In the past, biosolids was seen as a disposal problem rather than a resource. This point of view was amplified whenever the discussion turned toward incinerating biosolids. Concerns about the environment and personal health have outweighed the need for disposal, especially through incineration. The National Ambient Air Quality Standards (NAAQS) for lead sets the maximum allowable daily concentration for lead in the biosolids feed. The 503 regulations limit total hydrocarbon (THC) emissions in the stack gases. Specifically, the regulation requires that the monthly average concentration for THC in the exit gas from a sewage biosolids incinerator stack, corrected for zero percent moisture and seven percent oxygen, cannot exceed 100 ppm on a volumetric basis. The permitting authority specifies the maximum combustion temperatures and operating parameters for the sewage biosolids incinerator air pollution control device and is based on information obtained during performance testing.