LIUMu,LUOLi-tao,LIZe-hua,et al.Development and Application of Induced Crystallization Method in Hardness Removal from Reverse Osmosis Concentrate[J].China Water & Wastewater,2024,40(1):39-44.
Development and Application of Induced Crystallization Method in Hardness Removal from Reverse Osmosis Concentrate
China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU]
volume:
第40卷
Number:
第1期
Page:
39-44
Column:
Date of publication:
2024-01-01
- Keywords:
- reverse osmosis concentrate; hardness removal; induced crystallization; calcium sulfate crystallizer
- Abstract:
- This paper developed the optimized technology of calcium sulfate induced crystallization for hardness removal, so as to address the challenge of hardness removal from reverse osmosis concentrate in chemical fiber industrial parks. A crystallizer was designed and applied in a pilot test, while the optimized technique was evaluated. The achievements of the pilot test were further applied in a demonstration project, in which the recovery of calcium sulfate products was realized. The crystal products were analyzed by scanning electron microscopy-energy dispersion spectroscopy (SEM-EDS) and thermogravimetric analysis, which conformed that the crystal products were mainly CaSO4·2H2O. When the hydraulic retention time of calcium sulfate crystallizer was 60 min and the dosage of flocculant (11% polyaluminum chloride) was 100 mg/L, higher hardness removal efficiency was obtained, while the operating cost could be controlled. The operational results of the demonstration project showed that the calcium ions and sulfate ions in the reverse osmosis concentrate were fully recovered, and the yield of CaSO4·2H2O was 51-81 t/d. The induced crystallization technology for hardness removal overcame the shortcomings such as large chemical dosage and high operating cost of the traditional double-alkali method, reduced the yield of sludge and realized the recovery of calcium sulfate.
Last Update:
2024-01-01