Water treatment and quality control of dialysate.


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Seminar prepared by Dr. Praveen. DM Resident in Nephrology, IPGME&R Kolkata

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Water treatment and quality control of dialysate.

  2. 2. INTRODUCTION <ul><li>Survival of Haemodialysis patient is steadily improving which has led to increasing problems due to contaminants of dialysis water. </li></ul><ul><li>Haemodialysis patients are exposed to 25 to 30 times of water compared to normal individuals drinking water needs. </li></ul><ul><li>Contaminants enter the blood compartment of dialysers and accumulate in the body due to inability of these patients to excrete them via their kidneys. </li></ul>
  3. 3. INTRODUCTION contd.. <ul><li>Water treatment for preparation of dialysate is probably the most neglected area of renal replacement-with dialysis . </li></ul><ul><li>Quality of water contributes very significantly in morbidity and life threatening reactions in dialysis patients in both; an acute sense, as well as in long-term prognosis </li></ul>
  4. 4. Toxic effects of water contaminants in hemodialysis patients
  5. 5. Schematic representation of a water treatment device for haemodialysis
  6. 6. COMPONENTS OF WATER TREATMENT PLANT <ul><li>Water Supply </li></ul><ul><li>Back-flow preventer </li></ul><ul><li>Temperature blending valve </li></ul><ul><li>Booster pump </li></ul><ul><li>Acid injection metering device </li></ul><ul><li>Multimedia depth filter </li></ul><ul><li>7. Water softener </li></ul><ul><li>8. Brine tank </li></ul><ul><li>9. Carbon tanks </li></ul><ul><li>10. Reverse Osmosis (RO) Systems: Prefilter </li></ul><ul><li>11. RO membranes </li></ul><ul><li>12. Distribution System </li></ul>
  7. 7. Water supply <ul><li>There are two sources of municipal water: surface water and ground water </li></ul><ul><li>Surface water is generally more contaminated with organisms and microbes, industrial wastes, fertilizers, and sewage. </li></ul><ul><li>Ground water is generally lower in organic materials but contains higher inorganic ions such as iron, calcium, magnesium, and sulfate </li></ul>
  8. 8. Back-flow preventer <ul><li>All water treatment systems require a form of back-flow prevention device. </li></ul><ul><li>A back-flow preventer prohibits the water in the water treatment components from flowing back into the potable drinking water lines. </li></ul><ul><li>This protects the drinking water from contamination with disinfectants and cleaners that are used in the water treatment system. </li></ul>
  9. 9. Backflow Prevention Device ( Reverse Flow Prevention Device), <ul><li>What to monitor : Pressure drop across the device, annual testing </li></ul><ul><li>What to look for : A pressure drop change of 10 PSI from baseline </li></ul>
  10. 10. Temperature blending valve <ul><li>The temperature blending valve mixes hot and cold water to a RO membrane industry standard temperature of around 77 [degrees] F (25 [degrees] C). </li></ul><ul><li>These valves are widely used on large central RO systems that tend to have cold incoming water. </li></ul><ul><li>The colder the source water, the less purified water the RO membrane will produce </li></ul>
  11. 11. Temperature blending valve <ul><li>Per 1 [degrees] F temperature drop, the RO membrane produces 1.5% less purified water </li></ul><ul><li>For instance, an incoming temperature of 50 [degrees] F would result in an approximate loss of 40% (product water flow). </li></ul>
  12. 12. Booster Pump <ul><li>The RO system requires a constant supply of water flow and pressure in order to operate successfully. </li></ul><ul><li>Dialysis facilities experience fluctuating or decreased incoming water pressure and flow, especially since back flow preventers and temperature blending valves substantially lower pressure </li></ul>
  13. 13. Booster Pump
  14. 14. Acid injection metering device <ul><li>By increasing the pH of the city water supply using lime softening agents or calcium carbonate prevent leaching of lead, copper, and other metals from the city and residential piping systems. </li></ul><ul><li>In order for the RO to operate properly and carbon tanks to remove chlorine/chloramine effectively, the ideal incoming water pH should be between 5-8.5. </li></ul><ul><li>In many areas the pH is higher than 8.5, so an acid injection system may be incorporated into the design of the pretreatment, especially with the presence of chloramine. </li></ul>
  15. 15. Multimedia depth filter <ul><li>Large particulates of 10 microns or greater that cause the supply water to be turbid -- such as dirt, silt, colloidal matter (suspended matter) -- are removed by a multimedia filter, sometimes referred to as a depth bed filter. </li></ul><ul><li>Foulants can clog the carbon and softener tanks, destroy the RO pump, and foul the RO membrane </li></ul>
