Ecodas (Medical Waste Sterilizer) Serial No : 019/06 Prepared by : Puan Mariammah A/P Krishnasamy Reviewed by : Datin Dr Rugayah Bakri 1. INTRODUCTION There are many ways and technologies available for treating medical waste. The technology utilised in the Ecodas equipment is a modified autoclave technology, whereby it uses steam sterilization with the new feature of shredders incorporated in the equipment. The more recent designs have incorporated vacuuming, continuous feeding, shredding, mixing, fragmenting, drying, chemical treatment and compaction. The examples of these advanced autoclaves are ECODAS, Hydroclave, Sterival, STICHEM Clav, STS, and System Drauschke (www.noharm.org). Several factors and criteria should be considered by the health care facilities when considering a non-incineration technique for medical waste treatment. The factors include:- Regulatory acceptance Throughput capacity Types of waste treated Microbial inactivation efficacy Environmental emissions and waste residues Space requirements Utility and other installation requirements Waste reduction Occupational safety and health Noise Odour Automation Reliability Level of commercialization Background of the technology manufacturer Cost Community and staff acceptance ECODAS autoclaves are installed in several places in France, mostly in individual medical facilities. They are also operated as central units at some hospitals, such as in Santes or Loos. These systems are also operated in Cyprus, Hungary, Poland, Russia, Spain and some non- European countries such as Argentina, Brazil, Mexico, Japan, Egypt, Lebanon, Guyana and Morocco.
A company named Syarikat N.A.Z. Medical Supplies Sdn. Bhd. has promoted the usage of the ECODAS equipment to be placed at all hospitals in Ministry of Health, Malaysia (MOH). Following that they had a demonstration on ECODAS sterilization to the Medical Development Division on 13 March 2003. As a follow up from the above demonstration, a technology review was requested by the Director of Medical Development Division to ensure the appropriateness of this equipment for placement at MOH. 2. OBJECTIVE To assess the safety, effectiveness and cost-effectiveness of the ECODAS equipment. (MEDICAL WASTE STERILIZER). 3. TECHNICAL FEATURES There are three types of ECODAS models available for different capacity of medical wastes. They are the T300, T1000 and T2000.The major difference between T1000 and T300 is the height, and between T2000 and T1000 is the diameter. The T2000 and T1000 require a hoist loading system. ECODAS T300 has a treatment capacity of 300 litres per 30 minutes average cycle time.
ECODAS T1000 has a treatment capacity of 1000 litres per 40 minutes average cycle time ECODAS T2000 has a treatment capacity of 2000 litres per 60 minutes average cycle time. (www.ecodas.com) 1.1 Technical features of ECODAS ECODAS has been commercialised since 2003. Medical waste is loaded from the top of the machine into a chamber equipped at the bottom with a heavy duty shredder. If the medical waste contains some unbreakable objects, like metal parts, the shredder stops automatically, and the chamber is not opened until waste is sterilized by steam. Shredded waste falls by gravity into the lower chamber. The machine is steam heated to a temperature of 138 C and pressure is increased to 3.8 bars. The fully automated and online-controlled process has a cycle time of 40-60 minutes, depending upon the size of plant and the amount of waste. Sterile fragments (8 log 10 reduction) are
discharged from the bottom of the machine and disposed off in the environment landfill site. The original volume of waste is reduced by 80%. 4. METHODOLOGY The electronic database of Pubmed, OVID search engine, PROQUEST search engine, and Google search engine were searched. The following were the key words used either singly or in combination: safety, effectiveness, efficacy, cost-effectiveness, steam sterilizer, steam autoclave, medical waste treatments, medical waste disposable techniques, medical waste sterilization, Ecodas and incineration. 5. RESULTS AND DISSCUSSION 5.1 Safety The Ecodas system is equipped with a safety system, fully automated batch process. The shredding and sterilization are enclosed in a compact system. This ECODAS equipment, however, does not have intermediate waste handling. A study by Cofiell et al. (2003) indicated that compared to other methods, the steam sterilizer is relatively safe, inexpensive and reliable. Therefore, it has become the most widely used method of sterilization. The ECODAS system also uses the steam sterilization technology. The Ecodas system is fully automated with several safety features which ensures correct operating procedures such as: i) It can be opened only when the temperature and pressure are acceptable. The process cannot start if all locks are not in place and the process cannot be interrupted until sterilization is complete. ii) iii) As soon as a failure occurs, an automatic diagnosis is made by the machine which displays the nature of the failure. A security cycle can be activated before opening the machine. Therefore, the inside of the machine is sterilized, as well as the shredder, before the maintenance personnel s intervention. The remarkable feature of the system is the shredder. As it is well known by waste experts, it is difficult to achieve shredding of all types of waste, particularly of an unexpected item like a screw driver, which could ruin the mechanism, or melting plastic which can clog the moving parts. The shredder s design eliminates those eventualities. The ECODAS process has been tested by the Pasteur Institute and approved under the supervision of the French Higher Council of Public Health in the French Ministry of Health and Ministry of Environment. The ECODAS process is recognized and accepted by the Ministries of Health and Environment of the following countries: Algeria, Argentina, Brazil, Denmark, Cyprus, Egypt, England, France, Honduras, Hungary, Iran, Japan, Kuwait, Lebanon, Mexico, Morocco, Poland, Russia, Spain, Tunisia and USA.
