[Persistent Inhibition of Ammonium Released from Contaminated Sediments Through a Modified Zeolite and Biofilm System...

This experiment used a modified zeolite and biofilm system to find a long-term effective way of repairing sediment. Four types of modified zeolites[AlCl₃, Al(NO₃)₃, Al₂(SO₄)₃, and KAl(SO₄)₂] and a biofilm system were investigated for the removal of ammonia nitrogen from overlaying water. The results showed that, of the modified zeolites, AlCl₃ had the greatest effect on the zeolite and biofilm system, and the optimal modified concentration was 0.8 mol·L^-1. The persistence was further studied after adding OHHL, including the inhibition of ammonium released from contaminated sediment by the AlCl₃-modified zeolite and biofilm system, NaCl-modified zeolite and biofilm system, and natural zeolite and biofilm system. The results illuminated that the number of bacteria attached to the AlCl₃-modified zeolite and biofilm system was the highest, and the proportion of denitrifying bacteria was also high (the initial proportion was 82.1%; 30 days later it was 61.1%). Therefore, the biological regeneration was high (64.9%), which caused the zeolite service life to be up to 8.5 months. Thus, ammonium released from contaminated sediment can be inhibited effectively and continuously by an AlCl₃-modified zeolite and biofilm system.