Plasma Waste Treatment Process

Plasma pyrolysis

Pyrolysis

Pyrolysis is a thermochemical decomposition of organic material at elevated temperatures without the participation of oxygen. It involves the simultaneous change of chemical composition and physical phase, and is irreversible...

 is used to safely treat various types of waste

Waste

Waste is unwanted or useless materials. In biology, waste is any of the many unwanted substances or toxins that are expelled from living organisms, metabolic waste; such as urea, sweat or feces. Litter is waste which has been disposed of improperly...

, either in a furnace or in a reactor. This process allows for full decomposition and disintegration of organic components

Organic matter

Organic matter is matter that has come from a once-living organism; is capable of decay, or the product of decay; or is composed of organic compounds...

. The main element of plasma technology is a plasma arc torch. A plasma torch

Plasma torch

A plasma torch is a device for generating a directed flow of plasma. The plasma jet can be used for applications including plasma cutting, plasma spraying, and plasma arc waste disposal....

 uses gas or steam and metal electrodes (copper, tungsten, hafnium, zirconium, etc.) to create plasma, which is an ionized gas

Plasma (physics)

In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...

. The temperature of the plasma torch can be in the range 4 000 - 20 000° F; at these temperatures molecular bonds

Covalent bond

A covalent bond is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding....

 break down through a process called molecular dissociation, to create basic elements of materials – atoms. Molecular dissociation using plasma is called plasma pyrolysis.

The process allows the reception of pure high-calorific synthesis gas (CO, H₂, CH, etc.). The same temperatures are capable of melting various non-flammable

Flammability

Flammability is defined as how easily something will burn or ignite, causing fire or combustion. The degree of difficulty required to cause the combustion of a substance is quantified through fire testing. Internationally, a variety of test protocols exist to quantify flammability...

 inorganic components.

Properly picked up temperature of plasma reaction and structure plasma of forming gas allow to achieve the minimal content ballast products of oxidation (CO₂, N, H₂O, etc.) and high calorific capacity of syngas

Syngas

Syngas is the name given to a gas mixture that contains varying amounts of carbon monoxide and hydrogen. Examples of production methods include steam reforming of natural gas or liquid hydrocarbons to produce hydrogen, the gasification of coal, biomass, and in some types of waste-to-energy...

. As a result, its energy could fully be used for electricity production.

High temperatures in a furnace and in a reactor provide fusion of non-flammable inorganic components and their transformation to slag

Slag

Slag is a partially vitreous by-product of smelting ore to separate the metal fraction from the unwanted fraction. It can usually be considered to be a mixture of metal oxides and silicon dioxide. However, slags can contain metal sulfides and metal atoms in the elemental form...

 and metals. The metals obtained through plasma pyrolysis can be used as commodity products in various applications.

Plasma processing

Plasma processing

Plasma processing is a plasma-based material processing technology that aims at modifying the chemical and physical properties of a surface.Plasma processing techniques include:*Plasma activation*Plasma etching*Plasma modification*Plasma functionalization...

 of waste is an ecologically clean process. The lack of oxygen and high temperature in a reactor prevent the main elements of gas from forming toxic compounds, such as furans, dioxins, NO_X, or sulfur dioxide

Sulfur dioxide

Sulfur dioxide is the chemical compound with the formula . It is released by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide unless the sulfur compounds are removed before burning the fuel...

. Extensive filtration removes inorganic residue (ash) and gaseous pollutants (NO, HCl, H₂S, etc) and allows the production of ecologically clean synthetic gas. The gaseous compounds do not contain any phenols or complex hydrocarbons. The circulating water in these filtering systems has removed the hazardous substances and must be cleaned.

Synthetic gas it is used basically for reception of electric energy. Gaseous pollutants are converted to valuable chemical products. Inert slag could be granulated and subsequently used in construction. Metal could be used for production of alloys, etc.

Advantages of plasma technologies for waste treatment

• Clean destruction of Hazardous Waste streams
• Prevents Hazardous Waste from reaching landfills
• Environmentally-friendly
• No harmful emissions or toxic waste
  Toxic waste
  Toxic waste is waste material that can cause death or injury to living creatures. It spreads quite easily and can contaminate lakes and rivers. The term is often used interchangeably with “hazardous waste”, or discarded material that can pose a long-term risk to health or environment.Toxic waste...
  
  
• Production of clean alloyed slag which could be used as construction material
• Processing of organic waste
  Biodegradable waste
  Biodegradable waste is a type of waste, typically originating from plant or animal sources, which may be degraded by other living organisms. Waste that cannot be broken down by other living organisms are called non-biodegradable....
  
   allows production of combustible syn-gas which can be used in various applications

The pure synthetic gas can be simply submitted into the natural gas pipeline system.

• Electric and thermal energy
  Thermal energy
  Thermal energy is the part of the total internal energy of a thermodynamic system or sample of matter that results in the system's temperature....
  
   generation
• Production of value-added
  Value added
  In economics, the difference between the sale price and the production cost of a product is the value added per unit. Summing value added per unit over all units sold is total value added. Total value added is equivalent to Revenue less Outside Purchases...
  
  products

Disadvantages of plasma technologies for waste treatment

• Waste gasification and combustion ultimately releases carbon dioxide to the atmosphere instead of sequestering a large fraction of the carbon in a landfill
• Large capital costs relative to current landfills
• Requires large electrical energy input if the waste stream does not contains a large fraction of unoxidized hydrocarbons
• The highly corrosive plasma flame may lead to frequent maintenance and component replacement with associated facility down time
• The filters and gas treatment systems are themselves sources of toxic waste, some of which (e.g. acidified water) are poor candidates for plasma processing