For Wastewater Operator Certification study, it helps to know where EPA's sewage sludge (biosolids) rule stops. 40 CFR Part 503 sets standards "for the final use or disposal of sewage sludge generated during the treatment of domestic sewage in a treatment works" (503.1(a)(1)). Section 503.6, Exclusions, then lists ten exclusions, (a) through (j). This explainer reads 503.6, with the definitions it relies on in 503.9, as they stand in the eCFR. It does not describe a rule change. In 503.6, "does not establish requirements" means Part 503 sets none; it does not say no other rule applies (503.6(e), for example, refers to 40 CFR part 261 for hazardous sewage sludge).
Are grit and screenings sewage sludge?
No. 503.6(h) states that the part "does not establish requirements for the use or disposal of grit (e.g., sand, gravel, cinders, or other materials with a high specific gravity) or screenings (e.g., relatively large materials such as rags) generated during preliminary treatment of domestic sewage in a treatment works." The definition of sewage sludge in 503.9(w) says the same thing from the other side: sewage sludge "does not include ash generated during the firing of sewage sludge in a sewage sludge incinerator or grit and screenings generated during preliminary treatment of domestic sewage in a treatment works."
By contrast, 503.9(w) says sewage sludge "includes, but is not limited to, domestic septage; scum or solids removed in primary, secondary, or advanced wastewater treatment processes; and a material derived from sewage sludge."
What about ash from a sewage sludge incinerator?
Also excluded. 503.6(g): "This part does not establish requirements for the use or disposal of ash generated during the firing of sewage sludge in a sewage sludge incinerator." Part 503 does apply to a sewage sludge incinerator and to the exit gas from its stack (503.1(b)(3) and (4)), except an incinerator in which sewage sludge is co-fired with other wastes (503.6(c)); the exclusion in (g) is for the ash.
A related exclusion, 503.6(c), covers sewage sludge "co-fired in an incinerator with other wastes" and the incinerator in which sewage sludge and other wastes are co-fired. It adds: "Other wastes do not include auxiliary fuel, as defined in 40 CFR 503.41(b), fired in a sewage sludge incinerator."
Does Part 503 cover sludge from a drinking water plant?
No. 503.6(i): "This part does not establish requirements for the use or disposal of sludge generated during the treatment of either surface water or ground water used for drinking water."
What about industrial sludge?
503.6(d) excludes "the use or disposal of sludge generated at an industrial facility during the treatment of industrial wastewater, including sewage sludge generated during the treatment of industrial wastewater combined with domestic sewage." Note the condition: this exclusion is about sludge generated at an industrial facility. A treatment works is defined in 503.9(aa) as a device or system used to treat "either domestic sewage or a combination of domestic sewage and industrial waste of a liquid nature".
Are hazardous or high-PCB sludges covered?
No. 503.6(e) excludes "sewage sludge determined to be hazardous in accordance with 40 CFR part 261", and 503.6(f) excludes "sewage sludge with a concentration of polychlorinated biphenyls (PCBs) equal to or greater than 50 milligrams per kilogram of total solids (dry weight basis)."
Which septage is covered, and which is not?
503.6(j) excludes "commercial septage, industrial septage, a mixture of domestic septage and commercial septage, or a mixture of domestic septage and industrial septage." Domestic septage itself is part of sewage sludge under 503.9(w). 503.9(f) defines it as "either liquid or solid material removed from a septic tank, cesspool, portable toilet, Type III marine sanitation device, or similar treatment works that receives only domestic sewage", and says it does not include material removed from a septic tank, cesspool, or similar treatment works that "receives either commercial wastewater or industrial wastewater" and "does not include grease removed from a grease trap at a restaurant."
Does Part 503 regulate treatment processes, or choose a disposal method?
503.6(a) says the part "does not establish requirements for processes used to treat domestic sewage or for processes used to treat sewage sludge prior to final use or disposal, except as provided in §§ 503.32 and 503.33". And 503.6(b) says it "does not require the selection of a sewage sludge use or disposal practice. The determination of the manner in which sewage sludge is used or disposed is a local determination."
Where to practice
The rest of Part 503 is quoted in our biosolids use and disposal study guide and its practice test, and the pathogen and vector attraction reduction requirements in the pathogens and vector attraction study guide. goraedu does not certify wastewater operators, and our questions are not a state operator certification exam.