As mining managers are constantly trying to find the answers to reduce operational costs it is possible that sewage treatment is being overlooked as part of the solution.
Sewage treatment is often considered in the balance sheet as a compliance cost. For medium sized mines such as those in the Bowen Basin in central Queensland, the costs can be considerable.
Three or four decently sized sewage plants across a lease could mean a sludge cartage bill in the millions per year. In addition to sludge there is also effluent discharge often wasted to a natural water way. Discharge into the water way often comes with a permit fee, by volume, adding further cost to the bottom line.
Thinking of sewage treatment purely as a cost centre is missing the opportunity to look at sewage treatment from the perspective of a process that generates re-usable by-products.
A number of industries and councils are now considering zero discharge which, as you can image, means nothing leaves the site or the region. With zero discharge as a lens, clients start thinking of innovative ways to reuse the final products of effluent and sludge instead of looking at the issue as a costly disposal exercise.
For example, why import soil for surface mine reforestation when it could be just a compost bin away?
Some mine sites in the region are already composting their sludge after drying it out and then putting it to use in landscaping applications along road-ways. Reforestation of previous surface mine operations is an on-going process for modern mining and one of the needs for reforestation is the application of organic amendments required to facilitate soil development.
In short both by-products can be used in mining operations.
Effluent re-use should be a key topic for Australian mining operations as they are often located in regions where water is in short supply. With the appropriate tertiary treatment, mines have the opportunity to use effluent on haul road dust suppression, flushing of toilets and subsurface landscape irrigation. A perfect application of the two products being to reduce the cost of surface mine reforestation by, on the one hand, assisting soil development and on the other, providing plant irrigation.
All sewage treatment processes are capable of producing these outcomes with the appropriate addition of modern systems such as the containerised Hydroflux Epco system featuring the ROS3 screw press for sludge dewatering. Taking effluent to the next level for aerosol discharge, such as dust suppression, requires the addition of tertiary treatment as supplied by the Hydroflux Epco tertiary treatment skid.
When looking at sewage treatment from a compliance perspective, it’s useful to consider how sewage treatment processes might be able to reduce mining operation expenses through by-product use.
About the Author
Paul Cobbin is the general manager of Epco Products at Hydroflux Epco. His 30 plus years of experience has been focused on working with mining clients and their communities to find sewage solutions to keep in step with changing environmental compliance and efforts to reduce operational costs.
About the Hydroflux Group
The Hydroflux Group comprises eleven companies based in Australia, New Zealand, Fiji and the UK, providing design and build, equipment, processes and operational services in water and wastewater treatment. Hydroflux Epco specialises in mining and municipal wastewater and sludge treatment, is the exclusive Australian representative for HUBER Technology, AEROSTRIP, CNP Technologies, Flootech MBBR, Organica Water, Neutralox and incorporates EPCO Australia.
Hydroflux Epco Pty Ltd is a member of the Hydroflux Group.
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