This is an interesting patent for an artificial kidney dialysis system, which in fact combines waste removal and "an implantable fluid removing device". It seems to propose to use the sort nanoengineered dialysis membrane that Dr. Steinman described in video two of the CIMIT presentation. They use the phrase "another embodiment" often in the filing which I take to mean that this is in the early stages.
I was interested because I had not considered peritoneal dialysis as a way to make wearable dialysis practical. The nanoengineered filters cleanse the dialysate not the blood directly. This eliminates the blood access issue which I think is wearable hemodialysis's biggest challenge. Wearable peritoneal sounds more practical.
It's also interesting to consider the advantages of an implantable device that removes only fluid. I wonder if such a device could be used temporarily to get people to their dry or to eliminate the need for fluid control. Dialysis would be much less of a burden if people did not have to remove fluid. It's the buildup and rapid removal of fluid that causes the heart so much stress. Continuous fluid removal would make blood pressure control less complicated.
Rather than trying to match a kidney feature for feature, maybe the best approach is an incremental approach. First create an internal device to remove water only while, the current technology is used to cleanse the blood.