S.D. Codified Laws § 34A-2-115
For purposes of administering the provisions of this chapter, the term, sewage sludge, means any solid, semisolid, or liquid residue removed during the treatment of municipal waste water or domestic sewage. Sewage sludge includes solids removed during primary, secondary, or advanced waste water treatment, scum, septage, portable toilet pumpings, and sewage sludge products. Sewage sludge does not include grit, screenings, or ash generated during the incineration of sewage sludge.
For purposes of administering the provisions of this chapter, the term, toxic pollutants, means any pollutant listed as toxic under section 307(a) of the Federal Water Pollution Control Act as amended to January 1, 2011, or, in the case of "sludge use or disposal practices," any pollutant identified in regulations implementing section 405(d) of the Federal Water Pollution Control Act as amended to January 1, 2011.
For purposes of administering the provisions of this chapter, the term, significant industrial user, means any discharger subject to categorical pretreatment standards and any other industrial user that discharges an average of twenty-five thousand gallons per day or more of process wastewater, excluding sanitary, noncontact cooling and boiler blowdown wastewaters, to the publicly owned treatment works or that contributes a process wastestream which makes up more than five percent of the average dry weather hydraulic or organic capacity of the publicly owned treatment works treatment plant; or one that is designated as such by the secretary on the basis that the industrial user has a reasonable chance of adversely affecting the publicly owned treatment works operation or violating a pretreatment standard or requirement.
SDCL 34A-2-115