Not necessarily just due to depletion - could be just better technology (eq. some massive robotics deployment, gassification & atomic sorting, etc.) that makes it a no-brainer to process all regular waste & the old ones when you are at it.
Even modern waste incineration comming quite close with iron & even alluminium collected from the slag & the mostly inert reminder reused in consturction. The local waste incineration plant already covers all district heat requirements of the 400k people city in the summer and is poised to cover 50% of the inter load once their new nr. 3 furnace is installed.
Even modern waste incineration comming quite close with iron & even alluminium collected from the slag & the mostly inert reminder reused in consturction. The local waste incineration plant already covers all district heat requirements of the 400k people city in the summer and is poised to cover 50% of the inter load once their new nr. 3 furnace is installed.