(123b) Study of Treating Ammonium-Nitrogen Wastewater

In present research, a novel chemical precipitation technology through struvite formation was developed for removing ammonium-nitrogen from FCC catalyst manufacturing waste water. Comparing with the traditional technology,via this new technology side reactions can be limited, which resulted in higher precipitation efficiency and reagent reaction percent. The pilot-scale experimental results showed that the most important factors influencing the ammonium-nitrogen removal rate are pH value in each steps and the reactants ratio. It showed that for water with 3444mg/L initial ammonia nitrogen when the final pH at 9.0, magnesium ammonium and phosphate molar ratio of 1.15:1:1, the ammonia remnants is under 50mg/L, the removal efficiency is above 99%,and the residual phosphate is very low. Using present technology the complex manufacturing waste water with 1200~1500mg/L initial ammonia nitrogen can be treated in one step accorded with the draining standard. Since the precipitate magnesium ammonium phosphate can be sold as a fertilizer, treating waste water with 1000mg/L ammonia nitrogen will cost 0.36$ per ton via this new technology. So it is a high efficiency and economical method to be put into practice widely.