Understanding the Four Characteristics of Hazardous Waste

Just because you’ve generated a waste doesn’t mean you’ve generated a hazardous waste. If you know you have a waste, but you’re not completely sure whether your waste is, in fact, hazardous, the first step in making that determination is to check whether it is on one of the EPA’s four hazardous waste lists: F, K, P and U.

Different types of wastes were added to these lists because they are toxic, reactive, ignitable or corrosive (the four hazardous waste “characteristics”). If your waste is listed, it is assumed to have one or more of these hazardous characteristics and, therefore, must be managed as “hazardous waste”; no testing or analysis is required.

F-list (40 CFR 261.31)

Found at many different types of businesses, F-list waste comes from a nonspecific source. Examples of F-list wastes include “spent” halogenated or non-halogenated solvents, spent cyanide plating bath solutions and residues, and petroleum refinery oil/water separation sludge.

Inclusion on the F-list is based on the process and the chemical used to create the waste. For instance, methylene chloride, a chemical that can be used in different ways, is commonly used as a degreaser. Methylene chloride-based degreaser solutions would carry the F001 code. However, if you have methylene chloride that was used for purposes other than for degreasing, it would not carry the F001 code for halogenated solvents used for degreasing. In fact, it might not carry an F-code at all, if you used it as a reagent in a chemical reaction, for example. (Note: Even if your methylene chloride–containing waste is not a listed waste, if must still be evaluated for hazardous waste characteristics, including toxicity.)

F-list (40 CFR 261.32)

K-list waste comes from any of 13 very specific industries or various processes. Examples include wastes from wood preservation (K001), inorganic pigment manufacturing, explosives manufacturing and veterinary pharmaceuticals manufacturing.

P-list (40 CFR 261.33) & U-list (40 CFR 261.33)

Both P- and U-list wastes are off-spec or unused commercial chemical products (CCP). U-list is hazardous waste, and P-list is acutely hazardous waste. These lists contain discarded commercial chemical products, where the listed material is the sole active component. As an example, unused/off-spec epinephrine is a P-listed waste (P042), however epinephrine salts (as found in many medical epinephrine injectors) would not carry the P-042 code. Federal P and U codes do not apply to mixtures with other components, but they do apply to soil or debris contaminated with U- or P-listed materials.

Also, some states, including California, have state-specific lists of “extremely hazardous substances,” in addition to the EPA list. An example of a P-list waste is unused/off-spec epinephrine (P042).

The amount of P-coded waste you produce can have an effect on your generator status. We’ll discuss generator status — large-quantity generator, small-quantity generator or very-small-quantity generator — in a later post, but generating as little as 1 kilogram of P-list waste in one month is enough to move you from a small-quantity generator to a large-quantity generator.

The mixture rule for listed wastes

Mixtures of listed wastes and non-hazardous solid wastes carry a presumption of “hazardousness,” which means they are considered hazardous wastes regardless of concentration. In other words, even if a small amount of listed waste is mixed with a large amount of non-hazardous waste, the whole mixture will carry the waste codes from the listed waste. This very conservative rule was adopted by the EPA to ensure unscrupulous generators did not “dilute” their hazardous wastes with other materials.

There are limited exceptions to the mixture rule for wastes that were listed due to ignitability, corrosivity or reactivity. In those cases, if the mixture is no longer ignitable, corrosive or reactive (as defined in hazardous waste regulations), then the waste is no longer considered hazardous. For example, if a spent solvent carrying EPA waste code F003 (listed due to potential ignitability) is mixed with non-flammable materials, so that the flash point is greater than 140 degrees F, it would no longer be considered “ignitable.” Since F003 is listed only due to potential ignitability, that code would no longer apply, though the waste may still exhibit other hazardous waste characteristics.

This may seem like a loophole, but unless it is an inherent part of the process that generates the waste, then mixing hazardous waste with other materials to remove or change hazardous characteristics is considered “treatment” and requires a permit from hazardous waste regulators. This exception does not apply to wastes listed due to toxicity, as there is really no way to “mix” out or dilute toxicity. Waste listed due to toxicity that are mixed with non-toxic materials will still be considered toxic and carry a toxicity code.

Remember: Even if your waste is not listed, you’re not off the hook. The next step is to check if it has any of the four EPA characteristics of hazardous waste.

