Desorption rate of volatile compounds in polishing ponds

摘要

Increase of pH in polishing ponds can be predicted quantitatively from variations in alkalinitynand acidity. These variables are affected by processes that develop simultaneously in ponds:n(1) CO2 desorption, (2) biological CO2 removal by photosynthesis and (3) NH3 desorption. Annexperimental investigation was carried out to determine the desorption rate of carbon dioxide andnammonium. It is shown that CO2 and NH3 desorption can be described by Fick’s law, whichndescribes desorption of a gaseous compounds from water as a first order process with respect tonthe degree of oversaturation, which is the driving force of the process. An experimentalninvestigation was carried out to determine the desorption rate constants. The value of thenconstant proved to be inversely proportional to the depth of the pond (H) and its value for H¼1mnand at 261C was established as KCO2 ¼0.34/H du00021 for carbon dioxide and KNH3 ¼0.33/H du00021 fornammonium.