Biofilm filtration device and backwash method for biofilm filtration device

• Main Author: MATSUI, KATSUNORI
• Format: Patent
• Language: English
• Published: 14.04.2016
• Subjects: CHEMISTRY; METALLURGY; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; SEPARATION; TRANSPORTING; TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE

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 medium is provided. The biofilm filtration device has a biofilm formed on the surface of a granular filter medium filled into a container main body and cleans water to be filtered by passing the water in a filtration direction to a filter layer formed from the filter medium. 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 filter medium 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 medium is 0.