引言目前,在砂快滤池到达过滤周期之后,有各种清洗方法。例如,在英国通常采用先用空气冲洗,接着用低速水冲洗的方法,而在法国及欧洲大陆其他地区却常常采用空气-水同时冲洗的方法。另外在美国,则主要采用高速水冲洗的方法。在贝尔法斯特的昆士大学(Queen＇s Unive-rsity)用模拟进水和三种不同级配的砂子,对这些清洗方法的清洗效果进行了对比研究。反冲洗方法的沿革早期的砂快滤池是基于对砂颗粒进行轻轻的清洗,以便在滤床表面留下一层不受破坏的有机膜。当时认为这一薄膜是进行有效过滤所需要的,这种认识是从砂慢滤池过滤工艺沿袭下来的。美国最早出现的砂快滤池是圆形的木制桶,装有在清洗过程搅动砂子用的环形搅动耙子。以此来帮助把砂子和 INTRODUCTION At present, there are various cleaning methods after the sand fast filter reaches the filtration cycle. For example, in the United Kingdom, air-water flushing is often used first in air and then in low-speed water. In France and other parts of continental Europe, air-water flushing is often used. In the United States, high-speed water washing is mainly used. A comparison of the cleaning effects of these cleaning methods was conducted at the Queen’s Unive- rsity in Belfast using simulated influent water and three different grading sands. The sand filter in the early stages of the backwashing process was based on the gentle cleaning of sand particles to leave a layer of undamaged organic film on the filter bed surface. At that time, it was considered that this film was required for effective filtration, and this recognition was inherited from the sand slow filter filtration process. The earliest sand filter in the United States was a round wooden barrel with an annular stirring rake used to agitate the sand during the cleaning process. In order to help put sand and