The rules of migration and distribution regulation of tubifex in filtration were studied in the pilot system. Meanwhile

the influences of filtration rate

filtration cycle and backwashing on the worm’s migration and distribution in filtraion were discussed. The results showed that both the worm’s length and the particle size of filter media had obvious effects on migration and distribution: the smaller the worm’s length and the larger the particle size of filter media were

the stronger the worm’s migration capacity was. The filtration rate was the main migration power of tubifex in filtration

which meant high filtration rate could result in the worm’s leakage risk. Prolonging filtration cycle promoted migration

thus it is beneficial to control tubifex leakage risk that shortening filtration cycle. The remove of tubifex in a real sense can be realized by backwashing. And the stronger the backwashing intensity is

the better the removal efficiency is. Based on the experimental results

to control the worm’s leakage risk effectively

filtration rate and cycle would be lower than 9.4 m/h and 12 h

respectively. Backwashing intensity would be controlled about 25 L/s·m2

at which the obtained tubifex removal efficiency was 97.7%.