Simultaneous removal of ammonium and phosphate by zeolite synthesizedfrom coal fly ash as influenced by acid treatment
ZHANG Bao-hua , WU De-yi , WANG Chong , HE Sheng-bing , ZHANG Zhen-jia , KONG Hai-nan
DOI:
Received May 22, 2006,Revised August 21, 2006, Accepted , Available online
Volume 19,2007,Pages 540-545
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Zeolite synthesized from fly ash (ZFA) without modification is not e cient for the purification of NH4+ and phosphate at low
concentrations that occur in real e uents, despite the high potential removal capacity. To develop an e ective technique to enhance the
removal e ciency of ammonium and phosphate at low concentrations, ZFA was modified with acid treatment and the simultaneous
removal of ammonium and phosphate in a wide range of concentration was investigated. It was seen that when compared with
untreated ZFA, only the treatment by 0.01 mol/L of H2SO4 significantly improved the removal e ciency of ammonium at low initial
concentrations. The behavior was well explained by the pH e ect. Treatment by more concentrated H2SO4 led to the deterioration of
the ZFA structure and a decrease in the cation exchange capacity. Treatment by 0.01 mol/L H2SO4 improved the removal e ciency
of phosphate by ZFA at all initial P concentrations, while the treatment by concentrated H2SO4 (> 0.9 mol/L) resulted in a limited
maximum phosphate immobilization capacity (PIC). It was concluded that through a previous mild acid treatment (e.g. 0.01 mol/L of
H2SO4), ZFA can be used in the simultaneous removal of NH4+ and P at low concentrations in simulating real e uent.
