As an effective method for chloride removal from saline wastewater, Friedel's salt (FS) precipitation generates high concentration of precipitate requiring efficient solid-liquid separation. Effects of temperature, reaction time, polyacrylamides (PAM) type and dosage on settleability and dewaterability of FS precipitate were investigated to explore improving strategies for separation by using actual flue gas desulfurization wastewater. Raw FS precipitate was difficult to separate by gravity settling and mechanical dewatering owing to their small particle size and high solid concentration. Anionic PAM with higher hydrolysis degree and molecular weight greatly improved settleability and enlarged particle size of FS. The composition and crystal structure of FS varied with reaction temperature. Increasing temperature to 40 °C obtained the highest chloride removal, and improved settleability because layers spacing of FS decreased. FS precipitate was gradually broken down to Ca₃Al₂(OH)₁₂ and NaCl at temperature above 60 °C. Prolonging reaction time enhanced chloride removal by adsorption effects, and improved settleability by facilitating crystals growth and aging. The 0.5 m³/h pilot-scale experiment confirmed that the FS precipitation process was operated stably with improved settleability and dewaterability of precipitate by dosing PAM and elevating temperature. Techno-economic analysis showed that 37 °C was optimal for chloride removal and solid-liquid separation.

作为从含盐废水中去除氯化物的有效方法，弗里德尔盐（FS）沉淀产生高浓度的沉淀物，需要有效的固液分离。研究了温度，反应时间，聚丙烯酰胺（PAM）类型和用量对FS沉淀物沉降性和脱水性的影响，以探索使用实际烟气脱硫废水进行分离的改进策略。原始FS沉淀物由于粒径小且固体浓度高，因此难以通过重力沉降和机械脱水进行分离。具有较高水解度和分子量的阴离子PAM极大地改善了FS的沉降性并增大了其粒径。FS的组成和晶体结构随反应温度而变化。将温度提高到40°C可获得最高的氯化物去除率，并改善了沉降性，因为FS的层间距减小了。FS沉淀逐渐分解为Ca温度高于60°C的₃ Al ₂（OH）₁₂和NaCl。延长反应时间可通过吸附作用增强氯化物的去除，并通过促进晶体的生长和老化来提高沉降性。通过进行0.5 m ³ / h的中试实验，证实了FS沉淀过程可以稳定运行，并通过添加PAM和升高温度提高了沉淀物的沉降性和脱水性。技术经济分析表明，37°C最适合去除氯气和固液分离。