Pollutions: what is pH (hydrogen index)

рH (hydrogen index) – is a magnitude of hydrogen-ion activity in a solute, which quantifies its acidity.

Before purification industrial wastewater often has pH indexes, that are distinct  in different ways from normal. Water with pH indexes at the limit 6,5...8,5 is considered as safe. As for the degree of acidity, wastewater can differentiate in the following way:

Neutral wastewater    pH 6,5-8
Mildly aggressive wastewater weakly acidic рН 6-6,5
weakly alkaline рН 8-9
Aggressive wastewater highly acidic рН less than 6
highly alkaline рН more than 9

The process of pH degree normalization is called neutralization. In some cases the primary neutralization is needed before the purification of wastewater, as the superacidity along with the superalkalinity cause the premature corrosion of containers, pipelines and equipment units, which are the parts of wastewater treatment facilities.