ACTenviro has experts available to help you with your waste at each step along the way, from determining what you have to proper disposal. Please reach out to us at [email protected], and let us know how we can help.

James Kapin is Principal Advisor for safety, health and environmental compliance for ACTenviro.  Jim is a Certified Industrial Hygienist (CIH) and a Certified Safety Professional (CSP) with over 25 years of workplace safety and environmental protection experience.   Do you have any hazardous waste questions for Jim?  Or any other workplace safety or environmental compliance questions?  Let us know at [email protected]

How to Use the Four Lists for Hazardous Waste

Just because you’ve generated a waste doesn’t mean you’ve generated a hazardous waste. If you know you have a waste, but you’re not completely sure whether your waste is, in fact, hazardous, the first step in making that determination is to check whether it is on one of the EPA’s four hazardous waste lists: F, K, P and U.

Different types of wastes were added to these lists because they are toxic, reactive, ignitable or corrosive (the four hazardous waste “characteristics”). If your waste is listed, it is assumed to have one or more of these hazardous characteristics and, therefore, must be managed as “hazardous waste”; no testing or analysis is required.

F-list (40 CFR 261.31)

Found at many different types of businesses, F-list waste comes from a nonspecific source. Examples of F-list wastes include “spent” halogenated or non-halogenated solvents, spent cyanide plating bath solutions and residues, and petroleum refinery oil/water separation sludge.

Inclusion on the F-list is based on the process and the chemical used to create the waste. For instance, methylene chloride, a chemical that can be used in different ways, is commonly used as a degreaser. Methylene chloride-based degreaser solutions would carry the F001 code. However, if you have methylene chloride that was used for purposes other than for degreasing, it would not carry the F001 code for halogenated solvents used for degreasing. In fact, it might not carry an F-code at all, if you used it as a reagent in a chemical reaction, for example. (Note: Even if your methylene chloride–containing waste is not a listed waste, if must still be evaluated for hazardous waste characteristics, including toxicity.)

F-list (40 CFR 261.32)

K-list waste comes from any of 13 very specific industries or various processes. Examples include wastes from wood preservation (K001), inorganic pigment manufacturing, explosives manufacturing and veterinary pharmaceuticals manufacturing.

P-list (40 CFR 261.33) & U-list (40 CFR 261.33)

Both P- and U-list wastes are off-spec or unused commercial chemical products (CCP). U-list is hazardous waste, and P-list is acutely hazardous waste. These lists contain discarded commercial chemical products, where the listed material is the sole active component. As an example, unused/off-spec epinephrine is a P-listed waste (P042), however epinephrine salts (as found in many medical epinephrine injectors) would not carry the P-042 code. Federal P and U codes do not apply to mixtures with other components, but they do apply to soil or debris contaminated with U- or P-listed materials.

Also, some states, including California, have state-specific lists of “extremely hazardous substances,” in addition to the EPA list. An example of a P-list waste is unused/off-spec epinephrine (P042).

The amount of P-coded waste you produce can have an effect on your generator status. We’ll discuss generator status — large-quantity generator, small-quantity generator or very-small-quantity generator — in a later post, but generating as little as 1 kilogram of P-list waste in one month is enough to move you from a small-quantity generator to a large-quantity generator.

The mixture rule for listed wastes

Mixtures of listed wastes and non-hazardous solid wastes carry a presumption of “hazardousness,” which means they are considered hazardous wastes regardless of concentration. In other words, even if a small amount of listed waste is mixed with a large amount of non-hazardous waste, the whole mixture will carry the waste codes from the listed waste. This very conservative rule was adopted by the EPA to ensure unscrupulous generators did not “dilute” their hazardous wastes with other materials.

There are limited exceptions to the mixture rule for wastes that were listed due to ignitability, corrosivity or reactivity. In those cases, if the mixture is no longer ignitable, corrosive or reactive (as defined in hazardous waste regulations), then the waste is no longer considered hazardous. For example, if a spent solvent carrying EPA waste code F003 (listed due to potential ignitability) is mixed with non-flammable materials, so that the flash point is greater than 140 degrees F, it would no longer be considered “ignitable.” Since F003 is listed only due to potential ignitability, that code would no longer apply, though the waste may still exhibit other hazardous waste characteristics.

