Mangere Sewage Treatment Plant
From Wikipedia, showing that several anaerobic bacteria are used in the solid waste digester to turn the carbon compounds into methane:
Bio-decomposition in the anaerobic digester involves a four-staged cooperative action performed by different microorganisms.
Hydrolysis of insoluble polymerized organic matter by anaerobes such as Streptococcus and Enterobacterium.
Acidogens (bacteria that make fatty acids) break down dissolved organic pollutants in wastewater to fatty acids.
Acetogens (bacteria that make acetates) convert fatty acids to acetates.
Methanogens (bacteria that make methane) metabolize acetates to gaseous methane.
The byproduct methane leaves the aqueous layer and serves as an energy source to power wastewater-processing within the digestor, thus generating a self-sustaining mechanism.