Sewage sludge


Responsible partner: CETAQUA

Type of feedstock: Reject water

Nutrients recovered: Nitrogen as ammonium nitrate

Process technologies: Filtration unit; Ion exchange; Hollow Fibre Membrane Contactors


The aim of this pilot plant is to recover nitrogen from reject water. It consists in three main units: a filtration pre-treatment process to remove the suspended solids presented in reject water; an ion exchange column loaded with 0.5-1 mm zeolites for nitrogen concentration; and two membrane contactors with an unitary surface of 1.4 m2 (3M™ Liqui-Cel™ EXF-2.5×8). These membranes allow the ammonia transport from the feed solution and to the acid one, in this case, nitric acid, producing ammonium nitrate which is free of PTEs and organic micropollutants (OMPs) because the selected membrane is gas permeable and none of these compounds should pass through.