Production of biogas and ethanol from stationery wastes using a microbial consortium isolated from soil as starter culture

Abstract

The conventional pretreatments used during the valorization of paper waste in renewable energies are expensive, long, slow, require high temperatures and particularly not eco-friendly. However, the application of microbial cultures with cellulolytic capabilities becomes an attractive and low-cost strategy. Therefore, the aim of this study was to screen an efficient microbial culture and its evaluation as a starter culture during hydrolysis process of biogas and bioethanol production. Our results indicated that from 18 isolates, two bacteria (identified as Pseudomonas horyzihabitans and Serratia liquefaciens) and one consortium (CS2, predominated by Enterobacteriaceae) had an important cellulosic hydrolysis activity. The application of the selected consortium as a starter culture during the hydrolysis process of biogas and bioethanol production improved yields. Indeed, the application of CS2 enhanced the biogas and bioethanol yields to 9.4 mL g−1 and 78.2 μL g−1 (P < 0.05) respectively. Also, starter culture CS2 addition reduced the time needed for cellulosic hydrolysis to 21 days, respect to 24 days in control sample, during biogas production under psychrophilic temperature. Thus, this low cost and practical procedure can be used as an efficient strategy to release sugars from paper waste, to reduce the time needed for cellulosic biodigestion, and to enhance the biogas and bioethanol recovered.