Ammonia Stripping with Plant Ash Enhanced Removal and Recovery Rate of Ammonia Nitrogen From Biogas Slurry

This study was conducted to evaluate the effects of plant ash based ammonia stripping process on removal and recovery of ammonia-nitrogen (NH3-N) in biogas slurry (BS), in order to provide theoretical reference for the feasibility of plant ash, as replacement of sodium hydroxide. The best mixing ratio of plant Ash and biogas slurry, gas-liquid ratio, stripping time and stripping temperature was also determined to optimize the process. The results showed that the (NH3-N) removal rate was 85.27% and the recovery rate was 76.45%, at 10:2 biogas slurry and plant ash mixing ratio, the gas-liquid ratio of 2000, the stripping temperature of 30oC and the stripping time of 2 h. Compared with sodium hydroxide as stripping promoter the removal rate and recovery rate of ammonia nitrogen in biogas slurry were increased by 4.15% and 6.49% respectively, and the operation cost of ammonia nitrogen stripping process was reduced by plant ash replacing sodium hydroxide. The comprehensive analysis suggested that it is feasible to combine the plant ash with biogas slurry to remove ammonia nitrogen.