Simultaneous hydrolysis and fermentation of unprocessed food waste into ethanol using thermophilic anaerobic bacteria

•One pot single step demonstration of hydrolysis and fermentation of untreated food waste.•Ethanol production from untreated food waste without enzyme supplementation.•Tests using inexpensive solid adsorbents for removal of fermentation inhibitors.•Demonstration of “High Temperature High Pressure” ethanol distillation technique.•Extrapolation of CRUDE laboratory process to pilot scale and techno-economic analysis.

The one-pot CRUDE (Conversion of Raw and Untreated Disposal into Ethanol) process was developed for simultaneous hydrolysis and fermentation of unprocessed food waste into ethanol using thermophilic (growing at 65 °C) anaerobic bacteria. Unlike existing waste to energy technologies, the CRUDE process obviates the need for any pre-treatment or enzyme addition. A High-Temperature-High-Pressure (HTHP) distillation technique was also applied that facilitated efficient use of fermentation medium, inoculum recycling, and in-situ ethanol collection. For material balancing of the process, each characterized component was represented in terms of C-mol. Recovery of 94% carbon at the end confirmed the operational efficiency of CRUDE process. The overall energy retaining efficiency calculated from sugars to ethanol was 1262.7 kJ dry weight kg−1 of volatile solids using HTHP. These results suggest that the CRUDE process can be a starting point for the development of a commercial ethanol production process.

Graphical abstractA3: Thermoanaerobacter mathranii A3; FW: Food waste; MFC: Microbial Fuel Cell; TAD: Thermophilic Anaerobic Digestion.Download high-res image (90KB)Download full-size image