Zirconium phosphate is a common material used in sorbent cartridges for sorbent dialysis. Zirconium phosphate can remove ammonium ions from spent dialysate, generated by the breakdown of urea in the spent dialysate by urease, as well as potassium, calcium, and magnesium ions from spent dialysate. Known sorbent dialysis systems generally require the sorbent materials to be discarded and the sorbent cartridge replaced after each use. Discarding and replacing of expensive sorbent materials, such as zirconium phosphate, increases both costs and waste.
Zirconium phosphate operates by exchanging sodium and/or hydrogen ions bound to the zirconium phosphate for ammonium, potassium, calcium, magnesium and other cations present in spent dialysate. The ratio of sodium to hydrogen ions released by the zirconium phosphate into the dialysate may depend on the ratio originally bound to the zirconium phosphate. When the zirconium phosphate is recharged using acid solutions, neutralization is necessary in order for the zirconium phosphate to be reused in a dialysis session. Known sorbent dialysis systems do not provide a way to recharge the zirconium phosphate, wherein the additional neutralization is not necessary. Known sorbent dialysis systems do not provide for a way to recharge the zirconium phosphate present in a sorbent cartridge so that the zirconium phosphate can be reused for future dialysis sessions. Instead, known sorbent dialysis systems generally require the sorbent materials to be discarded and the sorbent cartridge replaced after each use. Although traditional sorbent cartridges can be broken down to extract the sorbent materials for recharging, the sorbent materials must be re-processed at a processing plant, and cannot be recharged by the dialysis machine, a recharging device, or an in-clinic apparatus. The exhausted sorbent materials must be transported to a processing plant, the sorbent cartridge disassembled and the sorbent materials recharged by the plant. At some point, a new cartridge must be manufactured and the recharged sorbent materials re-packaged into the cartridge and transported back to the dialysis clinic for use. Traditional cartridges also cannot isolate specific materials into compartments for recharging, and therefore, cannot be adapted to recharge expensive rechargeable sorbent materials. Single- and limited-use sorbent cartridges drive up not only the unit cost of dialysis, but also the total cost of dialysis.
As such, there is a need for systems and methods for recharging sorbent materials such as zirconium phosphate for reuse. There is also a need for methods and systems for separating sorbent materials within a sorbent cartridge into single and multi-use modules that can facilitate recharging and reuse of at least one of the sorbent materials. There is a further need for systems and related methods whereby rechargeable sorbent materials can be separated into multi-use modules and single-use modules wherein non-rechargeable sorbent materials can optionally be contained in the single-use modules. There is also a need for systems and methods wherein the recharge solutions can result in different ratios of sodium to hydrogen ions bound to the rechargeable sorbent material according to the needs of the patient. There is a need for a recharge process and apparatus that can establish capacity of the zirconium phosphate for cation removal and provide a consistent predicable, pH profile during a therapy session.