GUOYiqun,DINGYanyan,YUHongyu,et al.Struvite Crystallization for Phosphorus Recovery from Slurry of Advanced Anaerobic Digestion of Sewage Sludge[J].China Water & Wastewater,2026,42(7):106-112.
Struvite Crystallization for Phosphorus Recovery from Slurry of Advanced Anaerobic Digestion of Sewage Sludge
China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU]
volume:
第42卷
Number:
第7期
Page:
106-112
Column:
Date of publication:
2026-04-01
- Keywords:
- advanced anaerobic digestion slurry of sludge; recovery of phosphorus; struvite; ammonia nitrogen
- Abstract:
- Crystallization of struvite (magnesium ammonium phosphate, MAP) from slurry is an effective method for phosphorus recovery. This study investigated the optimization of MAP crystallization conditions in slurry with a high nitrogen-to-phosphorus (N/P) molar ratio, resulting from thermal hydrolysis combined with high-solid anaerobic digestion. Through single-factor experiments and Box-Behnken Design (BBD) response surface methodology, the phosphorus recovery rate was used as the response variable to optimize reaction parameters, including pH, magnesium-to-phosphorus (Mg/P) molar ratio, reaction time, and stirring speed. The results indicated that under optimal conditions—pH of 8.8, Mg/P molar ratio of 1.36, stirring speed of 292 r/min, and reaction time of 10 minutes—the phosphorus recovery rate exceeded 99%, even when the N/P molar ratio was as high as 29. Furthermore, at pH of 9.0, Mg/P molar ratio of 1.0, stirring speed of 300 r/min, and reaction time of 20 minutes, the purity of MAP crystals reached a maximum of 98.04%. Increasing the Mg/P molar ratio beyond this point led to a decrease in MAP purity. Ammonia nitrogen concentration was identified as a critical factor influencing MAP crystallization. While an excess of ammonia nitrogen was required for efficient phosphorus recovery, the phosphorus recovery efficiency stabilized and approached 100% once the ammonia nitrogen concentration surpassed a certain threshold. Therefore, for slurry with an excessively high N/P molar ratio, adding a phosphorus source can facilitate the simultaneous recovery of nitrogen.
Last Update:
2026-04-01