The 10 μm plankton sampling network was used to survey the microfauna in the outflow of granular active carbon (GAC) filter in Plant A, which showed that the dominant species were Rotifera, Nematode, Oligochaeta and Crustacea. When the thickness of quartz sand filter layer was 40 or 50 cm, the grain size was 0.3~0.5 mm and the flow rate was 10~12 m·h-1, more than 50% of the large Metazoan, such as Rotifera, Crustacean, and Oligochaeta, could be intercepted, but few Nematode could be intercepted. It was proposed that the 10 μm microstrainer should be added after the chlorine chamber...