This may seem like a loophole, but unless it is an inherent part of the process that generates the waste, then mixing hazardous waste with other materials to remove or change hazardous characteristics is considered “treatment” and requires a permit from hazardous waste regulators. This exception does not apply to wastes listed due to toxicity, as there is really no way to “mix” out or dilute toxicity. Waste listed due to toxicity that are mixed with non-toxic materials will still be considered toxic and carry a toxicity code.

Remember: Even if your waste is not listed, you’re not off the hook. The next step is to check if it has any of the four EPA characteristics of hazardous waste.

ACTenviro has experts available to help you with your waste at each step along the way, from determining what you have to proper disposal. Please reach out to us at [email protected], and let us know how we can help.

James Kapin is Principal Advisor for safety, health and environmental compliance for ACTenviro.  Jim is a Certified Industrial Hygienist (CIH) and a Certified Safety Professional (CSP) with over 25 years of workplace safety and environmental protection experience.   Do you have any hazardous waste questions for Jim?  Or any other workplace safety or environmental compliance questions?  Let us know at [email protected]

Three Steps to Identifying Hazardous Waste — And What to Do About It

Hazardous waste regulations in the U.S. are based on the Resource Conservation and Recovery Act (RCRA). Under RCRA, in order to be a “hazardous waste,” something must first be a “waste” (as that term is defined by the regulations), then it must be “hazardous,” based on a specific set of criteria. Some materials are obviously waste and are clearly hazardous — but things are not always that simple. If a material doesn’t satisfy both elements — if it isn’t a waste and if it isn’t hazardous per regulatory definitions — it may be “hazardous,” and it may be a “waste,” but it isn’t regulated as “hazardous waste.”

Here are three steps to help determine whether you are, in fact, dealing with a hazardous waste:

1. Determine if your waste actually is a waste.

Manufacturing, construction, academic, transportation, medical and other enterprises use a wide variety of hazardous materials as part of their business activities. These entities may need to address personal safety, worker health, flammability, corrosivity or other hazards. They also may have to comply with OSHA, DOT or regulatory requirements associated with the use of these materials. However, EPA (and state) hazardous waste requirements won’t apply until the material actually becomes a waste. Something is a waste when it is no longer needed or wanted, and when it’s not suitable for its intended purpose, including materials that are abandoned or are “inherently waste-like.” Materials that are recycled are also considered wastes.

Most of the time, determining whether something is a waste is pretty straightforward, but we’ll talk about some situations where it is not so straightforward in a later post. For now, let’s assume you have a waste, and move on to the next step.

2. See whether your waste is a listed hazardous waste.

Once you have determined that your waste is really a waste (as defined by hazardous waste regulations), the next step is to see if it is a “listed” waste, according to EPA lists. Waste from non-specific sources are included in List F (40 CFR 261.21), wastes from certain specific sources are included in List K (40 CF 261.32), and wastes from certain discarded commercial chemical products are included on the U and P lists (for acutely hazardous materials; found in 40 CFR 261.33). If you find your waste on one of those lists, it is a hazardous waste. 

3. Evaluate whether your waste has federal and/or state characteristics.

Even if your waste is not listed, it may still exhibit hazardous waste “characteristics.” According to the EPA, “A hazardous waste characteristic is a property which, when present in a waste, indicates that the waste poses a sufficient threat to merit regulation as hazardous.” There are four federal hazardous waste characteristics: ignitability, corrosivity, reactivity and toxicity. If your waste exhibits any of these characteristics (based on specific technical definitions), then the waste is a hazardous waste subject to federal regulation. Note that some states have added extra characteristics that are more stringent. For example, California and Washington each have additional toxicity criteria. Wastes that are “hazardous” with respect to a state definition (but not RCRA definitions) are referred to as “non-RCRA” hazardous wastes and must be managed as hazardous within that state. Wastes that are listed or that exhibit characteristics must be managed as hazardous waste.

Once you have determined you have a hazardous waste, based on steps 1–3, you need to manage it appropriately on-site, as required by applicable federal and state hazardous waste management requirements. This includes labeling waste, complying with specific waste accumulation limits, managing waste containers and disposing of the waste properly. All hazardous waste must be transported for disposal by a licensed hazardous waste transportation and disposal partner, who will take it to a permitted hazardous waste treatment, storage or disposal facility (TSDF). Disposal of hazardous waste must be documented on a Uniform Hazardous Waste Manifest.

