Waste Disposal in the Undergraduate Teaching Labs

It’s the end of a lab period and the lab space needs to be cleaned. But what should I do with the chemicals I no longer need?  The answer not only affects how long you are required to stay in the lab but it also has a major environmental impact. Even introductory chemistry labs deal with harmful chemicals that need to be disposed of properly. This is the responsibility of not just the student and teaching assistant, but also a major task of the university staff to ensure harmful chemicals – from all the teaching labs – are handled with the proper precautions.

Recently I was able to tour the University of Arizona chemistry teaching labs in the Koffler building and got an insight into the waste procedures in place at the university and how the labs are being restructured to reduce waste. After all, waste management begins with the students. Each lab generates solid, liquid, glass, or sharps waste; which is then separated by the lab facilities into different containers depending on the type of waste. Once each type of waste has been sorted, it is then stored in heavy-duty, ventilated cabinets until it can be picked up by the Risk Management facilities on campus.

liquid_waste2[1]To ensure that nothing contaminates the local water supply, students in the labs are told that only pure water goes down the drain. However, this implies that everything else is liquid waste. All liquid waste is disposed of into 10-liter buckets in each lab, ranging from suspected carcinogens like dichloromethane and chloroform, to toxic liquids such as mercury(II) chloride and potassium dichromate, to corrosive acids and bases at a variety of concentrations. Sometimes even very flammable chemicals like lithium aluminum hydride are placed into the waste bucket, making for a very dangerous cocktail. For an average week, the chemistry teaching labs handle about 550 liters of liquid waste. The 10-liter buckets, which again are safely stored in ventilated cabinets for pickup by Risk Management, cost $1.80 per liter for disposal. This comes to be an average of $1000 per week to remove liquid waste. However, these are just averages, the amount of liquid waste and the cost of removing that waste does fluctuate throughout the semester.

Solid and sharps waste is disposed of via an incineration process, which generates energy for the university, while glass waste is pulverized and disposed of in a landfill.  On average, two large waste bags of solid waste are removed per week from the labs. Each large bag contains about 6-10 smaller bags of solid waste, which come from the solid waste containers found in each lab classroom. Each of these solid waste containers can hold paper towels used to clean chemical spills, silica that was generated in making columns, and other solid chemical waste, such as metals or insoluble salts. The amount of glass waste can fluctuate greatly and as such it is hard to determine an estimate on how much glass waste is generated. However, glass waste can include beakers and test tubes still lined with chemicals, or silica-backed chromatography plates; all which end up in the landfill.

From my tour of the chemistry teaching labs, the staff at the University has efficient processes in place to deal with the large amount of waste that is generated. However, as efficient as these processes are, they still allow for the incineration of solid waste and the pollution that is associated with that incineration. It is also disturbing that the glass waste generated in a chemical laboratory is disposed of in a landfill. As a student who has taken a laboratory class, I know this glass waste can still carry traces of many harmful chemicals. If this waste is disregarded in a landfill then it is allowing for the accumulation of hazardous chemicals into soil and water streams. The amount of liquid waste is also a surprise. Averaging 550 liters of liquid waste a week seems incredible over a whole semester. It begs the question, how is that much liquid waste disposed of? A question to be further explored in future GREEN articles, along with how Risk Management incinerates solid and sharps waste.

Luckily the staff at the university has taken charge in trying to not only reduce the amount of waste produced in the labs, but have also taken steps to be more environmentally conscious. Currently a project is swooping through the general chemistry course that looks to cut the waste by one-third in some labs, and in other labs by one-fifth. Dubbed “chemical thinking”, this project looks to switch the general chemistry labs to “milli-scale” labs, where the amount of chemicals used by students is reduced and more experiments are brought out of the hoods and onto the bench tops. Along with the “chemical thinking” project, projects like implementing acetone recycling in the organic chemistry labs look to the greener side of things. Acetone recycling is still in a trial phase, as monetary and logistic issues are worked out, but this project could greatly reduce the amount of liquid waste in the organic labs. However, these are just overviews of these projects. In future GREEN articles I look to explore every step of the projects mentioned and a few others I got a glimpse at during my tour.

I would like to thank Mark Yanagihashi for the in-depth tour of the Koffler facilities and the great amount of data he was able to provide for us.