Microwaves for disinfection of biomedical waste
Microwaves are a form of non-ionizing electromagnetic waves which falls in the wavelength range of 0.3 and 300 GHz (i.e., with wavelengths from 1 meter to 1millimetre, respectively).[1] Microwaves are reflected, transmitted or absorbed by materials in their path, in a similar manner to light. Metallic materials totally reflect microwaves while non-metallic materials such as glass and some plastics are mostly transparent to microwaves.[2] The energy of Microwaves is sufficient to cause vibrations in atoms of a molecules but they cannot ionize hence they are called non-ionizing radiations. In daily life we are exposed to microwaves through mobile phones, RADAR, Wifi and Bluetooth, etc. [3]
Biomedical waste is waste containing infectious (or potentially infectious) materials and is generated by Healthcare or Biomedical Research facilities. Biomedical waste includes diagnostic samples, used syringes, dressings, body parts, pharmaceuticals, cultures containing microbes, blood samples, chemicals, etc which are potentially infectious. Thus these wastes are needed to be properly managed with primary treatment at point of generation only and subsequently its terminal disposal.[4]
Biomedical waste management: Biomedical waste generated by healthcare units needs to be managed with utmost caution as improper management can lead to health risks for patients, healthcare staff, society and environment. As per WHO report, in 2000, contaminated syringes caused 21 million hepatitis B virus (HBV) infections (32% of all new infections), two million hepatitis C virus (HCV) infections (40% of all new infections) and 260 000 HIV infections (5% of all new infections).[5] For proper management of the wastes generated at healthcare facilities, the government in India has changed it norms making pretreatment of the generated waste mandatory to reduce HAI likelihoods either in hospital facilities or during the transportation of the waste to incineration units.[6]
For Pretreatment the government has authorized autoclave, chemical disinfectants and microwaving as methods for disinfection before the terminal disposal of the waste at secondary care plants
Microwave based disinfection system[edit]
Microwave irradiation is possibly one of the most powerful techniques for non-contact heating. Microwave chemistry is based on the efficient heating of materials by microwave dielectric heating effects. Substances such as water possess a dipole moment which generates heat when irradiated with microwaves. When exposed to microwave frequencies, the dipoles of the water align with the applied electric field. As the field oscillates, the dipoles attempts to realign itself with the alternating electric field and in this process, energy is lost in the form of heat through molecular friction and dielectric loss. This generated heat results into rise in temperature inside cells of microbes which eventually bursts upon exposure to microwaves as 70% of the cellular composition is water.
A microwave based disinfection system is potentially best suited for biomedical waste disinfection due to the following properties:
- As microbial cells contain at least 70% water, they effectively absorb microwaves and are instantly killed because of thermal and non-thermal effects of microwaves.
- Microwaves penetrate through most of the materials. This property of microwave is utilized worldwide for communication network. Since, biomedical waste mainly consists of plastics, which are bad conductors of heat, hence, convective or conductive heating mechanisms take lot of time to kill microbes, confined within these materials. However, microwaves are totally permeable to plastics. Thus, Microwaves are most suited method for disinfection of thermally nonconductive materials such as plastic, textile, fibre etc.
- Materials which absorb microwaves are heated uniformly producing volumetric heating effects. This property makes the microwaves more suitable for disinfection purposes as compared to convective or conductive heating methods.
References[edit]
- ↑ Tang J (2015) Unlocking Potentials of Microwaves for Food Safety and Quality. J Food Sci 80: 5.
- ↑ "WHO - Electromagnetic fields & public health: Microwave ovens". WHO.
- ↑ Zhi WJ, Wang LF and Hu XJ (2017) Recent advances in the effects of microwave radiation on brains. Mil Med Res 2017; 4: 29.
- ↑ "08.0 Biohazardous Waste". extranet.fhcrc.org.
- ↑ Pruthvish S (2015) Health Care Waste Management: Are we Serious? J Clin Biomed Sci 2015; 5(2):50-51.
- ↑ http://www.moef.gov.in/sites/default/files/BMW%20Rules%2C%202016_0.pdf
Microwaves for Disinfection of Bio-Medical waste[edit]
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