Phosphorus from industrial and urban ways arrives at WWTP within the influent water, at concentrations that make necessary its removal either chemically or biologically, in order to protect the receiving waters. This removal leads to an increase of the phosphorus content in the obtained sludge, becoming in a higher sludge production and an operational cost increase.
In addition, the presence of phosphorus at the sludge line gives rise to a very well-known phenomenon at the WWTPs, the uncontrolled precipitation of phosphorus in the form of struvite along the sludge line. This phenomenon is very common at facilities with nutrient removal configuration coupled with anaerobic digestion, giving the optimal conditions for the precipitation of this compound.
Struvite, with chemical formula NH4MgPO4·6H2O, precipitates along the sludge line reducing pipes capacity as well as causing damage at the equipment.