Improved urea removal system utilizing anion-transfer membrane（A.T.M.） is investigated. For various solutes overall membrane resistances of A.T.M. and cellophane membrane are determined by a dual closed-loop dialysis technique. Using 0.2 M sodium phosphate-citrate buffer, effects of urease enzyme concentration on urea removal and effects of activators such as DL-alanine and glycine on urea removal are investigated. Comparison with other urea removal systems are made by simulation using two compartment model.
Experimental results showed that 1.5 unit/ml urease enzyme concentration is adequate for the system of 0.5 L blood bath and 0.5 L dialysate bath. Effects of activators are not observed probably owing to very low urea concentation in dialysate. The simulation has shown that A.T.M. system is more efficient than other systems in urea removal and toxic ammonium ion removal. The results suggest further work for developments of A.T.M. suitable for artificial kidney.