Dried microbial sludge granule as additive for wastewater treatment

A process for aerobically treating wastewater comprising the steps of:

• a) contacting a composition comprising air-dried anaerobic sludge granules with a wastewater having an original chemical oxygen demand (COD) to form a wastewater:
• granules mixture, wherein the granules comprise a mixture of anaerobic bacteria, facultative anaerobic bacteria, and anaerobic and facultative anaerobic archaea microorganisms, wherein at least 30% dried granules are the archaea microorganisms, and wherein the archaea microorganisms comprise a species from the genera Candidatus Nitrosocaldus and Methanobrevibacter;
• b) incubating the mixture to achieve at least a 50% decrease of the original COD to obtain a treated wastewater, wherein said incubating is carried out with the introduction of an oxygen-containing gas;
• and;
• c) separating said granules from said treated wastewater.