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UTILITY Week 25th September 2015

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UTILITY WEEK | 25TH SEPTEMBER - 1ST OCTOBER 2015 | 25 • 75 microns HeadCell removes 95% of grit  particles down to a size of  75 microns  • 200 microns 60% of grit in wastewater is  smaller than 200 microns – the  smallest particle size wastewater  companies are required to remove • Energy A 1% increase in upstream grit  leads to a 1% increase in energy  costs for wastewater treatment  plants Operations & Assets Hard facts: TM Utility Week's Game Changers series seeks to champion innovation in the utilities sector. To put forward a technology for coverage contact assistant editor (insights) Jane Gray, email: janegray@fav-house.com Why hasn't grit management been a priority in the UK? Getting advanced grit management on the agenda in the UK has not been straightforward, despite claims of great results from technology providers such as Hydro International. "Innovation in the UK water industry is very much like a parachute jump. You get a gang of people at whatever level and they all want to do it, but nobody wants to be the first person out the door," says Hayward. Furthermore, with the UK regulatory regime until recently dividing capital expenditure and operational expenditure when making its five-yearly price settlements, there has been little incentive to focus on the lifetime costs that grit creates. Both these factors are changing. Hydro International has invested a lot of effort in wearing down UK risk-aversion and showing HeadCell to be a "proven innovation". It has more than 200 North American deployments of the technology to point at, but to further reassure potential UK investors it has set up a mobile pilot unit for water companies to experiment with – free of charge – and conducted a range of independently verified technology tests. Combined with these efforts, the introduction of totex metrics in the UK mean that technology providers are hopeful AMP6 will see a swathe of investment in advanced grit management. Hydro International is now in what Hutchings describes as "close discussions" with four UK water companies for the deployment of HeadCell and the realisation of associated savings. Coming soon: Our next Game Changer feature will look at a copper/zinc battery being  developed by start-up technology firm Cumulus to provide grid-level  electricity storage. In addition to the efficiency saving HeadCell promises, it also has a much smaller  footprint than most other grit removal technologies. "If you assume you are draining the digesters down just to clean them out, instead of every seven years you could reckon on every 35 years and still at a lower cost. It's a colossal saving." Keith Hayward, UK sales and marketing manager, Hydro International drains from surface run-off, something exacerbated by storm events. All this grit eventually ends up in the same place – the wastewater treatment works – and there it creates problems. It builds up within the system, clogging the aeration machines and increasing the wear rates of other parts of the facility, such as filters. Alongside this, it decreases the efficiency of the plant, so electricity bills go up. Currently, wastewater companies are obliged by the Water Industry Mechanical and Electrical Specifications (WIMES) to remove grit down to the size of 200 microns. However, according to research by Hydro International at least 60 per cent of grit is smaller than this. So while con- ventional grit removal systems remove up to 95 per cent of grit from wastewater, they count only "classified" grit of 200 microns or more. In reality, therefore, they may be removing only around 20 to 30 per cent of the true incoming grit load. Hydro International's UK sales and marketing man- ager, Keith Hayward, explains that this leads to grit accumulating in the various treatment components and adding to wear and abrasion rates, making the whole system less efficient. From a maintenance point of view, a wastewater treatment works designed to serve a popu- lation of 250,000 people needs draining and clearing every five to seven years because of accumulated grit. "On one plant recently there has been a cost of £750,000 for cleaning out digesters," says Hayward. In other cases, the process can cost as much as £100,000. "That's shutting down the digesters, draining them down, digging them out and transporting the grit away. That is occurring every seven years or so, but would not occur if HeadCell was in place," he states. "If you assume you are draining them down just to clean them out, instead of every seven years you could reckon on every 35 years and still at a lower cost. It's a colossal saving." It's not just periodic maintenance costs that can be slashed with the installation of advanced grit manage- ment technology. So too can day-to-day costs. Hayward says many treatment plants have their aera- tion specifications "over scoped" to ensure that, even when clogged with grit, they are still able to operate to the minimum required standards. He says that for every 1 per cent increase in grit down- stream in the wastewater treatment process, there is a 1 per cent increase in wasted energy. Cutting down on grit in the system cuts down on power bills.

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