混凝/平板膜光催化联合反应器工艺处理高速公路桥面雨水径流研究

Treatment of stormwater runoff from the expressway bridge through the coagulation/flat membrane photocatalytic reactor process

运用混凝/平板膜光催化联合反应器工艺对穿越自然保护区的高速公路桥面雨水径流进行处理。首先,利用混凝沉淀将雨水中的悬浮物(SS)和CODCr进行去除。以SS、CODCr为去除对象,通过试验对聚合氯化铝(PAC)和聚合硫酸铝(PAS)两种混凝剂进行性能测定和比选,考察混凝剂的处理效果,以确定合适的混凝剂。结果显示,混凝剂PAS对雨水的处理效果好。经药剂混凝之后的水再用平板膜光催化反应器进行处理,其中膜技术可以将小分子及剩余SS去除,光催化技术可以将难降解物质去除,同时光催化技术中紫外灯可将出水中的细菌消灭,达到光催化降解污染物和消毒的双重功效。在最佳工艺运行条件即100 mg/L混凝剂聚合硫酸铝(PAS)投量下,经曝气量250L/(m2·h)、停留时间20 min的光催化平板膜反应器处理后,出水SS、CODCr去除率分别为100%和94.5%,可达到地表水环境质量标准(GB 3838—2002)Ⅱ类水的水质要求。

The paper is concerned with the ways to treat stormwater runoff from the highway bridge. For the topic,the paper hasproposed the coagulation/flat membrane photocatalytic reactor processing approach through the coagulation coupled with the flat membrane photocatalytic reactor technology. For the said purpose,we have made an experiment by choosing suspended solids（ SS） and CODCras the removal objects to identify and determine the appropriate coagulant and the treating effects of the coagulants. As the first step,we have managed to remove SS and CODCrvia coagulation and sediment,and chose two kinds of coagulant,polyaluminium chloride（ PAC） and the polymeric aluminum sulfate（ PAS） to identify and examine their performance. As a result,we have found that,at a dosage of 100 mg/L of PAC,it would be possible to achieve the removal rate of SS and CODCrby86% and 69%,respectively. At the same dosage of PAS,we have been successful in gaining a removal rate of SS and CODCr by 90% and 72%,correspondingly. Thus,it can be concluded that the treatment effect of PAS tends to be better and more effective than that of PAC,whereas the adaptability of PAS to pH value proves to be more advantageous. When properly coagulated,the stormwater can be treated by the flat membrane photocatalytic reactor,so as to remove the minute molecules and the rest of the SS residents by the membrane technology. What is more,the above experiment,that is,the cross-flow filtration,has mainly been achieved by the aeration that took place in the flat membrane photocatalytic reactor. Furthermore,a slow development of membrane fouling can be done by means of the aeration quantity of250 L/（ m2·h）. Moreover,it would be possible to let the rest part of the difficultly degradable substance be removed by the photocatalytic technology. Besides,it is also possible for the UV lamp in photocatalytic technology to kill or destroy the bacteria in the effluent so as to help to degrade and disinfect the pollutants.We have also disclosed in this experiment that it is favorable to increase the treating effect by extending the hydraulic retention time（ HRT） to 20 min to heighten the photocatalytic processing efficiency. Under the optimal operation conditions（ at a dosage of PAS is 100 mg/L,when the aeration quantity is 250 L/（ m2·h）and HRT of the reactor is 20 min）,SS and CODCrremoval efficiency can be made so high as to 100% and 94. 5%,accordingly,implying that the effluent quality of the treatment system can meet the demands of the second level of the surface water quality treating standards（ GB 3838—2002） set by the state government departments.