Nitrite Accumulation and Removal in a Sequencing Batch Reactor

Pak, Dae Won; Jung, Jin-Young; Jung, Yun-Chul

Environmental Engineering Research 1996;1(1): 37-41.

Dae Won Pak^†, Jin-Young Jung, and Yun-Chul Jung

Environment Research Center, Korea Institute of Science and Technology, P. 0. Box 131, Cheongryang, Seoul 130-650, Korea

Corresponding Author: Dae Won Pak ,

Received: March 1, 1996; Accepted: April 2, 1996.

ABSTRACT

A pilot-scale sequencing batch reactor(SBR) was operated to remove organic substance and ni¬trogen from the wastewater from an egg-processing industry. The wastewater contains high concentrations of organic substance(3000~7000 mg/i COD) and nitrogen (200-400 mg/f TKN). More than 95 percent of TKN was oxidized to nitrite or nitrate. During oxic period ammonia nitrogen in the wastewater was oxidized to ni¬trite or nitrate. Sizable nitrite concentration was observed in the SBR pilot. The factors associated with nitrite accumulation was investigated. High loading rates of organic substance and nitrogen were appeared to cause ni¬trite accumulation during nitrification. High BOD/TKN ratio in the influent resulted in nitrite accumulation in the effluent. In order to reduce nitrite build-up in the SBR pilot, post-anoxic period was provided during REACT phase. During post-anoxic period the wastewater was added to the reactor as a carbon source for denitrification. Total nitrogen removal was increased by ca. 40 %. Amount of wastewater addition to the SBR during post-anoxic period was appeared to affect total nitrogen removal efficiency.

Keywords: Sequencing batch reactor | nitrification | nitrite accumulation | post-anoxic | step-feeding