The present day wastewater treatment practise can be significantly imp
roved when new microbial processes are introduced. In this paper a new
concept is discussed along general lines. The concept consists of a f
irst stage in which a maximal sludge production is achieved. In this w
ay COD is removed as sludge and aeration requirements minimized. This
sludge can be digested to yield methane for energy generation. The nit
rogen removal is based on a partial oxidation to nitrite and subsequen
t denitrification with ammonium as electron donor. (C) 1997 IAWQ. Publ
ished by Elsevier Science Ltd.