Petroleum hydrocarbons are frequently detected in wastewater
and sewage. Their highly hydrophobic properties enable them
to be adsorbed onsludgeflocs , whichincreases their accumulation
and the potential influence on the subsequent sludge digestion.
Petroleum derivatives can be used by microorganisms as an additional
source of carbon not only in aerobic but also in anaerobic
conditions. Some denitrifying and sulphate-reducing bacteria
use both the individual hydrocarbons and crude oil. However,the
negative impact of petroleum derivatives on the anaerobic
digestion was also observed . Unfortunately, the existing
data concerning the influence of the petroleum contaminants on
the biogas production process are still incomplete. Most of the
available research data concern the harmful influence of polycyclic
aromatic hydrocarbons (PAHs) on wastewater treatment microbial
communities. However, due to the complex composition and the
presence of specific additives of commercial petroleum products,
the effects of their presence in digested sludge may differ from
those observed for pure fractions of PAHs.