Chem. Q. (Disposal of residue)

I suppose the waste are from lab test so the resulting are only in very small amount . You can just flush them into toilet or this is a regular routine test then you may contact some waste disposal collection company to ask them to dispose the waste for you . But starch solution is no harm to flush into the toilet because it is biodegradable .

Dilute with water and mop up if the spill is small. Small amount can be flushed down the drain with excess water. Large amount can be absorbed with an inert dry material and place in an appropriate waste  disposal  container.