After a chemical waste has been generated, determined to be hazardous, and sent through the hazardous waste management program, there are 4 primary ways in which the waste is handled: bulk drums, lab pack drums, recycling/reclamation, and drain/trash disposal.
9.1 Lab Pack Drums (Top)
Chemicals that cannot be bulked are lab packed. Lab packing first involves segregating chemicals according to hazard class. Chemicals in the same hazard class are placed into various size drums (55-gallon is the most common), then a packing material, such as vermiculite, is added to prevent the containers from breaking during transportation.
9.2 Bulk Drums (Top)
Certain categories of liquid chemicals can be bulked and combined into drums. Examples include flammable solvents, acids, bases, and some types of aqueous waste. Bulking waste (as opposed to lab packing) can result in significant cost savings for the University and ultimately your department. Bulking first involves segregating chemicals according to hazard class. Then a small amount of chemical from each container is mixed in a 1-gallon size container to determine if a reaction occurs. If no reactions occur, then the rest of the chemical is poured into a 30- or 55-gallon drum. Accurately labeling chemicals helps to avoid potential reactions, fires, or explosions when chemicals are bulked.
The cost for disposal of labpacks is based on the number of drums of waste, whether the drum is completely filled with solvents or contains (as in most cases) partially filled bottles packed according to DOT regulations. Thus, the cost of the disposal of a partially filled bottle is the same as the cost of one which is full. Given this situation, partially filled bottles become very expensive for the amount of material being shipped. In part, this explains the high disposal cost per gallon of material. In order to reduce this empty but costly space, compatible solvents (not including the above recyclables) may be combined in a single container. As with all hazardous waste containers with multiple constituents, when solvents are thus combined, the approximate volume percent of each solvent should be noted on the Cornell two-part Hazardous Waste label. However, halogenated solvents should not be combined with solvents which do not contain halogens, because of differences in handling and ultimate disposal techniques. Solutions of halogenated and non-halogenated solvents will be considered as halogenated solvents and disposed of accordingly.
The preferred method of managing spent solvents is recycling for reuse. Current regulations prohibit the disposal of hazardous waste chemicals and most liquid wastes in municipal landfills. Solvents that cannot be recycled will be shipped as hazardous waste for incineration or treatment.
9.2.1 Solvent Recycling (Top)
Cornell EH&S and Animal Health Diagnostic Center Department of Biomedical Sciences have jointly purchased a solvent recycling unit. Reduction of non-halogenated solvent hazardous waste generated in the Histology Department is estimated to be approximately 3 tons annually. The reduced cost of waste disposal annually is approximately $1500.00, while the reduction in annual purchase of new xylene and ethanol is estimated to be just over $8,000.00. The return of investment for this unit should be just over 2 years.
The recycling accomplished by Histology is not feasible in all laboratories because of an inability to segregate halogens from non-halogenated solvents. Therefore, the afore-mentioned procedure in section 9.2 is an effective way to reduce costs for solvent disposal.
The following solvents should be segregated from other waste chemicals and stored in their own labeled container whenever possible:
- Xylene (can have Propar mixed)
9.3 Recycling / Reclamation (Top)
Chemicals such as used oil, free-flowing mercury, and silver from photographic fixer are sent for recycling/reclamation. Photographic fixer is collected and run through a filtration media to collect the silver. Items containing mercury, such as thermometers and manometers are collected and the mercury is removed. It is important to minimize the amount of other material that is mixed in with these items. The addition of chemicals or other solid waste to these items can result in the material being unable to be reclaimed and having to be disposed as hazardous waste instead.
9.4 Ultimate Disposal (Top)
There are a variety of treatment/destruction methods that environmental companies use after they receive the waste generated on campus. Some wastes (bulk flammable liquid drums) are used as a secondary fuel source at cement kilns. Wastes such as acids/bases and oxidizers/reducers can be treated at a facility to render the waste nonhazardous. Most waste will be sent to a hazardous waste incinerator. Any resulting ash from the incineration process is stabilized and then placed into a hazardous waste landfill. While there are other methods that can be utilized, the hazardous waste generated at Cornell University will generally be handled using the above technologies.