Canisters used to collect solvent waste must be certificated for this purpose. You may detect this by the "UN-number" found at the canister. As a rule you may get suitable canisters including proper labelling at the "Materialverwaltung" (=Material Management).
Never use bottles with a volume more than 5 liters, because bigger volumes of organic solvents may then ignite because of electrostatical charging unless you do a lot of effort to keep bottle and content discharged.
You may also dispose reagents into the solvent waste - but do this carefully to avoid hazardous reactions! At the end it is more safe to dispose even solid compounds into the solvent waste than to collect solid materials separately. Without a solvent reactive compounds may react with a perfidous time delay of several hours - and because there is still no cooling solvent they will then ignite! It may happen that in this case the institute building will burn down at night! But if you dispose small quantities of reactive chemicals into the solvent waste there is a chance that they react at once and before the next reactant is disposed the first one is already decomposed. It is OK if the solvent waste contains precipitations.
Never dispose heavy metal compounds into the solvent waste.
Small quantities of water are OK, but the content of the canister must still be inflammable. If this is not the case the content has to be disposed as "low calorific solvents", but try to avoid this because this is more expensive.