Section 98.350 - Definition of source category(a) This source category consists of anaerobic processes used to treat industrial wastewater and industrial wastewater treatment sludge at facilities that perform the operations listed in this paragraph.(1) Pulp and paper manufacturing.(b) An anaerobic process is a procedure in which organic matter in wastewater, wastewater treatment sludge, or other material is degraded by micro-organisms in the absence of oxygen, resulting in the generation of CO2 and CH4. This source category consists of the following: anaerobic reactors, anaerobic lagoons, anaerobic sludge digesters, and biogas destruction devices (for example, burners, boilers, turbines, flares, or other devices). (1) An anaerobic reactor is an enclosed vessel used for anaerobic wastewater treatment (e.g., upflow anaerobic sludge blanket, fixed film).(2) Ananaerobic sludge digester is an enclosed vessel in which wastewater treatment sludge is degraded anaerobically.(3) Ananaerobic lagoon is a lined or unlined earthen basin used for wastewater treatment, in which oxygen is absent throughout the depth of the basin, except for a shallow surface zone. Anaerobic lagoons are not equipped with surface aerators. Anaerobic lagoons are classified as deep (depth more than 2 meters) or shallow (depth less than 2 meters).(c) This source category does not include municipal wastewater treatment plants or separate treatment of sanitary wastewater at industrial sites. 75 FR 39767 , July 12, 2010, as amended at 76 FR 73903 , Nov. 29, 2011