Circular economy

What is the circular economy?

There is no exact definition for 'circular economy' but broadly speaking it is an economy which encourages zero waste.

The Ellen MacArthur Foundation report provides a useful definition of the circular economy:

There are powerful drivers for pursuing a circular economy: although a circular approach may not be a feasible solution in every circumstance, the conventional take, make, use, dispose route cannot continue to be the dominant economic model – not just from a waste management point of view but also because of the growing issue of resource scarcity. A burgeoning global middle class can only add more pressure at both ends.

 

Outlining the circular economy - www.ellenmacarthurfoundation.org

Water and the circular economy

The reuse and recycling of water is an essential aspect of the circular economy, but one which is often overlooked by material recycling.

This is starting to change; on current trends, demand for water will exceed supply by 40% by 2030. This is clearly a huge issue that requires addressing before the problem is too big to handle.

The reasons for the current situation can be put down to:

  • Aged infrastructure
  • Bad policies
  • Ill-defined markets

However, the larger issue is that we are not careful and innovative when it comes to water use (especially in the developed world).

Generally, all over the world water turns from initially clean to dangerously polluted as it travels through the system, rendering future use impossible, until it needs to be dumped often after one use. This linear model is economically and environmentally unsustainable.  However, water is still one of the most undervalued resources on earth and this undervaluing leads to carelessness on the part of individuals, industry and governments. 

The obvious approach is to circulate water in closed loops for domestic and industrial purposes. In this model, water is reused time and again, retaining full value.

An essential part of the water recycling process is to remove contamination from water, creating clean water that can be reused, and potentially collecting and reusing the contaminant that is also likely to have a value.

Common contamination removal techniques include:

  • Coagulation/settling/filtration water treatment
  • Granular activated carbon (GAC)
  • Aeration
  • Ion exchange
  • Membranes

However the best technological solution depends on raw water characteristics, affordability, acceptability and level of application.

There are disadvantages to every individual treatment technologies and, thus, hybrid technologies are always beneficial; however, availability, selection, optimization, etc. are important for the best performances of the system.

Capacitive recovery technology

One technology that is beginning to establish itself within the water industry is Capacitive Recovery Technology.

Capacitive Recovery technology has the capability of removing ions from any waste stream, producing a flow of clean water (purification phase and positive voltage) and a significantly smaller flow of dirty, ion rich water (regeneration phase and negative voltage) in two different phases.

CRS technology is mainly an electrostatic process with a cell containing an anode and a cathode drawing the ions towards them. The technology also utilises membranes to increase the effectiveness of the ion recovery by preventing the ions travelling all the way to the opposite pole during regeneration. These membranes do not require pressure and act solely as a semi permeable barrier.

The technology has been proven to efficiently (up to 99%) remove a range of ions from a waste stream including nitrates, ammonia, phosphates and heavy metals allowing water to be reused for the original application. Compared with a traditional, commonly used, membrane technology like reverse osmosis it is; low energy (low pressure, ion treating, typically uses 0.5kWh/m3 versus 1-3 kWh/m3 for RO), low cost (no high pressure pump, no high pressure membranes, no moving parts) and reduced waste (recovers between 85-90% waste compared to reverse osmosis at 30-50% waste).

In order for the water industry to become truly circular there must be innovation.

SME’s along with larger businesses are likely to do the bulk of this innovation, however it will not happen unless end customers see and understand the benefit of recycling water and governments provide a suitable environment to stimulate this innovation. As the technologies are developed households, organisations, business’ and governments will have a range of tools allowing them to recycle water and move towards the world towards a circular water economy.

Outlining the circular economy interactive diagram - www.ellenmacarthurfoundation.org
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