Engineer proposes purification
YEPPOON environmental engineer Robert Ellison is more than willing to be the first person to drink the treated water from the Mt Morgan mine pit.
In fact, he says the water will be too pure once it comes out of the first stage of reverse osmosis, and that some additions like iron and manganese will need to be added to make it safe for drinking.
Mr Ellison, who runs REA Environment and Engineering, was working as a contractor for Fitzroy River Water when he proposed the idea to use the 12,000 mega litres of water in the mine dam to guarantee Mt Morgan's supply.
“If I thought there was a one in a billion chance of health impacts, this is not an idea I would have proposed to Fitzroy River Water,” Mr Ellison said.
He said the purification process worked in three stages, relying on tried and tested methods.
The contaminants and heavy metals in the dam come from the rocks, dissolved by the sulfuric acid found in the water.
The first stage of treatment (lime precipitation process) involves introducing hydrated lime and would see the pH level brought back to around neutral.
Most of the contaminants and heavy metals would drop out at this stage.
The second stage (ion exchange process), sees the water passed over a resin, which would see the sulfur bind with carbonates and form solid gypsum which would drop out of the water.
The third stage (reverse osmosis) uses high pressure to push the water through a membrane, which doesn't allow larger molecules and ions to pass through, and removes any remaining contaminants.
The result is pure water, which Mr Ellison said was a “very corrosive substance” and the next stage was to add elements like iron and manganese to make the water drinkable.
Mr Ellison said the waste products from the process would be better quality than the solution originally put in, and could be returned to the dam and improve the overall water quality.
He said Mt Morgan's current water supply was 99% reliable, and the mine dam water purification process was developed to ensure the town had water that one month out of 100 when the supply might fail.
“If done properly, there's no chance at all of any significant levels of contaminants getting into the supply.”