Ahead of the March issue’s major review of mine water management – covering, among other trends, the growing use of seawater and desalination plants, clean up of waste waters and recovery of valuable metals where practical, water management and water delivery – comes news of great interest from Finland. Freezing technology can be used in waste water treatment, researchers at the Lappeenranta University of Technology have shown. When waste water freezes, it can be purified through the formation of a cleaner layer of ice. The clean layer of ice can be removed from the rest of the waste water, and the remaining waste water is more concentrated. The new energy-efficient method of purification is based on the natural freezing process of water: energy is required only to break the ice and transport it from the waste water pool.
Similar research was undertaken by the University of Alberta and AMEC Earth and Environmental over ten years ago that demonstrated the effectiveness of spray freezing to remove dissolved chemicals from tailings water at the Colomac gold mine 220 km north of Yellowknife in Canada.
Colomac picture courtesy of Aboriginal Affairs and Northern Development Canada – remediation activities at Colomac have been underway since 2005. These include remediation of hydrocarbon-impacted soil, treatment of hydrocarbon-impacted water, waste consolidation, non-hazardous landfill capping, quarry remediation, waste rock berm and caribou ramp construction. Project oversight and support for these activities is provided by the Colomac Advisory Team (CAT) which includes AANDC and PWGSC staff as well as a representative of the prime consultant for the site.
The Tlicho people have been longstanding partners with the Northern Contaminated Sites Program on this site, including development of the remediation plan to ensuring that approved activities are carried out effectively. Their strong involvement will continue as planned remediation activities are completed, a close-out plan is developed and the project moves into extended monitoring.
Last year, in a major program, VTT Technical Research Centre of Finland is developing energy-efficient methods for reuse of water in industrial processes and means for recovering valuable minerals and materials from waste for recycling. Rapid tools were also developed for identification of environmental pollutants. It is possible to recover valuable metals and other materials and secure availability of clean water. Cleaning and treatment processes can also be linked to energy production, and the processes and urban structures designed in such a manner that wastewater treatment does not consume energy or cause extra costs.
“Wastewater treatment and waste treatment have mainly been implemented by legal necessity. Now we should modify our way of thinking so that we would be able to regard waste disposal sites and purification plants as sources or raw materials and energy. In the near future, technology has been refined far enough to allow such waste treatment plants to operate on their own,” says Mona Arnold, Principal Researcher at VTT.
Demand has arisen for technologies capable of recovering even tiny amounts of minerals from waste flows. Recovering them from municipal or mining wastewaters requires better recovery methods than those available today. VTT has developed extraction methods for metals and minerals from waste materials. Biological extraction methods by which metals are recovered from mining, metal and recycling industry waste by using microbes and chemical reactions are under test and are expected to be commercialised within the next few years.
Treatment of water in purification plants and industrial facilities consumes vast amounts of energy. Usually water recycling and seawater desalination are based on the use of filtration membranes that consume energy. VTT has developed intelligent membrane materials, reducing the need of purification, for filtration purposes.
Membrane solutions using only small amounts of energy were developed for water treatment purposes. VTT has collaborated with a university in Singapore to develop a method based on forward osmosis technology, by which metals and biocomponents can be recovered and concentrated from industrial process waters.
The pumping and distribution of water to consumers and industry also consumes major amounts of energy. The need for pumping can be minimised if the process water can be recirculated within the plant, and the distribution network is made more effective by enhanced monitoring and location of leaks.
The VTT program also developed sensor technology for easy and rapid detection of pollutants.
