Answer:
Flushed down in the patient's toilet
Step-by-step explanation:
Patients having highly contagious diseases are put in isolated rooms so that the disease can not be spread by the patient to the other people. Person who provide any foodstuff to these patients use appropriate safety clothing like gloves, masks, etc to protect themself from the infection.
Therefore when a patient did not drink juice that was given to him/her then the juice should be flushed in the patient's toilet to avoid any cross-contamination of the infectious agents between the patient and other people and that juice should not be given to any other person.