Overcoming a mining legacy that makes the river run red

FOR decades it has been known as the red river, the stream running through a former mining village overlooking the North Sea.

But now scientists at the University of Teesside in Middlesbrough, England, believe they have the answer to the rust-coloured staining of the river caused by ochre – the earthy pigment containing ferric oxide – that leeches out of the old underground workings 40 years after the last mines closed.

The team from Teesside University’s Clean Environment Management Centre (CLEMANCE) has identified ways of extracting the ochre and recycling it for use in the cement-making industry.

They say their environmentally-friendly solution could help to clean up hundreds of similar rivers and streams polluted by mining all over Europe, and beyond!

In the case of the red river running through Skinningrove, north of Whitby, the pollution is a legacy from the days when there were 86 ironstone mines in East Cleveland and North Yorkshire and Teesside was the iron and steel-making capital of the world.

The mines have gone. But the dissolved ochre still seeps out; smothering the organisms, blocking sewers and clogging fish gills when it arrives further down stream in coastal areas like Skinningrove.

Several years ago, villagers obtained funding to install a filter-based treatment system. But this rapidly became clogged up with ochre. So they called in the University of Teesside team to find a new solution.

Heading the research has been Dr Richard Lord, from CLEMANCE’s Bioremediation Programme, an expert at cleaning up old industrial sites for re-use who has conducted extensive research into mine-water pollution.

The ochre sludge is collected in large tanks, which are emptied every four months. After experimenting with various extraction methods, the team of scientists settled on specially designed geotextile bags to filter the ochre sludge pumped from the filters, extracting solid iron oxide and returning clearer water to the river.

Handling iron oxide is very difficult because it turns back into a liquid when transported. Previously, ochre residues tended to be land-filled because they are of so little use, but with changes in landfill regulations this is becoming either very expensive or unacceptable.

So, Dr Lord and the University’s Industrial Symbiosis Project Manager, Christine Parry, looked for new ways of re-using waste rather than sending it for disposal.

They linked up with Sheffield-based waste disposal company Onyx Glacier, which can use the salvaged substance as a component of cement.

Chemical analysis also revealed that the material was clear of heavy metals and could be used for other purposes, such as in the manufacture of CDs and DVDs.

It is also absorbent and could potentially be used to soak up oil spills although a significant problem is that it is very slow to dry, remaining a sludge for a long time.

Christine Parry explained: “We set out to find a use for the ochre working on the principles of nature, where nothing is wasted. It is perfect for making cement, which is a potential use for it in the short term, but in the longer-term we are exploring other options, incorporating it into pottery or converting it into the recording material for CDs and DVDs.”

Villagers are now considering how to obtain funding to further develop the project as the agreement with Onyx Glacier requires the villagers to finance removal and transportation of the ochre.

Dr Lord said: “Removing the iron oxide has a benefit all round and raises some interesting research issues which we will be exploring further. This kind of solution could address a wider environmental problem by diverting the material from landfill.

“We now have a novel method of extraction and re-use which is innovative and which we know works. It could also be used elsewhere because this kind of mine-water pollution is a major problem for rivers and streams near coal workings in many parts of North-East of England and our solution could be applied to other former mining areas in Europe and beyond.”

Tommy Evans, a villager and local environmental officer, says: “It has been great working so closely with the University and residents are amazed to see that the ochre from the red river can now turn up in locally-made pottery.”