Water is a rare and precious commodity. Moreover, this liquid, which is essential for fauna, flora and human life, could well and truly be lacking in the years to come, according to many experts located in different countries.
The cause is global warming!
The latter is already and increasingly impacting the global landscape: intense, long and unprecedented periods of drought have appeared all over the world - including in living areas that until now have been spared by the lack of water. In this context, managing and optimizing the use of water in quarries is a priority both ecological and economic.
For good reason, out of the 3300 quarries present in France, nearly 1,750 wash the materials for their production. However, the awareness of the importance of water management in a career is not new for you, professionals in the sector!
For several years, it has been a major subject at the origin of many strategies aimed at finding effective water management.
At a time when every drop of water counts, Synaxe takes stock of water in a career for you.
Water: a short-term challenge for all careers
More than 10% of total water consumption in Europe, here's what represented in 2017 the mining and quarrying sectors, manufacturing and construction.
By 2030, as an aggregate operator, you will have to increase the profitability of your career while minimizing its consumption of expensive water resources. Because it is a fact, regardless of the sector, scarcity is driving up prices! However, it is impossible for your sector to do without water.
The Aggregate washing Is a essential industrial step to remove fine particles naturally contained in deposits. It is thanks to it that aggregates acquire sufficient adhesion to be used with binders such as cement, lime or even bitumen.
Likewise, Water makes it possible to classify and correct the absorption of aggregates and therefore allows you to meet customer needs as well as regulatory constraints.
Quarry water: what exactly are we talking about?
Because of its use, quarry water can be classified into five categories:
- THEwater taken (water taken underground or surface by the site for its treatment activities in addition to recycled water)
- THEprocess water (incoming and outgoing water used during the production process)
- THEwater + fines (outgoing water to be recycled, because it contains the fines from the deposit following the washing of the aggregates)
- THErecycled water (water which, after natural decantation or other recycling method, returns to the washing circuit)
- Les Ancillary waters (rainwater, dewatering, cleaning, sanitary and dust suppression)
Process water path used for the treatment and washing of aggregates
Once washed, the materials extracted in quarries see their value increase considerably. An observation that gives water even more value!
However, in the face of the climate emergency and its impact on the availability of water in the world, environmental regulations are tending to tighten for quarry operators.
For you, the challenge is no longer simply to have water, it is to achieve ensure the regular supply of clean water to your treatment units in a cost-effective manner. While optimizing your water consumption as much as possible and guaranteeing an ultra-efficient recycling process.
To be up to this challenge, keep three pieces of background information in mind.
1. Quarries are not the only ones that need water!
As a career operator, you are in direct competition with the water needs of populations urban areas, farms and the environment.
This competition is particularly felt in Australia.
As a reminder, the country has less than 1% of the world's freshwater resources while its population growth continues to increase - slowly but surely. In addition, in recent years, the country's water supply has been seriously threatened by the gigantic forest fires that have hit it.
As a reminder,Forests provide water to 90% of the most populated cities in the world. !
Their fire has serious consequences for the water supply. And this, for decades: pollution of drinking water, sedimentation of reservoirs, flash floods, reduction in the recreational functions of rivers... Each fire changes the quantity of water coming from the forests as well as the seasonal flow calendar.
This increases the value of water even more.
And tomorrow?
Global climate projections suggest that the pace of fires is likely to increase and that water supplies are likely to become even less reliable - in particular due to poor surface water quality. A situation that is not unique to Australia. Canada and the United States are also increasingly concerned by this water problem.
2. The use of water in quarries is regulated by the European Union.
In 2012, the European Union launched a Action plan for the protection of Europe's water resources.
Objective: to ensure the availability of water of sufficient quality for all legitimate uses. Long before this plan, regulations specific to quarrying were created in 1993. The latter aims to control the impacts associated with quarrying.
The risk of water pollution at the top of the list!
In practice, quarry installations using process water are subject to the application of Article 18.2.1 of the MA of 22 September 1994 for those subject to the authorization regime (installed capacity > 550 kW).
Water regulations in quarries: 3 things to remember!
- The discharge of process water from material treatment facilities is prohibited outside the authorized site.
- The water must be completely recycled.
