Advanced photo-oxidation process for ammonia removal from industrial wastewater.

摘要

An advanced photo-oxidation process (APP) for the removal of ammonia from industrial wastewater has been developed. Detailed investigations on the effect of operating parameters indicate that pH is the most important process parameter for the effective conversion or nitrification of ammonia. In the acidic range, irrespective of the oxidant used, the conversion of ammonia is not significant. While in the basic range, the reaction proceeds at a considerable rate. Therefore, it is concluded that unprotonated ammonia is the form most amenable for photo-oxidation. Besides the pH, the photo-oxidation of ammonia was also affected by UV dose, initial ammonia concentration and oxidant concentration.; A very significant result obtained in this study is the dramatic dependence of the product distribution on the type of the oxidant employed. In the case of UV/H₂O₂ oxidation process, nitrate is the predominant product, whereas, in the case of UV/K₂S₂O₈, nitrogen gas is the predominant product.; Reaction schemes are postulated to indicate the most probable mechanism for the overall photo-oxidation reactions. A competitive-consecutive reaction model is found to fit the data for the UV/H₂O₂ process, while a competitive-parallel reaction model fitted the UV/K ₂S₂O₈ process well.