化学结晶造粒流化床系统软化城市中水的实验研究

Experimental Study on Softening Urban Reclaimed Water by Chemical Crystallization Granulation Fluidized Bed System

通过中试实验及生产实验研究了化学结晶造粒流化床系统软化城市中水的控制机理及处理效果。中试实验中,流化床反应器上升流速为150 m/h,NaOH投加量为154 mg/L时,反应器出水pH为10.32,Ca2+质量浓度为5.61mg/L,去除率为82.05%,Mg2+质量浓度8.1 mg/L,去除率为16%,浊度为2.01 NTU。结合中试实验结果控制生产实验系统运行条件,系统进水流量为400 m3/h,出水pH为10.5时连续稳定运行30 d,流化床出水中Ca2+质量浓度稳定在40 mg/L左右,去除率为83.7%,总硬度稳定在170 mg/L左右,去除率为71%,循环水浓缩倍率提升至5.5倍,吨水处理成本0.7元。对软化中产生的结晶颗粒物进行表面形态及元素分析可知,其表面光滑质密,脱水性良好,表面CaCO3含量高,可进行回收。因此整个系统无副产物产生,可以达到零排放,具有良好的经济及环境效益。

In this paper, the control mechanism and treatment effect of chemical crystallization granulation fluidized bed system on urban reclaimed water are studied through pilot test and production test. In the pilot test, when the upward flow rate of fluidized bed reactor was 150 m/h and the NaOH dosage was 154 mg/L, the pH of reactor effluent was 10.32, Ca2+concentration was 5.61 mg/L and its removal rate was 82.05%, Mg2+concentration was 8.1 mg/L and its removal rate was 16%, the turbidity was 2.01 NTU. The production system control conditions were controlled based on the results of the pilot test, and the system flow rate was set at 400 m3/h, and the effluent pH was 10.5. The system was continuously operated for 30 d, the Ca2+content in the fluidized bed effluent was stable at 40 mg/L, the removal rate was 83.7%, and the total hardness was stable at 170 mg/L,the removal rate was 71%, the circulating water concentration rate was increased to 5.5 times, and the tons of water treatment cost was 0.7 yuan. The surface morphology and elemental analysis of the crystal particles produced during softening showed that the surface was smooth and dense, and the dehydration property was good. Crystalline particles had a high CaCO3 content and could be recycled. Therefore, the entire system has no by-products,can achieve zero emissions, and has good economic and environmental benefits.