Articles & Case Studies

Recycling/Reuse of Water for a Blue Growth Future

Posted: Friday 19th August 2011

Kieran Healey, Synergies and Integration Managerat Veolia Water Solutions & Technologies discusses the sustainable water approach for the future.

Although 70% of the planet is covered by water, only 0.7% of the global water resource is readily available as freshwater, and it is very unevenly distributed across the planet. Unlike oil, for which there are multiple energy options, freshwater has no substitute. And unlike oil, our needs for water can’t be sustainably addressed by transporting water from water rich areas to water-poor, high demand areas. Over the next few decades, projected population and economic growth levels will, locally push the stress on this finite resource to the limit. In turn, limits on freshwater availability could become the worlds, main growth limitation factor.

To put things in perspective, it is estimated that if we maintain a “business as usual” approach to water management, by 2050, over $63 trillion dollars of the global GDP will be at risk. Industry can make a significant contribution to adopting a ”blue growth” strategy, improving our water productivity (economic output per drop) by embracing water management practices, centred on sustainable water use. Water recycling and reuse is a key and achievable part of this strategy, and below we give an overview of the different approaches for a number of industrial sectors.

Firstly by water recycling, we mean treating an effluent resulting from a manufacturing process to such a standard that it can be incorporated back into the original manufacturing process line. With water reuse, the water is treated to allow use for other purposes. The opportunities for both recycling and reuse encompass the entire water cycle for the use of ultrapure water, process/manufacturing water, cooling tower make up, boiler feed water and utility water (washing, cleaning, fire network, and irrigation). Treatment technology is available and proven in a number of industry sectors, typically involving site specific combinations of unit processes such as clarification, filtration, membranes, biological treatment, evaporation, GAC and UV.

The opportunities for recycle and reuse will vary from industry to industry, the sustainability of operation being interlinked with both the environmental impact of water use and associated carbon footprint.

The power generation industry is a significant water consumer requiring several different levels of treatment for water use. Here there are many opportunities to reduce freshwater consumption by recycling certain streams such as boiler and cooling water tower blow down, Where water discharge is not possible, or freshwater viability is limited, partial or zero liquid discharge programs can be operated. Other process industries can also indirectly off set water use in power generation, by reducing site electricity use, either by efficiency measures, or on site generation of electricity through anaerobic digestion of process wastes.

In the metal plating and processing industries, where water does not form part of the product, recycling has been employed for many years. This is because stages of the process will accept relatively high levels of contamination in the rinse water so it has become common practice to only use fresh water for the final rinses and use progressively more contaminated water for the earlier stages. This results in disposal of a smaller volume of more concentrated wastewater. Due to the nature of the contamination from this industry, it is typically disposed of by tanker to a specialist works rather than to municipal sewer. This disposal route incurs a significantly higher cost, incentivising the manufacturer to reclaim as much as possible and minimise the volume. This is often done with ion exchange and evaporation technologies and there are many reference sites around the world using this equipment.

The approach is completely different in the microelectronics, pharmaceutical, food and beverage industries where contamination of the product is to be avoided at all costs. Potable or ultrapure water quality are used in the manufacturing of the product and whilst the direct water usage can involve high quantities, they are often insignificant compared to total site usage. For these industries water reuse is the answer, with treatment of production effluent being directed towards ancillary manufacturing operations such as boiler feed make up, washing and cleaning in place, together with fire networks and irrigation.

Opportunities for water reuse don’t stop with the manufacturing process; grey water from office accommodation can also be captured and re-used for low quality applications such as washing vehicles, watering plants and flushing toilets. This is now commonly being fitted to new office buildings and domestic dwellings; however, the cost of retrofitting to existing infrastructure can be relatively high

Industry has certainly recognised the risk posed by future water scarcity and there is clear evidence of major programs being undertaken to align water management with core business development. However whilst potable quality water is readily available at low cost particularly in Western Europe, investment in recycling/reuse technology needs to be based on more than just an economic basis. To ensure our future “blue growth” scenario we also need to consider the longer term environmental sustainability of investment decisions by looking at both the impact of water use and associated carbon footprint.

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