Environmental Engineering Reference
calculated content of methane) generated in the landfill life time (both collected and non).
The value of the overall energy conversion efficiency results about 15%.
In order to highlight the contribution to natural resources conservation, and in particular
to saved conventional fossil fuels, the EE production from this renewable source allows to
save about 40.599 TEP (ton of equivalent petrol) (assuming an average energy conversion
efficiency of 37% for conventional plants).
7. M ANAGEMENT O PTION TO I MPROVE E NERGY R ECOVERY
The Scholl Canyon equation based model has been applied to a second study case in
order to evaluate the possibility of improving energy recovery from LFG by means of
leachate recirculation (Corti et al., 2005). The practice of leachate recirculation has been
studied in several laboratory cells, pilot cells and real landfills highlighting its beneficial
effects on the waste biodegradation process (Reinhart and Townsend, 1998).
In the present chapter, the aim is to highlight the behaviour differences between a landfill
where leachate recirculation takes place and a conventional landfill, by means of adapting the
Scholl Canyon equation based model previously described.
In order to define the different parameters to be used to describe a conventional landfill
and a landfill where leachate is recirculated, the above described model has been applied to
simulate the behaviour of an existing reference landfill, where MSW are deposited, in the two
periods in which it was operated without leachate recirculation and with leachate
recirculation. In order to do this, measured data from a landfill where leachate recirculation
takes place were considered and the Scholl Canyon equation based model was built around
data and inputs -referred to the analysed landfill - reported in Table 10 and Table 11.
Table 10. Chemical composition of waste component fractions and their humidity,
biodegradability and biodegradation rate category
28,70% 3,10% 29,20% 1,90% 0,60% 36,50% 70,00%
44,40% 4,40% 40,90% 0,10% 0,30% 9,90% 5,50%
70,50% 11,50% 11,30% 0,90% 0,90% 4,90% 2,00%
39,60% 6,50% 25,30% 5,60% 0,70% 22,30% 10,00%
45,50% 8,70% 20,10% 1,80% 0,20% 23,70% 60,00%
49,50% 6,00% 42,70% 0,20% 0,10% 1,50% 20,00%
0,10% 0,00% 94,50% 3,00%