Key process for treatment of hazardous and medical waste is incineration. To destroy the pathogen and toxic components from medical waste different types of incinerators are used.

In this blog you will know about different types of incinerators. As we know, incineration is one of the most widely used techniques for waste treatment. Different types of incinerators are used across the globe depending on availability and need. An incinerator is a large furnace for burning waste. Waste treatment efficiently reduces the volume of waste and its infectious hazards. It also prevents scavenging along with health and environmental hazards.

The first incinerator for waste disposal was built in Nottingham, U.K. in 1874. By Manlove , Alliott & Co. Ltd. and design is patented by Alfred Fryer. Previously they were called destructors. Incineration plants are also known as waste-to-energy facilities. Incineration and other high temperature treatment of waste is defined as “thermal treatment”. 

Incineration is a high temperature, dry oxidation process. It reduces organic and combustible waste to inorganic, incombustible matter. The process is used to treat those waste that cannot be recycled, reused, or disposed of in a landfill site. In this blog I will cover the types of incinerators and their dust removal..

Incinerators in India

Incinerators in India
Incinerators in India

Source: Downtoearth.com

According to a report following details were found on incineration plants in India. There are 5 working incineration plants in India. It has a cumulative installed capacity of 66.5 MSW and is currently operational/under trial run in the country.

S.No.StateName of city/townCapacity (MW)
1MaharashtraSolapur3.0
2DelhiOkhla12.0
3DelhiGazipur16.0
4DelhiNarela-Bhawana24.0
5Madhya PradeshJabalpur11.5
Total66.5
Incineration Plants In India

The Ministry of Urban Development (MoUD) has received 53 proposals from 22 states with potential to generate 405.3 MW of electricity under Swachh Bharat Mission (SBM) which are currently under various stages of construction or tendering.

Types of Incinerators

Types Of Incinerators
Types Of Incinerators

There are various types of incinerator plant designs available. They can range from extremely sophisticated, high-temperature operating plants to very basic combustion units that operate at much lower temperatures. Three basic types of incinerator are of interest for healthcare waste treatment. They are:

  • Double-chamber pyrolytic incinerators: which may be especially designed to burn infectious health-care waste
  • Single-chamber furnaces with static grate: which should be used only if pyrolytic incinerators are not affordable
  • Rotary kilns: operating at high temperature, capable of causing decomposition of genotoxic substances and heat-resistant chemicals.

Different types of incineration in detail below.

Burn Pile

Burn to pile: A type of Incineration
Burn to pile: A type of Incineration

It is the simplest and earliest type of waste disposal. They basically refer to a collection of combustible materials piled on an open ground and set on fire. Due to combustion it results in reduction of volume and mass of wastes. But this type of incineration has high pollution risks. Burn piles often result in incomplete combustion therefore produce particulate pollution.These can and have a high risk of uncontrolled fire spreading. 

Pyrolytic Chamber Incinerator

This is also known as controlled air incineration or double-chamber incineration. It is the most reliable and commonly used treatment process for health-care waste. Pyrolytic incinerator has a pyrolytic chamber and a post combustion chamber. The pyrolytic chamber consists of a fuel burner that is used to start the process. 

Pyrolytic incinerator: A type of incinerator
Pyrolytic incinerator: A type of incinerator

In pyrolytic chamber waste is decomposed through oxygen deficient, medium temperature (800– 900°C), combustion process. That produces solid ashes and gases; which if treated properly can be disposed into landfill.     

Adequate waste type:

  • Infectious waste, sharps and pathological waste

 —  for efficient treatment and elimination of all pathogens.

  • Pharmaceutical and chemical residues

— causes disintegration of most residues however, only small amounts (e.g. 5% of total waste load) of these wastes should be incinerated in this process. 

Inadequate Waste Type:

  • Non-risk healthcare waste;would waste the resource.
  • Genotoxic waste; treatment probably would not be efficient.
  • Radioactive waste; treatment does not affect radioactive properties and may disperse radiation.
    Pyrolytic incinerator: A type of incinerator
    Pyrolytic incinerator: A type of incinerator

Waste that should not Incinerated through this Technique

  • Pressurized containers; may explode during incineration and cause damage to the equipment.
  • Halogenated plastics such as PVC; exhaust gases may contain hydrochloric acids and dioxins.
  • Wastes with high heavy-metal content; incineration will cause emission of toxic metals (e.g. lead, cadmium, mercury) into the atmosphere.

Capacity of the incinerator ranges from 200kg/day to 10 tonnes/day. Capacity of the hospital incinerator is basically less than 1 ton/day. 

Standard Protocols for Operating Pyrolytic Incinerator:

  • It should be operated and monitored by a well trained technician. This will reduce maintenance costs and extend the life expectancy of the equipment. 
  • Careful operational balance needs to be maintained between the two combustion chambers to maximize treatment efficiency and minimize the environmental impact of emission.
  • Cleaning of the combustion chambers, declogging of air inflows and fuel burners should be done periodically. 
  • Operators in charge of loading waste and removing ashes should wear protective gears. 

Rotary Kilns 

A rotary kiln comprises  a rotating oven and a post-combustion chamber. They are inclined at a slight angle vertically on its axis.It rotates 2 to 5 times per minute and is charged with waste at the top. Incineration temperature is 1200–1600°C, allowing decomposition of very persistent chemicals such as PCBs. Ashes are moved out at the bottom end of the kiln. Produced gases in the kiln are heated to a high temperature to burn off gaseous organic compounds in the post-combustion chamber. 

