Water company′s leading green credentials in national spotlight

Owen Paterson and Heidi Mottram

10.05.2013

A water company has helped to showcase first class environmental innovation and sustainability in the North East by hosting a senior ministerial visit at its largest sewage treatment works on Tyneside.

Owen Paterson, Secretary of State for Environment, Food and Rural Affairs, has seen how Northumbrian Water is converting sludge, remaining after sewage treatment, into green energy at Howdon sewage treatment works.

Mr Paterson spent an hour on site this afternoon, and was shown the plant’s advanced anaerobic digestion process by the water company’s CEO, Heidi Mottram.

He saw how more than half a million tonnes of sludge - from the treatment of domestic sewage and industrial effluent from a population equivalent of one million people from Tyneside and north of the River Tyne – is reduced to around 60,000 tonnes and generates enough electricity to power most of the Howdon treatment works site or up to 8,000 homes.

Environment Secretary, Owen Paterson, said: "This is a great example of innovation from a water company. Converting waste into renewable energy shows how technology can be used to benefit businesses and the environment at the same time. I want to see more ideas like this to encourage economic growth.”

The water company has an ever-increasing focus on energy management and the production and use of green energy through:

* being the first, and at the moment the only water company, to use almost 100% the 1.6 million tonnes of sewage sludge, remaining after wastewater treatment from 437 sewage treatment works across the North East, to create green energy;

* powering 70% of the company’s waste water treatment process by using green energy;

* producing electricity at three hydro power stations at Kielder reservoir, Northumberland, Mosswood water treatment works, County Durham, and Selset reservoir, Tees Valley, to power more than 6,000 homes – the hydro power station at Kielder reservoir is the largest in the country;

* catchment management, for example, increased engagement with the farming community to help them understand the impact of their operations on, and how they can help protect, raw water quality;

* Northumbrian Water’s sister company, Essex & Suffolk Water, being the first in the world to use reed beds to separate and recycle water from sludge remaining after the water treatment process (at Hanningfield water treatment works in Essex);

* future plans to inject biogas into the national grid and to also recycle food waste, alongside sewage sludge, to produce energy (co-digestion);

Heidi Mottram, Northumbrian Water’s CEO, said: “Our green credentials demonstrate to our customers that we take our responsibility to protect and enhance the environment now, and in the future, very seriously. It also reflects our commitment to ensure that our energy-intensive processes are managed in the most efficient manner as possible, which also has a positive impact on customers’ bills.”

For further information please contact Cara Charlton, Northumbrian Water, on 0191 301 6720,
cara.charlton@nwl.co.uk.

Anaerobic digestion process

* Sludge is loaded into pressurised reactors, heated at 165 degrees centigrade at 6Bar. This stage of the process can be compared to domestic pressure cookers, found in most people’s kitchens.

* It is then depressurised and cooled before being fed into large concrete tanks for the bacterial process to start.

* Methane given off by the bugs that digest the waste is collected in 11-metre diameter storage bags before being used to fuel gas engines generates four mega watts of green electricity.

* The advanced anaerobic digestion technology at Northumbrian Water’s five-acre sewage treatment works site on Tyneside complements another similar plant at its largest works at Bran Sands on Teesside, which provides sewage treatment for homes and businesses south of the River Tyne and in the Tees Valley.

* The digested sludge ‘cake’ remaining after the process is a Class A product, which is safe, low odour and contains no detectable levels of pathogens, and is used as a valuable agricultural fertiliser which is an alternative to man-made fertilisers.

Other

* Howdon sewage treatment works treats the equivalent of up to 17 Olympic-size swimming pools of wastewater every hour (12,000 litres per second) – more than 400 swimming pools a day.

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