Marrakech WWTP sewadge sludge (SULFOX Project) Metagenome

Recognized for their toxic, inhibitory and corrosive effect, sulfides (S2-, SH-, H2S) are an undesirable by-product of the anaerobic digestion of domestic wastewater treatment plants sludge in the city of Marrakech, Morocco (WWTP). They are produced mainly by the dissimilatory reduction of sulfur compounds (SO42-, SO32-, S2O42-) contained in these sludges. This process is performed by an anaerobic bacterial group called sulfate reducing bacteria (SRB). Once in the biogas, the sulfides in gaseous form shorten in addition the lifetime of the installations and equipment of the WWTP. It is thus equiped with biological and physicochemical installations allowing to eliminate these sulfides before the transformation of biogas into electrical energy. However, these processes are expensive and consume large amounts of energy. Hence the idea of minimizing the production of sulfides within anaerobic digesters. For this, it was first necessary to know the microorganisms at the origin of the production of sulfides (SRB), those potentially involved in their elimination (sulfur oxidizing bacteria), and a group of fermentative microorganisms (Synergistetes) involved in the good functioning of the anaerobic digestion. These studies were conducted by both molecular and cultural approaches. The results obtained allowed to understand how these bacterial groups, of great ecological and economic interest, are involved in the anaerobic digestion of sludge from the WWTP, which both accelerates the oxidation processes of the organic matter combined with the reduction of sulfur compounds and to minimize the concentration of sulfide in the biogas.Key words: Sulfides, anaerobic digestion, biogas, sulfate reducing bacteria, sulfur oxidizing bacteria, Archea, Synergistetes, MiSEQ, isolation and characterisation