The analysis unveils significant differences between the baseline scenario and the alternatives. Comparing the SU with the SUAD+CHP scenario, for the CClh category the impacts increase of 0.28 kg of CO2 eq/FU. The increase is due to the different by-product management: the advantages originating from electricity production (-0.06) are lower to those achievable by using the dry sludge as fertilizer (AnF, -0.29 kg of CO2 eq/FU). For this reason, despite the production of electricity from biogas obtained via AD is generally promoted by feed-in tariffs, in this case the alternative valorization route to organic fertilizer is shown to be advantageous from the environmental point of view. The SUAD+CHP scenario, furthermore, does not include the digestate management despite its appropriate valorization (e.g. amendment or fertilizer) could positively affect the credit.