Waste seashells created by the seafood sector are being used by Bath University in a new waste water cleaning project.
Dr Darrell Patterson, from the University’s Department of Chemical Engineering, used waste mussel shells to create what is claimed to be a cheaper and more environmentally friendly way of treating waste water, which could then be used to remove substances including hormones, pharmaceuticals or fertilisers.
Traditional wastewater treatment broadly involves the removal of any solids and oils; then the filtering and degradation of the biological content of the sewage, which is derived from human waste, food waste, soaps and detergent.
Finally a tertiary treatment is used to further improve the quality of the water before it is released. There are different methods of tertiary treatment, and one of the most effective is the photocatalysis of water to remove any final trace contaminants.
This process normally uses titanium dioxide which is expensive. By replacing this with hydroxyapatite (a material containing calcium that is derived from seashells), Dr Patterson is aiming to significantly reduce the cost and reusing a renewable unwanted waste product.
In a statement Dr Patterson said: ‘Mussel and other seashell farming is a fast growing industry around the world and the increase in the production of shellfish generates a large amount of shell waste.
‘Shells are a calcium rich resource that can be used to produce calcium oxide [lime]. This lime can be used in several different ways in environmental technologies, and our study has shown that the hydroxyapatite formed from them is an effective, green and potentially cost-efficient alternative photocatalyst for waste water treatment.’
The research was carried out using mussel shells, but other types of seashell could feasibly be used to produce photocatalysts, making this technique globally applicable.
The project will now go on to look at the wider applicability of this technology and the scaling up of shell-based photocatalysts to industrial level.