Effects of air and fluid flow rates on removing different concentrations of urea and ammonia from fluid by gas absorption in a capillary hemodialyzer.

Urease converts urea into ammonium and bicarbonate. Alkalinization converts ammonium into free ammonia which can be removed as a gas. Our approach is to use a capillary hemodialysis as a gas absorption unit with liquid moving through the blood compartment and air through the dialysate compartment to extract ammonia gas. This paper examines the effects of air flow rate, fluid flow rate, and concentrations of ammonia (and urea) in the fluid. It was observed that increasing air flow rate or dialysate flow rate increases the mass transfer rate for ammonia especially at low ammonia concentration levels. Ammonia removal rate increases with air flow rate linearly. Ammonia removal rate increases with increasing fluid flow rate, but reaches a plateau when flow rate was above 500 ml/mn.