Minimizing Waste in Teaching Labs*

Teaching laboratories are where future chemical users learn their usage habits. Incorporating waste minimization concepts and applications into chemical work from the beginning establishes habits that last a lifetime. Waste minimization techniques also have the potential for creating a safer teaching environment and for reducing purchase and disposal costs.

Waste minimization opportunities for teaching labs can be divided into four categories: administrative, reduction in scale, process modification, and continual improvement.

Administrative steps

The first thing to do is clean up the chemical storeroom. Make an inventory of the chemicals. Discard deteriorating containers. Put chemicals that are unlikely to ever be used out for disposal.

Next, assess how chemicals are dispensed. In cases, University staff preweigh chemicals for experimental use because students tend to take more than they need. Preweighing can reduce chemical usage by as much as two-thirds. For liquids, have students use the smallest container possible to discourage taking more than is necessary. Having groups of two or three students run experiments where feasible can also reduce chemical usage.

A third step is to evaluate equipment. For example, mercury thermometers can often be replaced with alcohol thermometers, thereby eliminating a cleanup problem when the thermometer breaks. (EHS will replace your mercury thermometer with a non-mercury alternative upon request.)

Reduction in Scale

Teaching laboratories are ideally suited for microscale techniques that reduce chemical usage by 2-3 orders of magnitude below the level required for traditional teaching methods. Several books on the market now specify microscale techniques for a wide variety of teaching laboratories. Because chemical usage is greatly reduced, ventilation requirements are reduced, as are disposal and purchase costs. The Chemistry Department has done extensive work with microscale techniques in their undergraduate labs for several years with great success.

A potential barrier to microscale laboratories is the initial investment in special microscale glassware. If this is a problem, there are still opportunities for reducing the scale of experiments. Many experimental requirements that have been unmodified for years can be reduced in scale by 10% or more without any deterioration in the teaching experience.

Process Modification

All teaching experiments should be analyzed for waste minimization possibilities. The general strategy in this type of review is to replace more hazardous chemicals with less hazardous ones. Heavy metals, especially mercury, should be targeted in such reviews, as should carcinogenic and highly toxic chemicals. In some cases, the experiments can be redesigned so that solutions can be reused rather than discarded after a single use, or so that the final products of one experiment can be used as starting materials in another.

Continual Improvement

All teaching laboratory experiments should be reviewed periodically, not just for waste minimization purposes, but also to make sure that the teaching experience is as effective as possible. When experiments are reviewed for possible modification, waste minimization opportunities should be incorporated into the decision-making process.

EHS can review your laboratory manual to offer suggestions for modifying teaching laboratory experiments. Contact Robin Izzo or James Boehlert at 258-5294.

*Reprinted in part from Chemical Health & Safety, November/December 1995