Rejects of municipal waste pretreatment process undergoes aerobic fermentation before landfilling in order to improve landfill management in long term
Organic waste is separately collected in Cordoba. However, as sorting by citizens is not perfect, a fraction of organic waste is rejected in pretreatment process and ends in the landfill. Therefore, an aerobic fermentation of waste is done inside landfill before final deposit, dividing landfill surface into four areas and following an 8 weeks’ procedure:
During the 1st and 2nd week, waste deposited in the landfill is disposed building 2-3 meters high piles.
From 3rd to 7th weeks, piles must be turned over every week, adding leachate through irrigation system in order to guarantee proper humidity and oxygen levels needed to ensure composting process.
Finally, during week 8 after completing the composting process, waste piles are spread out and compacted using waste compactor and the process starts over.
Composting allows to take avantage of energy emmitted to evaporate leachate, achieve waste stabilisation and avoid methane production; what are key factors for stability and safety regarding landfill management; diminishing the risk of fire and reducing global greenhouse emissions out of the landfill.
Moreover, organic fraction within landfill waste is reduced by 30% in volume, average waste density increased and hence, landfill life is extended.
A significant size opened landfill surface besides human resources and heavy machinery – bulldozer, waste compactor, a mobile irrigation system- are required to make the fermentation process feasible.
Evidence of success
Stabilisation of the organic waste before its landfilling is proven to be good. Fire risk is minimised, greenhouse gas emissions reduced and safety in the landfill improved, due to the fact that methane is avoided.
As waste becomes stable before landfilled, landfill becomes less active and thus, aftercare costs and risks are reduced.
Likewise, aerobic fermentation implies reducing waste volume, landfilled waste density (around 1.3 t/m3), thus the life of the landfill is extended
This practice requires a significant surface where waste can be outdoors.
Also, there are likelihood of nuisances, odours, vectors and high leachate production, that are collected through leachate capturing system and required treatment.
Potential for learning or transfer
This practice could be replicable in locations where rains are limited (geographical specificity) and where fires risk prevention is a target.
This practice can be replicable in any landfill in any location taking into account the challenges described above.
Indeed, the practice contributes to the following articles and annexes in the EU Directive 31/1999 on the landfill of waste, of applicability to landfills throughout the EU.
- Article 11: Waste acceptance procedures
- Article 12: Control and monitoring procedures in the operational phase
- Article 13: Closure and after care procedures
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