Coke-plant effluents contain free and combined (fixed) ammonia. The free ammonia may be stripped out by application of steam, but to strip combined ammonia, an alkalization of the wastewater, usually by the addition of lime, is required. The fate of ammonia nitrogen in the treatment of coke-plant effluents is presented in Table I. Poor performance of stripping facilities is caused by several factors such as fluctuation of wastewater flow to the still, insufficient alkalization, insufficient steam flows, and others. To obtain satisfactory performance of ammonia stripping, proper design and operation of stripping facilities is required. To achieve an advanced performance, in addition to the above requirements, an improved process control is needed. Fate of Ammonia Nitrogen in Treatment of Coke-Plant Effluents [<xref ref-type="bibr" rid="ref70_1 ref70_2">1</xref>–<xref ref-type="bibr" rid="ref70_3">3</xref>]

Concentration (mg/L)

Raw Wastewater


After Stripping of Free Ammonia


After Stripping of Free and Fixed Ammonia Poor Performance


Satisfactory Performance


Advanced Performance


After Biological Dephenolization


After Biological Nitrification