Nitrite Interference with Soluble COD Measurements from Aerobically Treated Wastewater

作者：Ferraz Fernanda M; Yuan Qiuyan^*

来源：Water Environment Research, 2017, 89(6): 549-554.

DOI：10.2175/106143017X14902968254485

• COD
• landfill leachate
• nitrite interference
• sequencing batch reactors

This study aimed to determine the interference of nitrite (NO2-) with soluble chemical oxygen demand (COD) measurements from the effluent of landfill leachate treated by sequencing batch reactors (SBRs). Synthetic wastewater assimilating young and old landfill leachate was used as influent for SBR1 and SBR2, respectively. A mixture of raw wastewater and landfill leachate was used as influent for SBR3. Due to the high ammonia concentration in the influent, different levels of partial nitrification were observed in all the reactors and NO2- was detected in the effluents. Theoretically, when NO2- is present in the effluent, 1 mg/L of NO2- accounts for 1.1 mg/L of COD (i.e., 1.1 mg COD/mg NO2-) due to the oxidation of NO2- to NO3-. It was found that the value of 1.1 mg COD/mg NO2- was 3 times higher than the values obtained in the experiments with SBR1 and SBR3. In addition, the values obtained in the experiments with SBR2 were much higher than 1.1 mg COD/mg NO2-. These results suggest that the theoretical value of 1.1 mg COD/mg NO2- cannot be applied to predict the COD values caused by nitrite in the tested wastewaters. To obtain an accurate measurement of soluble COD in samples that contain nitrite, nitrite should be eliminated before the measurements.

• 出版日期2017-6-1