Paper coating biomaterial from wastewater sludge a cost-effective alternative, finds study
19 Mar 2024 --- Researchers have unveiled what they say is a cost-effective and sustainable method for paper coating derived from anaerobic granular sludge. The technique, outlined in a peer-reviewed Environmental Science and Ecotechnology publication, showcases the potential of extracellular polymeric substances (EPS) recovered from wastewater sludge as a viable alternative to traditional paper coatings.
The demand for paper and paperboard continues to soar globally, particularly within the packaging sector. Traditionally, paper coatings have been associated with high financial and environmental costs.
However, this new approach by the researchers offers a solution by harnessing renewable materials from wastewater treatment processes.
The study involved coating paper with EPS extracted from various anaerobic granules found in wastewater collected from a brewery and a paper-industry wastewater treatment plant. Results demonstrated an improvement in waterproofing (65%) and enhanced resistance to oil and grease.
Furthermore, due to its multi-layered microstructure, the coated paper exhibited a smoother and less porous surface.
“This research establishes for the first time that EPS derived from anaerobic granules exhibits interesting water barrier properties when used as paper coating additives,” write the researchers.
“More importantly, from the paper industry’s perspective, these EPS enhance grease penetration and absorbance resistance. These biomaterials recovered from waste granular sludge provide a sustainable resource for industrial application and promise to realize a sustainable and circular economy.”
Promising paper-industry sludge
The study details that EPS compositions were predominantly composed of proteins, regardless of the origin of the sludge. Spectroscopic analysis confirmed the presence of “protein-like” components, particularly tryptophan, along with “humic-like” substances.
Adding EPS to paper coatings resulted in “significantly” improved water and grease-proofing properties. EPS samples from paper-industry sludge exhibited the most promising outcomes, with higher protein and hydrophobic contents. The structural properties of extracellular proteins were pivotal in enhancing paper coating effectiveness.
“Wastewater contains substantial resources, ranging from 50% to 100% of lost waste resources. Recovery of resources from wastewater (known as ‘water mining’ or ‘wastewater biofactory’) through product extraction is an emerging concept and becomes attractive for environmental protection, economy and industrial areas.”
“Our findings of rheological behavior reflecting strong similarities with gel materials can offer a vital theoretical basis for paper coating without additional modification.”
The findings hold promise for the paper industry, offering a cost-effective and environmentally friendly alternative to conventional paper coatings.
Global market researcher Innova Market Insights highlighted “Breakthrough Barriers,” as a top packaging trend for 2024. As paper-based packaging manufacturers unlock growth potential in fresh food with plastic-free barrier innovations, coatings are now a key focus in almost every part of the industry.
As the global push for sustainability intensifies, these biomaterials recovered from waste granular sludge provide a sustainable resource for industrial application and “promise to realize a sustainable and circular economy,” conclude the researchers.
Edited by Radhika Sikaria
