BioBar · Biological barriers for a sustainable landfill design

BioBar: Biological barriers for a sustainable landfill design

Waste final disposal can cause severe environmental impacts. Even in modern landfills, installed engineered barriers worsen their hydraulic performance after 8 years of landfill operation, which can lead to leachate leakage and environmental pollution in the medium to long term. In addition, the use of clay as landfill barriers relies on a non-renewable resource and entails high economic and environmental costs when such a resource is not locally available. Therefore, it is necessary to develop barriers made of renewable/recycled and locally available resources, which not only promote leachate containment but also enhance its in-situ treatment and attenuation. The BioBar project proposed to develop an innovative barrier applied to landfill liners, taking advantage of the bacteria naturally occurring in leachate that grow and form biofilms in different support materials. We adopted both construction and demolition, and tire wastes as supports to permit the attachment of bacteria and promote the clogging of the media. Such natural clogging reduced the permeability of the materials to values compatible with landfill barrier layers, and, additionally, enhanced the occurrence of processes that attenuate pollution. In this case, as the leachate collection system would be above the bio-barrier, the clogging would not affect the drainage of leachate. Therefore, by adopting a bio-barrier between the liner and the drainage system, it would be possible to: a) reduce the flow of leachate that reaches the liner (since the natural clogging of the bio-barrier would reduce its permeability); b) reduce the contaminants concentrations reaching the liner, as physicochemical and biochemical processes would enhance their attenuation. Both processes would protect soils and groundwater from leachate leakages due to the liner’s failure and could enable the partial reduction of the clay liner thickness and/or the increase of its operational lifetime. In this regard, the proposed project: 1) developed bio-barriers for landfill design by combining the rejected fraction from a construction and demolition waste treatment plant, tire waste and biofilm-forming bacteria; 2) verified the long-term performance of these new designs for representative environmental conditions. We have observed that incorporating the proposed biobarrier within the landfill design could enable the reduction of clay liner thickness, which would contribute to a more renewable and sustainable perspective. Nevertheless, care should be taken in dry climates, and a multibarrier approach that combines clay layers is necessary, to avoid leachate leakages during the first stages of biofilm development.

Data: CORDIS, © European Union