According to the Association for the Advancement of Medical Instrumentation (AAMI, US), Ozone is the most effective method to destroy microorganisms, and to prevent, reduce or remove the biofilm.
Common issues in dialysate preparation
- Typically RO water is stored in 2,000 to 5,000 litres stainless steel tanks. From this SS tank, water is piped into the dialysis stations. The SS tanks and pipe lines are typically cleaned completely atleast once a week. During this process, the system is shut down, and dialysis centre is closed for a minimum period of 12 to 24 hours. Very strong chemicals such as Chlorine, Formalin, etc., are used, in high concentrations.
- The chemicals require several hours of contact time with the equipment for effective disinfection.
- Post chemical treatment, fresh RO water is again used to flush out the residuals that are left in the tank, filters, UV chambers and piping systems, etc., This is done repeatedly to ensure 100% residual free equipment. Inspite of this, there is scale formation inside the SS storage tanks that builds up over a period of time. This base then acts as a foundation for formation of bio-film.
- This bio-film further acts as a protective shield for bacteria and other pathogens, under which they thrive.
- Several chemical such as Chlorine, Formalin etc., have little or no effect on the bio-film. Unless this bio-film is broken, the bacteria underneath continue to thrive.
- Further more Chlorine does not kill the entire range of bacteria. In typically used doses, it is only effective against 70% of the spectrum.
- If any bacteria get past RO membrane, there is no control over the pathogens after this point as constant dosing of chemicals right up to the time of use can not be done. These bacteria then have abundant opportunity to multiply in the storage tank, filters, and in the pipe lines. While UV lamps are used, these are not 100% reliable, and when there is power outage even for a few seconds, untreated water slips though.
Use in Dialysis centres
The microbiological monitoring of the water used for Hemodialysis is extremely important, especially because of the debilitated immune system of patients suffering from chronic renal insufficiency. Each patient using a kidney machine is exposed to between 20,000 ltrs to 40,000 ltrs of dialysate water a year. This is a very large quantity as compared to oral intake of water per year which be would be less than 1,000 ltrs per year. Furthermore, whereas drinking water reaches the bloodstream only after passing through the highly selective barrier of the gastrointestinal mucosa, dialysis fluids come into direct contact with the bloodstream with the only interposition of a semi-permeable artificial membrane from which, if it were not properly treated, a variety of chemicals, bacterial and toxic contaminants could be transferred to the patients. Finally, in dialysis units, water is not only used to produce dialysis fluids, but is also used for purposes, such as dialyser rinsing, loop and storage tanks disinfection. It is therefore very important to know and monitor the chemical and microbiological purity of dialysis water.
Advantages of Ozonation process for Hemodialysis
- Biofilm Prevention and Removal: The biofilm is very hydrophilic, making it a very watery substance. This property, in addition to the highly polar polysaccharides, makes a biofilm an easy target for ozone.
- Bactericidal: Highly effective and shortest possible contact time, reduces endotoxins and destroys algae.
- Virucidal: Broad spectrum coverage of all known water borne viruses and other pathogens. Micro-organisms cannot build up tolerance to Ozone.
- Environment friendly: No chemicals used, so does not leave any chemical residue or disinfection by-products (DBP).
- On-line and disruption free method of disinfection of dialysate water loop and storage tanks.
- Increased uptime and availability of dialysis center for patients.
- Increased patient convenience and scheduling.
- Continuously 100% safe status of dialysate every hour and every day, instead of steady deterioration of dialyste quality seen with the weekly disinfection process. Daily disinfection process can be run with just 15 minutes every 24 hours.
- Better quality waste stream, as COD and BOD are reduced due to higher dissolved oxygen dialysate.
- Reduced man power and avoids purchasing, storing and handling hazardous chemicals required for storage tank and loop disinfection. Results in ease of operation at low cost and highly effective.
- Infact, it is the most effective disinfection process for dialysis centre.
- Ozone is an effective disinfectant destroying all bacteria without a preference to one type of organism. It does not allow resistance to build up in bacteria, over a period of time.
- Ozone is the most powerful sterilant in the world and its function is to destroy bacteria, viruses and odours.
- Ozone is 51% more powerful on bacteria cell walls than chlorine and kills bacteria 3100 times faster.
- Ozone is extremely effective as a disinfectant at relatively low concentration and the contact time is very less due to its fast action.
- Ozone is clean and environmentally friendly; its only by-product is oxygen.
- Ozone leaves no residual, so only ozone injection is necessary. No second chemical for quenching is necessary.
- Ozone is produced on site from renewable resources and requires no chemical storage. Ozone is clean, safe and reliable, taking up less space and less equipment than many chemical treatment/storage systems.
Ozone has a very short half-life and in addition, exposure to UV irradiation will quickly remove it. So, all dialysis water must first pass through an UV light unit. The radiant energy of the UV lamp causes almost instantaneous breakdown of the ozone back to molecular oxygen. Finally, the dialysis machine itself de-aerates the water as one of its primary functions.
Wide acceptance and use in Hemodialysis centers around the world
Ozonation of dialysate water is the most promising ‘nonchemical’ methods for water systems disinfection in Hemodialysis. Recently, an increasing number of dialysis units in Europe (i.e. all Swiss cantonal hospitals), and the United States are using Ozone to disinfect their water distribution systems and dialysate concentrate containers.