Question 9 of 18: Management of Biomedical Wastes — Liquid vs. Solid

Question 9: Management of Biomedical Wastes — Liquid vs. Solid (4 marks)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

Biomedical waste management follows the general hierarchy of segregation at the point of generation, treatment to render the waste non-infectious, and final disposal — but the treatment route differs by physical form. Solid biomedical wastes (sharps, pathological/anatomical waste, contaminated dressings, laboratory cultures) are collected in dedicated, colour-coded, puncture-resistant (for sharps) containers, then rendered safe by autoclaving (steam sterilization) for most general biomedical solids and cultures, or by high-temperature incineration for pathological/anatomical waste and sharps where sterilization alone is not considered sufficient; once treated, the residue can generally be landfilled as ordinary solid waste. Liquid biomedical wastes (blood, body fluids, liquid cultures) are typically chemically disinfected (e.g. sodium hypochlorite) to inactivate pathogens, after which the disinfected liquid can usually be discharged to the sanitary sewer under a discharge permit, since municipal wastewater treatment provides a further level of biological treatment that a solid waste stream headed to landfill does not receive. The key distinction is therefore that solids require physical containment plus destruction/sterilization before landfill, while liquids can generally be chemically disinfected and discharged to sewer.