Official Mexican standard NOM-003-SEMARNAT-1997, which establishes the maximum permissible limits of contaminants for treated wastewater that is reused in public services. (Published in the Official Gazette of the Federation on September 21, 1998)
| MAXIMUM PERMISSIBLE LIMITS OF CONTAMINANTS | |||||
|---|---|---|---|---|---|
| REUSE TYPE |
MONTHLY AVERAGE | ||||
|
Fecal coliforms NMP/100 ml |
Eggs of Helminth (h/l) |
Fats and oils mg/l |
DBO5 mg/l |
SST mg/l |
|
|
PUBLIC SERVICES WITH DIRECT CONTACT |
240 | ≥ 1 | 15 | 20 | 20 |
|
PUBLIC SERVICES WITH INDIRECT CONTACT or OCCASIONAL |
1,000 | ≥ 5 | 15 | 30 | 30 |
KWT PTARs are designed to treat water to the most demanding level of the official Mexican standard.
That establishes the maximum permissible limits of contaminants in the discharge of wastewater and national assets
|
Parameters (*) (milligrams per liter, except when specify) |
Rivers, streams, channels, drains |
Reservoirs, lakes and lagoons |
Mexican marine zones and estuaries |
Floor | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Area irrigation green |
Infiltration and other risks |
||||||||||||||
| P.M | P.D | V.I | P.M | P.D | V.I | P.M | P.D | V.I | P.M | P.D | V.I | P.M | P.D | V.I | |
| Temperature (℃) | 35 | 35 | 35 | 35 | 35 | 35 | 40 | 40 | 40 | 35 | 35 | 35 | 35 | 35 | 35 |
| Fats and oils | 15 | 18 | 21 | 15 | 18 | 21 | 15 | 18 | 21 | 15 | 18 | 21 | 15 | 18 | 21 |
| Suspended Solids Totals |
60 | 72 | 84 | 20 | 24 | 28 | 20 | 24 | 28 | 30 | 36 | 42 | 100 | 120 | 140 |
| Chemical Demand for Oxygen |
150 | 180 | 210 | 100 | 120 | 140 | 85 | 100 | 120 | 60 | 62 | 84 | 150 | 180 | 210 |
| Organic Carbon Total* |
38 | 45 | 53 | 25 | 30 | 35 | 21 | 25 | 30 | 15 | 18 | 21 | 38 | 45 | 53 |
| Total Nitrogen | 25 | 30 | 35 | 20 | 25 | 30 | 25 | 30 | 35 | NA | NA | NA | NA | NA | NA |
| Total Phosphorus | 15 | 18 | 21 | 12 | 15 | 18 | 15 | 18 | 21 | NA | NA | NA | NA | NA | NA |
| Helminth eggs (eggs/litre) |
NA | NA | NA | NA | NA | NA | NA | NA | NA | 1 | |||||
| Escherichia coli, (NMP/100 ml) |
1000 | 1200 | 1400 | 1000 | 1200 | 1400 | 1000 | 1200 | 1400 | 1000 | 1200 | 1400 | 1000 | 1200 | 1400 |
| Fecal enterococci** (NMP/100 ml) |
1000 | 1200 | 1400 | 1000 | 1200 | 1400 | 1000 | 1200 | 1400 | 1000 | 1200 | 1400 | 1000 | 1200 | 1400 |
| pH (UpH) |
6.5 - 8.5 | ||||||||||||||
| True color | 15% purity | ||||||||||||||
| Acute toxicity (UT) |
Less than or equal to 5 | ||||||||||||||