Waste from age-old paper industry becomes new source of solid fuel

February 12, 2014, American Chemical Society

In today's search for renewable energy sources, researchers are turning to the hi-tech, from solar and hydrogen fuel cells, and the very low-tech. The latest example of a low-tech alternative comes from an age-old industry: paper. A new study, appearing in ACS' journal Energy & Fuels, reveals a sustainable way to turn the huge amounts of waste from paper production into solid fuel with the added bonus of diverting the sludge from overflowing landfills.

Chinnathan Areeprasert, Peitao Zhao and colleagues note that making paper, from debarking and chipping wood to the final steps of pulping and refining, creates a tremendous amount of wood fibers and other wastes. Sending this sludge to landfills can be problematic, because substances can leach out and pollute groundwater. But recently, researchers have been exploring ways to turn the planet's growing waste streams 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, . Early studies show it can transform paper sludge into fuel as well. Areeprasert's team decided to figure out the best HTT conditions for this process, and to test them in a pilot plant.

They tried different temperatures and defined the optimal conditions for converting paper waste into fuel using HTT. The resulting product had a composition similar to coal. Importantly, the amount of energy that can be recovered from the fuel is higher than the energy required to make it. The researchers conclude that this method for making is both sustainable and lends itself to commercialization.

Explore further: Energy from microbes for drying sewage sludge

More information: "Alternative Solid Fuel Production from Paper Sludge Employing Hydrothermal Treatment" Energy Fuels, Article ASAP. DOI: 10.1021/ef402371h

This paper aims to investigate the alternative solid fuel production from paper sludge employing hydrothermal treatment (HTT) in a lab-scale facility for implementation of the pilot-scale plant. The paper sludge was subjected to the HTT under subcritical hydrothermal conditions. In the lab-scale experiment, the temperature conditions were 180 °C, 200 °C, 220 °C, and 240 °C, respectively, while it was 197 °C in the pilot plant as the optimum condition. The holding time was 30 min in both cases. The hydrothermally produced solid fuel was evaluated for the fuel property, the water removal performance, and the mass distribution. Furthermore, the energy balance of the process was studied. The higher heating value of the HT pretreated paper sludge was slightly improved. In addition, the produced solid fuel had comparable H/C and O/C atomic ratios with that of coal, indicating the presence of carbonization during the HTT process. Using the mechanical dewatering, only 4.1% of moisture in the raw paper sludge can be removed while the solid fuel production from paper sludge by HTT at 200 °C showed 19.5% moisture reduction. According to the energy balance of the pilot plant, the recovered energy was significantly higher than the energy input, showing the feasibility of employing the HTT to produce alternative solid fuel from paper sludge.

Related Stories

Energy from microbes for drying sewage sludge

August 13, 2012

A new biodrying process from Siemens quickly converts sewage sludge into a usable form while saving energy. When dried with the new process, sludge from wastewater treatment can be used as fertilizer, dumped in landfills ...

Paper waste used to make bricks

December 19, 2012

Researchers at the University of Jaen (Spain) have mixed waste from the paper industry with ceramic material used in the construction industry. The result is a brick that has low thermal conductivity meaning it acts as a ...

New tech could be "Mr. Fusion" for biofuel

November 20, 2013

A new technology from Argonne may remind viewers of Mr. Fusion of Back to the Future fame, only with a biofuel twist: put in your waste and out comes diesel fuel.

Microbes strip power from poo

September 17, 2013

EPSRC-funded scientists have developed a process using microbes which removes the need to use electricity to process sewage at treatment plants. The microbes can also be used to produce large quantities of valuable hydrogen ...

Recommended for you

What can snakes teach us about engineering friction?

May 21, 2018

If you want to know how to make a sneaker with better traction, just ask a snake. That's the theory driving the research of Hisham Abdel-Aal, Ph.D., an associate teaching professor from Drexel University's College of Engineering ...

Flexible, highly efficient multimodal energy harvesting

May 21, 2018

A 10-fold increase in the ability to harvest mechanical and thermal energy over standard piezoelectric composites may be possible using a piezoelectric ceramic foam supported by a flexible polymer support, according to Penn ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Feb 12, 2014
Sometimes I wonder why we do not get more power from the Sun. Could it be that sunshine cannot be privatized?
Doesn't it make more sense to keep all the complex hydrocarbons, and even cellulose, whole?
Paper waste makes excellent building material. I have been using it for years. Recently, a process was patented to reunite cellulose fibers and lignin full resin into - wood? No, building blocks. For more information, see http://masongreenstar.com/

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.