| Organic compound | (Environmental Engineering) Any compound containing carbon except for the carbonates (carbon dioxide, the carbonates and bicarbonates), the cyanides, and cyanates. |
| Oxidative phosphorylation | (Environmental Engineering) The synthesis of the energy storage compound adenosine triphosphate (ATP) from adenosine diphosphate (ADP) using a chemical substrate and molecular oxygen. |
| Phenol | (Environmental Engineering) An aromatic benzene ring with a hydroxyl substituted for one hydrogen. |
| Phenyl- | (Environmental Engineering) A benzene ring named as a constituent group, C6H5-. |
| Phosphorylation | (Environmental Engineering) The synthesis of the energy storage compound adenosine triphosphate (ATP) from adenosine diphosphate (ADP). |
| Photoautotrophic | (Environmental Engineering) Organisms which utilize inorganic carbon dioxide for protoplasm synthesis and light for an energy source. See autotrophic and chemoautotrophic. |
| Photochemical pollutants | (Environmental Engineering) Chemicals which react photochemically (in the presence of sunlight) to destroy ozone in the stratosphere. |
| Photophosphorylation | (Environmental Engineering) The synthesis of the energy storage compound adenosine triphosphate (ATP) from adenosine diphosphate (ADP) using solar energy. |
| Phototroph | (Environmental Engineering) Organisms which obtain energy from light using photooxidation. |
| POTW | (Environmental Engineering) or Publicly Owned Treatment Works Any municipally owned wastewater treatment facility. |