Enhancing energy production from waste textile by hydrolysis of synthetic parts

Abstract

Waste jeans, containing cotton and polyester, are among the widely available sources for bioenergy production. In this study, the cotton part of waste jean was used for biogas and ethanol production. The hydrolysis of non-cellulosic part, i.e., polyester, and the pretreatment of cellulosic part was performed by sodium carbonate treatment. The effects of Na2CO3 concentration (0, 0.5, and 1 M) and temperature (50, 100, and 150 °C) on the cotton, polyester, and textile structure were investigated. The pretreated textile, with over 90% cellulose, was subjected to anaerobic digestion, enzymatic hydrolysis, and fermentation to produce biogas, sugars, and ethanol, respectively. The maximum methane yields of 328.9 and 361.1 mL/g VS were achieved from pure cotton and jeans after pretreatment with 0.5 M Na2CO3 at 150 °C for 120 min, respectively. Using the pretreatment, the highest glucose yields of enzymatic hydrolysis were 88.0% and 81.71% for cotton and textile, respectively, while the corresponding values for untreated samples were 36.9 and 28.0%. The maximum ethanol yields of 69.4% and 59.5% were obtained from cotton and textile, respectively. It was concluded that the pretreatment is promising for the hydrolysis of the synthetic polymer of textile and the improvement of the biodegradability of the cellulosic part with negligible cellulose destruction.