................................................................................. 26 3.4. Pretreatment of cellulose to improve hydrolysis and digestion ............................... 27 3.4.1. Pretreatment with sodium hydroxide .......................................................... 28 3.4.2. Pretreatment with phosphoric acid .............................................................. 30 3.4.3. Pretreatment with NMMO ........................................................................... 31 3.4.4. Effect of NMMO treatment on enzymatic hydrolysis of cellulose ............. 32 3.4.5. Effect of NMMO treatment on anaerobic digestion of cellulose ................ 34