5.2 Effectiveness Guideline document by Infection Prevention Guidelines, Sterilization, adapted from: Tietjen, Cronin and McIntoh (1992), revealed that sterilization by steam is an effective sterilant for two reasons. Firstly, saturated steam is an extremely effective carrier of thermal energy. It is many times more effective in conveying this type of energy to item than hot (dry) air. Secondly, steam was an effective sterilant because any resistant, protective outer layer of the microorganisms can be softened by the steam, allowing coagulation of sensitive inner portions of the microorganism (Cofiell et al., 2003). Steam sterilization requires four conditions: adequate contact, sufficiently high temperature, correct time and sufficient moisture. As an alternative to incineration, steam sterilization (autoclaving) places first as a medical waste treatment option. Decontamination by steam sterilization depends on the time and temperature, and it is determined by the minimum time required to kill bacillus stearothermophilus spores exposed to saturated steam (wet heat) at a particular temperature. (Cofiell et al., 2003). The ECODAS equipment does have an inactivation efficacy test which had been conducted by a controlled study of Waste Decontamination: ECODAS T1000 in Institute Pasteur de Lille, October 21 st, 2002 with the sterilization time of 10 minutes and cycle duration of 35 minutes. The experiments were conducted on the Spore strips containing Bacillus stearothermophilus spores that were kept in test tubes capped with water impregnated cotton and placed in the apparatus. A satisfactory result of 10 6 reductions in bacillus stearothermophilus was observed, following decontamination with ECODAS T- 1000 at 138ºC. (Material provided by ECODAS). Another study indicated that infectious clinical wastes which are most suited for steam sterilization are those with a relatively low density and low-to-moderate water content. Contaminated plastic single-use items and cellulose products are easy to decontaminate, provided that they are not packed tightly or encased whereby steam penetration is hindered. Conversely, materials such as body tissue, parts, and fluids are relatively dense and high in water content, thus inhibiting the amount of heat directly transferred by steam contact (Slavik, 1991). A review by Urbanowicz (1998) evaluated the technology between incinerators and other alternative treatment systems in American healthcare hospitals. In the review fifty states of America recognized steam sterilization as an acceptable method of treatment for medical waste prior to disposal. Another study done by Melbourne's Waste Energy Pty Ltd. found that around 95 percent of the hospital and biomedical waste currently processed by incinerators can instead be sterilized. Furthermore, the steam-injection sterilization technology enables such generating facilities as hospitals to process biomedical waste autonomously and in-house. (Field Trial study by the Royal Melbourne Hospital, Melbourne, Australia, of a highly advanced sterilization alternative to conventional incineration of biomedical wastes).
Autoclave with steam sterilization continue to be one of the most popular methods of treating medical waste.these technologies now incorporated maceration or shredding during the treatment process to ensure better penetration of steam. These systems achieve significant volume reduction up to 85% (http://www.oecs.org/esdu/documents/ waste%20management%20medical%20waste%20technologies.pdf.). 5.3 Cost Effectiveness No evidence was retrieved on the economy evaluation of the ECODAS equipment. However, there were some studies which indicated the cost aspects of the equipment. A study found that an efficient and cost-effective on-site infectious waste management program can be implemented by integrating the decontamination advantages offered by both steam sterilization and incineration. (Slavik, 1985). In a trial, results found that the capital and operating costs of sterilization are less than half that of conventional incineration. (Royal Melbourne Hospital, Melbourne, Australia, of a highly advanced sterilization alternative to conventional incineration of biomedical wastes-report). Autoclaving or steam sterilization represents the ability for generators to treat their waste in a cost-effective way. The equipment saves space, is easy to maintain and the destruction of pathogens is highly effective. The only problem that often arises after autoclaving is the transportation of the treated medical waste materials to the land fill. (Environmental Chemistry.com Environmental, chemistry & Hazardous Materials News, Information and resources. Traditional Medical waste treatments by Lupe Perez). 6. CAUTIONS Steam sterilization is limited in the types of medical waste it can treat but is appropriate for laboratory cultures and/or substances contaminated with infectious organisms. The waste is subjected to steam in a sealed, pressurized chamber. The liquid that may form is drained off to the sewer or sent for processing. The unit is then reopened after a vapour release to the atmosphere, and the solid waste is taken out for further processing or disposal. One advantage of steam sterilization is that it has been used for many years in hospitals to sterilize instruments and containers and to treat small quantities of waste. A disadvantage is ensuring that the proper time/temperature relationship has been met. Sterilization does not change the appearance of the waste; this poses a problem in gaining acceptance of the waste for land filling. (Cheremisinoff et al., 1990).The Ecodas technology uses steam sterilization and has a shredder to treat the medical waste prior to the treatment of heat and pressure. It ensures smaller waste volume and transportation to the landfill.
7. CONCLUSION ECODAS technology using steam sterilization is found to be an effective mechanism to treat and decontaminate medical waste. Steam sterilization is effective in killing the potential microorganism at the high temperature of 138 C, 3.8 bar, with an exposure time of 10 minutes. In summary, the process of the ECODAS invention provides a highly reliable and safe method for treatment of potentially infectious medical waste. The product of the operation is a residue that can be accepted in regular landfill disposal sites. The waste residue is significantly reduced in volume up to 80%, unrecognizable as medical waste. Such medical waste is essentially free of "sharps", and poses no chemical or microbiological hazard to the waste sites or the operators. The process further renders all equipment surfaces which are exposed to infectious matter completely sterile since the machinery and equipment cannot be opened and accessed for loading, unloading or maintenance until after the completion of the sterilization process. 8. RECOMMENDATION The ECODAS sterilization system can be recommended as a method for treating medical waste. However, there is a concern on the use of ECODAS system which should be assessed and certified by our local environmental safety agency. This ECODAS system also needs to be certified by the necessary agency on the safety aspects, with regards to its high temperature, pressure and trained authorized person whom should be certified to handle this kind of equipment.
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