Project explores new markets for paper mill waste sludge

London— A project to develop opportunities for recycling paper mill sludge into new products is being funded by WRAP (the Waste & Resources Action Program). Employing innovative technology from Canada, the overall aim of the project is to derive economic benefit from the waste by processing it into usable materials and reducing the amount that is landfilled.

The project, allocated significant funding by WRAP, will use the capabilities of the new KDS Micronex sludge processing plant developed by First American Scientific Corporation (FASC). Sited at Aylesford Newsprint in Kent, the demonstration plant is the first of its kind in Europe.

Paper mill sludge is the main waste product from the manufacture of white recycled papers, and can represent as much as 40% of the material input in the production of higher quality paper grades. In total, UK mills generate around one million tons of sludge per annum, and end uses for this material have been limited.

“With higher quality requirements for paper, and rising landfill costs, the volume and cost of sludge disposal is becoming an inhibiting commercial factor for the further expansion of recycled paper manufacture,” explains David Powlson, WRAP’s technical manager for paper.

Up until now, the potential to recycle the sludge has been limited because of its composition. Typically, it is made up of 50% fiber and 50% fillers (minerals used to increase smoothness, gloss and opacity); two components that can be recycled more easily individually than in combination. What the FASC equipment can do is cost effectively dry the sludge into a fluff, as opposed to a compacted residue, allowing the fiber and fillers to be separated out.

The project divides into three stages. Initially, the moisture content of the sludge is reduced from 50% to 10% by the KDS Micronex. The resulting sludge fluff can then be split into its fiber and filler constituents using screening equipment, and the materials assessed for their recycling potential. In the case of fiber, possible end uses include insulation, lower grade paper applications and fuel briquettes, and the filler material has properties that could be beneficial in the manufacture of a range of products, particularly for the construction sector.

Brian Nichols, president of FASC, is confident that the demonstration will deliver positive results.

Expected to be running at full capacity in June, the KDS Micronex and associated equipment will be installed and initially operated by RB Plant, which has in-depth experience in this field.