James Kapin is Principal Advisor for safety, health and environmental compliance for ACTenviro.  Jim is a Certified Industrial Hygienist (CIH) and a Certified Safety Professional (CSP) with over 25 years of workplace safety and environmental protection experience.   Do you have any hazardous waste questions for Jim?  Or any other workplace safety or environmental compliance questions?  Let us know at [email protected]

Medical Waste Disposal Guide

Overview

Medical waste can come from multiple facilities, especially in the health sector. Since it contains harmful and infectious components, it is certainly one of the more challenging types of waste to dispose of. That is why you can use this medical waste disposal guide, to stay on top of medical waste disposal management, and not be hit by HIPAA regulations or lawsuits.

Medical Waste

Before we discuss how to dispose of medical waste properly, let us first define what it is, and the types of medical waste that hospitals, pharmacies, dental clinics, doctor’s offices, etc. dispose of daily. Knowing what medical waste is and how to categorize it accordingly is one of the first few crucial steps to its proper disposal.

What is Medical Waste?

Medical waste is a type of waste produced from the medical or science sector. According to a 2018 study, the US alone produces more than 5.9 million tons of medical waste every year, and that only constitutes the medical waste from hospitals. That does not yet include medical waste produced from dental practices, home care, vets, and pharmacies.

There are various kinds of waste being produced each day. So, how is this segregated? Waste only becomes classified as “medical waste” when it contains or is from at least one of the following:

Types of Medical Waste

Where to Dispose of Medical Waste

Now that you have a clearer picture of what medical waste is, let us now move on to where it should be disposed of.

On-Premises vs Off-Premises

Should medical wastes be taken care of within the health facility itself or should it be dumped off at other facilities? The answer to that question is largely based on what the hospital can afford. Usually, it is only larger hospitals that feature state-of-the-art waste disposal equipment to take care of their medical wastes. That is because it is expensive to buy and maintain all the equipment that a hospital needs to get rid of all its waste properly.

So, for the smaller medical facilities, they typically utilize waste transport services. These services can help them transport their waste to a licensed facility that can properly destroy their waste. Usually, they come in the form of truck services.

Another type of transport service is the Postal Service. Small clinics, hospitals, centers, and nursing homes can safely use mail or boxes to transport their waste to facilities that can permanently get rid of the waste. This is said to be the most affordable way that a smaller health center can manage their medical waste.

However, these cover most of the types of medical waste except one, which are sharps and needles. They require a more delicate approach when it comes to getting rid of them. That is because if handled wrong, they are health risks to not only health workers, but also to the general public. We will talk about that in the next section.

Sharps/Needles Disposal

As stated earlier, disposal of sharps and needles should be handled with utmost care and importance. Since, they can pierce the skin, health workers can accidentally prick themselves from mishandling these “dirty” needles, which can potentially infect them with serious diseases. Aside from medical staff, pretty much anyone who comes in contact with improperly disposed sharps and needles can fall victim to this type of injury. Fair warning is advised when disposing of sharps and needles. 

Here is a guide to the process of correctly disposing of these high-risk medical waste:

Usually, sharps and needles come in a container where you can dispose of used needles. Take note that these containers are puncture-resistant, providing that extra layer of protection. Plus, these containers are also labeled to make all people aware that what is inside is extremely dangerous.

When you the container is already piling up, note that it should only be filled to about ¾ full, and not all the way to the brim of the container. Once that is done, you need to follow these next few steps, so that you can be sure of what to do:

  1. Seal the container tightly.
  2. Put the container on the red liner (the box that the container was shipped in).
  3. There should be a twist and tie attachment on the cover, tie it securely.
  4. Place the red bag into its postage storage box.
  5. Follow the box’s instructions on how to close it.
  6. Write down your return address on the label of the box.
  7. Now that you have sealed the box securely, you can now give it to your local mail carrier, so that they can ship it to the right medical waste facility.

That is the gist of how to stay on top of handling these risky types of medical waste. Again, use caution when it comes to disposing of these sharps and needles, as they can potentially contain life-threatening diseases, such as Hepatitis or the Human Immunodeficiency Virus or HIV.

