Application of microwaves in health care solid waste disinfection

This thesis intensively investigates the management of solid health care waste (HCW) and technologies available for collection at the generation point, segregation, transportation, storage and disposal. Many national and international environmental and health agencies have revealed their concerns towards these wastes as they may cause serious infectious diseases such as hepatitis, tuberculosis and HIV / AIDS. In addition, it would appear that most of the health care facilities and hospitals do not have adequate management and disposal technology systems which consequently leads to health and environmental problems of hygiene and sanitation in and out of hospital. Accordingly, the focus point of this thesis is to enhance the performance of the HCW management system, to achieve a high level of cleanliness and to protect humans and the environment from infection generated from HCW. This point arises from the need for appropriate management of that contains disease causing agents. Effective HCW management and disposal can be performed only by considering various components of the waste management system which are comprehensively investigated in this research. This study was conducted in two leading government hospitals in Kuala Lumpur, Malaysia, namely Serdang Hospital and Ampang Hospital. The study was initiated by site visits to the two general hospitals in order to investigate the HCW management components, the amount of the waste, the required cost, and the handling and transportation stages. Then, the disposal technology used to destroy the waste was examined and compared with various treatment technologies as the treatment and disposal of HCW are complementary stages to protect the environment. The results of site visits provided a wealth of data and were very useful to obtain real and practical findings in order to make a decision using information that is as accurate as possible. Based on the results obtained, the HCW management systems in these hospitals, the data collected on the amount of generated waste, and the required cost for managing the systems have been covered and estimated. Due to the bed occupancy rates which are influenced by the geographical location of the hospitals, the figures are higher in Serdang than in the Ampang hospital, and the monthly averages of the HCW generated and the associated management cost are higher for Serdang than for Ampang hospital. The current study then proceeds to propose microwave technology to be used as a disinfection technology in addition to assistance by shredding the artificial HCW before applying microwave radiation. To evaluate the efficacy of microwave disinfection technique, artificial HCW was inoculated with the most common disease causing bacteria in HCW, namely, Staphylococcus aureus (S. aureus) and Escherichia coli O157:H7(E. coliO157:H7). The assessment of the ability of microwave radiation to kill the selected bacteria was conducted by counting the bacterial cells before and after treatment with respect to the microwave radiation power and the time duration of the process. The most striking observation to emerge from the bioengineering work is that the bacteria reduced from five million cells per 500 gram of artificial HCW to non-viable bacteria after just 2.5 minutes of treatment with 700 W of microwave power for both species of bacteria. The findings show the influencing factor for killing the investigated bacteria is the microwave radiation; not temperature as bacteria are killed at the best range of temperature for growth. With this completed, the best solution has been selected to provide the highest confidence in the on-site HCW treatment in order to eliminate cross contamination, and by opting for microwave treatment technology to disinfect HCW on-site and at the point it is generated. By employing the conditions determined in this current study (700 W radiation and 2.5 minutes) which leads to complete bacterial reduction, if implemented, then the scientific result presented in this work can be used as a foundation study to build up an on-site HCW treatment machine by using microwave radiation as the disinfecting technology.

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