Water is one of the most important elements for sustaining life therefore water management is a critical process. Water availability and quality is important for the environment, vegetation, agricultural pursuits, erosion, fauna and the sustainability of communities.
Water is an essential raw material, used at every point of AWAC’s mining, refining and smelting operations such as:
- bauxite ore refining into alumina
- dust suppression, road watering and vehicle and equipment cleaning throughout mining operations
- ingot-casting process during smelting.
AWAC’s management of water resources is vital to its:
- licence to operate which is granted by local communities, governments and environmental agencies, and
- mitigation of business risks by ensuring business continuity.
The global water challenge is becoming more complex due to stress applied from:
- growing populations
- expanding urbanisation
- increasing agricultural and industrial sectors.
Alumina Limited believes that solutions to global water management issues require future technology advances combined with full community, government and business involvement and cooperation.
Water scarcity has the potential to impact AWAC’s costs, production volume and financial performance. In AWAC the largest water users are the alumina refineries. Most material to Alumina Limited are AWAC’s operations in Western Australia , which is recognised as a region subject to water-stress, having experienced changing rainfall patterns in recent years leading to a drying climate.
Alcoa of Australia (AofA) has undertaken several initiatives to conserve water, increase water efficiency and reduce water quality requirements, which include:
- Pursing secondary sources of water as an alternative to fresh water used in several refining processes.
- Projects aimed at recycling water already used in processing to reduce total water withdrawals.
- Projects evaluating applications to slow evaporation of stored water.
- Increasing pasture coverage on and around bauxite residue areas at Wagerup Refinery to supress dust and remove needs for water sprinklers
- Bauxite residue filtration.
Results and goals
In 2016, AWAC operations worldwide withdrew 31.4 million cubic metres of freshwater compared to 34.4 million cubic metres in 2015. Freshwater intensity measured by cubic metre/tonne of alumina produced increased in 2016 to 1.83m3 compared to 1.65m3 in 2015. Freshwater use at the Portland smelter improved from 1.17 in 2015 to 1.05 in 2016.
In response to the challenges of operating a business that requires significant water for operational purposes in some areas prone to water stress and working within community water needs, Alcoa has focussed on developing and implementing innovative and low-cost management technologies.
In 2016, at AWAC’s Kwinana alumina refinery in Western Australia, innovative technology has been implemented with multiple benefits of reducing water used and increasing recycling opportunities. A residue filtration system has been installed that forces bauxite residue through very large filters that squeezes out water that can be reused in the refining process. The system is expected to reduce freshwater use by 1.2 gigalitres (317 million gallons) annually and significantly reduce the active residue storage space. This technology is being evaluated for use at other AWAC refineries around the world.
By adopting natural-system applications for water reduction and treatment, water is being sustainably managed at significantly lower cost.
An example of the application of this technology is found at the joint venture Saudi Arabian alumina refinery where a Natural Engineered Wastewater Treatment (NEWT) was implemented in May 2013. The system utilises a passive wetland environment as well as bauxite residue to disinfect the treated effluent prior to its reuse in the manufacturing process. The refinery (25.1 per cent AWAC owned) facility is part of a fully integrated aluminium operation that shares the new lost-cost natural system for both water reduction and treatment towards a goal at the site of zero. All sanitary and process water will be collected for treatment through the engineered wetland system has the potential to reduce freshwater demand by an estimated 25% and achieve zero wastewater discharge. Collected storm water will be treated via an innovative activated alumina absorption process.
Using 2005 as a baseline, Alcoa established a global target to reduce average freshwater intensity by 10 per cent by 2020 and 25 per cent by 2030.
In 2011, as a result of exceeding the 2020 goal, Alcoa amended those targets by resetting the 2020 goal to 25 per cent and introducing a new 2030 goal of 30 per cent freshwater intensity.
Freshwater sources include:
- Groundwater pumped from or derived from wells, springs, or bores that is used for process/potable purpose
- Water purchased from a municipal water authority or other provider (including the output from a desalination plant)
- Water pumped from rivers, streams or lakes that is used for process/potable purpose; and
- Water produced from onsite and/or offsite, third party desalination systems
Freshwater does not include:
- Water pumped from or derived from saline sources, (i.e., oceans, seas, & saline aquifers) and used as is for process water;
- Fresh water that is supplied to local users (communities, adjacent industrial users) by the facility;
- Fresh water that is extracted from ground water for purposes of lowering the ground water table and is not used for process/potable use;
- Water derived from recycled sources that is being reused as process water.
AWAC water withdrawal 2015
Total freshwater withdrawal*
*Processes for collecting the data on a global level do not exist currently however we are able to provide the above known information on withdrawn water. At some operations, freshwater used cannot be calculated for the reason that a methodology currently does not exist to separate freshwater and other water which are stored in shared ponds. A significant proportion of water is collected from refinery and residue storage which is not considered freshwater therefore, freshwater makeup can vary considerably. At AWAC’s largest operations located in Western Australia, water reporting is based on water collected, not necessarily water used. As a result, freshwater variation between years can be a factor of rainfall received in each period.