Municipal Industrial Pretreatment Program

What is the Municipal Industrial Pretreatment Program (MIPP)?
The Municipal Industrial Pretreatment Program is a cooperative effort of federal, state, and local agencies to protect water quality by reducing the amount of pollutants discharged by industry and other non-domestic sources into sewer systems and the environment.

What is the difference between an SIU and a CIU?
An industrial user (IU) will be classified as a significant industrial user (SIU) if it meets any of the following:

  • Is subject to categorical pretreatment standards under 40 CFR 403.6 and 40 CFR chapter I, subchapter N;
  • Discharges an average of 25,000 gallons per day (gpd) or more of process wastewater to the publicly owned treatment works (POTW), excluding sanitary, noncontact cooling, and boiler blowdown wastewater;
  • Contributes a process wastestream that makes up 5 percent or more of the average dry-weather hydraulic or organic capacity of the POTW;
  • Is designated as such by the POTW on the basis that the IU has a reasonable potential for adversely affecting the POTW's operation or for violating any pretreatment standard or requirement [in accordance with 40 CFR 403.8(f)(6)].

A categorical industrial user (CIU) is an SIU [see (A) above], but an SIU is not always a CIU. Categorical users have specific limits and requirements that are determined by the federal government. States and local governments can develop requirements that are more restrictive, but not less restrictive.

What are the Objectives of the pretreatment program:
  • Protect the POTW from pollutants that may interfere with wastewater treatment plant operations.
  • Prevent introducing pollutants into a POTW that could pass through wastewater plants into rivers.
  • Manage pollutants discharged into POTW to ensure opportunities for reuse of POTW wastewater and residuals (compost).
  • Prevent introducing pollutants into a POTW that could cause worker health or safety concerns, or that could pose a potential endangerment to the public or to the environment.
The term "pretreatment" refers to the requirement that non-domestic (industrial) sources discharging wastewater into the sewer system control their discharges, and meet limits established by the United States Environmental Protection Agency (US EPA), the State of Pennsylvania, or the local municipality. This may necessitate prevention techniques, production practice improvements or treatment prior to discharging waste into the sewer system by a company.

Bethlehem currently has 35 significant industrial users. Regulatory oversight of industrial sources includes formal permitting, compliance monitoring (routine inspections and sampling), and enforcement.