Why is hazardous waste incinerated?

Whilst a lot of progress has been made to reduce or recycle hazardous waste, it’s not possible to completely eliminate its production. Consequently, that leaves businesses and organisations with the question – what to do with hazardous waste?

So, what are the options?

What are the treatment options for hazardous waste?

According to the waste hierarchy, disposing of waste is the least preferred option. Landfill and incineration without reclaiming energy both fall into this category. High temperature incineration with energy recovery falls into the recovery category of the hierarchy.

Is landfill an option for hazardous waste?

A large proportion of hazardous waste is contaminated soil which isn’t suitable for incineration. Therefore, the soil should be treated or sent to an authorised hazardous waste landfill facility.

Hazardous Waste Landfill

However, not all hazardous waste can be sent to landfill without first being processed; the waste framework directive states the following wastes can’t be accepted by a landfill site:

• Liquid waste
• Flammable waste
• Explosive or oxidising waste
• Hospital and other clinical waste that is infectious
• Used tyres

The regulations limiting hazardous waste going to landfill were introduced to tackle pollution and to protect the environment and public health. For example, chemicals can leach into the soil and pollute ground water or toxic emissions can be released into the atmosphere causing a risk to public health.

High Temperature Incineration

There are a number of benefits associated with incineration. For example:

• Incinerators reduce the solid mass of the original waste by up to 80% and volume by 95%.
• The high temperatures (up to 1200°c) ensure there are no toxic materials released to the atmosphere as the toxic compounds are broken down so that they are no longer toxic.
• Energy released from incineration can be recovered and converted into electricity and heat.

Sites that reclaim energy in this fashion move incineration from disposal to recovery which is a preferred option on the waste hierarchy.

Emissions from Incineration

The high temperature incineration process results in:

• bottom ash and
• air pollution control residues from cleaning flue gases
• emissions to the atmosphere, which are closely monitored

Bottom Ash

Bottom ash is the material left after the original waste is incinerated. This waste is hazardous and needs processing at approved hazardous waste landfill facility.

Flue Gases

Exhaust gases and particulates from incineration are a potential health issue as they contain undesirable compounds, elements and ultrafine particulates. The flue gases are cleaned before they enter the atmosphere. As a result of cleaning the flue gases air pollution control residue (APCR) collects in the filters.

APC Residues

A lot of work and technological advances to remove pollutants are now in use; such as activated carbon filters and fabric filters which trap any dioxins present before the exhaust plume enters the environment. When the filters that clean the flue gases complete their useful life they are considered as hazardous waste – along with the bottom ash the filters are encapsulated and sent to landfill.

In conclusion

The production of hazardous waste will continue for the foreseeable future and landfill is not a viable option for all hazardous waste. High temperature incineration reduces the mass and volume of the waste whilst potentially providing a source of energy making incineration an integral element of waste management.