| 초록 |
A novel bioreactor (airlift submerged biofilm reactor) was designed and used for nitrification of the wastewater from steel-making plant with an aim to reuse it as irrigation water. In spite of variation of ammonia concentration in the raw wastewater, ammonia was successively converted to nitrate in the bioreactor at the hydraulic retention time of 24, 12 and 8 h. However, at the hydraulic retention time of 4 h, the ammonia concentration in the treated wastewater was found to be 28 mg NH3-N dm-3 which corresponded to 67.9% of nitrification conversion. The nitrification rate was significantly enhanced by the reduction of hydraulic retention time. The increase of air flow rate resulted in improvement of nitrification conversion because of the increase of oxygen transfer rate. At the air flow rate of 4 dm3 min-1 and the hydraulic retention time of 4 h, the nitrification conversion was 92.6% and the nitrification rate was 34.6 mg NH3-N dm-3 bed h-1.
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