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Burnley WwTW: New Thermal Hydrolysis Plant

Franklyn Yates Engineering Limited were contracted by KMI who partnered with United Utilities to deliver a new Thermal Hydrolysis Plant (THP) at one of their waste water treatment works in Lancashire. Burnley WwTW was producing treated sludge of which the extracted solids had no environmental benefits. With the successful installation of this new system the sludge will become known as ""enhanced"" treated sludge that can then be used in agriculture.


There were a number of specifically different work scopes on this project that included the design, supply, manufacture and installation of various pipework systems, pipe bridges, pipe racks and pipework supports that were also utilised to carry the odour control ducts and a selection of cable trays. 

Some of the different disciplines included the following:

  • Installation of ductile Iron, scotchkote carbon steel and stainless steel pipework in all areas.
  • Screened sludge & sludge thickening centrifuge feed pumps and associated pipework, supports, macerators, steelwork and valves.
  • Thickened sludge transfer pumps, PN25 pipework, supports, magflow, valves and all instrumentation.
  • Thickened sludge cake storage silo – THP feed pumps, PN25 pipework, supports, valves and instrumentation.
  • Thickening centrate transfer pumps, pipework, supports, valves and flowmeter.
  • UV disinfection units, automatic back flushing filter, associated pipework, valves and supports.
  • Primary sludge digester & sludge recirculation pumps, pipework, valves and supports.
  • Sludge storage feed pumps, pipework, valves and supports.
  • Complete new installation of final effluent and service water booster systems.
  • Site drainage pumping station, consisting of submersible pumps and guiderails along with the design, supply and installation of the associated pipework and steelwork.
  • Complete design, manufacture and installation of various pipe rack support frames and pipe bridges.
  • Fully pressure tested pipework ranging from 6bar to 25bar.
  • All pipe banding, flow markings and valve tags.


The Thermal Hydrolysis Plant is basically a boiler. It heats the sludge then pressurises it. A rapid decompression follows which enables the solids in the sludge to break down considerably more and significantly improves the dewatering ability of the sludge. This combined action sterilizes the sludge and makes it more biodegradable. Sterilization destroys any pathogens present resulting in a more agricultural friendly land application.

Burnley - New Thermal Hydrolysis Plant

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