The ability of an environmentally-friendly method to remove and recover the CCA from end-of-life trellis posts to enable the wood to be repurposed is being investigated as part of a PhD funded with a top-up scholarship from Wine Australia.
Anwarul Islam, a PhD candidate at the University of Adelaide, is aiming to develop a leaching solution, known as a lixiviant, that can extract at least 90 per cent of the chromium, copper and arsenic used to protect the majority of timber trellis posts in Australian vineyards from fungal and insect attack.
Lixiviants have been used for many years in industries, such as mining, to extract metals from a material. Anwarul says the lixiviant he is working with is a water-based, green chemistry-induced product that generates zero secondary pollution and zero liquid waste.
Trellis posts are treated with the lixiviant once chipped, with the CCA extracted within a matter of hours. The metal-rich solution then undergoes a secondary, chemical-free process to precipitate the CCA from the liquid. The remaining timber material, now almost absent of CCA, can then be repurposed.
PhD candidate Anwarul Islam
“This project is all about turning a persistent hazardous waste issue into a recycled re-source that can reduce the load of fresh wood for other usages, such as medium density fibreboard,” Anwarul said. “By removing the hazardous CCA from the posts to enable them to be either disposed of safely or the timber reused, we hope to offer vineyards a sustainable alternative to stockpiling or landfilling.”
Anwarul’s research is currently preliminary but the results to date are promising. Once his laboratory-scale experiments have been optimised, a larger-scale prototype will be developed and tested before embarking on the design of an industrial-sized facility.
“Our primary objective is to minimise the liquid waste from the extraction process and re-use the same liquid in a closed loop process. Another goal is to remove the metals recovered from the lixiviant as pure metals so they can be reused,” Anwarul explained.
“With this circular economy solution, vineyards can protect their soil and groundwater, reduce waste, and contribute to a cleaner wine future,” he said.
Anwarul’s research is one of several Wine Australia-backed initiatives helping growers turn end-of-life CCA posts into high-value, low-emission products to keep them out of landfill.