Oxygen – Aeration practice
Oxidation and reduction applied to water treatment - Oxygen, chlorine and derived products

Oxygen in air is the cheapest of all oxidizers, but it's also one of the weakest. By direct chemical action, it can only react with certain easily oxidizable inorganic elements, such as the Fe ²⁺ ion and, at high pH and in the presence of a catalyst (e.g. MnO ₂ ), the Mn ²⁺ ion. On the other hand, under the influence of specific bacteria, it can enzymatically oxidize numerous mineral elements (Fe ²⁺ , Mn ²⁺ , NH ₄ –N, S ^2– ...