METHOD AND APPARATUS FOR TREATING ACTIVATED SLUDGE

摘要

PROBLEM TO BE SOLVED: To provide an activated sludge treatment method and an apparatus therefor capable of enhancing the decomposition capacity of modified sludge and that of industrial wastewater and reducing the volume of activated sludge to stably obtain treated water of high quality. SOLUTION: Industrial wastewater is divided to be injected into respective aeration tanks 1a, 1b, or the like from a raw water dividing injection passage 4 to be mixed with activated sludge and aerated by the air from aeration devices 6a, 6b, or the like. The mixed liquid 20 in the aeration tanks is successively passed through the aeration tanks from the front stage aeration tank 1a to the rear stage aeration tank 1d while subjected to biological reaction and the mixed liquid 20 in the final stage aeration tank 1d is sent to a solid-liquid separation tank 1d from a transfer passage 11 to be subjected to solid-liquid separation treatment. The separated liquid is taken out of a treated water taking-out passage 7 as treated water while a part of separated sludge is returned to the first stage aeration tank 1a as return sludge from a sludge return passage 8 and a part of remaining sludge is drawn out to a modification device 3 as drawn-out sludge from a drawing-out passage 12 to be subjected to modification treatment so as to be made easily biodegradable and the modified sludge is returned to the first stage aeration tank 1a from a modified sludge supply passage 9.