Browsing by Author "Sötemann, Sven"

Now showing 1 - 1 of 1
  • Thumbnail Image
    Item
    Open Access
    External nitrification in biological nutrient removal activated sludge systems
    (2000) Sötemann, Sven; Ekama, George A; Wentzel, Mark C
    Biological nutrient removal activated sludge (BNRAS) systems have become the preferred treatment system for advanced municipal wastewater treatment in South Africa. They have proven to be cost-effective systems that produce effluents of excellent quality that can be re-introduced to the receiving water bodies without a significant negative impact on the scarce surface water of South Africa. The widespread implementation of the BNRAS system has drawn attention to some of the weaknesses of the system, predominantly (i) the long sludge ages and resulting large biological reactor volumes required for nitrification, (ii) filamentous organism bulking of the sludge that develops in the system, (iii) treatment of the P rich waste sludge from the system and (iv) containment of the large mass of P in the sludge during a failure of the aeration in the system. In order to overcome the first two weaknesses of the system, it is proposed to separate the process of nitrification from the BNRAS mixed liquor and achieve nitrification externally to the BNRAS system.