What distinguishes anaerobic conditions from anoxic conditions?

Anaerobic conditions are characterized by an absence of dissolved oxygen, while anoxic conditions, though also lacking oxygen, can have the presence of other compounds such as nitrates. In anaerobic environments, microorganisms rely on other electron acceptors for respiration, which may include various organic or inorganic molecules, but they do not utilize oxygen or nitrates. In contrast, anoxic conditions allow for the presence of nitrate, which can be used by certain bacteria in a process called denitrification. This distinction is essential in understanding various biological processes in wastewater treatment and how different microorganisms function in these environments.