Six trillion cigarette butts pollute our world each year. Their plastic filters make them slow to biodegrade, while they leach arsenic, chromium, nickel, and cadmium into our soil and water. And thanks largely to China’s growing appetite for cigarettes, things may not improve any time soon.
But in 2005, Dr. Abbas Mohajerani—a researcher at Royal Melbourne Institute of Technology's School of Engineering—had an idea. What if he used his specialization in studying construction materials to tackle the problem of cigarette waste?
11 years later, Mohajerani has published a promising paper demonstrating that cigarette butts can be baked into typical clay bricks. His process—which is not funded by the tobacco industry—not only traps the dangerous pollutants, but requires less energy than producing a typical brick.
By his team’s calculations, if a mere 2.5% of the world's annual brick production incorporated 1% cigarette butts, it would completely offset cigarette waste.
The process is fairly simple. First, cigarette butts are collected through recycling programs. They’re disinfected at 105 degrees Celsius (or 221 degrees Fahrenheit) for a day, then stored in plastic bags. These butts are mixed with a typical sand-clay blend, then fired into bricks at 1,050 Celsius, or about 1,922 Fahrenheit.
"The high temperature in the firing process changes the chemical characteristics of the materials; materials are combined, and harmful chemicals are immobilized through the fixation process," Mohajerani explains via email. "The results from our comprehensive leachate study show that the concentration of heavy metals in the leachate were in trace amounts that did not exceed the regulatory limits specified by USEPA and EPAV."
At the same time, the process saves energy. That savings stems from the cellulose acetate in the cigarettes (the plastic), which burn hot in the oven—and thus contribute to the efficiency of firing the clay. Energy savings can reach as high as 58% if you use a high ratio of butts and are unconcerned about the brick’s structural integrity; for example, if you're firing bricks for use in a non-load bearing wall. Meanwhile, mixing cigarettes in the clay at a ratio of just 1%—the optimal ratio to create a brick that functioned as well as a typical brick—required 9% less energy. The bricks also demonstrate superior levels of insulation.
Mohajerani isn’t the first researcher to consider how we could build bricks out of various waste products. Sludge, sawdust, tea leaves, beer bottles, and even urea has been considered for brick production in the past.
Meanwhile, a company called Terracycle—with funding from the tobacco industry—has set up collection containers in many cities to recycle the plastic in cigarettes. Its process isn’t very efficient though. It takes a thousand cigarette butts to produce a quarter pound of plastic, and the remaining organic materials still need to be processed.
Mohajerani’s idea may not take off. Proving out science is one thing. Developing a viable model for distributing that information, making policy changes to promote it, and creating a business plan to disrupt established industries, is another. But it’s a promising approach because it doesn’t require a fundamentally new methodology than is already used to produce clay fired bricks. It basically just demonstrates that mixing some whole cigarette butts into clay is a perfectly feasible way to produce eco-friendly bricks.
"I wanted to make a meaningful contribution to our environment," Mohajerani writes. "It has been a long and exciting research project. And I can see a future where the problem of cigarette butt pollution has been completely removed from our environment. Sometime in the future, all waste will be recycled on our planet."