Fluid purification system

Abstract

Certain disclosed embodiments concern systems and methods of preparing dialysate for use in a home dialysis system that is compact and light-weight relative to existing systems and consumes relatively low amounts of energy. The method includes coupling a household water stream to a dialysis system; filtering the water stream; heating the water stream to at least about 138 degrees Celsius in a non-batch process to produce a heated water stream; maintaining the heated water stream at or above at least about 138 degrees Celsius for at least about two seconds; cooling the heated water stream to produce a cooled water stream; ultrafiltering the cooled water stream; and mixing dialysate components into the cooled water stream in a non-batch process.

We claim: 
     
         1 . A fluid purification system comprising:
 a pump adapted to pump household water through a pump outlet;   a microfluidic heat exchanger downstream of the pump and coupled to the fluid flow pathway, the microfluidic heat exchanger comprising an inlet in fluid communication with the pump outlet, an inflow microchannel downstream of the inlet, a heater downstream of the inflow microchannel, an outflow microchannel downstream of the heater and in thermal communication with the inflow microchannel to permit heat transfer between water flowing in the outflow microchannel and water flowing in the inflow microchannel, the microfluidic heat exchanger being configured to heat the water to a pasteurization temperature, maintain the water at the pasteurization temperature for a period of time effective to pasteurize the water, and cool the pasteurized water to a temperature lower than the pasteurization temperature; and   a mixer downstream of the microfluidic heat exchanger, the mixer comprising dialysate components for addition to water flowing from the microfluidic heat exchanger.   
     
     
         2 . The system of  claim 1  wherein the microfluidic heat exchanger further comprises a plurality of inflow microchannels in fluid communication with the inlet and a plurality of outflow microchannels in fluid communication with the mixer. 
     
     
         3 . The system of  claim 2  wherein the microchannels are disposed in a plurality of stacked laminae. 
     
     
         4 . The system of  claim 3  wherein the inflow microchannels and the outflow microchannels are separated by the laminae. 
     
     
         5 . The system of  claim 4  wherein the inflow microchannels and the outflow microchannels are formed from flow paths etched in facing surfaces of adjacent laminae. 
     
     
         6 . The system of  claim 3  wherein the microfluidic heat exchanger further comprises a heat transfer layer disposed between a lamina of inflow microchannels and a lamina of outflow microchannels. 
     
     
         7 . The system of  claim 3  wherein the inlet comprises an inlet opening extending through a plurality of laminae in fluid communication with the plurality of inflow microchannels in the plurality of laminae. 
     
     
         8 . The system of  claim 3  wherein the microfluidic heat exchanger further comprises an outlet opening extending through a plurality of laminae and in fluid communication with the plurality of outflow microchannels in the plurality of laminae and with the mixer. 
     
     
         9 . The system of  claim 3  wherein the microfluidic heat exchanger further comprises a heater region in which the heater is disposed, the heater region being in fluid communication with a plurality of laminae. 
     
     
         10 . The system of  claim 2  wherein the microfluidic heat exchanger further comprises a residence chamber comprising a flow pathway downstream of the heater and upstream of the outflow microchannels. 
     
     
         11 . The system of  claim 1  wherein the inlet microchannel and the outlet microchannel are disposed in a counterflow arrangement. 
     
     
         12 . A method, comprising coupling an input water stream to a microfluidic device that heats the input water stream for a period of time and at a temperature sufficient to provide an output water stream having a bacterial load at a level suitable for dialysis. 
     
     
         13 . The method of  claim 12 , wherein the output water stream is a continuous flow of pasteurized water. 
     
     
         14 . The method of  claim 12 , wherein the device heats the water to a temperature of at least 138° C. for at least two seconds. 
     
     
         15 . The method of  claim 12 , wherein the device mixes the output stream with dialysate components to produce dialysate having a bacterial load of no greater than 0.1 CFU/ml. 
     
     
         16 . The method of  claim 12 , wherein the output water stream is in thermal communication with the input water stream, to cool the output water stream and heat the input water stream.