Waste Minimization / Pollution Prevention

The Waste Management Hierarchy

There are a variety of methods to deal with the challenges of hazardous wastes.

The Waste Management Hierarchy

Most desirable

  • Reduce waste production at the source.
  • Recover and reuse wastes on-site (i.e., recycling).
  • Recycle off-site.
  • Treatment.
  • Dispose of wastes in a manner that protects the air, water quality, land quality, and human health and safety.

Least desirable

The waste management hierarchy above shows methods of dealing with hazardous waste in order of preference. The most preferable option on the hierarchy is to reduce the amount of waste that is produced in the first place. This approach—known as source reduction—means that no one has to deal with the waste at all. This is the cornerstone of pollution prevention.

Chemical Purchasing

Effective waste minimization begins with effective purchasing decisions. The idea is to buy only what you need because if you don't buy it, you don't have to get rid of it.

In many laboratories, unused chemicals have not yet made it into the waste stream. These laboratories have an inventory of unused chemicals left over by former teachers or researchers. They may be useless (or even unstable) because their shelf life has expired. Containers may be in poor condition. They may be poorly labeled or unlabeled. Unused chemicals can present a safety hazard in the lab and are likely to be difficult and expensive to dispose.

The Myth Of Buying In Bulk

All researchers estimate the quantity of a chemical that they will need before purchasing that chemical. Problems arise when these estimates are inaccurate. The simplest way is to estimate the quantity of a chemical that you will need for a single experiment. That estimate is likely to be more accurate than an estimate of how much you will need for an entire year. An important fact to consider, however, is that the cost savings associated with buying in bulk are frequently offset by the costs of disposing of the unused chemicals.

Other Purchasing Strategies

In addition to buying chemicals in smaller amounts, there are other purchasing strategies that can reduce the amount of chemical waste generated, such as:

  • Select a chemical supplier who will support waste minimization efforts and can deliver small amounts of chemicals on short notice.
  • Standardize chemical purchases. If all (or most) experiments are designed to use chemicals from an approved list, then another researcher may be able to use your surplus chemicals.
  • Consider passing all orders by one person. A laboratory may be able to take advantage of bulk pricing because the purchaser will be buying for more experiments at once.

Conducting Experiments

Waste minimization in the laboratory doesn't necessarily require major changes in the way experiments are performed. Some basic efforts to be more efficient and careful with experimental procedures can substantially reduce the amount of waste generated.

Implement and Develop Resource Efficient Procedures

A starting point for waste minimization is being efficient in your use of resources.

  • Have students use solvents and other hazardous materials sparingly.
  • Monitor experimental reactions closely and add additional chemicals only as necessary.
  • Emphasize water conservation by reducing rinse times where possible.
  • Be alert for opportunities to save electricity. For example, don't leave equipment running when it's not being used.

Scale Down Experiments

  • Reduce scale of experiment (and associated quantities of chemicals) where possible.
  • Move to microscale chemistry.

Utilize Less Hazardous Chemicals

  • Use laboratory detergents rather than hazardous cleaning baths (e.g., substitute detergents for chromic acid solutions).
  • Use non-halogenated rather than halogenated solvents (e.g., substitute cyclohexane for carbon tetrachloride).
  • Use less toxic/hazardous solvents rather than more toxic/hazardous solvents.

Encourage Waste Minimization

Finally, a good way to get students thinking about waste minimization as they run experiments is to have them actually research waste minimization techniques. You might think of including an experiment in your curriculum that actually gets the students to identify ways to minimize use of hazardous chemicals or generation of hazardous byproducts.

Document Initiator: Kirk Matin
Rev: 4/04

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