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.

A3: Thermoanaerobacter mathranii A3; FW: Food waste; MFC: Microbial Fuel Cell; TAD: Thermophilic Anaerobic Digestion.90