Plan: Bio.Lea.R project is undertaken in the landfill for non-hazardous waste of Cerro Tanaro (Asti Province), managed by GAIA S.p.A.; the experiment is carried out in the landfill cell which has just begun its post-management phase.
The project target is to optimize the chemical and physical processes that naturally occur within waste, in order to quicken their stabilization and to benefit as much as possible from the energy recovered.
The method we use consists in adjusting waste moisture through leachate and waste waters recirculation, managing the landfill as a “bioreactor”. A bioreactor is a landfill in which waste moisture is kept under control, with the aim to improve biogas production and to shorten the natural production time.
The material landfilled has a moderate quantity of organic matter and a little moisture rate; therefore it produces low amount of biogas. Without optimization, the energy recovery is less efficient, as well as sinking and biological stabilization last for many years, increasing costs for the post-management phase.
Moisture is a crucial parameter that acts on biological processes for biogas generation: too less moisture inhibits activities of methanogen bacteria; an optimal moisture degree develops a greater biogas production in the first post-management years and accelerates landfill stabilization (mineralization, settlement, biological stabilization). Considering that biogas amount produced by waste is constant, moisture causes a peak of the initial production, that is compensated by a reduced trend in the next years, inducing an increased biogas production in a shorter period of time. This allows an efficient exploitation for electricity production, through biogas combustion in an energy recovery plant. Inside it, heat energy produced by combustion, is exploited to generate mechanical energy, which is turned into electricity.