硝化グラニュールを利用した高塩濃度産業廃水処理

Abstract

Wastewater containing high nitrogen and high salinity is discharged from the processes of recovering precious metals from industrial waste. Because high salinity inhibits metabolic activity of microorganisms, biological nitrogen removal from such a wastewater has a lot of difficulties. The purpose of this study is to develop an effective nitrification denitrification process for industrial saline-wastewater. At first, nitrogen removal from this wastewater was attempted using a normal suspended nitrifying sludge system. In consequence of estimating tolerance of such a sludge system to salinity, nitrification progressed up to 5% of salt concentration. However, keeping MLSS at 5, 000 g/m3 is necessary to achieve practical nitrification rate. Therefore, nitrifying granules resulting from an aerobic upflow fluidized bed reactor for inorganic wastewater containing high concentration of NH4-N were applied to this industrial saline-wastewater. In consequence of operating nitrification reactor at various salt concentrations, MLSS was kept at 12000g/m3 throughout the operation, and sufficient nitrogen removal rate was achieved. Finally, the nitrifying granules were applied to an aerobic reactor in the aerobic-anaerobic nitrogen removal system. As a result, nitrogen in the saline wastewater was completely removed for 150 days. Through these experiments, it is demonstrated that nitrifying granules are effectively applied to nitrogen removal from industrial saline-wastewater.