Anaerobic Digestion Technology (ADT)

About anaerobic digestion (AD)

What is biogas

What is anaerobic digestion

A brief history of anaerobic digestion technology development in the world

 Anaerobic digestion is a microbiological process that anaerobically (in the absence of oxygen) decomposes biodegradable materials.

 It consists of three main phases (hydrolysis, acidogenesis, and methanogenesis).

 The products of anaerobic digestion include biogas and biodegraded organic wastes (digestate).

 Biogas is a combustible mixture of gases and a renewable energy.

 It also has other names such as manure gas, methane gas, marsh gas, etc.

Burning of biogas in a stove (image from internet)

 10 BC: marsh gas to heat bath water in Assyria

 (not dated): marsh gas to make salt from sea water in China

 1859: first biogas system in Bombay (Mumbai), India

 1895: biogas lighted street in Exeter, U.K.

 1920s -1930s: application in sewage systems in Europe, USA, Latin America, and China

 1950s: application in rural areas in some countries, e.g., China

 1970s-1980s: worldwide application in response to the energy crisis

 1990s: sluggish development

 2000s - now: application steadily increasing in many countries and technology improved

Biogas digester design in Indian in the 1970s

1 MW dairy biogas system in China in 2007 (Photo: Hangzhou Energy & Environmental Engineering Co. Ltd., China )

Feedstock for anaerobic digestion

Most often used feedstock:

 Animal manure

 Agro-industrial wastes

 Municipal wastes

 Food wastes

It must Have:

 Enough quantity

 Long term stability

 Sufficient concentration

Digesters at Lafayette WPCD, Indiana

Compound in biogas

 %

Methane (CH4)

5075

Carbon dioxide (CO2)

2550

Hydrogen sulfide (H2S)

03

Hydrogen (H2)

01

Nitrogen (N2)

Trace

Ammonia (NH3)

Trace

Oxygen (O2)

Trace