The first technique to reduce the emissions of pollutants in the water is the reduction “at source”, which requires better control of the processes and results in the reduced production of wastewater.
The hazard level of certain products or the sensitivity of certain milieus can lead to banning their discharge or even their usage in certain areas.
With the exception of certain activity sectors, total reduction in liquid industrial wastewater remains limited.
Therefore, treatment processes consist of trapping, concentrating or transforming the pollutants in order to reduce the polluting nature of the industrial wastewater before discharge.
In most cases, these techniques result in the production of waste which must also be disposed of (sludge, salts, concentrates, used filters etc.).
There are two main categories of liquid wastewater treatments:
|Type of pollution||Biological treatment||Physical-chemical treatment|
|Organic||Depending on biodegradability||Yes|
|Phosphorus||Alternately anaerobic / aerobic||Precipitation-settling|
|Metallic||No||Oxidation/precipitation/settling Concentration by recycling, ion-exchange resins, membrane techniques, electrolysis Activated carbon adsorption|
|Pesticides, PAH, benzene and organochlorines||No||Powerful chemical oxidation Activated carbon adsorption Nanofiltration, reverse osmosis (significant cost)|
|VOC||Attached growth||Stripping Chemical oxidation Activated carbon adsorption|
|PCB||No||Specific high temperature incineration Activated carbon adsorption|
|Arsenic||No||Precipitation Adsorption ion-exchange resins Membrane filtration|