It can be a hard sell: a metal recycling yard that’s environmentally responsible. But that’s exactly what we’ve been up to lately, helping a scrapyard not only meet their eco commitments, but exceed them!
Christchurch’s Urban Legacy
Specialists in the collection, processing and exporting of ferrous and non-ferrous scrap metal, Resource Recycling Technologies had a problem. It was one ECAN didn’t want, and one Resource Recycling wanted to flip on its head. It was a century-old problem, not helped by a widespread historical legacy of contaminants pumped into the Avon River by multiple generations of numerous industries.
Resource Recycling wanted to clean up their act, and while efforts had been made to purify their wastewater, their unit was proving problematic. In short, it had issues meeting ECAN standards. And that’s when we came in. Two years on, the system is now reliably meeting, and even exceeding, the environmental standards.
Protecting Our Waterways
Resource Recycling’s Electrocoagulation (EC) unit had issues meeting ECAN standards. Essentially, EC is a wastewater treatment technology capable of removing suspended solids, dissolved organic matter and nutrients, faecal indicator bacteria, heavy metals, oils and other organic contaminants.
The subtraction of suspended particles from wastewater to improve water quality is often achieved by adding a coagulating chemical. When mixed in the wastewater, the chemicals dissolve to form aluminium or ferric ions, which carry a positive charge. Natural suspended particles carry a negative charge which is neutralised by the positive ions, causing the particles to clump together and form a sludge. The removal of the sludge leaves cleaned water ready for discharge.
In its simplest form, EC is a means of putting aluminium or ferric ions into water. However, rather than adding a chemical, the ions are ‘dissolved’ directly from metal or aluminium or iron electrodes using an electric current. It’s a concept with a long history, first proposed in 1889 for treating a London sewerage treatment plant! By 1906 the EC technique for treating ship bilge water had been invented and patented. And of course, today, EC is a cost-effective wastewater treatment commonly used across New Zealand for the treatment of industrial wastewater.
EC’s end result? Clean water that can be confidently and safely released into urban stormwater and ultimately into natural waterways.
Widely used for the treatment of industrial wastewater, chemical-free EC technology makes sense!
The Benefits of Electrocoagulation
- Environmentally friendly: chemical free and can be powered by green energy sources.
- Cost-effective: economical to run and has relatively low maintenance costs.
- Efficient: Quickly and effectively purifies wastewater.
- Sludge reduction: produces less sludge than other methods. What sludge is produced is easier to dewater.
- Water quality: clear, odourless and colourless water.
- Flexibility: can be integrated into existing wastewater systems.
- Metals recovery: can recover metals from wastewater.
- Arsenic removal: can remove arsenic from water without the need for an oxidation step.
Engineering a Cleaner Tomorrow
Our work with Resource Recycling’s EC unit began two years ago. Understanding EC requires chemistry and physics, as well as an appreciation for the challenges of water contamination – a complex combo, but a task our engineers were up for!
While electrocoagulation is a relatively simple process to operate and maintain, it needs the right setup and operation. Through research and thorough testing, we were able to form conclusions and implement repairs to the system.
There wasn’t one simple fix, and it was an ongoing process. We’re pleased to report that recent ECAN testing showed the system is now performing above the required standard, with results exceeding expectations.
Today, Resource Recycling can safely release their cleansed and treated wastewater into Christchurch’s stormwater systems, doing their bit for the environment and ultimately helping with the healthy structure of the Avon River.
As we continue to face challenges with pollution, technology will play an increasingly important role in ensuring the safety and sustainability of our water supplies. By understanding and harnessing the power of engineering and technology, we can contribute to a cleaner tomorrow.