Control system and environmental monitoring in the urban waste-to-energy process
Eighteen months before the commissioning of the first incineration line, Zabalgarbi conducted a thorough analysis of the environmental situation around the plant. Tests and analyses were performed to ascertain the quality of the soil, vegetation, surface and ground water, and odours.
On the basis of this initial analysis, Zabalgarbi has been steadily incorporating the latest technologies, seeking to further reinforce the adoption of control and environmental monitoring measures over and above those legally required. These include the entire process of control systems and environmental monitoring, from the delivery of UW to the plant through to its transformation into energy.
Stack emission control systems
Previously scrubbed gases are discharged through the stack into the atmosphere by means of an induced draft fan.
The stack is a seventy-metre high cylindrical structure for removing the scrubbed gases from both the incineration line and the recovery boiler.
Halfway up the stack there is a ring platform holding the sensors for continuous emission sampling, as follows:
- Before and after scrubbing
- The system is redundant
- Continuous link to the Basque Government Environmental Authority
- Whenever emission limits are exceeded, the system will shut down within four hours
Emissions are monitored directly by the Basque Government through both real-time analyses and the regular sampling conducted in the stack.
Immissions are monitored as follows:
- Continuous analysis of the surrounding air (PM10, O3, NOx, SO2, VOC, HCl and weather data) at three monitoring stations located on Mount Arraiz (Bilbao), and in the towns of Alonsotegi and Larrazabal (Barakaldo).
- Continuous parameters (air): PM10, O3, NOx, SO2, VOC and HCl.
- Weather data.
- Regular readings: sampling of water, soil, vegetation and air.
- In water, soil and vegetation: heavy metals, dioxins and furans.
- In air: hydrogen fluoride (HF), heavy metals, dioxins and furans.
Other environmental controls
Licensed companies conduct regular olfactometric studies both on site and in the plant’s vicinity. The results of these studies recorded to date by both public and private bodies certify that the plant does not emit odours that impact upon the environment. The only odours perceived are confined to the pit and the reception hall.
Since 2005, a group of researchers from the Department of Preventive Medicine and Public Health at the University of the Basque Country has also been performing an Epidemiological Study to ascertain whether the plant’s industrial activity is having any impact on the environment or people.
After all these years of operation, their findings indicate that the Zabalgarbi urban waste incinerator “will not pose an ecological or carcinogenic risk, or significantly contribute to increased pollution in the area, either for the population or for ecosystems”.