HAZARDOUS WASTE
Waste Minimization Program: Reducing or Eliminating the Use of Heavy Metals
If you generate waste heavy metals, please be aware that disposal of this waste costs the university almost twice as much as other waste types. Metals of concern due to their toxic characteristics are the following:
Most often, these waste metals are generated with waste corrosive liquids. However, we have seen cases in which a broken mercury thermometer ends up in a bucket containing other waste, including paper, glass, gloves, etc. This contamination causes the entire container to be classed as metal-contaminated waste, thus increasing the disposal costs.
General Reduction Strategies
Source Reduction: substitute alternative thermometer types (red liquid, digital), eliminate experiments involving metals all together, use microscale laboratory techniques.
Segregation: separate, as much as possible, metal-containing waste from other wastes (combining metal waste with other, less costly waste, causes the entire quantity to be disposed of as the more expensive and regulatory-sensitive metal waste). Use a separate waste-collection container and emphasize training of lab personnel.
Specific Reduction Strategies
- Review waste-streams and lab procedures for elimination or reduction of quantities of metals used. The use of microscale equipment or increased instrumentation can reduce the quantities of waste generated.
- Teaching lab experiments using less hazardous metals can be substituted for those involving heavy metals.
- Experiments which brings the raw material through a series of steps to the product and then back to the raw material again can eliminate disposal of that metal.
- Metals used as catalysts can be eliminated by simply allowing more time for the reaction to come to completion.
- Substitute mercury thermometers with non-mercury instruments wherever possible.
Cadmium Reduction
Chromium Reduction
For glassware cleaning, substitute chromic-sulfuric acid cleaning solutions with the following:
- Alconox Lab Cleaner Powder or similar cleaners
- Pierce RBS-35 or similar
- potassium hydroxide/ethanol
- dilute hydrochloric acid
- No Chromix by Godax Labs
Lead Reduction
Mercury Reduction
- Mercury reagents alternatives for mercuric chloride when used as a biocide are solutions such as 5-10% methylene chloride, 1% formalin, 1 N hydrochloric acid, sodium azide, and sodium hypochlorite. When mercury compounds are used as catalysts for reactions, one alternative is to eliminate the catalyst and simply let the reaction run longer.
- Mercury-free catalysts, such as CuSO4-TiO2-K2SO4, can be used in Kjeldahl digests instead of mixtures that contain mercury metal or salts. There are also alternatives for mercuric chloride circuit board etching reagents. One is available through Kepro Circuit Systems (1-800-325-3878).
- Thermometers and Manometers:
Replace mercury thermometers with alternative instrumentation. Red alcohol or mineral spirit filled thermometers can adequately meet accuracy and range requirements. If mercury thermometers must be purchased, those with Teflon coatings should be utilized. In physics labs, thermocouples may be used to replace mercury thermometers. Manometers can be phased out in favor of pressure transducers in mechanical engineering experiments. Bimetal or stainless steel thermometers can be used instead of mercury thermometers in heating and cooling units. Stainless steel thermometers may work in some labs as well. Mercury-containing equipment should always be stored in a secondary container, such as a plastic tray or bin, to contain any spills or leaks.
Selenium Reduction
Use micro rather than macro Kjeldahl apparatus in nitrogen determinations. Kjeldahl waste is considered hazardous waste due to the selenium or mercury compounds used as catalysts.
Silver Reduction