Bemidji State University Reduces Chemistry Lab Waste by Almost 35%
Downsizing Instructional Chemistry Lab Experiments
Bemidji State University (BSU) had an undergraduate enrollment of 5,366 in the 1997-1998 academic year. The Chemistry Department offered approximately 15 courses each year, with 115 students enrolled in the classes.
Incentives for Change
In one year, BSU’s chemistry labs generated 57 liters of hazardous waste. The majority of the waste, 38 liters, came from the organic chemistry labs. Of those experiments, 90 percent produced hazardous waste.
The department wanted to reduce hazardous waste from its instructional chemistry laboratories. It wanted to reduce exposure to chemicals, decrease the likelihood of spills and reduce the inventory of toxic materials. Achieving these goals would increase student safety and decrease exposure liability. The department also hoped to reduce the cost of experiments. By better characterizing the lab waste, BSU hoped to decrease the need to test it and allow for a less expensive disposal method. Disposal cost for lab waste was greater than the cost of reagents.
The department started integrating microscale experiments in its general organic chemistry course in 1990. For each experiment, half of the students used microscale procedures and equipment. The other half used conventional-or macroscale-glassware with semi-microscale procedures. Students alternated in their use of the two techniques.
A MnTAP intern reviewed BSU’s undergraduate instructional chemistry laboratories during the summer of 1998. She identified alternative experiments and modified current experiments to produce fewer types and smaller quantities of hazardous waste. The intern’s work built on some experiment evaluation that the department had already done.
Bemidji State University-Success at a Small Educational Institution
With the help of the intern, Bemidji State decreased lab waste by nearly 35 percent and reduced reagent use by 33 liters per year. The department estimates $1,800 in annual savings from purchasing less reagent and reduced disposal cost. By reducing inventory, it also has recovered storage space, allowing for better organization.
Changes at BSU included scaling down additional experiments to small and microscale, distillation and reuse, and eliminating or finding alternative experiments. Over 90 percent of the savings from the intern project resulted from microscaling experiments.
Education and Lab Practices
The university’s first priority was to meet all of the educational objectives for teaching chemistry. Lab experiment changes could not compromise learning.
Students need exposure to microscale techniques and equipment. By promoting laboratory waste reduction, educational institutions can train future generations of scientists to be environmentally sensitive and conservation minded.
Microscale techniques teach precision and accuracy. Working with reduced quantities of chemicals promotes attention to detail, improving the quality of the science being done. Students develop excellent laboratory manipulative techniques and good lab practices. Also, shorter experiment time is needed for reactions to occur.
Bemidji State found that students who are inexperienced in chemistry may have difficulty producing a product in a microscale experiment. Without a product to analyze, students potentially miss out on the learning derived from product characterization. Some students may also find this lack of success discouraging.
The National Research Council notes that students who learn using microscale techniques need to understand potential hazards-due to rates of reactions and the hazards of exothermic reactions-when reactions are run on a larger scale.
Eliminate, Substitute Experiments
BSU eliminated the experiment Nine Bottles: An Adventure in Chemical Identification. This eliminated a large quantity of toxic precipitate waste produced from mixing solutions for identification purposes.
Less hazardous reagents can substitute for more hazardous ones. Bemidji State substituted sodium chloride (NaCl) solution for isopropyl alcohol in its inorganic analytical class’s thin layer chromatography experiments. This change also required adaptations in the food dyes. Now the experiment generates no hazardous waste.
When the use of nonhazardous or less hazardous materials cannot be avoided, many experiments still can be carried out on a smaller scale. Scaled down experiments use smaller quantities of reagents and result in smaller quantities of other waste-filter cakes, filter papers, filtrate from washings, and distillation residues.
Small Scale. According to Battelle Memorial Institute, most macroscale experiments can be scaled down by about 50 percent with little effort or cost, and without sacrificing quality. This usually can be done using conventional glassware.
