Within the scope of a scientific project financially supported by the MUNLV (Ministry of the Environment,Conservation,Agriculture and Consumer Protection) and the PUR-AC GmbH,Germany,the process of deammonification for the biological treatment of sludge water was investigated in a full-scale pilot plant in cooperation of the Institute of Water Quality and Waste Management,University of Hanover (ISAH),the Ruhrverband,and the PURAC GmbH.The pilot plant was erected at the Hattingen WWTP near Bochum,Germany,by the Ruhrverband.During the process of deammonification a fraction of 50-60 % of the incoming ammonia load was oxidized to nitrite (NO_2) which was then converted to elementary nitrogen together with the remaining ammonia under anoxic conditions.Since deammonification is a completely autotrophic process,no organic carbon is needed for bacteria growth.In consequence,deammonification is suitable for the treatment of wastewater with unfavorable COD/N ratio without dosage of an external carbon source,such as methanol or acetic acid.For deammonification it is essential to enrich a population of slow-growing organisms which associate to the group of planctomycetales,whereby a technical installation within a biofilm process seems to be most promising.
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