| NPDES | (Environmental Engineering) The National Pollutant Discharge Elimination System. The discharge criteria and permitting system established by the U.S. EPA as a result of the Clean Water Act and its subsequent amendments or the permit required by each discharger as a result of the Clean Water Act. |
| Organic nitrogen | (Environmental Engineering) Nitrogen contained as amines in organic compounds such as amino acids and proteins. |
| Phenyl- | (Environmental Engineering) A benzene ring named as a constituent group, C6H5-. |
| Runoff | (Environmental Engineering) The water that flows overland to lakes or streams during and shortly after a precipitation event. |
| Suspended growth reactor | (Environmental Engineering) A reactor in which the microorganisms are suspended in the wastewater. Examples of suspended growth reactors are activated sludge reactors and anaerobic digesters. See attached growth reactor. |
| Total dissolved solids | (Environmental Engineering) (TDS) is the amount of dissolved matter in the water. |
| Total solids | (Environmental Engineering) (TS) is the amount of organic and inorganic matter which is contained in a water. |
| Total suspended solids | (Environmental Engineering) (TSS) is the amount of suspended (filterable) matter in a water. |
| Toxicity | (Environmental Engineering) A U.S. EPA hazardous waste characteristic defined with a rigorous test procedure, the TCLP (for Toxicity Characteristic Leaching Procedure). In the procedure, a waste is extracted for 24 hours with an acetic acid solution. The acid extract is then analyzed for the presence of any of the contaminants listed in the procedure. |
| Trace contaminants | (Environmental Engineering) Contamination found in trace (very low) levels. |