Dialysis is a medical procedure where a patient's blood is passed through a machine which uses membranes which remove urea, potassium, and waste products from the blood. It's a standard treatment for patients who have suffered from kidney failure and essentially replaces the function of the kidney. However, it's inefficient compared to a functioning kidney and also damages blood cells over the long term. As such, it's only used as a stopgap measure until a patient can receive a transplant.
Dialysis is generally not a continuous procedure, with patients coming in for treatment a few times a week. Patients on dialysis must avoid potassium in their diet and must limit the amount of protein they get in their diet as well.