United Utilities has been given the go ahead to build a £200million extension to its waste treatment plant on the banks of the River Mersey in a scheme that could create up to 350 jobs.

The existing works at Sandon Dock will be extended into the redundant Wellington Dock.

As a result, the plant able to cope with 11,000 litres of waste a second, serving one million people in Liverpool from Crosby in the north to Speke in the south.

Treated water leaving the new plant will be cleaner and greener, helping the continuing rejuvenation of the River Mersey and ensuring it meets strict European standards for water quality.

Back in 1985, the river was the most polluted in the UK but it now sustains a wide range of fish such as salmon, trout, lamprey and dace.

United Utilities said it has worked closely with local businesses, residents and Liverpool City Council to devise a scheme that will have a minimal impact on the famous Liverpool skyline.

The treatment facility, based on successful plants in other coastal cities, such as Cardiff and Dublin, will be sunk into Wellington Dock and coping stones, dock features and furniture will be retained where possible.

Liverpool City Council's planning department approved the plans at a meeting on Tuesday. Dredging of Wellington Dock has already taken place and work will start next month.

The scheme is scheduled to take up to four years to complete and United Utilities estimates up to 350 people could be employed to work on the scheme.

Mark Walker, United Utilities' Principal Project Manager, said:

"This is great news for the people of Liverpool. Our existing plant has played a key role in the clean up of the River Mersey and the new works will ensure we can continue to build upon that legacy.

"The expansion of Liverpool as a city down the years meant the current works were beginning to reach the end of their useful life. The new works will ensure we can continue to provide one of the city's most essential services for many years to come."