Emissions from Energy-from-Waste Facilities
The Rookery South ERF has been designed in a way that emissions released from the stack are well within the strict requirements of EU and UK legislation. Modeling has been carried out of the dispersion of potential emissions, which shows that they will not have unacceptable effects on local air quality, health or nature conservation sites.
Public Health England advises that well run and regulated EfW facilities do not pose a significant threat to public health. They also state that the effects are likely to be so small that they would be undetectable. All EfW facilities in the UK are tightly regulated and must operate within the national and EU's requirements, set out in the Waste Incineration Directive (now covered by the Industrial Emissions Directive). The Environment Agency also carries out spot-checks to ensure that the monitoring equipment is operating correctly.
Controlling Air Emissions
Covanta strives to reduce emissions from our EfW facilities and keep these below the strict air emissions limits set by regulatory bodies that have been demonstrated to protect human health and the environment. We employ sophisticated technologies to achieve superior environmental performance and minimise our impact.
Did You Know?
Our sustainability program has been an important driver of our success to reduce emissions and is an example of our commitment to achieving strong environmental performance. Since launching our program in 2007, we have reduced emissions by up to 53 percent.
State-of-the-art emissions control technologies
Our boilers are specifically designed to recover as much energy as we can out of the waste resource, minimize formation of dioxins and ensure complete combustion, including volatile organic compounds (VOCs) and other organic compounds.
Nitrogen Oxides (NOx) Control:
Our facilities are equipped with selective non-catalytic reduction (SNCR) systems, which inject ammonia or urea into the furnace to chemically convert NOx into gaseous nitrogen, a harmless gas that makes up the majority of our atmosphere.
After leaving the boiler, combustion gases travel through an extensive air pollution control system. At many of our plants, activated carbon is added to the flue gas stream as it exits the boiler. Gaseous phase contaminates such as mercury and dioxins adsorb to the surface of the carbon so it can be removed downstream in the baghouse.
A scrubber neutralizes acid gases, including sulphur dioxide and hydrochloric acid, by spraying a lime slurry into the exhaust stream. This process removes more than 95 percent of sulphur dioxide and hydrochloric acid.
Operating like a very efficient vacuum cleaner, the baghouse removes 99.5 percent of the particulate matter from the combustion gases. As air is drawn through the baghouse, particulate matter and fly ash are caught on the surface of the bags. Periodically, the bags are cleaned by temporarily reversing the airflow or, in other designs, pulsing the bags with a strong jet of air. The particulate and fly ash are removed from the bottom.
All our EfW facilities operate under strict air emissions control limits. To demonstrate compliance, we use a combination of continuous emission monitoring systems that monitor emissions 24 hours a day, seven days a week and perform regular stack testing.