Construction and demolition (C&D) materials make up one of the most significant components of the waste stream. As such, operators and regulators searching for ways to divert this material from landfill are actively pursuing new and innovative recycling solutions.
WasteExpo 2019 kicked off May 6 with a session titled, Change is Coming: Insights Into C&D. The session, moderated by Construction & Demolition Recycling Association (CDRA) Executive Director Bill Turley, brought together University of Florida Department of Environmental Engineering Sciences professor Tim Townsend and U.S. Biochar Initiative Director Tom Miles to talk about creating markets for two of the most difficult to recycle materials: fines and wood.
The issue of finding end markets is an especially critical one for recyclers. At CDRA’s 2019 C&D World conference held March 9-12 in Brooklyn, New York, attendees cited finding end markets—along with regulation—as the most crucial challenge facing the industry today.
While Townsend acknowledged that contaminated fines are often in low demand, he noted that recyclers can find a home for fines by being more scrupulous in how these materials are processed and marketed. Fines, which are the byproducts produced after incoming C&D material has been screened, are commonly contaminated with aggregate, wood, gypsum and shingles—all of which pose unique challenges. However, because different recyclers have different sources of incoming material, Townsend said the process and need to clean up fines will vary by facility.
“You as a facility operator have the ability to create the product you want,” Townsend said. “[You have to ask yourself], ‘What can we pull out to make the best product that we can?’”
“One of the themes I'm going to try to convince you of is that the way facilities operate now is that the fines are considered a waste product, a residual,” Townsend continued. “To really market these things correctly, though, you need to begin to think of them as an actual material that you're going to try to market.”
Once these fines are cleaned up, Townsend said common uses include application as landfill cover for odor control, fill material for shaping and grading projects and as an agricultural amendment.
He cautioned, however, that it is critical for operators to be aware of state regulations that may impact the market for their materials. While chemicals like lead, arsenic, polycyclic aromatic hydrocarbons (PAH) and sulfate are often found in fines, Townsend said that taking proactive steps like pulling out drywall from incoming material, separating construction from demolition debris, washing the material, or applying treatment applications can help improve fine concentrations down the line.
“You have to be aware of what your local contaminate thresholds are,” he said.
Although cleaning up fines can be a lot of work, Townsend said it can pay dividends by way of an improved bottom line.
“C&D fines are important if you're a C&D recycling facility,” he said. “If you can't get rid of them and you're paying a huge tip fee to put it in a landfill, you can't always make your facility work [from a financial standpoint]. So, finding markets is important.”
Beyond fines, C&D recyclers have struggled to derive value from wood. According to Miles, converting wood into biochar offers a solution for transforming a low value byproduct into one that can be used across industries.
Biochar is fine-grained, highly porous charcoals that come in different forms and qualities for different uses, but according to Miles, some of the most common applications are in agriculture, environmental remediation, and as a non-soil carbon product. In agricultural and landscaping applications, biochar can be introduced as a form of compost or fertilizer or in granulated products for hydro-seeding. Miles said that including biochar for agricultural use has been shown to help with root structure of organic material—improving water holding capacity by 25-30 percent, which is especially important in drought-prone areas of the country. In environmental applications, biochar can be used for sewage treatment, mine reclamation and oilfield remediation, or water treatment. As a non-soil carbon product, Miles said biochar can be included in animal feed or building products.
Although biochar has been around for a while, Miles said that the C&D recycling industry is just scratching the surface for its use.
“When you're talking about the production of biochar and enhanced biochar products for use in agriculture and industrial markets, the markets are expanding with better quality products, as well as for applications in non-soil uses,” Miles said. “What we're seeing actually is the maturing of an industry that could turn the clock back on construction, demolition and composting. That's kind of where we are. We're just starting out. Production systems are increasing in quality, capacity and mobile flexibility and biochar is creating new market opportunities for increased value for clean, recycled wood. So, we think there are opportunities especially on the wood paper and mixed fraction side of things. I think we're just kind of getting started seeing how biochar might fit in [with C&D recycling], but we think there might be some compatibility in terms of reducing volume and producing value-added products.”