  16. 16. Multi-Media and Cartridge Filter
  17. 17. Multimedia depth filter <ul><li>Multimedia filters contain multiple layers of various sized rocks ranging from sand to gravel that literally trap the large particles as the water is filtered downward. The first layer is usually composed of anthracite coal, followed by layers of garnet, sand, then gravel. </li></ul><ul><li>All the tiers are constructed of different sized media so that not all the particulates are collected at the top but rather distributed through the media bed, a phenomenon known as depth filtration. </li></ul>
  18. 18. Water Softener <ul><li>Water containing calcium and magnesium form scale deposits on the RO membrane and eventually foul the membrane </li></ul><ul><li>Softeners work on an ion exchange basis. The resin beads within the tank have a high affinity for the cations calcium and magnesium (both divalent) present in the source water and release two sodium ions (monovalent) for one calcium or magnesium captured </li></ul>
  19. 19. Water Softener <ul><li>The softener needs regenerating on a routine basis with concentrated sodium chloride solution (brine) before the resin capacity is used up </li></ul><ul><li>The resin is backwashed to loosen the media and clean any particulates from the tank. After the backwashing step, the brine solution is drawn into the tank to regenerate the resin. </li></ul>
  20. 20. Water Softener
  21. 21. Water softener <ul><li>A hardness test on the effluent softened water should be done, at a minimum, once a day and recorded. However, to determine the efficacy of the softener, it is best to test the softened water twice a day; once in the morning to determine that the softener did regenerate and once at the end of the day to prove that the softener performed adequately all day. </li></ul><ul><li>Hardness tests should be less than 2 grains per gallon (gpg) hardness (35 mg/L) and performed on &quot;fresh&quot; water, </li></ul>
  22. 22. Carbon tanks <ul><li>One of the most critical tasks regarding patient safety in the day of a dialysis technician is checking the water treatment system for chlorine and chloramines. </li></ul><ul><li>Chlorine and its combined form, chloramine, are high-level oxidative chemicals. They are added to municipal water systems to kill bacteria—but they also destroy red blood cells. </li></ul><ul><li>Injection of sodium metabisulfite </li></ul>
  23. 23. RO Pre-filter
  24. 24. RO Pre-filter <ul><li>Prefilters are particulate filters positioned after all the pretreatment and immediately before the RO pump and RO membrane. Carbon fines, resin beads, and other debris exiting the pretreatment destroy the pump and foul the RO membrane. </li></ul><ul><li>Typically, prefilters range in pore size from 3-5 microns </li></ul>
  25. 25. RO pump and motor <ul><li>The RO pump increases water pressure across the RO membrane to increase both product water flow and rejection characteristics of the RO membrane. RO systems typically operate between 200-250 PSI </li></ul><ul><li>RO pumps are made of high-grade stainless steel, inert plastics, and carbon graphite-wetted parts. Brass, aluminum, and mixed metal pumps will leach contaminants into the water and are not compatible with peracetic acid type disinfectants </li></ul>
  26. 26. RO membranes <ul><li>RO membranes reject dissolved inorganic elements such as ions of metals, salts, and chemicals and organics including bacteria, endotoxin, and viruses. </li></ul><ul><li>Rejection of charged ionic particles ranges from 95-99%, whereas contaminants such as organics that have no charge are rejected at a greater than 200 molecular weight cut-off. </li></ul><ul><li>Ionic contaminants are highly rejected compared to neutrally charged particles, and polyvalent ions are more readily rejected than monovalent ions. </li></ul>
  27. 27. Reverse Osmosis system <ul><li>The RO membrane is the heart of the system. It produces the purified water through RO. RO is just that, it is the opposite of osmosis. </li></ul><ul><li>Thin film (TF) RO membranes made of polyamide (PA) are the most common type used in HD. </li></ul>
  28. 28. Deionisation <ul><li>Do not remove nonionic contaminants,bacteria or endotoxins </li></ul><ul><li>Cationic resins contain sulfuric radicals and exchange hydrogen radicals for other cations such as sodium,calcium and aluminium </li></ul><ul><li>Anionic resins contain ammonium radicals, which exchange hydroxyl ions for chloride,phosphate and flouride </li></ul>
