Environmental and Sustainability Practices in the Laboratory
Laboratories generate hazardous and non-hazardous waste streams that must be segregated at the point of generation. Candidates must know the categories: clinical or biohazard waste (sharps, contaminated consumables), chemical waste (halogenated and non-halogenated solvents, heavy metals, acids and bases), and general waste. Sharps go into rigid, puncture-resistant, labelled sharps containers filled only to the marked line. Chemical waste is never poured down the sink unless the SDS and local rules permit it, and incompatible wastes (oxidising agents with solvents, acids with cyanides) must never be mixed. Understand waste minimisation: reduce, reuse, recycle, and substitute greener reagents where validated.
Traps: mixing waste streams, which makes the whole container hazardous and expensive to dispose of; overfilling containers; placing chemically contaminated gloves in general waste; assuming a fume hood protects the environment (it vents to atmosphere, it does not treat). Understand energy and water conservation (switching off equipment, closing sashes, recycling water from condensers where safe), and the role of green chemistry principles such as using less hazardous solvents and designing for energy efficiency.
Worked example: A technician has 50 mL of waste acetone and 50 mL of waste chloroform. Correct action is to place them in separate, labelled, compatible containers, because mixing halogenated and non-halogenated solvent waste changes the disposal category and increases cost and hazard.
Rule of thumb: segregate at the bench, label clearly, and never mix what you cannot identify.