预氧化对再生水混凝沉淀工艺助凝效果研究

摘要

Taking secondary effluent from urban sewage treatment plant as the research object, the effects of different preoxidants of ordinary coagulation sedimentation process and preoxidation-coagulation sedimentation process on reclaimed water treatment were compared. The results showed that, when using KMnO4 as preoxidant, the best treatment effect could be obtained under the follow condition: the KMnO4 dosage was 1.8 mg/L, the pH value of the raw water was 7 - 8. To reach the same turbidity removal efficiency, the flocculation and sedimentation time were 12 and 15 min shorter respectively, and the PAC dosage was decreased by 8 mg/L by the preoxidation-coagulation and sedimentation process in contrast with that by the ordinary coagulation sedimentation process. Furthermore, the removal rate of turbidity could be increased by 15% with KMnO4 preoxidation under the optimal condition. It could be seen that, preoxidation could obviously accelerate the formation and sedimentation of floes, increase the density of floes, which showed a significant coagulation aid effect for the coagulation and sedimentation technology in reclaimed water treatment.%以城市污水处理厂二级出水为处理对象,比较了常规混凝沉淀工艺和预氧化-混凝沉淀工艺不同预氧化剂对再生水原水的处理效果.结果表明,以KMnO4为预氧化剂能够取得最佳的处理效果:当KMnO4的投加量为1.8 mg/L、原水pH值为7～8、且达到相同的常规混凝沉淀浊度去除效果时,絮凝时间缩短12 min,沉降时间缩短15 min,PAC的投加量减少8 mg/L.在优化试验工况下,KMnO4预氧化可使浊度去除率提高15％以上.预氧化可明显加快絮体的形成、提高絮体的密实度与沉降速率,对再生水混凝沉淀工艺助凝效果显著.