Waste is increasingly viewed as a resource. From
well-established practices such as recycling paper and aluminium, to the
development of the circular economy, an increasing volume of resources are now
being recovered from materials that were previously seen only as inconvenient
Waste valorisation is the
process of recovering value from waste materials, for example through reusing
or recycling them, or by composting or anaerobically digesting them and
converting them into more useful products such as materials, chemicals, fuels
or other sources of energy. In a circular economy, compared to a linear one,
the materials within products are reused, turning previously burdensome wastes
into valuable resources. Moving to a circular economy can have a positive
effect on economic growth and strengthen the competitiveness of companies, in
addition to providing a number of environmental benefits.
The European Union has
proposed to double its rate of resource productivity by 2030 and as part of
this, adopted a communication, Towards a circular economy: a zero
waste programme for Europe, in July 2014.
potential for liquid waste streams
Wastewater treatment and ‘water mining’ has been identified as a key platform
on which to base the technological
development of such circular production systems. In addition, every cubic
metre of recycled or reused water results in a corresponding reduction in mains
water demand and wastewater discharge. There are also benefits in terms of
energy and carbon footprint, and waste streams are increasingly being viewed as
a resource for the development of bio-based products and processes.
Examples of resource
While we are still a significant way away from the commercial development of
large scale biorefineries, parts of this process are already established. The
use of anaerobic digestion is now widespread, and there are various examples of
material recovery from different waste streams in operation at various scales
around the world.
Some examples include:
- Recovery of phosphorous from sewage for use as agricultural fertilisers.
- The potential recovery of biopolymers from the wastewater from olive mills.
- Treating cheese whey wastewater to produce products for food manufacturing and pharmaceuticals.
- The recovery of spent yeast products for use in food production.
Fruit processing is another
sector that is ideally placed to capitalise on the potential value of some of
its waste products. Citrus peel waste accounts for up to half the total volume
of citrus fruit processed globally and is a potential source of many useful
products including dietary fibre, antioxidants, food colorants and flavours,
and contains a wide variety of compounds.
Moving towards zero
liquid discharge (ZLD) is a technique by which liquid waste streams are
eliminated: any wastewater is purified and recycled, while other residues,
which often include the type of valuable by-products mentioned above, are
Various processes are
employed in ZLD, but evaporation is a key process, both in order to concentrate
residues sufficiently to allow their economic extraction or physical removal,
and as part of the water purification process. However, solid-liquid mixtures
are complex and it is important that the first stage of any potential project
includes a research study to evaluate the nature of the waste stream/s and the
saturation levels required.
HRS Heat Exchangers have
been involved in ZLD projects in Europe using evaporation systems, including
the recovery of potassium and sodium sulphates from organic brine waste
For more information on how HRS Zero liquid discharge systems can be used to recover valuable resources from your waste stream, please contact us today.
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