New Mexico
Environment Department

Contact Information:
(505) 827-2855 MAIN // 1-800-219-6157 (toll free)
Environmental Emergencies:
505-827-9329 (24 hrs)

Liquid Waste Program

Advanced Treatment Systems

Advanced Treatment means any process of wastewater treatment that removes a greater amount of contaminants than is accomplished through primary treatment.
  • Advanced Treatment may include physical or chemical processes.
  • Often referred to as:  Advanced Treatment Systems (ATS) or Advanced/Aerobic Treatment Units (ATU’s).
  • ATU’s utilize aeration and manipulation of bacteria in order to biologically treat waste water to higher standards than a conventional primary treatment system.
Secondary Treatment means a reduction of the 5-day biochemical oxygen demand (BOD5) and total suspended solids (TSS) concentrations to 30 mg/l and 30 mg/l respectively.
Tertiary Treatment means additional treatment beyond secondary treatment standards, specifically, the reduction in the total nitrogen concentration to levels calculated with the simplified standard loading equation:  Total Nitrogen concentration (in mg/l) = [lot size (in acres) / design flow (in gpd)] x 30,000.
Advanced Treatment Systems can be used to overcome site limitations that would otherwise prohibit installation of a conventional septic system.  Because ATU’s are more complex, they require a maintenance contract for the life of the system and may also require a sampling contract to verify proper functionality.

Typical applications of Advanced Treatment include:

  • Small Lots
  • > 500 gpd/acre
  • Shallow Ground Water
  • High Strength Waste
  • Reduction in Setbacks
  • Poor or limited Soils

Section 20 .7.3.605 NMAC provides additional information about the Minimum Required Treatment Levels for Site Conditions.

NMED maintains a list of Approved Advanced Treatment Systems.



Conventional Treatment Advanced Treatment
Primary Treatment Secondary Treatment Tertiary Treatment
  • 2 Compartment Tank
  • Allows of settling of solids to form “Sludge” layer in bottom of tank
  • Flotation of Fats, Oils, and Greases (FOG) to form “Scum” layer
  • Aeration (aerobic)
  • In addition to Primary Treatment, also includes:
  • Reduction in TSS and BOD
  • Aeration (aerobic)
  • In addition to Secondary Treatment, also includes:
  • Reduction in TN (as calculated)
Treatment Standards
  • BOD 200 mg/L
  • TSS 100 mg/L
  • TN 60 mg/L
  • FOG 60 mg/L
  • TSS 30 mg/L
  • BOD 30 mg/L
TN (mg/L) = [lot size (in acres) / design flow (in gpd)] x 30,000

Typical Parameters for Measuring Wastewater Strength

BOD = Biochemical Oxygen Demand means the rate at which organisms use the oxygen in water or wastewater while stabilizing decomposable organic matter under aerobic conditions.
TSS = Total Suspended Solids means the measurable component of solid matter suspended in water or wastewater.
TN = Total Nitrogen means the combined organic nitrogen, ammonia, nitrite and nitrate contained in the wastewater or effluent.
FOG = Fats, Oils and Grease