Quick But Important Tips/Reminders

Other Medical Waste Disposal

So, a quick recap; we have already discussed medical waste, the disposal of medical waste, and how to handle the disposal of sharps and needles. Now, let us discuss the other ways that you can dispose of your medical waste. There are quite a few of them; mainly:

Autoclaving

Basically, the autoclaving method is sterilization by the use of steam. This process renders the hazardous waste as non-infectious, making it possible to throw away in solid waste landfills. They can also be incinerated afterwards.

Biological

Before we discuss what this method does, you should note that this process is not yet widely accepted as a proper way to dispose of waste. This is still under its development phase. Having said that, the biological method enables the use of enzymes to counterbalance the harmful organisms in those medical waste.

Chemical

This type of waste disposal method centers around taking care of chemical-related waste. Simply put, reactive chemicals are applied onto these chemical waste to neutralize it, and make it inactive.

Incineration

Did you know that incineration was used to destroy more than 90% of medical waste before August of 1997? Well because in that year, the US Environmental Protection Agency or US EPA disseminated regulations on emission standards. That is due to the growing concern of the quality of the air, which may affect the overall health of a person. This led to other means of disposal. However, for pathological waste, this is still the only method to properly destroy it.

Microwaving

This method also makes medical waste non-hazardous. Thus, making it safe to be thrown away to landfills. As the name of this method implies, healthcare waste is microwaved using powerful equipment to destroy harmful bacteria and viruses.

Disposal of Medical Waste - Best Practices

The medical industry is currently the third biggest industry in the US in 2021, according to a study by IBISWorld. That could mean multiple things, but it also means that there is a ton of waste produced by the health sector every month. So, what would be the first thing to do when it comes to this?

Firstly, healthcare facilities must be registered with the government as a“Medical Waste Generator”. This step is quite crucial as all medical facilities are regulated by state law and must adhere to it. The next step is to always segregate waste, which is usually required by each state.

On top of that, you can also observe a few guidelines below, so that you can always stay on top of your medical waste disposal practice:

Frequently Asked Questions

Upon the expiry of the 1988 Medical Waste Tracking Act in 1991, the EPA has not had any authority over regulation of medical waste, specifically. These are now mostly regulated by environmental and health dpeartments per state. It's best to contact your local agencies for assistance in these maters. 
It's also good to that that federal agencies such as (but not limited to the) Centers for Disease Control (CDC), Occupational Safety and Health Administration (OSHA), U.S. Food and Drug Administration (FDA) have their own regulations covering medical waste disposal.

Normally, you can visit your local hospital, clinic, or doctor’s office, since they can help you dispose of it, especially sharp waste. It is vital that you do not throw away sharps and needles in the recyclable bin as these cannot be recycled anymore.

A few examples of medical waste include culture dishes, glassware, bandages, gloves, tissue, and discarded sharps such as needles and scalpels.

Conclusion

Disposing of medical waste is easier said than done. That is why it is vital that you stick to the implemented laws and guidelines to help you dispose of it in the right way. Doing so in an unseemly manner can lead to harmful effects and could lead to a public safety hazard. So, it is always best to stay extra careful, for your sake and those around you – whether you work in the health care sector or not.

Solid Waste Incineration

It’s common knowledge that the global accumulation of waste is a long-term environmental threat for future generations.  We haven’t found the perfect way to dispose of all of our waste. There are, however, existing technologies that allow us to manage our waste more effectively. One of the best examples of these is responsible solid waste incineration.

This article will discuss the process of incinerating solid waste, how solid waste incinerators work, and how today’s solid waste incineration processes can turn its byproducts into energy.

What is Waste Incineration?

Waste incineration is simply the burning of garbage. The incineration process, often described in the industry as thermal treatment, uses special incinerators that burn waste materials to ash, heat, and flue gas (i.e., gas exiting from a flue, such as a chimney, to the surrounding air). 

The ash, heat, and gas can be dissipated into the surrounding environment without energy or material recovery. This was especially true in older facilities in the US, and in other parts of the world without adequate environmental regulation. These older facilities run the risk of producing hazardous substances due to the unsatisfactory level of combustion process control and gas cleaning as well as untreated disposal.

