Ammonia Removal in Water Treatment

Small amounts of Ammonia (NH3) is present in aquifer naturally. Higher content is considered an impurity, often resulting from sewer backflow and drainage system problem, runoff in agricultural areas where it is used as a fertilizer, inadequate wastewater and solid waste disposal and treatment. 

Ammonia is undesirable in water because ultimately it gets converted into nitrites and nitrates which can cause vitamin deficiency, and if combined with other components can cause cancer. Moreover, elevated ammonia concentration can create favorable conditions for intensive growth of aquatic organisms, including algae, which leads to deterioration of commodity water quality, especially its clarity, smell, taste as well as bacterial contamination.

For ammonia treatment to underground water caustic soda (30 %), activated carbon and ferric chloride (FeCl3) are used. Caustic soda is a chemical reagent, pH-regulating, ion exchanger regenerating agent, catalyst, etching or cleaning agent. It leaves no residual colour. 

Activated carbon is used as filter media for dissolved organics, as well as for the removal of color-, tasteand odor-causing compounds. It helps to improve the adsorbing capacity of ammonia. 

Ferric chloride is a coagulant used for the treatment of turbidity and for further removal of color, natural organic materials, and arsenic from the raw water. 

The ammonia is stripped away from the process. Sulfuric acid (50 %) is used as a stripping medium. Sulfuric acid added to the adsorption tower converts ammonia into ammonium sulfate ((NH4)2SO4). Ammonium sulfate is an inorganic salt which has commercial value. Its most common use is as a soil fertilizer.

• Inorganic salt with a number of commercial uses, e.g. soil fertilizer.

Chemical curve: Ammonium Sulfate, (NH4)2SO4. per Conc. % b.w. at Ref. Temp. of 20˚C