#58. MARCH 2019

Ecocentral Granada is a mechanical-biological treatment facility where municipal solid waste from the province of Granada is processed. It is located in the municipality of Alhendín, around 15 km south of the city of Granada. For the purpose of reducing diffuse emissions, the Provincial Council of Granada and the concessionaire of the facility, Fomento de Construcciones y Contratas S.A., have promoted an initiative consisting of capturing the biogas for recovery and preventing uncontrolled gas emissions. This active degasification project is unusual in that the biogas is captured while the landfill is in operation, without the need to wait until the end of its service life, as is required under current legislation.

Background

FCC Aqualia central, Inodoro

Ecocentral Granada is a mechanical-biological treatment facility where municipal solid waste from the province of Granada is processed. It is located in the municipality of Alhendín, around 15 km south of the city of Granada. In addition to the waste treatment facility, the complex also has a controlled landfill, where over 300,000 tonnes of reject not recovered during treatment is disposed of every year. This landfill is a live entity, i.e., it is in a constant state of evolution, in which a series of reactions take place. These reactions can be both physical and chemical, depending to a greater or lesser extent on very diverse factors, such as compaction or density of the landfill, waste age, type and characteristics of covering material, characteristics of impermeable materials used, quantity of organic matter, moisture content of the waste, etc. The capacity of the landfill to generate emissions, such as leachate or biogas, depends to a greater or lesser degree on these factors.

One of the chemical reactions that takes place in the landfill is waste fermentation. This depends mainly on the moisture content and quantity of organic matter, and generates a biogas
that must be evacuated to prevent internal overpressures, as well as explosions and fires.

In the absence of an active gas collection system, biogas from these types of landfills is emitted passively through flues, in accordance with the current environmental authorisation. These emissions generate foul odours and noxious gas effects, which is a considerable environmental problem, given that landfill biogas is considered one of the main greenhouse gases.

For the purpose of reducing diffuse emissions, the Provincial Council of Granada and the concessionaire of the facility, Fomento de Construcciones y Contratas S.A., have developed a project consisting of capturing the biogas for recovery and preventing uncontrolled gas emissions. This active degasification project is unusual in that the biogas is captured while the landfill is in operation, without the need to wait until the end of its service life, as is required under current legislation. This means degasifying the landfill with the varying traffic on its surface, the existing settlements, the movement of heavy machinery in the area of the wells…, making operation of the gas field more complicated than in the case of a sealed, closed landfill. Nonetheless, the challenge has been accepted of availing of this resource whilst, at the same time, minimising odour emissions, generating savings and putting the facility at the forefront of the waste treatment sector in Granada.

 

Carlos Saiz Valera
Head of the degasification and biogas recovery facility (Fomento de Construcciones y Contratas)

Ricardo Alonso Pérez
Civil engineer (Granada Provincial Council)

Francisco Peula López
Operations technician (Granada Provincial Council)