Biological wastewater treatment plant with a separate regeneration circuit for activated sludge and its operating process

摘要

Biological waste-water treatment is effected in a plant comprising a pre-clarifier, an activated-sludge (AS) tank and a post-clarifier. The sludge suspension from the post-clarifier is comminuted to break up of flocs and then oxidised with air before being recycled to the AS tank. The sludge suspension is pref. coarsely screened and then passed through an impeller mill or nozzle to reduce the floc size by 10-30%, esp. to 10-80 microns. The sludge suspension is then aerated for 5-50 (5-25) min in the presence of 1-10 mg/l Fe(2+) or Fe(3+) as catalyst. ADVANTAGE - The process prevents bulking sludge formation by preventing build-up of filamentous microorganisms.