The treatment that wastewater undergoes can be of three types: physical: that is, the water is screened to remove non-biodegradable and floating solids, then any sand, oils and grease are eliminated, and finally it is left to “rest” to allow for the sedimentation of the suspended particles; biological, in which case, “good” bacteria are used, which feed on the pollutants; and/or chemical, to eliminate specific substances. Sometimes the water is subjected to “ultra-filtration” using membranes.
And sometimes it is "decanted" in constructed wetlands, acting as natural bio-filters, where plants create the bacterial flora which allow for the removal of pollutants.
Every wastewater treatment plant is a world unto itself, designed in line with the pollution level of the effluent, the place where the water is discharged, and the possible industrial or agricultural reuse of the purified water.
And it is thanks to these wastewater treatment plants that today we can notice a positive change in the quality of our rivers and seas!
