Our research group is working to develop an AD biorefinery for producing bioenergy and biobased products from high yielding energy crops as illustrated in Fig. 1. Ideally, a biorefinery should be able to generate significant volumes of biofuel (either liquid or gaseous in nature) with the concurrent generation of value-added co-products. Waste streams from these facilities can also be bioremediated via AD for additional biomethane (and energy) production.
Fig. 1 Schematic diagram of an example biorefinery
AD is currently being examined for the production of carboxylic acids, such as acetic acid (C-2) and propionic acid (C-3), which can be converted into biofuels using thermo-chemical methods that include hydrotreatment, dehydration and oligomerization. Additionally, AD is also being explored for the production of many platform chemicals which are presently derived from non-renewable (petroleum-based) resources.
Anaerobic digestion is widely employed for waste treatment. Some of the major applications of AD in waste remediation include the stabilization of waste activated sludge, high strength industrial wastewater, food waste and animal manure, and human feces in many developing countries. AD is a less energy-intensive process for the removal of organic matter, and generates useful products such as biogas (containing biomethane). The AD process also prevents the emanation of malodorous compounds, especially hydrogen sulfide.
Greenhouse Gas (GHG) Emission Reduction
AD has the significant potential to curb GHG emissions by capturing methane from animal manure. The replacement of traditional fuel, such as firewood and kerosene in developing countries, improves energy use and efficiency for heating and cooking. In addition, biogas burns cleaner than traditional resources and mitigates indoor air pollution (IAP).