Gulf Construction Online - Meeting green goals through water recycling

Manufacturers & Procurement

AquaCycle ... an efficient water management solution that ensures up to 90 per cent of the process water is recycled for immediate recirculation.

Manufacturers & Procurement

Meeting green goals through water recycling

Water management and water recycling are prevalent issues that will only become more tightly regulated and monitored in years to come, says CDE Global, which offers efficient wet processing solutions to the quarrying and mining industries.

01 August 2020

It’s incomprehensible for most; the notion that around the globe we face issues arising from water stress on a planet whose surface area is made up of over 70 per cent water and whose total water volume – a staggering 96.5 per cent – is contained within our oceans. Whether for consumption or sanitation, clean water in some parts of the world is taken for granted, as we fail to recognise the processes and infrastructure needed to maintain a clean water supply or neglect to acknowledge that basic access to clean water is not universal.

In 2017, 785 million people lacked a basic drinking water service, including 144 million people who were dependent on untreated surface water, 206 million who had access to an improved water source but were required to make a 30-minute trip for collection, and 435 million who were extracting water from unprotected wells and springs1.

While at the most extreme end of the scale more than two billion people live in countries experiencing high water stress2, almost two-thirds of the world’s population experience severe water scarcity during at least one month of the year3.

Essential for life, water is also vital for economies and climate regulation. It is of utmost importance, therefore, that our water resources are protected – even regulated.

The mining and quarrying, manufacturing and construction sectors accounted for 10.6 per cent of total water use in Europe in 20174. Developing technological solutions to tackle these mounting challenges is paramount for many materials processors seeking to boost the profitability of their operation by minimising the consumption of costly water resources.

The 2030 Agenda for Sustainable Development5, adopted by all United Nations member states in 2015, provides a shared blueprint for peace and prosperity for people and the planet, now and into the future. At its heart are the 17 Sustainable Development Goals (SDGs) with 169 associated targets and 230 indicators, which are an urgent call to action by all countries.

CDE recognises that the benefits arising from sustainable practice and processes are two-fold; they are economically advantageous and minimise our impact on the environment. Indeed, they are green from both perspectives. To that end, CDE has adopted number six of the SDGs: Clean Water and Sanitation.

Common Challenges

The Middle East and North Africa (Mena) is home to 6.3 per cent of the world’s population, yet only 1.4 per cent of its accessible fresh water supply6. Water scarcity in Mena involves multiple factors such as climate change leading to droughts and floods, low water quality, and poor water management in the context of fragility, conflict, and violence. This is why at the World Economic Forum 2015, experts on the Mena region stated that the water crisis is “the greatest threat to the region – greater even than political instability or unemployment”7.

Innovations in the washing sector and the continued advancement of CDE’s pioneering wet processing solutions are supporting quarry operators and materials processors alike to overcome the challenges stemming from water management: cost-based efficiency, sustainability and regulatory.

Commenting on the severity of water management challenges in the region, Ruchin Garg, CDE Regional Manager for Mena, says: “The Middle East and North Africa is the most water-scarce region on Earth and its total water productivity is half that of the global average,” according to data from The World Bank8.

According to data from the World Resources Institute, “Twelve out of the 17 most water-stressed countries are in the Middle East and North Africa”9.

“In a region where an incredibly high percentage of GDP is vulnerable to water stress, it’s vital that an effective water management strategy is identified – and ours is an industry that can adapt to the call for better water management. The technology exists and CDE is working with many in the region to set the benchmark.”

Water Economics

Water as a resource delivers economic value to a range of industries. Within the extractive industries, the value of materials is significantly increased when washed, but wet processing in mining and quarrying operations is hinged on water availability and processing plant efficiency.

Garg comments: “More often, it’s water availability and access that prevents producers getting into the washing business in the first place – that, and the uncertainty around typical top-up water requirements which, in the case of CDE water management solutions, are very low. The focus is on recycling and recirculating as much water as possible through the system.”

CDE consistently invests in research and development with the aim of enhancing the capabilities of its premier water recycling and management equipment. At the forefront of its water recycling systems is the AquaCycle, a single, compact, and user-friendly unit that can be applied to high and low tonnages across many markets.

Delivering competitive advantage to its customers, CDE’s AquaCycle accelerates return on investment by maximising production efficiency, minimising the loss of valuable fines, and reducing water and energy costs.

An alternative to water extraction and the costly process of pumping water to the plant, CDE’s AquaCycle is a highly efficient water management solution that minimises costly water consumption by ensuring up to 90 per cent of process water is recycled for immediate recirculation.

