Wastewaters nitrifying: Biomass in suspension and biofilms processes.

Organic- and ammonia- nitrogen can be removed from wastewaters by using biological processes. This requires ammonia aerobic oxidation to nitrite and nitrate (nitrification) by the bacteria Nitrosomonas ea. acid Nitrobacter sp., respectively. The nitrogen anions produced in the aerobic process are reduced in other system to nitrogen. Biological nitrification can be achieved both in suspended biomass systems (activated sludge) and in biofilm systems (biofilters, rotating biological contactors, submerged filters, fluidized bed, airlift). In this article the principal characteristics of suspended biomass systems (activated sludge) and biofilm systems (airlift reactor) are analysed. A comparison of these systems, applied to the nitrification of wastewaters from ureaformaldehyde adhesives factories with a high content of nitrogen, is shown.