Plastic and biomedical waste disposal is a serious concern in India. Plastic waste has a huge adverse impact on us and the environment as well. The development of various new technologies are running continuously to minimize their adverse effects. Incineration is the current most accepted technology for plastic and biomedical waste treatment. However, due to some shortcomings, it is strongly opposed by various organizations.
“Plastic is the most destructive weapon than a nuclear bomb or an atom bomb, its impact shall remain for centuries on the future generation”
-Sir P.S. Jagadeesh Kumar
In India, FCIPT, Institute for Plasma Research develops a safer and cleaner technology i.e. plasma pyrolysis. Plasma pyrolysis is recommended to treat plastic waste because:-
- Plastic has high calorific value.
- Surplus energy recovery is possible from the system.
As plasma pyrolysis is currently a new ray of hope for us for plastic and bio-medical waste treatment. As energy recovery is possible, it is also economically viable. In this blog, I’ll tell you about plasma pyrolysis, Its treatment process, and the advantages and disadvantages of plasma pyrolysis.
First of all, I would like to mention the main components of the technology i.e. plasma and pyrolysis. So, buckle up sweeties and let’s get started.
Plasma And Pyrolysis
Plasma is the fourth state of matter after solid, liquid, gas. Plasma’s core temperature is 20,000°K. These are used in this technology for bond dissociation.
Pyrolysis is the thermal decomposition of organic materials at an upraised temperature in the absence of oxygen. The word is derived from the Greek language, “pyro” means fire and “lysis” means separation.
Now, let’s take a look at the technology.
What is Plasma Pyrolysis
During the early 1990’s, plasma pyrolysis emerged which destroys plastic, medical, and other hazardous waste safely. Plasma pyrolysis is an extreme thermal process for the disintegration of organic compounds into gasses and unreachable solid residue. It is done in an oxygen starved condition. Organic compounds are degraded into syngas.
Plasma torches powered by electric arcs are used for the ionization of gas which catalyzes organic matter to syngas and slug. Commercial use of this technique as a waste treatment technology is tested on many compounds like:
- Medical waste
- Industrial waste
- Refuse-derived waste
- Plastic waste
- Hazardous waste
- Solid hydrocarbons such as coal, oil sand, oil shale, pet coke, etc.
Plasma Pyrolysis of Plastic and Bio-medical waste
Plasma torch and electric supply are responsible for making hot plasmas. Small plasma torches have inert gasses like argon, while large torches use nitrogen. Non-transferred types of arc are selected for organic waste treatment. Graphite plasma torches are used for plastic treatment.
Plasma torches have three graphite electrodes i.e. one anode and two cathodes. Electrodes are connected with the power supply. Torches convert electrical energy into heat energy. Range of torch temperature is 2,000 to 14,000 °C (3,600 to 25,200 °F). Temperature is responsible for plasma structure and forming gas.
In the primary chamber, pyrolysis takes place at a high temperature.The temperature of the primary chamber is >1000ºC near the pyrolysis zone and >650ºC close to the chamber wall. After preheating, waste is decomposed into an inert atmosphere (no oxygen). Gases like methane, carbon monoxide, hydrogen, are produced.
In the secondary chamber, one electrically operated igniter is mounted. It is to ignite the combustible gases coming from the primary chamber. The combustion of gases increases the temperature upto 800-1000°C. The product gas formed after the reaction is mainly carbon dioxide and water. These gases are released into the atmosphere by an induced draft fan.
Advantages and Disadvantages of Plasma Pyrolysis
There are more pros than cons of this technology. Some of them I’m mentioning below.
Advantages of Plasma Pyrolysis
The main advantage of this technology are:-
- It prevents hazardous waste from reaching landfills.
- It has no harmful emission of toxic gases.
- Firm slag produced by the process can be used in construction.
- Combustible syngas from biomass can be used to generate electric and thermal energy.
- Slag produces value-added products like concentrated metals.
- Hazardous, medical, plastic and many other types of waste are destroyed safely.
- Can be installed at any tourist or hilly locations in the country.
- Emission of non-toxic gasses.
- Harmful gases like dioxins and furans are not formed.
- Eco-friendly and safe way for waste treatment.
- Have no harmful effect on the environment, except carbon dioxide emission.
- Better alternative against incineration.
- Plays an important role in waste minimization.
Disadvantages of Plasma Pyrolysis
The main disadvantage of this technology are:-
- Large initial investment, as compared to present alternatives like incineration and landfills.
- High operation cost, compared to incinerators.
- Net energy production is very little or very low. Progressive developments are being run to gain energy recovery.
- Limited plants are available across the country.
- Frequent maintenance is required to ensure proper functioning.
- Wet feedstock should be avoided, as it produces less syngas and takes more energy.
Plasma pyrolysis is one of the leading waste treatment technologies. It destroys waste in a safe and eco-friendly manner. This technique has major pros over incineration. And waste minimization being a great concern this technology has the upper hand. It resolves the problems associated with non-recyclable and low grade plastic waste.
Energy recovery development is also being developed that can make these reactors energy efficient. This technology is of considerable significance in the Indian context. To resolve the associated problems with waste treatment especially in case of non-recyclable multilayer and disinfected medical plastic waste. We should choose wisely to protect ourselves and our planet.
It is one world. And it’s in our care. For the first time in the history of humanity, for the first time in 500 million years, one species has the future in the palm of its hands.”
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