252
J. R. S. Selvan Christyraj et al.
10.5 Biomedical Waste Treatment
10.5.1 Conventional Methods
The main objective of BMW management was to either minimize or to totally eradicate the hazardous waste with better treatment method. Various conventional waste
treatment methods are existing to decontaminate or destroy or disinfect the infectious bio-wastes such as autoclaves, pyrolysis, incineration, landfills, chemical disinfectants, plasma pyrolysis, microwave irradiation and gasification methods. This
section explains in detail about the role of autoclaves, dry heat (pyrolysis), chemicals
disinfectants and landfills in the BMW management process.
Autoclaves
Autoclave is a heat treatment process which is more similar to the working of standard pressure cooker. Autoclaves are operated at high temperatures of about 121
°C for 60–90 min and under steam pressure of 15 psi. At higher temperatures, the
steam produced inside the system interacts with the waste materials and destroys the
microorganisms. Three types of autoclaves are commercially available viz., Gravity
type, Pre-vacuum type and Retort type [31]. In Gravity type, air is evacuated with the
influence of gravity alone. In pre-vacuum type, vacuum pumps are used to remove
air with the reduced time cycle (30–60 min) at 132 °C. Retort type autoclaves are
manufactured to achieve much higher steam temperature and pressure to destroy
the infectants. Categories like waste sharps, soiled, solid wastes, microbiology and
biotechnology waste can be effectively treated with autoclave treatment method.
Dry heat (Pyrolysis)
Pyrolysis is a treatment process for bio-waste decomposition with heat in an oxygen
deficient atmosphere. Before dry heating the bio-wastes, metallic components have to
be segregated as metals cannot be decomposed at that temperature. During heating
process, there is emission of gases like (methane, ethane, hydrogen, and carbon
monoxide); liquids (oil and tar); and solids (char and carbon black). The gases can
be stored or purified and used as fuel for other purposes to heat the radiant tubes.
The solid residues left over after heating process was landfilled.
Chemical Disinfection
Disinfection is one of the best methods to reduce the pathogenic organisms which
are involved in the transmission of infectious diseases. The cleaning and disinfection protocols can be performed in many approaches such as simple surface
cleaning, sterilization, usage of chemical disinfectants like antiseptics, biocides and
sanitizers. Plentiful chemical agents are available to disinfect healthcare facilities.
Generally, liquid-based chemical disinfectants are classified into nine wide categories
as acids, alcohols, alkalis, halogens (hypochlorites and iodine-based iodophors)
aldehydes, biguanides, phenolics, oxidizing agents, and quaternary ammonium
J. R. S. Selvan Christyraj et al.
10.5 Biomedical Waste Treatment
10.5.1 Conventional Methods
The main objective of BMW management was to either minimize or to totally eradicate the hazardous waste with better treatment method. Various conventional waste
treatment methods are existing to decontaminate or destroy or disinfect the infectious bio-wastes such as autoclaves, pyrolysis, incineration, landfills, chemical disinfectants, plasma pyrolysis, microwave irradiation and gasification methods. This
section explains in detail about the role of autoclaves, dry heat (pyrolysis), chemicals
disinfectants and landfills in the BMW management process.
Autoclaves
Autoclave is a heat treatment process which is more similar to the working of standard pressure cooker. Autoclaves are operated at high temperatures of about 121
°C for 60–90 min and under steam pressure of 15 psi. At higher temperatures, the
steam produced inside the system interacts with the waste materials and destroys the
microorganisms. Three types of autoclaves are commercially available viz., Gravity
type, Pre-vacuum type and Retort type [31]. In Gravity type, air is evacuated with the
influence of gravity alone. In pre-vacuum type, vacuum pumps are used to remove
air with the reduced time cycle (30–60 min) at 132 °C. Retort type autoclaves are
manufactured to achieve much higher steam temperature and pressure to destroy
the infectants. Categories like waste sharps, soiled, solid wastes, microbiology and
biotechnology waste can be effectively treated with autoclave treatment method.
Dry heat (Pyrolysis)
Pyrolysis is a treatment process for bio-waste decomposition with heat in an oxygen
deficient atmosphere. Before dry heating the bio-wastes, metallic components have to
be segregated as metals cannot be decomposed at that temperature. During heating
process, there is emission of gases like (methane, ethane, hydrogen, and carbon
monoxide); liquids (oil and tar); and solids (char and carbon black). The gases can
be stored or purified and used as fuel for other purposes to heat the radiant tubes.
The solid residues left over after heating process was landfilled.
Chemical Disinfection
Disinfection is one of the best methods to reduce the pathogenic organisms which
are involved in the transmission of infectious diseases. The cleaning and disinfection protocols can be performed in many approaches such as simple surface
cleaning, sterilization, usage of chemical disinfectants like antiseptics, biocides and
sanitizers. Plentiful chemical agents are available to disinfect healthcare facilities.
Generally, liquid-based chemical disinfectants are classified into nine wide categories
as acids, alcohols, alkalis, halogens (hypochlorites and iodine-based iodophors)
aldehydes, biguanides, phenolics, oxidizing agents, and quaternary ammonium