RESUMO
Effect of hydraulic load distribution on sewage treatment efficiency of earthworm bio-filter was studied by analyzing influent and effluent of earthworm bio-filter and earthworm behaviors. The results show that when hydraulic load varying from 2.0 m3/(m2 x d) to 6.0 m3/(m2 x d), the concentration of each pollutant in earthworm bio-filter effluent increases slowly and is little effected by hydraulic load. When hydraulic load reaches 6.7 m3/(m2 x d), the concentration of COD, BOD5, SS, NH4(+) -N and TP in earthworm bio-filter effluent increases obviously, but the TN concentration in effluent presents descending tendency. The earthworms become rather inadaptable to the living conditions at this operating mode. As hydraulic load increasing, the earthworms' relative ingestive ability is improved at first, and then decreases. The earthworms' relative ingestive ability comes to the maximum at hydraulic load of 4.8 m3/(m2 x d), with good organic removal efficiency. The relation ships between hydraulic load and average weight, average density, unit-area biomass of the earthworms are significant negative correlation. The hydraulic load of 4.8 m3/(m2 x d) is recommended, but not over 6.7 m3/(m2 x d).