Rotary kilns: A type of incinerator
Rotary kilns: A type of incinerator

Adequate Waste Type:  

  • Infectious waste, sharps.
  • Pathological waste.
  • All chemical and pharmaceutical wastes, including cytotoxic waste. 

Inadequate Waste Type:

  • Non-risk health-care waste; would waste the resource.
  • Radioactive waste; treatment does not affect radioactive properties and may disperse radiation.

Waste that should not be Incinerated through this Technique:

  • Pressurized containers; may explode and cause damage to the equipment.
  • Wastes with high heavy-metal content; causes emission of toxic metals (e.g. lead, cadmium, mercury) into the atmosphere. 

Capacity of incineration ranges from 0.5 to 3 tonnes/hour. The incineration of chemical waste produces exhaust gases and ashes that may be loaded with toxic chemicals. So, ash treatment and exhaust gas treatment is required. It has a high consumption of energy. Equipment and operation is costly so a highly trained professional is required. 

Single Chamber Incinerator  

If pyrolytic incinerators are not affordable, single chamber incinerators are used. Healthcare waste at those sites is incinerated in a static grate, single chamber incinerator. It treats waste in batches. Incineration temperature ranges from 300–400°C. Operations like loading and de-ashing are performed manually. Air inflow is based on natural ventilation, sometimes maintained mechanically depending on the conditions.If incinerator is properly operated pathogens are annihilated. Ashes can consist of more than 3% of unburnt matter. It can be disposed of in landfill. 

 Single chamber incinerator: A type of incinerator
Single chamber incinerator: A type of incinerator

Adequate Waste Type: 

  • Infectious waste, sharps
  • Pathological waste
  • General health-care waste (similar to domestic refuse)

Inadequate Waste Type:

  • Pharmaceutical and chemical residues; may exhaust gases mixed with toxins. Therefore, these wastes are less recommended for safety reasons. 
  • Genotoxic waste;treatment by this means is not efficient.
  • Radioactive waste has no effect on radioactive properties and may actually cause dispersal of radioactivity.
  • Inorganic compounds.
  • Thermally resistant waste.

Waste that should not be Incinerated through this Technique:

  • Pressurized containers; may explode and cause damage to the equipment.
  • Wastes with high heavy-metal content; causes emission of toxic metals (e.g. lead, cadmium, mercury) into the atmosphere.  

Capacity of incineration ranges from 100–200kg/day. This type of incinerator should not be set up because air pollution is already a major problem. Soots and slags should be removed regularly. Emissions usually include acid gases such as sulfur dioxide, hydrogen chloride, and hydrogen fluoride, black smoke, fly ash (particulates), carbon monoxide, nitrogen oxide, heavy metals, and volatile organic chemicals. To limit these emissions, the incinerator should be properly operated and carefully maintained.

Drum Incinerator and Brick Incinerator 

Drum incinerator: A type of incinerator
Drum incinerator: A type of incinerator

It’s the simplest type of single chamber incinerator. It is only used as a last resort to incinerate the waste as it causes air pollution. It is only appropriate in emergency conditions as during acute outbreaks of communicable diseases. Drum incinerators should be designed with proper airflow and ample fuel quantities. A 210-litre (55 US gallon) steel gallon can be used with both ends removed. It will allow one bag of waste each time.  

It can cause public nuisance, generating acrid odors and fumes that make eyes burn and water.

Fluidized bed

In this type of incinerator, a strong airflow is forced along the sandbed. Air penetrates through sand to a point where it separates sand particles. The airflow starts in mixing and churning, it makes a fluidized bed. Then fuel and waste can be introduced. The sand particles with pre-treated waste are suspended in air via airflow. Which takes fluid like character.

Therefore, the bed is violently mixed and ruffled, which keeps small particles in air. This method allows mass of waste, fuel and sand particles to fully course in the furnace. 

Specialized incinerators   

An example is furniture factory sawdust incinerators. They need much attention as they have to handle many flammable materials and saw sin dust. Controlled burning, back burn prevention systems are crucial. As the dust can easily catch fire under the influence of LPG.

Conclusion

There are many types of incinerators available. They can greatly reduce the weight and volume of healthcare and municipal waste. They are the most primitive and effective waste handling technique. But as the saying goes “every coin has two faces; one good and one bad”. Incineration also has good as well as bad effects on us and our environment.

The most concerning issue regarding incinerators is emission of harmful gases in the atmosphere. Which leads to increase in air pollution, air borne diseases, cancer, skin problem, mist, etc. Fixing appropriate air filters, chimneys can reduce this problem.

Depletion of nature
Depletion of nature

Using the correct type of incinerator with appropriate technology is advisable. Waste management is very important right now. So, be a responsible and aware human of our planet. And let’s take a step toward a clean and safe future. If you want to say something about this subject please let me know in the comments. I would love to hear from you. Please subscribe to us for more informational blogs. 

Let's protect our earth together
Let’s protect our earth together
andleep zahra
Author

She is a biotechnologist and received her master degree in biotechnology from V.B.S. Purvanchal University. Being a biotechnologist she loves to do research and write articles on the same. She’s best known for writing articles and blogs on environmental issues. Through her writings she likes to provide more information on environmental conservation and provide knowledge on how to address the issue, mainly focused on waste management. She looks for ways to get involved and also attended several conferences, workshops and webinars. “Increasing waste around the globe that is affecting our ecosystem and reducing our biodiversity is the most critical issue we humans often overlook and it will be the greatest challenge our younger generation will ever face,” she says.

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