External nitrification in biological nutrient removal activated sludge systems

In conventional nitrification-denitrification biological excess phosphorous removal (NDBEPR) activated sludge systems, such as the UCT system for example, both nitrification and phosphorous uptake (P uptake) occur simultaneously in the, usually large, aerobic reactor. In the UCT system the nitrate load to the anoxic reactor is limited by the a-recycle (i.e. system constraint recycle from the aerobic to the anoxic reactor) and the internal aerobic nitrification performance. The latter process, is mediated by the nitrifiers having a slow growth rate of 0.45/d, governs the sludge age of the biological nutrient removal activated sludge (BNRAS) system and thus results in long (20 - 25 day) sludge ages and large aerobic mass fraction requirements to nitrify completely. However, if stable nitrification could be achieved outside the BNRAS external nitrification (EN) system then nitrification and the suspended solids sludge age become uncoupled allowing greater flexibility into the BNRAS system.

Grantor dc:publisher.institution

Department of Mechanical Engineering

Year dc:date.issued

1999

Author dc:creator

• Moodley, Rajan

Advisors dc:contributor.advisor

• Ekama, George A
• Wentzel, Mark C

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/11427/9945

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/9945