Growing green with bark sand - New life for industrial waste

Substrate specialists Kekkilä Group are using bark sand as a new raw material for landscaping products. Bark sand is a side stream of UPM’s pulp and paper production processes.

Kekkilä Group is the Nordic market leader in home gardening, substrate and landscaping products. Its products are developed and marketed for professional growers, landscapers and
hobby gardeners.

“One of our business areas specialises in substrates for big landscaping projects like public parks and urban spaces. We use bark sand as a raw material in these products,” explains project development manager Pekka Järvenpää from Kekkilä.

Bark sand is a side stream of the pulp and paper production process. Wood coming to the mill is peeled in the barking drum, after which bark sand is separated on the precipitation conveyor.
Bark sand is a mixture of fine bark, soiland sand wedged in the trees.

Improving soil biodiversity

The main raw material of horticultural substrates is sand and composted peat. The proportion of bark sand in the end product is rather small, but the composted bark increases the activity of microbes and thus​ improves the biodiversity of soil.

“A good-quality soil always contains a lot of fungi, bacteria and invertebrates that feed on bark. The substrate is also more weatherproof and generally of better quality when there are plenty of microbes in the end product.”

The Kymi mill has been supplying bark sand to Kekkilä since summer 2014. There is a constant need for the raw material, says Järvenpää, so the Kymi mill makes an excellent supplier for the company.

Exploiting side streams

Both UPM and Kekkilä benefit from this cooperation as UPM aims to recycle all side streams of its production processes. Before the collaboration began, the bark sand was used as landfill.

“We also recycled all ash from the mill’s power plant last year. Sludge from the effluent treatment plant will be incinerated to generate energy and the lime waste will be provided to fertilizer manufacturers,” says environmental technician Teija Ahola from the Kymi mill.