Final answer:
The nurse should seal the contents of the portable wound suction apparatus in a biohazard bag.
Step-by-step explanation:
The nurse should seal the contents of the portable wound suction apparatus in a biohazard bag before disposal. This is because the client underwent a modified radical mastectomy, which involves the removal of breast tissue and lymph nodes, and there is a risk of biohazardous material being present in the suction apparatus.