Water & Wastewater Treatment Magazine
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www.wwtonline.co.uk | WWT | XXXX 20XX | 19 Gasification of Sludge: Innovation in Action The Works Y orkshire Water has unveiled a first- of-its-kind innovation at its Lower Brighouse WWTW which is set to raise the bar for the amount of renewable energy that water companies are able to extract from their sewage sludge. The demonstration-scale, proof-of- concept Advanced Thermal Conversion (ATC) gasification plant is the result of ten years of research and development by Yorkshire Water and its partners. It has now operated successfully for 10,000 hours – meeting established industry benchmarks – and has generated 3.2GWhrs of electricity in that time. The process uses dried, pelletised sludge, mixed with pelletised wood, as fuel for a gasifier which produces syngas, which is then used to generate electricity, heat and char. If deployed at a suitable scale, the process has the potential to generate four times as much renewable electricity as anaerobic digestion (AD), the most commonly used technology for sludge treatment, while reducing the risks of recycling sludge cake to agriculture. Yorkshire Water plans to recover nutrients for more efficient, beneficial use; if deployed widely, the level of energy generation involved would make energy neutrality a realistic prospect for Yorkshire Water, as well as carbon neutrality – in fact, analysis from the Carbon Trust has confirmed that the operational ATC site is significantly carbon negative. The key technology at the heart of the process - the gasifier - has been designed and developed by Yorkshire Water's commercial partner Enertecgreen. Based on a system originally used in Latvia, it uses a proprietary process to produce a consistently high quality gas and avoid the problems of clogging which have hindered previous R&D efforts in the gasifier space. Suitable for deployment on a relatively small scale, as well as large modular deployment at wastewater treatment works, the emergence of the technology is extremely timely given Ofwat's imminent reforms to the sludge market. www.wwtonline.co.uk | WWT | NOVEMBER 2017 | 19 Yorkshire Water's advanced thermal conversion (ATC) gasification plant at Lower Brighouse WWTW has achieved a timely breakthrough in the extraction of energy from sludge By James Brockett The Lower Brighouse ATC plant seen from above