Water and Effluent Treatment Magazine
Issue link: https://fhpublishing.uberflip.com/i/1062776
10 WET NEWS JANUARY 2019 | wwtonline.co.uk Finding value in liquid waste streams W aste is increasingly being viewed as a resource. From well-es- tablished practices such as recycling paper and alumini- um 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 wastes. Why recover waste? 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, com- pared to a linear one, the mate- rials within products are reused, turning previously burdensome wastes into valuable resources. The European Union has HRS Unicus Series scraped-surface evaporators are used to maintain thermal efficiency and remove fouling during evaporation in ZLD installations • INSIGHT HEAT EXCHANGE Matt Hale, international sales and marketing director at HRS Heat Exchangers, looks at how value can be extracted from liquid waste streams and what to consider when choosing technology to achieve this proposed to double its rate of resource productivity by 2030 and as part of this, adopted a communication, 'Towards a cir- cular economy: a zero waste programme for Europe', in July 2014. Like key industrial stake- holders and businesses, it asserts that 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 environ- mental benefits. Unleashing the potential for liquid waste streams Wastewater treatment and 'water mining' has also been identified as a key platform on which to base the technological development of such circular production systems. Effective water treatment and material recovery can provide a double economic return. Every cubic metre of recycled or reused water results in a corresponding reduction in mains water demand and wastewater dis- charge. There are also benefits in terms of the energy and car- bon footprints associated with material recovery when com- pared with primary extraction and processing, together with further environmental benefits arising from reduced waste dis- posal impacts. In addition, researchers are increasingly identifying food processing and supply-chain waste streams as a major resource for the development of bio-based products and pro- cesses, suggesting that the val- orisation of food waste should focus on both commodity and higher-value speciality products. Examples of resource recovery While we are still a significant way away from the commercial development of large-scale biore- fineries that can treat wastewater streams to produce a range of products including biofuels, energy, fertilisers, metals, inert media and a whole range of fine chemicals, parts of this process are already established. The use of anaerobic digestion (AD) to recover energy and create organic biofertiliser (digestate) from food and sewage waste is now wide- spread, and there are various examples of material recovery from different waste streams at all scales, from early research through to fully commercial recovery units at industrial facili- ties and water treatment works around the world. Some examples of this type of material recovery include: l Recovery of key nutrients such as phosphorous from sewage streams for use as agricultural fertilisers l The potential recovery of biopolymers such as polyhy- doxyalkanoates (PHAs) and polyphenols from the waste- water from olive mills l Cheese whey wastewater (CWW) comprises waste streams including whey and wash-out water, and could be treated using various pro- cesses to produce a range of products which are useful in food manufacturing and phar- maceuticals, such as whey proteins, peptides, lactose, glucose and other useful chemicals l The recovery of spent yeast products from various pro- cesses for use in food produc- tion, such as stabilising and pH buffering Fruit processing is another sec- tor that is ideally placed to capi- talise on the potential value of some of its waste products. Cit- rus peel waste accounts for up to half the total volume of citrus