Water way to come up clean! (From Bradford Telegraph and Argus)

Water way to come up clean!

8:28am Wednesday 16th September 2009 in News By Helen Mead

Watching brown water, flecked with toilet paper, sanitary wear and other unsavoury items, flowing from a giant tunnel, it is hard to imagine how it could, just more than a day later, end up in the River Aire.

But it does. Filthy water from the sewers of Bradford is cleaned in a natural process that sees it discharged into the river looking as clear and fresh as that from a mountain spring.

And, from tomorrow until September 30, the public will be able to see for themselves how the effluent from thousands of homes across Bradford district is cleaned to a standard where it looks good enough to drink.

“That’s not recommended, although it is very clean,” says Matthew Thompson, community relations officer with Yorkshire Water, pointing some ducks happily swimming at the company’s Esholt sewage works.

“More than ever, people want to know what they are paying their bills for,” says Matthew. “So we are inviting them to come along and see where their money goes.”

The tours will also show how Yorkshire Water is using state-of-the-art green technology to produce renewable energy.

Esholt works serve a population equivalent of 700,000, made up of 340,000 people, with the remainder being industrial waste.

The historic 4km-long brick-lined tunnel was opened in 1924. The cost of the scheme at the time was £2.5 million – a far cry from the £75 million investment made on this site since November, 2005.

Polluted with items like tampons, dishcloths, pairs of tights and condoms, the brown water surges at key times of the day.

“It peaks at around 10am with all the effluent from the morning when people get up and get ready for work,” says site operator Paul Blackburn.

“There’s another after lunch, and another between 6pm and 8pm when people come home, have their tea and have a shower.”

Cleansing follows a number of stages, beginning with a process in which larger items of solid material such as tampons, sanitary towels and baby wipes, are trapped and extracted.

Yorkshire Water tries hard to educate people that their toilet is not a bin. “Items like condoms, sanitary towels and make-up pads should be binned, as they can cause blockages, which lead to serious incidents of pollution.”

The collected debris is washed and compacted before being transported to landfill.

Once the larger solids are removed, the smaller ones run on to be collected in fine filters where grit, which has flowed into drains from roads, is sifted out and transported to a skip.

“Sixteen tonnes of grit is removed every week,” says Paul, leading me to a skip where, among the gravel, can be seen a number of spoons, SIM cards, small plastic toys and hundreds of cigarette ends.

“This is currently sent to landfill, but we are looking at alternative ways of using it,” says Paul.

The site treats the equivalent of 112 Olympic swimming pools full of waste every day.

After the grit has been removed through settlement in a moving stream of water, fine screens filter out smaller particles of waste, before heading to a giant Archimedes screw that moves water downhill rather than the usual uphill.

This 12-metre-long hydro-generator machine – the first ever to be installed in a waste water treatment works – is used to harness energy from water, shaving £100,000 a year off Yorkshire Water’s £50 million annual electricity bill. “It can provide ten per cent of our energy needs on the site, and will have paid for itself in five years,” says Matthew.

Screened sewage is then mixed with good bacteria in aerated tanks. The good micro-organisms eat the bad, cleansing the water further. By tapping into a supply of methane gas emitted from sludge in giant digesters, the site also runs two combined heat and power generators. “Combined, they can produce up to a third of the energy that the plant consumes every day – a huge saving,” says Matthew.

Final settlement tanks spell the end of the journey for the sewage. At 35 metres in diameter and around four metres deep, they allow the good bacteria that have feasted and grown fall to the bottom. The clean water pours over weirs at the edge before being discharged into the river. The discharge meets the standards of the European Freshwater Fish Directive.

“Those ducks are a good endorsement,” adds Matthew, as another pair of mallards join the two already paddling around.

To book a place on a free tour, visit yorkshirewater.com/book, or phone 08451 242424. For a virtual tour of the water treatment works, go to yorkshirewater.com/see-how-your-water-works.aspx.