Laboratories are doing an immeasurable service to mankind and their contribution towards promotion of commerce and trade is well recognized. However, all the benefits offered by laboratories can get nullified if laboratory wastes are disposed irresponsibly and without concern for the preservation of our environment.
Laboratory wastes are potentially hazardous as they can have the following characteristics:
- Highly reactive
- Bio- hazardous
Laboratory wastes can result from several sources of which the common ones are:
- Expired and unused reagents and chemicals
- Reagent bottles and broken glassware and plastic ware items
- Used syringes, needles and other sharp objects
- Solvents used for rinsing and cleaning laboratory ware
- Used oil collected from pumps and generators
- Supernatants from centrifuge tubes
- Body fluids and other biological waste resulting from microbiological testing
It is very convenient for anyone to simply empty out the waste liquids in washbasin drains, discard expired chemicals, reagents, broken glass, empty bottles and tested samples in community-waste bins without caring for the potential hazards that such materials can pose. Such carelessness and irresponsible behavior cannot be excused and laboratory workers should adopt the recommended practices for waste disposal.
Recommended collection and disposal practices
The first and foremost step is to monitor and regulate the inventory of laboratory chemicals. Ordering of new chemicals should be planned keeping in view their projected use and expiry dates of already procured materials.
Collection of laboratory waste requires a knowledge of the nature of material before it is segregated and disposed off.
Acids and Bases
Laboratory drainage is not meant for disposal of laboratory liquid wastes and all materials discharged into such outlets finds their way into the general city waste water system. Such chemicals can pose serious health hazards and dangers to aquatic life in rivers and other water bodies.
Small amounts of acids and alkalis can be neutralized first and then poured into drains along with larger amounts of water.
Organic Waste Solvents
Organic solvents should be collected in separate organic waste containers and not mixed with aqueous solvent wastes. Do not use containers larger than 25 liters capacity as these can pose handling problems. Incompatible chemicals or oxidizers should not be added to same containers as these can result in corrosive fumes or violent reactions. Always keep such containers capped but do not overfill to permit thermal expansion.
Solvents used in rotary evaporators or distillation processes remain mostly uncontaminated and can be reused. Re- distillation can be carried out if further purification is required.
It is possible to collect together different organic waste solvents keeping in mind that halogenated solvents are collected separately and never mixed with inorganic acids or oxidizing agents. It is further advised that the label of the waste drum provide details of organic solvents mixed.
Needles, Syringes and Broken Glass
Sharp objects should be stored in thick walled plastic containers. Needles should not be removed from syringes before discarding and needles should not be recapped to prevent accidental injuries. Such items recovered from biological tests should be first autoclaved before collection and disposal
Supernatants from centrifugation tubes can be discharged into the washbasin but such supernatants resulting from biological testing require to be treated with bleaching powder before pouring into wash basin drains.
Empty reagent bottles should be rinsed several times with water or appropriate organic solvent, labels should be removed or defaced and disposed of with other routine glassware waste,
The collected containers of different wastes should be handed over to waste disposal agencies to provide specialized services of environmental friendly disposal through incineration or dumping. However, it is always helpful if the waste containers are properly labelled and carry other mandatory instructions.
Training of laboratory personnel in collection and disposal practices of laboratory waste is a social responsibility of all labs. However, it is equally important that all laboratory workers do not conceal any material facts and information if they use any new material or any material that has a hazard potential during handling and disposal.