CHEMICAL PRECIPITATION OF AMMONIA-N AS STRUVITE FROM LANDFILL LEACH ATE EFFECT OF MOLAR RATIO UPON RECOVERY

摘要

Struvite precipitation has the potential for removing ammonia-N from landfill leachate. A laboratory scale study was performed to investigate the recovery of NhV-N as struvite using MgCl2.6H_2O and Na_2HPO_4 as Mg and P sources, respectively. Seven different molar ratios (Magnesium: Ammonium: Phosphate) were used to optimize the removal efficiency of ammonia-N. Around 58 % of ammonia removal was obtained in 1:1:1 molar ratio. Maximum removal efficiency of 76 and 78 % achieved at the molar ratio of 2:1:1.5 and 1.5:1:2, respectively. Leachate pH varied from 6.5 to 6.9 in supernatant samples obtained from different molar ratio. Leachate COD increased (from 3,461 mg/L to 10,481 mg/L) and TOC decreased (from 2,448 mg/L to 1,825 mg/L) with ammonia removal in leachate. Leachate quality in terms of calcium, potassium, nitrate, nitrite and phosphates were unaffected by the struvite precipitation.