WANG Xiang-hui,CHENXu-dong,KANGJing,et al.Calcination and Thermal Decomposition of Pellet Struvite and Effect of Its Product on Ammonia Removal from Wastewater[J].China Water & Wastewater,2023,39(15):8-14.
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Calcination and Thermal Decomposition of Pellet Struvite and Effect of Its Product on Ammonia Removal from Wastewater

China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU] volume: 第39卷 Number: 第15期 Page: 8-14 Column: Date of publication: 2023-08-01
Author(s):
WANG Xiang-hui1; 2;  CHEN　Xu-dong1;  KANG　Jing1;  LU　Yin3;  ZHENG　Min4;  WANG　Cheng-wen5;  XU　Kang-ning1
（1. Beijing Key Laboratory for Source Control Technology of Water Pollution， College of Environmental Science & Engineering， Beijing Forestry University， Beijing 100083， China； 2. Shanghai SUS Environment Co. Ltd.， Shanghai 201703， China； 3. Beijing Guohuan Tsinghua Environmental Engineering Design & Research Institute Co. Ltd.， Beijing 100084， China； 4. Advanced Water Management Centre， The University of Queensland， Australia； 5. School of Environment， Tsinghua University， Beijing 100084， China）
Keywords:
struvite;  calcination and thermal decomposition;  ammonia nitrogen recovery;  nitrogen removal
Abstract:
This paper investigated the optimization of calcination and thermal decomposition conditions of pellet struvite with sizes of 2-2.36 mm, explored the effect of thermal decomposition products on nitrogen removal efficiency of wastewater containing ammonia nitrogen, and discussed the mechanism, so as to solve the problems of large dosage, high cost and difficulty in precipitate-liquid separation of the traditional struvite precipitation process for ammonia nitrogen recovery. Increasing calcination temperature, heating rate and constant temperature time all contributed to the thermal decomposition of pellet struvite, but led to the increase of unavailable phosphorus content and the decrease of particle strength. The optimal conditions of calcination and thermal decomposition were as follows: the calcination temperature was 150 ℃, the heating rate was 15 ℃/min, and the constant temperature time was 2 h. Under this condition, the particle yield of thermal decomposition products was 58%, the ammonia release rate was 66%, the unavailable phosphorus content was 9.6%, and the particle strength was 1.8 N. The molar ratio of P to N and the initial pH of wastewater were the main factors affecting the calcination and thermal decomposition products for ammonia nitrogen removal, the optimal conditions were P to N molar ratio of 3.5 and initial pH of 8.0, and the removal rate of ammonia nitrogen was approximately 72%. The analysis of crystal properties showed that the MgHPO4 formed after the release of NH3 in calcination of pellet struvite effectively removed ammonia nitrogen from wastewater by forming struvite precipitation again.
Last Update: 2023-08-01