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Removal and Recovery of Ammonium Nitrogen from Phosphorus-removed Human Urine by Modified Zeolite Column
  
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KeyWord:dephosphorus urine wastewater; modified zeolite; adsorption column; ammonium recovery; zeolite regeneration
Author NameAffiliation
WEN Guo-qi College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China 
HU Zheng-yi College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China 
LIU Xiao-ning College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China 
MENG Xian-chao College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China 
ZHU Chun-you College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China 
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Abstract:
      Struvite precipitation is an effective way to remove phosphorus(P) from human urine, but leaves most of nitrogen in the treated urine. Its direct discharge to the environment could lead to water nitrogen pollution and waste nitrogen resource. In this study, an adsorption column filled with zeolite modified by 5% HCl rinsing, calcination under 400 ℃ and subsequent treatment by microwave, was built to investigate the effects of column height(H), column number(N) and hydraulic retention time(T) on the removal of ammonium nitrogen from phosphorus-removed human urine. Effects of eluting solvents(HCl, NaCl, HCl+NaCl) on the desorption of ammonium nitrogen adsorbed on the column were also assessed. The adsorption capacity of this modified zeolite was 17.9 mg·g-1, 2.6 times that of natural zeolite(6.9 mg·g-1). The optimal parameters of the modified zeolite column for removing ammonium nitrogen were 35 cm for H, 2 hours for T, and 3 for N. The concentration of ammonium nitrogen in the effluent was less than 30 mg·L-1 at up to 6370 mg of ammonium nitrogen load in adsorption column. Combination of 10% HCl+5 g·L-1 NaCl released 88.3% of ammonium nitrogen adsorbed on the modified zeolite. The equilibrium adsorption capacity of the regenerated zeolite was 16.4 mg·g-1, or 91.6% of that of the original modified zeolite. Our results suggest that the modified zeolite could be used to effectively remove ammonium nitrogen from phosphorus-removed human urine and be reused via regeneration.