Waste from Paper Industry Transformed into Viable Solid Fuel

In the search for viable renewable resources, researchers have been testing hi-tech, including solar and hydrogen fuel cells, as well as the very low-tech. The latest breakthrough in low-tech alternatives comes in the form of paper.

In a new study, appearing in the journal Energy & Fuels, researchers report a sustainable way to turn the huge amounts of waste from paper production into solid fuel while also diverting the sludge away from our already overflowing landfills.

Chinnathan Areeprasert, Peitao Zhao and colleagues noticed that making paper, from debarking and chipping wood to the final steps of pulping and refining, created a vast amount of wood fibers and other wastes. Dumping this sludge of by-products into a landfill can be problematic, as substances can leach out and pollute groundwater.

Recently, researchers have been exploring ways to utilize waste from human productions and turn it into useful products, such as fuel and fertilizer. "One such process is called subcritical hydrothermal treatment (HTT), and it uses heat and pressure to break down and remove various components of a mixture. In one case, researchers used HTT to turn sewage into a clean, solid fuel. Early studies show it can transform paper sludge into fuel as well," according to the press release announcing the findings.

In the study, Areeprasert's team figured out the best HTT conditions for turning waste into useable fuel, and to tested them in a pilot plant. By testing various temperatures, the team was able to define the optimal conditions for converting paper waste into fuel using HTT. The resulting fuel is very similar to coal. Most notably, the amount of energy used to make the fuel is less than the amount of energy that can be used for productive work from the fuel. The researchers concluded that the HTT method is both sustainable and commercially viable.

This study represents one small step toward a more sustainable planet.