After the feed material has been washed and classified, waste is sent to the AquaCycle thickener tank. Here, a small amount of polyelectrolyte flocculant is added to the water via an automatic dosing station which forces fine particles to settle on the bottom of the thickener tank. The clean water on the top overflows the weir and is stored in the AquaStore tank before being re-circulated around the plant. The result is a highly efficient water recycling system that requires only a 10 per cent supply of top-up water.

Waste sludge is discharged into a buffer tank where a motorised rake, in constant rotation, ensures the material does not settle and solidify. If further dewatering is required, a filter press or decanter is added to the wet processing solution to eliminate the need for settling ponds.

Garg says: “In Mena, we have 75 wet processing plants successfully utilising CDE water management and recycling technology.”

Intelligent Design

Though water recycling may seem simple in theory, it is, in practice, much more complex. Water thickeners are not born equal and their efficiency is the result of years of dedicated research, development, and refinement. Every aspect of its design is carefully considered so that the system is responsive to the site-specific needs of its owner.

“We sweat the small stuff,” says Kevin Vallelly, Director of Engineering at CDE. “CDE has been co-creating with customers for over 25 years to deliver collaborative, imaginative and unique processing systems, and this process has been informing and refining our water recycling technologies.”

All CDE equipment is designed to allow plug-and-play operation; that is, the equipment is pre-wired and pre-tested before despatch, designed for rapid assembly and set-up and can start processing material within days of arrival onsite. These design considerations and factory acceptance tests significantly reduce installation time and accelerate return on investment.

He adds: “Fast return on investment is a very real proposition when the CDE AquaCycle thickener is introduced to a washing operation. It boosts the efficiency of the wet processing plant by maximising the settlement of solids which reduces the quantity of flocculant required, cuts running costs, and optimising the overall efficiency of the plant.”

Return on investment with a CDE AquaCycle is typically achieved in just six to nine months.

Settling ponds are known to be the source of significant revenue losses, not only due to the high maintenance costs, site footprint, and downtime, but also because high-value fines can become lost and trapped at the bottom of ponds.

He continues: “By recycling up to 90 per cent of process water, the requirement for settling ponds is greatly reduced.

“With the addition of a filter press tailings management system that need is completely eliminated. When combined with a CDE filter press custom-built fines management system this figure increases to 95 per cent, removing the need for settling ponds altogether.”

Long-term Benefits

Water management systems are becoming a must-have for mine and quarry operations to comply with environmental regulations. Matters concerning the protection of finite resources on the planet will only become more prevalent, too.

“The benefits of the CDE AquaCycle significantly outweigh their initial investment; not only for the short period until return on investment is achieved, but for the preparedness it offers. Water management and water recycling are prevalent issues that will only become more tightly regulated and monitored in years to come. The AquaCycle ensures operators stay ahead of the curve while extracting maximum value from available resources and driving down operating costs,” Vallelly concludes.

The AquaCycle system is available to operators around the world and is ready to complement wet processing applications in five sectors – sand and aggregates, mining, construction and demolition waste recycling, environmental applications, and industrial sands.

*CDE is a leading provider of wet processing equipment for quarries, mines and recycling operations on the global market. Its equipment has applications across a wide range of materials and is delivering significant efficiencies in the construction and recycling (CD&E), mining, industrial sands and environmental sectors. Working across five sectors and eight regions globally, CDE has been co-creating with customers for over 25 years to deliver collaborative, imaginative and unique processing systems. Headquartered in Northern Ireland, its office in Dubai, UAE, serves the Mena market.

References:

1. WHO | www.who.int/news-room/fact-sheets/detail/drinking-water

2. UN | www.unwater.org/app/uploads/2018/12/SDG6_SynthesisReport2018_WaterandSanitation_04122018.pdf

3. Mekonnen and Hoekstra | advances.sciencemag.org/content/2/2/e1500323/tab-figures-data

4. EEA | www.eea.europa.eu/data-and-maps/daviz/annual-and-seasonal-water-abstraction-7#tab-dashboard-02

5. UN SDGs | sustainabledevelopment.un.org

6. EcoMENA | www.ecomena.org/water-scarcity-in-mena/

7. Relief Web https://reliefweb.int/report/world/water-stress-poses-greatest-threat-mena-region

8. The World Bank | www.worldbank.org/en/topic/water/publication/beyond-scarcity-water-security-in-the-middle-east-and-north-africa

9. WRI | www.wri.org/blog/2019/08/17-countries-home-one-quarter-world-population-face-extremely-high-water-stress