New device for ultra-clean water aims to boost hydroponics, sustainable agriculture

A photoelectrochemical water treatment device is being developed by a team from the University of Canterbury, led by Professor Alex Yip from the Chemical and Process Engineering department.

According to Yip, the project’s goal is to ensure a food supply that is resilient to climate change. He outlines that hydroponics, a method where plants grow in water rather than soil, is gaining global significance as it offers a way to cultivate crops in environments shielded from rising risks like storms, pests, and disease. However, this approach depends on access to ultra-clean water that is free from contaminants and pollutants.

He also adds that if hydroponics is applied on a large scale in developing countries where water is scarce and not entirely clean, it can lead to the buildup of pollutants in the plants, a process known as bioaccumulation.

“With a closed system with recirculating water, it is very important to keep the water clean, especially from emerging micropollutants, which is what we are targeting with our new device. These micropollutants include pesticides, endocrine-disrupting chemicals and long-lasting pollutants,” Yip said .

Dual power solution for round-the-clock water purification

The team’s device stands out for being both affordable and unique, as it harnesses solar energy, minimizing dependence on electricity. During the day, the device converts solar light into chemical energy to purify water, and at night or in low-light conditions, it automatically switches to an electrical system to continue the purification process. This dual power feature makes the device more versatile and reliable.

Once the product is developed, it can be marketed globally, especially to countries where access to clean water is limited, Yip said.

The project team, which includes PhD students Chunyan Zeng and Vicky Tsui, the latter funded by the Joint Postgraduate School Food Transitions 2050, has already demonstrated the device’s effectiveness in a laboratory and is now testing it in a real-world hydroponic system.

Hydroponic farming could cut food miles and reduce carbon emissions

Yip emphasizes the importance of hydroponic farming due to its potential to reduce the carbon footprint of the food supply chain. Establishing urban farms, including high-rise farming in city centers, would eliminate the need for long-distance transportation of produce.

This approach could also allow year-round cultivation of crops, enabling off-season growth of high-value plants while cutting down on carbon emissions linked to food transport.

While the photoelectrochemical water treatment device is intended for large-scale use, it can also be utilized in individual households as an alternative or complement to traditional water filters. Water filters effectively remove substances that are not soluble in water, but they are less effective against the smaller micropollutants targeted by this device.