  29. 29. Distribution System <ul><li>RO distribution systems can be grouped into two categories, direct feed and indirect feed. </li></ul><ul><li>A direct feed system &quot;directly&quot; delivers the product water from the RO unit to the loop for distribution. </li></ul><ul><li>An indirect feed system involves a storage tank that accumulates the product water and delivers it to the distribution loop. </li></ul><ul><li>Unused portions of the product water are recirculated back into the storage tank </li></ul>
  30. 30. Distribution piping systems <ul><li>Though there continues to be some water treatment systems that have nonreturning lines that go to drain, a continuous loop design is recommended by AAMI. No dead-ends or multiple branches should exist in the distribution system, as these are places for bacteria biofilm to grow. </li></ul>
  31. 31. Bacterial filters
  32. 32. Ultraviolet Irradiation <ul><li>This is used finally just prior to the dialysis machine, to inhibit bacterial growth, after all other water treatment is done. </li></ul><ul><li>Bacteria may grow resistant to ultraviolet light. </li></ul><ul><li>If used without pro- treatment the effectiveness is lost because suspended particulate matter may block light waves. </li></ul>
  33. 33. Composition of the dialysate <ul><li>The composition of dialysis fluid should be similar to that of normal interstitial body fluid appropriately corrected for protein content </li></ul>
  34. 34. Composition of extracellular fluid and a standard dialysis fluid Serum water (mmol/l) Dialysis fluid (mmol/l) Sodium 152 140–145 Potassium 4.5 0-4 Calcium 1.5 1.5 Magnesium 0.5 0.5 Chloride 109 100–110 Acetate 0 2-4 or  Bicarbonate 32–38 Glucose 5 0–10
  35. 35. Scheme of dialysate flow
  36. 36. Water Treatment System
  37. 37. Bacteriological Monitoring : Hemodialyzers <ul><li>The maximum level of bacteria in water used to prepare dialysis fluid and reprocess hemodialyzers must not exceed the AAMI standard of 200 colony forming units (CFU). The AAMI action level is 50 CFU for bacteria in water used to prepare dialysis fluid. </li></ul><ul><li>An action level is defined as a point when measures must be taken to correct the potential source to remain in compliance with AAMI standards. </li></ul>
  38. 38. Endotoxin Standard for Water Used to Prepare Dialysis Fluid and Reprocess Hemodialyzers <ul><li>The maximum level of endotoxin in water used to prepare dialysis fluid and reprocess hemodialyzers must not exceed the AAMI standards of 2 Endotoxin Units per Milliliter (EU/ml). </li></ul><ul><li>The action level of endotoxin in water used to prepare dialysis fluid is 1 EU/ml </li></ul>
  39. 39. Frequency of Testing for Bacteria and Endotoxin levels <ul><li>Testing should be performed monthly. </li></ul><ul><li>If standards are exceeded, testing should be performed weekly until the problem is resolved. </li></ul><ul><li>. </li></ul>
  40. 40. Ultrapure dialysis solution <ul><li>Decrease c-reactive protein and il-6, </li></ul><ul><li>Improve response to anaemia to epo </li></ul><ul><li>Promote better nutrition </li></ul><ul><li>Reduce plasma levels of b2-microglobulin </li></ul><ul><li>Slow loss of residual renal function </li></ul><ul><li>Lower cardiovascular morbidity </li></ul><ul><li>Bacteria level below 0.1cfu/ml and endotoxin level below 0.03EU/ml </li></ul>
  41. 41. Sample Collection <ul><li>The sample ports used to collect the samples must be rinsed for at least one minute at normal pressure and flow rate before drawing the samples. Samples should be collected using a “clean catch” technique to minimize potential contamination of the sample, leading to false positive results. </li></ul><ul><li>Sample ports should not be disinfected. If a facility insists on disinfecting the ports, alcohol should be used and allowed to completely dry before the sample is drawn. </li></ul><ul><li>Bleach or other disinfectants should not be used </li></ul>
  42. 42. Sample collection <ul><li>Samples for bacteriological testing should be processed within 1-2 hours or refrigerated and processed within 24 hours. </li></ul><ul><li>The AAMI standard recommends culturing samples of 0.5 to 1.0 cc for 48 hours at 35 C, using tryptic soy agar as the culture medium. </li></ul>
  43. 43. CONCLUSION <ul><li>Water treatment is a generally neglected area of dialysis therapy. </li></ul><ul><li>Due to increased survival of dialysis patients, in creased use of bicarbonate dialysate and high flux membranes water treatment has become essential. </li></ul><ul><li>It is worthwhile achieving the goal of sterile, pyrogen tree and chemically pure water for dialysis. </li></ul><ul><li>The above goal is achievable with a combination of various technologies available. </li></ul><ul><li>After designing a system based on requirements of individual unit both quality, quantity and cost effectiveness, it is essential to monitor the effluent water regularly. </li></ul>
  44. 44. Thank you