engleski

Ammonium and Nitrate Removal from Fertilizer Factory Waste Water by Ion Exchange Process

The treatment of waste water from fertilizer factory in Kutina (Croatia) is realized by ion exchange process by the use of strong acid cationic and weak basic anionic ion exchangers. Regeneration of cationic exchange resin is performed by HNO3 56 % and anionic resin regeneration by ammonium hydroxide 16 % under use of external regeneration process. In the investigation period, waste water was characterized by high content of nitrogen in ammonium form (with the average 375 mg/l N-NH4+ and nitrogen in nitrate form (with the average 235 mg/l N-NO3-). Due to this the dilution is done prior to the ion exchange processing. Treated waste water contains 12,0 mg/l of ammonium nitrogen and 8,6 mg/l of nitrate nitrogen. This water with obtained conductivity 150 ěS/cm is used to be added into cooling water system. Because of nitrate acid activity upon anionic resin during subsequent saturation with a part of eluate from cationic regeneration under laboratory conditions the influence of HNO3 2% to the ion exchange resin was examined. Due to affection of HNO3 2%to anionic resin EWATIT S 4428 during 24 days the exchange capacity has decreased from initial 1.19 mol/l to final 0,71 mol/l. This approved the harmful influence of nitrogen acid upon the nitrate binding capacity and upon the resin stability. Under real conditions four types of anionic resins were used. The best results were obtained with the resin LEWATIT S 4428, which exchange capacity after 18 months of use was 1.01 mol/l. Good results in ammonium nitrogen removal can be obtained with cationic resin DUOLITE C 265 H, which exchange capacity after two years of use was 0.93 mol/l. v

ammonium; nitrate; ion exchangers; waste water

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