Diverting waste from landfill can avoid methane, long-term disposal, leachate management and loss of recoverable resources. The size of that benefit depends on what landfill was actually avoided and what system replaced it.
A carbon calculation can change substantially depending on whether it includes only direct facility emissions or also feedstock, transport, energy, avoided treatment, recovered products and final use. The boundary must therefore be defined before the result is interpreted.
A system can appear environmentally favourable or unfavourable simply because the analysis has been stopped at a convenient point. Credible comparison begins by defining where the system starts, where it ends and what alternative it replaces.