| Parameter | Purpose of Test | Method |
|---|---|---|
| BOD5 | Provides a relative measure of "food" available, the degree of stabilization of the wastewater and to estimate the effect of the effluent on the receiving water body. Used for plant loading/design, discharge rate for industrial facilities, and EPA NPDES reporting. 5 day test is too long for process control — many plants use COD or TOC as early estimate. Used to calculate % removal. | 8043 8215 8229 |
| COD Chemical Oxygen Demand |
Used as a correlative/ early indicator of BOD levels. Some NPDES permits include COD as a surrogate for BOD; however, BOD is the standard reportable parameter for oxygen demand in municipal wastewater. COD provides a measure of organic "food" available to biological treatment steps and to estimate the effect of the effluent on the receiving water. (Note: Can be correlated to BOD on a plant-by-plant basis, if influent characteristics are constant.) | 8000 10067 |
| Ammonia | Monitor conversion of ammonia and organic nitrogen forms to nitrite and nitrate during the WW treatment process. Provices information on process conditions in biological treatment stages. At high concentrations an pH, ammonia can be toxic to sludge digestion microbes. | 8038 10031 10205 |
| Nitrate, HR | Indicative of the stage of conversion of ammonia and organic nitrogen forms to nitrate by the aerobic biological treatment steps (nitrification). | 8039 10020 10206 |
| Phosphate, Reactive LR | Phosphorus effluent concentrations are often controlled by discharge permits, to limit addition of nutrients to the receiving body. Phosphate is removed via biological nutrient removal prcesses and/or chemical precipitation. Reactive (ortho) phosphate is the phosphorus form that is most available to biological species. Total Phosphate includes ortho-, poly-, and organic forms. | 8048 8178 10209 |
| Alkalinity | Maintain buffering to mediate effects of acidic industrial discharges. Control nitrification conditions in secondary treatment processes. Maintain proper bacterial conditions in sludge digester. | 8203 8221 |
| pH |
Maintain proper (narrow) pH range for optimal biological processes — especially nitrification. Can indicate plant upsets by industrial discharges or development of anaerobic conditions within the plant. Important condition for methane formation and avoiding ammonia toxicity in sludge digesters. | pH meter & electrode - see instrument manual |
| Solids | Most commonly measured and regulated parameter on NPDES permits. Used to measure mixed liquor suspended solids concentration, return activated sludge/waste activated sludge concentration, influent suspended solids concentration, effluent suspended solids concentration, and % removal. | 8006 |
| Phosphate, Total LR | Phosphorus effluent concentrations are often controlled by discharge permits, to limit addition of nutrients to the receiving body. Phosphate is removed via biological nutrient removal prcesses and/or chemical precipitation. Reactive (ortho) phosphate is the phosphorus form that is most available to biological species. Total Phosphate includes ortho-, poly-, and organic forms. | 8190 10209 10210 |
Application - Wastewater Chemistries - Sludge Management
Most Frequently Asked Questions
Also Consider
| Parameter | Purpose of Test | Method |
|---|---|---|
| Coliforms, Fecal E.Coli |
Monitor and Quantity of microbial concentrations in the effluent. NPDES reporting requirement for some facilities. | |
| Volatile Acids | Measured to monitor performance of sludge digesters. Closely tied to alkalinity in controlling methane production. | 8196 8218 8291 |
| Nitrogen, Total | Total of ammonia, nitrate, nitrite, and organic nitrogen forms. | 10071 10072 10208 |
| TKN Total Kjeldahl Nitrogen |
Total of organic and ammonia forms of nitrogen. | 8075 |
| Nitrate, LR | Indicative of the stage of conversion of ammonia and organic nitrogen forms to nitrate by the aerobic biological treatment steps (nitrification). | 8192 |
| Metals | Nickel, Molybdenum, Lead, Mercury, Zinc, Chromium, Copper, Arsenic — Measure heavy metal concentrations in effluent waters and ensure compliance with NPDES permit. Of concern in effluents and land-applied biosolids due to potential toxicity. | |
| TOC Total Organic Carbon |
Used as a surrogate for BOD or COD, as a measure of organic content. | 10128 10129 10173 |


