混凝/预氧化去除微污染水源水中拟柱孢藻的效能

饮用水源中藻类的大量繁殖极易给饮用水的生产带来诸多困难,尤其是对于微污染水中拟柱胞藻这种线状藻类。考察了不同混凝剂和预氧化剂对藻类的去除效果,并据此在水厂进行了氯梯度生产性试验。结果表明,单独釆用聚合氯化铝(PAC)混凝剂的除藻效果优于氯化铁,预氯化的除藻效果优于高链酸钾预氧化。预氧化剂的投加可以明显改善水中由于藻类活动而形成的小尺寸的松散絮体,进而形成尺寸较大、密实度较高、沉降性较好的絮体。生产性试验表明,对于这种典型的低纬度微污染水库水,采用PAC最佳投加量为15 mg/L,同时将前加氯量控制在2.0 ~3.0 mg/L时,对藻类的去除率可以达到92%以上,并且可以使沉后水浊度控制在1.60 NTU以下。这为低纬度地区微污染水中拟柱砲藻的去除提供了很好的指导作用。

Removal of Cylindrospermopsis raciborskii from Micro-polluted Source Water by Coagulation and Preoxidation

The large-scale reproduction of algae in drinking water sources has brought many difficulties to production of potable water, especially for linear algae such as Cylindrospermopsis raciborskii in micro-polluted water. The performance of different coagulants and preoxidants was studied l)y coagulation experiment along with productive experiment of chlorine gradient. The results showed that the PAC coagulant was more efficient than that of ferric chloride in the coagulation treatment. Further research showed that compared with potassium permanganate, chlorine preoxidation could more effectively remove algae. The addition of the preoxidant could significantly improve the small-sized loose flocs formed in the water due to algae activity, thereby forming flocs with larger size, higher density and better settleability. The productive experiment proved that for this typical low-latitude micro-polluted reservoir water, the optimal dosage of PAC was 15 mg/L, and when the prechlorination was controlled at 2. 0 -3. 0 mg/L, the algae coukl be removed by more than 92% and the efflent turbidity of sedimentation tank could be controlled below 1. 60 NTU. This method provides a good guiding role for the removal of Cylindrospermopsis raciborskii in the micro-polluted water at low latitudes.