Tossing the ransom price for the sins of this world in the trash? The blood of Christ treated as garbage? More than one person has raised this criticism against LCMS parishes with the rise of those little plastic cups that you can toss. (Note that when individual cups were introduced they were many times made also of precious metal - my home parish had miniature silver chalices! - or glass. That would still seem to be the preferred way to go if you absolutely HAVE to keep them, but better far, in my opinion, is to do what the Churches of the Augsburg Confession did from the beginning of the Reformation: drink from the one chalice.)
In later Lutheran Orthodoxy, the teaching of receptionism took hold: namely, that the Lord joins His Body and Blood in sacramental union only to that which is actually consummed. Thus, if you spill from the chalice, all you've spilled is wine. For the Lord's blood joins itself only to what goes down the gullet. This shows up, for example, in Loehe's Catechism at question 863:
"Why is there no danger of spilling any of Christ's blood?
Answer: Because the Almighty Lord unites His Blood with the wine that is drunk, but not with the drops of wine that are spilled. The error of the Romanists is a consequence of their wrong teaching that there is only Blood, and nerely the appearance of wine, in the Holy Supper." (p. 174)
This sort of thinking is what has led to the sloppy practice that shows up across our Synod. What a contrast with the Blessed Reformer, Dr. Luther, who when the chalice was spilled during distribution in his later years, actually cut out the part of the lady's dress on which it was spilled and had the chair where the drops fell also planed and then both fabric and wood shavings burned. Or consider how, when he spilled the chalice and it fell to the floor, he carefully set the chalice back on the altar and got on his hands and knees and lapped it up off the floor like a dog - upon which the congregation burst into tears.
Was Luther merely retaining his catholic piety and Loehe expressing the true Lutheran view? Or was it vice-versa? And which approach accords with the actual words of institution? Did the Lord say: "What you drink, that is my blood?" Or did He say: "Drink from it all of you - this cup is the new testament in my blood?" If you confess that our Lord's Words accomplish what they promise, it seems to me that we must confess that not merely what is received, but also what is on the altar and consecrated by the Words, is our Lord's body and blood - just as He himself declared.
All of which then brings us to the question of the disposal of the reliquae, the sacramental "left-overs". Obviously, the very best Lutheran precedent (witnessed by both Luther and Chemnitz) is to remove the question by making sure that ALL the reliquae are consummed immediately following the Divine Service. Who can argue with such practice? For surely of everything that our Lord declared His body and blood, of that He told us: "Take, eat, and drink."
But if your parish uses the disposable individual cups? Should they just be thrown into the trash? Reverence dictates: NO WAY, JOSE! At bare minimum the cups should all be rinsed and then that water reverently consummed or poured out upon the earth (not put down the sewer!), preferably through a piscina. This is a bit of a hassle, of course, but so are the individual cups from the get go. But it confesses with great reverence that what our Lord has said is most certainly true, and that we do not doubt His Word.
And if there are any avowed receptionists who read this (Dr. Strickert, are you still out and about?), I would argue that reverence for our Lord's Holy Supper would still dictate not allowing anything that was given over to the Lord's holy use to be treated as "common" and so "trashed."