Conversely, in more modern facilities, the resulting byproducts can be recovered and used for other purposes, recycling them in effect. For example, the heat produced from the burning process can be utilized for generating electricity and solid wastes, such as fly ash can be used as the material for making bricks, shingles, or tiles. 

Incinerating waste is widely practiced, and actually popular, in nations such as Singapore, the Netherlands, and Japan where there is a scarcity of land. Other European countries such as France, Germany, and Luxembourg also use incineration to dispose of municipal waste.

Waste Incineration in the United States

The first incinerator in the US was constructed in 1885 in Governor’s Island, New York. This and later incinerators were seen as an effective way of solving the nation’s trash problem and hundreds of facilities became operational by the end of the mid-20th century.

During the Industrial Age and until the late 1960s, there was virtually no concern about the negative environmental and health impact of the air and water pollution from these facilities. Since then, however, people have become more aware of being proactive in protecting the environment. 

In the US, the Clean Air Act of 1970 (CAA) established strict standards to limit pollution. To continue operating, incineration facilities needed to conform to strict standards that prohibit the uncontrolled burning of trash and that limited pollution.

This led to the closure of many facilities as well as the construction of new CA-compliant facilities in the 80s. 

The CAA requirements are regularly updated.  For example, new more stringent requirements for Maximum Achievable Control Technology (MACT) were adopted in the 1990s as the EPA recognized the hazards of mercury, dioxins, and other hazardous pollutants from incineration.

Waste to Energy

A more recent development is facilities that recover the heat from incineration and use that energy to generate electricity.  These are referred to as “waste to energy” facilities or WTE in short. The terminology refers to the energy recovery process that makes some modern incinerators an electricity-generating utility as well as a waste disposal service.

Benefits of Waste Incineration

Proper and responsible waste incineration provides various benefits:

Some progressive countries use modern waste treatment and incineration facilities to convert heat used in the burning of trash to electric power. The governments of Sweden and Denmark have turned many of their incinerators into energy generators, making them world experts in recycling energy. Waste incineration produced 13.7% of Sweden’s domestic heat consumption and 4.8% of electrical consumption in Denmark. 

The incinerator bottom ash can be used as an aggregate in creating lightweight blocks, pavement concrete, bulk fill, and more. Environment conscious entities are using novel technologies to create bricks, tiles, shingles, and other construction materials from ash.

Incineration can decrease the solid mass of the original waste, which is already compacted by garbage trucks, to a further 80 to 85%. It can also reduce the volume of trash up to 95%. How compacted the mass depends on the composition of the garbage materials.

At present, there are 72 incinerators operating in the US handling a percentage of the nation’s garbage, with the rest of the garbage being composted, recycled, or disposed of in landfills. The reduction of solid waste by incineration drastically reduces the amount of trash that ends up in a landfill. 

Incineration can also be used to treat hazardous waste (such as materials contaminated with hazardous chemicals)  or medical waste (such as hospital waste contaminated with blood or other potentially infectious materials).  The high heat of incineration can destroy these hazards.  Hazardous and medical wastes can only go to special incinerators that are permitted to treat these types of wastes.

Waste Incineration Process

All wastes that are intended to be incinerated undergo a process called “mass burn.” Each facility has different ways to do a mass burn, but each follows a general process outlined below:

Waste sorting and shredding

The waste is first sorted out, both mechanically and manually. Machines and personnel remove oversized items, recyclable items, and metals. The remaining trash is then shredded.

Waste drying and batching

In some facilities, the waste material is processed or dried so that only around 30% moisture remains. After this, the waste is divided into more manageable batches. The volume of each batch is carefully computed and monitored so it can be burned at the lowest cost and in the shortest time possible.

Combustion

The remaining garbage undergoes the combustion processes. For specifics on how waste is burned, check out the earlier section titled “Parts of an incinerator”

Energy recovery

The heat from the combustion process is used to generate steam. The steam is then used to provide energy to run generators that produce electrical power.

Environmental control

The cooled gas is subjected to thorough cleaning in the facility’s flue gas cleaning system. Here, it is treated with filters, precipitators, and scrubbers to ensure that most pollutants are removed before discharge.

Environmental release

Finally, the treated gas is discharged to the atmosphere. Ideally, the gas coming out from the chimney should be transparent with no visible smoke since the discharged gas should be particle-free.

