The Sustainable Initiatives Fund Trust provided local firm, Tech Design and Consultancy Ltd, with a $5,000 grant to assist with a feasibility study, prototype trials and patent searches for their heavy metal filtration system, which were carried out last year. The focus of the project was to determine the effectiveness of using a modified wool copolymer product to filter out heavy metals that are commonly discharged into the rinse water stream from the electroplating industry. In Christchurch, the waste currently enters the Bromley sludge ponds, or is deposited into the ocean via offshore pipelines.
Tech Design have been trialing their prototype filtration system at the Pratt & Whitney Air New Zealand Engineering Centre where electroplating is used in the maintenance and servicing of aviation equipment and jet engines. There are strict controls on the levels of heavy metals entering the Canterbury waste water system and discharges are regularly measured. But, a solution still needs to be found to reduce the amount of heavy metals (such as nickel, cadmium and silver) entering the waste water and potentially into surrounding environments. Tech Design’s filtration solution will remove the heavy metals at source and keep the different metals separated. They are also looking into the recovery of these metals for reuse in the electroplating or other industries.
Tech Design’s filtration system not only diverts heavy metals from local sewage systems (so they don’t end up in municipal biosolids sludge), but it allows a considerable reduction in the rinsewater consumption by electroplaters who no longer have to rely on dilution within the waste water to comply with local requirements. The collection of individual metals at source rather than as a catch-all in the final discharge pipe, opens up the potential for being able to recover and reuse the heavy metals. After stripping, the wool filter media is likely to be suitable for processing through a composting operation. Absorbents other than wool are also being evaluated and some are proving particularly effective in removing cyanide as well. (Cyanide is commonly used in the electroplating process to solubilise metals).
It is also a good thing for the local economy and local industry that the filter units are manufactured in New Zealand.
Project trials have shown positive results. Absorbency of nickel into the wool copolymer product was 90% effective as opposed to an earlier wool trial that was only 50% effective. Other absorbents have also demonstrated metal removal efficiencies of close to 100%. As the efficacy of the product has been established, Tech Design can now trial new ways to reuse or sell on the heavy metals.
The next step is to start to close the process loop by testing some of the other potential benefits such as recovery and composting and developing a sound commercial model.
This project is important in that it is about reducing the harmful effects of toxic heavy metals on Canterbury’s waste water system and surrounding ecosystems. Once the wastewater goes down the drain it still ends up somewhere (as sludge which goes to landfill or into the ocean) no matter how diluted and that will have a negative impact on the environment. And the heavy metals are a resource that could be recovered for reuse as well, reducing our need to import more.
Tech Design also received funding from TechNZ for this project.
Tech Design Consultancy Ltd
Tech Design Consultancy Ltd are a Christchurch based consultancy that manages projects in the manufacturing and processing sector including investigating specialist treatments in the woolscouring industry, machine design and automation, effluent treatment and the production of wool and synthetic knops for carpet and bedding products. They also work with Fibrespill environmental products (manufactured by Fibretech NZ Ltd) to sell wool and synthetic based products to remove oil from waste and storm water as well as other oil spill recovery products.