AMMONIUM REMOVAL FROM CONCENTRATED WASTE STREAMS WITH THE ANAEROBIC AMMONIUM OXIDATION (ANAMMOX) PROCESS IN DIFFERENT REACTOR CONFIGURATIONS

Many concentrated wastewater streams produced in food and agro-industr y are treated using sludge digestion. The effluent from sludge digeste rs frequently contains ammonium in high concentrations (up to 2 kg m(- 3)). This ammonium-rich effluent is usually treated by a normal wastew ater treatment plant (WWTP). When ammonium removal from this concentra ted stream is considered, steam stripping or a combination of two biol ogical processes, aerobic nitrification and anoxic denitrification, ar e the (costly) options. Recently a novel process was discovered in whi ch ammonium is converted to dinitrogen gas under anoxic conditions wit h nitrite as the electron acceptor. It has been named Anammox (anaerob ic ammonium oxidation). The aim of this study was to demonstrate the f easibility of ammonium removal from sludge digestion effluents with th e Anammox process. Using a synthetic wastewater, it was shown that a f ixed-bed reactor and a fluidised-bed reactor were suitable reactor con figurations. The effects of sludge digestion effluent on the Anammox p rocess were investigated; during 150 days, 82% ammonium removal effici ency and 99% nitrite removal efficiency was achieved in a fluidised-be d reactor inoculated with Anammox sludge and fed with sludge digestion effluent from a domestic WWTP. The maximum nitrogen conversion capaci ty was 0.7 kg NH4+-N m(reactor)(-3) day(-1) and 1.5 kg total N m(react or)(-3) day(-1). (C) 1997 Elsevier Science Ltd.