- The recycling circuit must prevent any accidental pollution.
3. Wetlands from quarries are an asset for biodiversity
Career water management is an opportunity for biodiversity!
The reason?
Material extraction and redevelopment work in quarries create aquatic spaces and wetlands more or less floodable. Spaces that can be colonized by fauna and flora currently threatened by drought.
As proof, natural settling areas have been able to demonstrate their ecological value in active and redeveloped quarries. Natural gravity decantation is a solution based on nature that offers three concrete advantages:
- The creation of environments rich in biodiversity (wetlands...)
- The restoration of land surface
- Zero energy consumption
Ecological engineering is now an integral part of career development.
Since 1971, quarries have had the obligation to rehabilitate their site of operation. Translation? After exploitation, restore a site that is both secure and well integrated into the landscape.
However, the last few decades have proven that careers are an opportunity to go much further in terms of ecology and biodiversity. Mainly thanks to their use of water! Ecological engineering makes it possible to rebuild natural environments conducive to sustainable biodiversity.
In practice, depending on the geographical and climatic context of a quarry, it is possible to guide the evolution of the site by promoting certain types of natural habitats.
For example, by creating as many gently sloping banks as possible to facilitate the establishment of macrophytes and species that prefer shallow depths, or by creating shoals and islands capable of hosting breeding birds.
Did you know that?
70% of the population of bank swallows in Rhône-Alpes lives in active quarries, according to the League for the Protection of Birds.
Optimizing water consumption in your career is possible!
1. By focusing on efficient water recycling
Water can be recycled via different methods: natural decantation, clarification, basin with regular cleaning...
In practice, the most effective recycling method is the one that takes into account the specificities of the site concerned (usable area for recycling, availability of available water resources, need to create ecological areas during redevelopment, level of investment). Each recycling method offers advantages, but also requires a certain level of vigilance in relation to career challenges.
The solution? Anticipate the benefits and the points of vigilance of the recycling method chosen at the time of the design of the installation.
Don't miss out on technical innovations in water management!
Water is a global issue. This is why the innovation sector is multiplying solutions in terms of recycling and water management. AquaCycle is the perfect proof of that! This water management solution reduces outdoor water consumption by allowing wastewater to be recycled by up to 90%. All with the immediate recirculation of the water in the process. Simple, compact and easy to use, the AquaCycle can be applied to both high and low tonnages in a variety of markets. It also only requires a 10% supply of make-up water.
Coupled with the installation of two additional settling tanks to treat all the water used on the site, every drop of water present on the quarry will be optimized - both in its use and in its recycling.
2. Using non-drinkable water
Not all quarries are located near a drinking water point. This is for example the case of the massive eruptive rock quarry of La Mole, in the Var. To supply water, the site was therefore equipped with a 3,000 m3 storm basin collecting rainwater.
3. By ensuring the good quality of the discarded water
The discharge of process water is prohibited outside the quarry site. Likewise, other discarded water (sewage, cleaning water, etc.) is regulated by section 18.2.3 of the ministerial decree. Their rejection is therefore subject to quality controls whose thresholds are imposed:
- pH between 5.5 and 8.5;
- Temperature less than 30°C;
- Total suspended matter concentration (TMS) less than 35 mg/l (NF T 90 105 standard);
- Concentration of the chemical oxygen demand on non-decanted effluent (D.C.O.) of less than 125 mg/l (NF T 90 101 standard);
- Hydrocarbon concentration less than 10 mg/l (NF T 90 114 standard).
Think about it! 3 reliable solutions to ensure the quality of discarded water
- The establishment of a second sealed area equipped with a high-capacity hydrocarbon separator.
- The installation of retention tanks to store fuels and oils − ideal for preventing any risk of accidental pollution.
- Systematic analysis of water discharged into the natural environment.
Indispensable for careers, water requires the greatest attention for ecological reasons, of course, but also economic. Fortunately, the more the years pass, the more the strategies for managing and recycling water in careers are being perfected! However, it is highly likely that water will maintain its status as an endangered resource in the years to come. Therefore, on the career side, the challenge is and will remain to pursue the search for a fair balance between one's own water needs and those of the environment (fauna and flora combined). A guarantee of economy and sustainability!
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