<P> Biogenic sulfide corrosion is a bacterially mediated process of forming hydrogen sulfide gas and the subsequent conversion to sulfuric acid that attacks concrete and steel within wastewater environments . The hydrogen sulfide gas is biochemically oxidized in the presence of moisture to form sulfuric acid . The effect of sulfuric acid on concrete and steel surfaces exposed to severe wastewater environments can be devastating . In the USA alone, corrosion is causing sewer asset losses estimated at around $14 billion per year . This cost is expected to increase as the aging infrastructure continues to fail . </P> <P> Corrosion may occur where stale sewage generates hydrogen sulfide gas into an atmosphere containing oxygen gas and high relative humidity . There must be an underlying anaerobic aquatic habitat containing sulfates and an overlying aerobic aquatic habitat separated by a gas phase containing both oxygen and hydrogen sulfide at concentrations in excess of 2 ppm . </P>

Corrosion in sewer system occurs due to production of
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