Concentration of ammoniacal nitrogen in effluent from wet scrubbers using reverse osmosis membrane

Sulphuric acid is commonly used in acid scrubbers as a highly efficient ammonia trap and results in the production of ammonium sulphate. The disposal of the large amount of effluent produced from an acid scrubber is one of the major issues that limit its application. Two reverse osmosis membranes were tested for their effectiveness in concentrating the ammoniacal nitrogen, which can be used as a fertiliser, from acid scrubber effluent. The permeate flux was substantially affected by membrane type, feeding total ammoniacal nitrogen (TAN) concentration, applied pressure, and feeding flow rate. However, TAN retention was only significantly affected by membrane type. The highest TAN retention of 98.1% was achieved with the SG membrane at a feeding TAN concentration of 6.4 g l−1, applied pressure of 5.5 MPa, and feeding flow rate of 3.1 l min−1.