WATER TREATMENT APPARATUS

PURPOSE:To keep the activity of bacteria even when the movement of activated carbon particles is generated by backwashing, in a water treatment apparatus equipped with a biological activated carbon bed, by arranging a dissolved oxygen supply device having a dissolved oxygen injection port provided thereto in the biological activated carbon bed. CONSTITUTION:Bacteria grown using an ozone oxidation product as a nutrition source consume dissolved oxygen in the upper bed part of an activated carbon bed 2 to propagate and, when nutrients are rich and propagation is actively performed, oxygen becomes deficient in the lower bed part of the activated carbon bed 4. Oxygen is sent out of an oxygen cylinder 4 but, at this time, the pressure of oxygen is adjusted by a pressure adjusting valve 5 so that oxygen is not blown in as oxygen gas bubbles and oxygen is introduced into the intermediate bed part of the activated carbon bed 2 from oxygen injection ports 3. Bacteria are propagated using activated carbon particles as a carrier but, when the gaps between particles are filled with bacteria, the pressure loss of water passage becomes large and, therefore, the supply of water from an inflow pipe 9 is stopped in a specific ratio and an air washing valve 12A and a backwashing valve 13A are opened to send air and backwashing water to backwash the biological activated carbon bed 2.