Does the ammonia nitrogen content in the aerobic effluent affect COD?
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Does the ammonia nitrogen content in the aerobic effluent affect COD? By how much will the COD values increase when the ammonia nitrogen levels at the outlet are 10 ppm and 100 ppm during COD monitoring?
The effects of reducing substances such as Cl-, NO2-, Fe2+, S2-, NH3, and NH4+ on the determination of chemical oxygen demand were examined, with a focus on the methods and principles for removing these ions. It was concluded that the silver column method can be used to eliminate the interference caused by chloride ions, especially in water samples with high chloride concentrations (>20,000 mg/L), where this method is particularly effective. The interference of NO2- can be eliminated by adding sulfamic acid. The interference from Fe2+ and S2- can be eliminated by introducing air into the water sample to oxidize and remove them. The interference caused by NH3 or NH4+ can be eliminated by removing chloride ions from the water or by using a solution of low concentration of K2Cr2O7 for measurement.
http://wenku.baidu.com/view/de40876bb84ae45c3b358c5e.html The influence of reducing substances on the determination of chemical oxygen demand (COD) and methods to eliminate it