Microscale. This reduces chemical use to the minimum level at which experiments can be run effectively.
Microscale Experiments Reduce Chemical Use
|10 – 50g
|100 – 500ml
|25 – 100mg
|100 – 2,000mL
National Microscale Chemistry Center, 1995
Equipment. In general, revised laboratory methods, glassware and means of chemical analysis are necessary to carry out experiments on a microscale level. Smaller equipment is required for these experiment. BSU had to purchase 96-well plates, 24-well plates and disposable micropipets for General Chemistry labs. The Organic Chemistry labs required the purchase of microscale kits.
For many microscale experiments every day supplies can be used. Toothpicks can be used as mixing rods. Straws, forceps and a Beral pipette serve as a buret.
Glassware used in microscale procedures is generally not as fragile as conventional glassware. Less broken glass improves safety and decreases equipment cost.
Distillation and Reuse
The BSU Chemistry Department’s stockroom now distills more spent solvents for reuse. BSU distills potassium acid phthalate (KHP), standardized sodium hydroxide (NaOH) and hydrochloride (HCl) for use in freshman analytical labs where accuracy is less important. These less selective solvents are used in initial washes to remove reactants from the bound product. These washes are followed by a pure solvent. Staff time for distilling was calculated in assessing the value of reuse.
In some circumstances, the products of one experiment can be used as reagents in another. This reduces the amount of reagent purchased and eliminates waste shipping costs. BSU’s organic labs run a multistep synthesis using products of one experiment as reagents for another. The extra products from each step are saved to supplement the next class’s reagents. In BSU’s thin layer chromatography experiments, developing solvents are reused.
Neutralizing acids and bases. Pure acid and base solutions can be neutralized and disposed down the sewer. Although this eliminates the shipping of waste, it is not a true waste reduction. The amount of acids and bases must still be reported as hazardous waste. The salt formed from neutralizing contributes to water pollution.
More accurate labeling. Much of BSU’s lab waste was not properly labeled. As a result, the department had to lab pack it-carefully pack together each waste in separate containers for safe shipping. This method of disposal is much more costly than bulking wastes that are readily identified.
Reviewing Your Experiments
- Assess What Waste is Generated. Review current laboratory experiments to determine the amount of reagents used, and the amount and type of waste produced. Have the environmental services staff from facilities management determine if the waste from each experiment is considered hazardous by law. Bemidji State found that 35 of its 63 lab experiments produced hazardous waste. Twenty four experiments produced waste that was not hazardous but could be reduced.
- Outline Educational Objectives. Determine the desired educational objectives.
- Evaluate Experiments. See if the current experiments can be modified to produce less waste by changing a procedure or substituting another reagent. Changing experiments can be time consuming. Plan for the greatest reduction possible. Many excellent sources for alternative experiments are available (see Additional Resources below). Assess the waste that will be generated from all the new experiments you are considering.
New experiments need to be tested for clarity. A small number of students should test the new procedures before full scale use in a classroom.
University of Minnesota-Success at a Large Educational Institution
Using microscale techniques, the University of Minnesota, Department of Chemistry, reduced the volume of waste generated per student from 3.1 liters to 0.03 liters. With about 3,350 students enrolled in chemistry courses, total waste per year is decreased from approximately 10,400 liters to 100 liters. Changes to general chemistry undergraduate courses resulted in $35,000 in savings annually. In 1992, revised experiments were introduced to all chemistry labs.
A number of good sources are available for alternative experiments. Here are a few favorites:
- Davis, Michelle, et al. Laboratory Waste Minimization and Pollution Prevention, WA: Battelle.
- Schaap, T. Combs and J. Young, J., Microchemistry 1. West Chester, OH: Kemtec, 1996. pp 57-59.
- Schaap, T. Combs and J. Young, J., Microchemistry 2. West Chester, OH: Kemtec, 1996. pp 55-56, 64-70.
- Partnership for Environmental Technical Education (PETE). North Central PETE 319.398.5893.