COMPLETE OXIDATION OF HIGH-CONCENTRATION OF AMMONIA BY RETAINING INCOMPATIBLE NITRIFICATION ACTIVITIES IN 3-VESSEL SYSTEM

A three-vessel system (3-V system) that has three equal-volume compart ments was used for oxidizing inorganic synthetic wastewater containing 500 mg-l(-1) NH4-N. This system was inoculated with polyethylene glyc ol granular activated sludge. Inorganic synthetic wastewater was suppl ied to the first vessel at the granular loading rate of 15 g-N.(l-gran ule)(-1)d(-1) (volumetric loading rate of 3.0-g N l(-1)d(-1)), which i s 5.0 g-N (l-granule)(-1) d(-1) (volumetric loading rate of 1.0 g-N l( -1)d(-1)) overall, respectively. About half of the NH4-N supplied was oxidized in the first compartment and the remaining half was oxidized in the second compartment. Nitrite oxidation was not significantly det ected in the first two compartments, but that solely occurred at high levels in the third compartment. The results suggest that these nitrif ication processes may be incompatible, resulting in a series of sequen tial reactions in the 3-V system. It was hypothesized that different n itrifying populations came to predominate in each compartment by parti tioning the vessel. It was reproducibly observed that about half of th e NH4-N supplied to a single-vessel system at the granular loading rat e of 5.0 g-N(l-granule)(-1)d(-1) remained Thus, complete ammonia oxida tion was first achieved and ammonia-and nitrite-oxidizing populations can be segregated by the 3-V system. (C) 1998 Elsevier Science Ltd. Al l rights reserved.