BIOFILM FILTRATION DEVICE AND BACKWASH METHOD FOR BIOFILM FILTRATION DEVICE

摘要

A non-chemical-feed biofilm filtration method is elucidated, and a biofilm filtration device that can achieve a desired filtration water quality level by controlling the backwash flow for a filter media is provided. The biofilm filtration device has a biofilm formed on the surface of a granular filter media filled into a filter vessel and cleans water to be filtered by passing the water in a filtration direction to a filter layer formed from the filter media. A backwashing mechanism is provided such that the flow velocity (V) for backwashing water passing through in a direction opposite to the filtration direction during backwashing of the filer media is set in a range having a lower limit which is a value (Vs) at which a prescribed backwashing effect can be obtained and an upper limit which is the value (Vm) when the backwashing expansion coefficient for the filter media is 0.

主权项

1. A biofilm filtration device having a biofilm formed on a surface of a granular filter media filled into a filter vessel the biofilm purifying water to be filtered by passing the water in a filtration direction to a filter layer formed from the filter media, the biofilm filtration device comprising:
a backwashing mechanism that a flow velocity (V) for backwashing water passing through in a direction opposite to the filtration direction during backwashing of the filter media is set in a range having as lower limit which is a value at which a prescribed backwashing effect can be obtained, and an upper limit which is a value when a backwashing expansion coefficient for the filter media is 0.