Using biochar from alien bluegum tree for water filter

A LOW-COST water filter using biochar made from alien bluegum trees is being developed at the University of Stellenbosch.

The vision is that the filter would be ideal especially for rural communities, which could also use the bacteria-saturated biochar as compost to enrich the soil on their agricultural land.

The project is headed up by Professor Gunnar Sigge, of the Department of Science and Technology – National Research Foundation Centre of Excellence in Food Security at Stellenbosch University, and is being tackled in collaboration with the universities of Venda and Pretoria.

The study was still at laboratory scale and the focus was on water containing organic pollutants.

But it was likely it could also in the future be used for industrial pollution and there was potential for a national roll-out, Sigge said.

Biochar is wood or other plant material transformed via pyrolysis, a process where the temperature is increased in the absence of oxygen. Sigge’s team checked the filtering capacity of various types of biochar and the product made of bluegum wood came out tops related to its internal structure.

Sigge said the aim was to make the filter sustainable and simple.

“My personal idea would be to look at making a very basic, easy to use, low-cost type of filter which can be used in rural communities.

“The intention would be that it would not end up in landfill and that it could instead be recycled or easily restocked with fresh biochar which could possibly also be produced by the users.”

Alien bluegums compete with indigenous trees for resources and guzzle groundwater supplies, which is why they are often targeted in alien removal programmes.

Sigge said his biochar project could also promote this clearing of bluegums, indirectly generating jobs and ecological benefits.

There was also potential for recapturing and recycling useful organic compounds, he said.

“In instances where a specific organic compound is present in the wastewater of an industrial or agricultural source, there is scope for using biochar to filter this out of a waste stream and then recovering the compound,” Sigge said.

The new “bluegum biochar water filter” presented exciting possibilities, he said.

“A lot more research is needed but in time there may be the possibility of rolling out the product across the country.”

The new filter did not diminish the need to avoid polluting fresh water resources, Sigge said.

“I would always advocate the prevention of pollution . . . the water on our planet is all we’ve got.”

It might even be possible to install the bluegum biochar filters in rivers, he said, “but the scale would be quite something”.