Waste reactor removes iron from polluted mine water

Focusing on six former coal mining sites, the National Mine Site Research Facility, based at Newcastle University, will use techniques pioneered by Newcastle scientist Paul Younger.

“Because land in many of the areas affected by past mining activities has a low economic value, there is a real need to find low cost, low energy solutions,” says Paul Beck, Chief Executive of remediation group CL:AIRE supporting the new centre.

The chosen sites have different drainage conditions and are being remediated using different techniques. Continual monitoring will detect physical and chemical changes over time and establish whether these interfere with treatment.

Professor Younger’s research is geared towards passive treatment that exploits biogeochemical processes naturally occurring in soils and rivers.

One project, Optimisation of Ochre Accretion at Source, uses the natural phenomenon by which iron oxidises and clusters to form ochre. The group designed reactors – cylinders containing wide surface areas – to remove excess iron by precipitating it on the surfaces. The reactors were placed beneath waters discharged from an old iron mining site, and were able to remove at least half of the iron in the water.

The reactors, tested first with synthetic filters, were then redesigned using cheap waste materials such as blast furnace slag and non-recyclable plastic. After six months in the field, the furnace slag performed as well as the filter, but the plastic captured less iron, possibly because of the smoothness of its surface.