Other types of biogas are called digester gas, marsh gas or even swamp gas, depending on the source of origin.

Some topics such as digestion approach, reactor volume and dimension, agitation, heating and gas collection system are discussed in this paper concerning Process Design for Sludge Anaerobic Digestion.

This paper states the geological conditions of the formation of mineral water at the five linking lakes the formation process of the CO_2 gas in mineral water and its evolution tendency.