Residuals, or the solids that remain after combusting, are dumped in an ash pit ready to be disposed of in a landfill.

Parts of a Solid Waste Incinerator

While many facilities may differ in processes and technologies, waste incinerators usually have standard parts. 

The most common type of waste incinerators is called a moving grate incinerator, often referred to as a Municipal Solid Waste Incinerator (MSWI). Rubbish is dumped into a moving grate that goes through the different chambers of an incinerator. The constantly moving grate enables a fast, efficient, and complete movement and processing of waste products. A properly maintained moving grate incinerator can handle 35 metric tons of waste per hour at 8,000 hours per year. 

Understanding how a typical moving grate incinerator works is best illustrated by understanding how each of its major parts works:

Waste Crane

A waste crane picks up massive loads of garbage from a sorted mound.

Throat

The throat is a large long tunnel that leads to the primary combustion chamber.

Primary Combustion Chamber

Waste from the throat goes to the main combustion chamber where the material is burned. Most often, this chamber is already hot thanks to the high ambient temperature that is constantly controlled and retained.

Secondary Chamber

The secondary chamber is often called the “afterburner.” Facilities in Europe, Australia, Canada, and the US are required by law to have an afterburner. This chamber helps reduce or prevent harmful particulates from forming by burning them off.

Many countries have laws that require all flue gas remain in the secondary chamber for at least 2 seconds at a temperature of 850 degrees Celsius to break down toxic organic substances.

Superheater

Using superheaters, heat from the flue gasses can be used to convert water to steam. The superheated steam can then be used to drive turbines to generate electric power in WTE facilities. The flue gas is now at 200 degrees Celsius at this point.

Flue Gas Cleaning System

Before exiting the facility, the flue gas goes through the cleaning system to purge acids, heavy metals, and other toxic particulates.

Flue Stack

Once the flue gas is treated, it exists through the flue stack, commonly called a chimney. Laws require a stack height of at least 3 meters for localized incinerators. Bigger ones, however, have multi-story chimneys, especially those that handle the massive trash produced by large cities. Also, chimneys may be built higher or lower than recommended due to various atmospheric conditions.

Burners

The flame coming from the burners ignites the garbage. The majority of the incinerators are equipped with low nitrous oxide burners or modulated gas flow burners. The intensity of the flames is carefully controlled.

Fuel tanks

Fuel tanks are used to store fuel. Fuel tanks must be carefully insulated for safety.

Ash pit

After incineration, the remnant ash is then collected in an ash pit for disposal. Some entities purchase the ash for their own use.

Incineration Waste Disposal

Waste from solid waste incineration includes flue gas, heat, and ash.

Harmful particles and substances are filtered through the flue gas cleaning system. At a prescribed time, the filters and scrubbers of the systems are replaced or cleaned. Facility operators always keep a close watch of the system. That’s because clogged systems make the gas treatment less efficient. This material may be combined with ash for recycling or disposal or sent to landfill. 

The heat from combustion converts water to steam, which is then sent into turbines to produce electrical power. This electricity is used to power the other electrical systems of the facility. In some countries in Europe, excess electricity is released into the grid to power nearby communities.

Proper disposal of waste incineration ash constitutes its own special process. The ash is run through a baghouse filtering system that captures particulates. Minute amounts of ash that escape the system, called fly ash particles, are captured via funnels called hoppers.

All resulting ash is dumped into an ash pit. Water is poured on the ash pit to prevent ash dust from escaping. The moist residue is then transported into a building where it is loaded to leak-proof disposal trucks.

Finally, the trucks transport the remaining ash to a designated landfill. That landfill must be certified and designed to prevent groundwater contamination; ash particles are so tiny that it might seep into the groundwater beneath the bedrock.

Alternatively, incinerator ash may be recycled to manufacture, bricks, tile, or other items.

Conclusion

As you can see, there is a lot more to solid waste incineration than simply burning garbage. There are complex processes involved. Whether a community resorts to waste incineration or dumping their garbage in a landfill depends on a variety of factors including resources, amount of land, and eco-vulnerabilities of that community.

When done and managed right, waste incineration is a cleaner, more efficient, and one of the most efficient modern waste management systems. 

Still, whatever waste management process is used, in the end, producing less waste is the best and most effective way to reduce the environmental, health, and social impacts of garbage.