Water & Wastewater Treatment Magazine
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www.wwtonline.co.uk | WWT | DECEMBER 2016 | 17 share information, but our thinking at the outset is that the information companies provide will be something quite straightforward that they can publish on their own website, giving the location, the quantity of sludge and an indication of its quality," says Fergusson. "That information in the public domain will be enough to start a conversation, although obviously if you are going to contract with somebody then the information you are going to write into that contract will be much more detailed than what you would be publishing." One of the key metrics from the sludge quality point of view is its thickness, measured by percentage dry solids (DS). Sludge which has been through a dewatering process might have a DS three or four times that of raw sludge slurry, making it cheaper to transport and easier to digest, and therefore a more attractive proposition for a trade. What will assist such deals is that many recently-built sludge treatment centres will have some spare capacity, so as long as the sludge is similar in quality then using this capacity is likely to make economic sense for the receiving utility. However, where things could get really interesting is when new treatment capacity is required. A€er the reforms, there is no reason why a new sludge treatment centre should have to be built by a single water company; it could be built by a joint venture between companies, or by a third party with an entirely different funding model. "I see it really as a market in two phases," says Neil Corrigall, Head of Strategy at Severn Trent. "The first phase of the market is using the existing capacity that's out there more efficiently. What can everyone do with the existing capacity through trade with neighbours and to sweat the assets a bit more? That first phase is all about the existing incumbents and using their assets better. The second phase is when you start to need new capacity across the system, and how that is delivered for customers. That's one where we can definitely see the potential for new business models emerging, whether it's new specialist players, new entrants, or joint ventures between companies." What is challenging about this second phase of the market, adds Corrigall, is defining the role of the incumbent wastewater company in securing the new capacity that is needed. Although new plants need not be created by the utility themselves, it equally cannot be le€ entirely to the free market as the utility will need to demonstrate that it has a long-term plan in place to deal with the sludge from its region. Potential new entrants to the market could include large waste companies which already use anaerobic digestion and related technologies to deal with waste streams such as food waste. One complication is that where different waste streams are processed on the same site - co-digestion – then the subsequent product is subject to two different sets of environmental regulation, limiting the ability of the treating firm to recycle the material to agriculture, for example. However, this is not an insurmountable problem, as demonstrated by some water company-owned sludge treatment sites which have gone in the other direction and begun to take in food waste. One such site is Wessex Water's Avonmouth Wastewater Treatment Works near Bristol, where the sludge The extent of the UK's anaerobic digestion industry has been mapped in full for the first time, thanks to a new online interactive map unveiled by the Anaerobic Diges- tion and Bioresources Association (ADBA). The map, available on ADBA's website (adbioresources.org), shows details of 540 operational sites on the association's da- tabase, which are producing biogas from food waste, agricultural materials, industrial effluents or sewage. Sewage sludge AD sites are marked on the version above.