Qt is the total quantity of MSW generated at the source (t/yr).
Qr is the total quantity of recyclables that were separated at
source (t/yr).
Qtr is the quantity of the residual waste containing some recyclables
that were not separated at the source (t/yr).
Qr1 is the quantity of recyclables collected by residents at the
source (t/yr).
Qr2 is the quantity of recyclables collected by cleaners and scavengers
at the source (t/yr).