Solar-powered water purification

Fresh water is a precious commodity that needs to be managed carefully, particularly in rural areas with developing industries that have limited wastewater treatment options. In the agricultural and seafood industries, for example, standard filtration and microbial wastewater treatments do not remove all organic matter from recycled water.

The EU-funded ‘Photocatalytic materials for the destruction of recalcitrant organic industrial waste’ (PCATDES) project is using sunlight to remove organic pollutants from wastewater. This photocatalytic approach targets the final stage of water treatment and aims to remove residual matter from oil pressings and chemicals from fish/prawn farming.

Radiation energy from ultraviolet light is often used to purify water since it destroys pathogens by producing damaging oxygen-free radicals. This purification process can be boosted by a light-activated material called a photocatalyst, which absorbs light and passes on the increased energy to other molecules.

A commonly used photocatalyst is titanium dioxide, which upon light activation reacts with water to generate hydroxyl-free radicals that break down organic molecules. To increase the energy of the photocatalytic reaction, PCATDES used commercially available light-emitting diodes (LEDs), which operate in the high-energy violet-blue part of the spectrum.

Having evaluated the activity and stability of the improved photocatalysts, researchers are designing and building standardised LED-illuminated photoreactors. Next, they will scale up the prototype reactor and test it in the field, focusing on the palm oil and seafood industries.

PCATDES' ultimate goal is to provide a cost-effective, energy-efficient, automated, portable photocatalytic reactor for wastewater treatment in remote areas. Apart from generating new knowledge on photocatalytic materials, the project's conclusion will increase the global population's access to clean and safe drinking water.