An Analytical System for Measuring Continuously Concentration of Trace Amounts of Nitrite and Nitrate Ions in the Activated Sludge Aeration Bath for Ammonia Liquor Treatment

Abstract

A new analytical system for measuring continuously concentration of trace amounts of nitrite and nitrate ions in the activated sludge aeration bath for treatment of ammonia liquor discharged from coke oven, has been developed. The developed system is based on the principle that nitrite and nitrate ions are spectrophotometrically determined at 355 nm and 302 nm, respectively, in the ultraviolet region after elimination of co-existing activated sludge and interferring materials. The proposed system are performed as follows: Sample solution taken from the aeration bath is subjected to centrifugal separation to eliminate the co-existing sludge. And then supernatant solution is passed through activated charcoal column to remove interferring colored materials. Subsequently, the solution is passed through anion exchange column for concentrating nitrite and nitrate ions. The both ions eluted separately from the anion exchange column by sodium chloride solution, are spectrophotometrically determined by ultraviolet detector. Down to 0.1 ppm and 1 ppm of nitrite and nitrate ions, respectively, can be simultaneously measured. The analytical results are automatically given once in every 10 minutes. The results agree well with those obtained by the manual method. The developed system is well applied to the ammonia liquor treatment process.