Anaerobic Digestion

What is anaerobic digestion?

Anaerobic digestion is defined as biological processes in which organic matter is metabolized in an environment free of dissolved oxygen or its precursors (e.g. H2O2). It is also known as non-oxidative metabolism in which organic matter is primary funneled into useful products (Yx/s) such as alcohols (ethanol, butanol, methanol), hydrogen, methane and organic acids as illustrated by the chemical formula shown below. During non-oxidative metabolism, over 90% of the organic matter is stored into the end products (energy-rich products) and only about 10% is diverted into the synthesis of new cells.

The non-oxidative metabolism can be illustrated as shown in Fig. 1.

Fig. 1 Flow diagram of non-oxidative metabolism.

What are the merits of anaerobic digestion (AD)?

Anaerobic digestion is becoming immensely popular due to its potential to produce renewable biofuels and value-added products from diverse feedstocks such as waste streams, agri-residues and energy crops. In addition, it also provides an opportunity for (economical) waste remediation. Please see the link, Bioenergy Recovery, for more detail about AD for renewable energy production, and for more information about value-added products, bioremediation, etc., please see AD Biorefinery.