Water Quality Improvements

River Irwell gets the treatment
12:40pm Sunday 12th October 2008 – Bury Times

WHAT was once one of the most polluted rivers in the North West is about to get a massive boost, thanks to a major project at water treatment works in Stoneclough.
Thousands of people and the environment will benefit, along with the much-neglected River Irwell.
The work at the United Utilities site, in Ringley Fold, is ahead of schedule and should be virtually completed by the end of the year.
It is the biggest scheme that United Utilities has undertaken in the region in terms of scale and cost and is funded by a slice of the £2.9 billion that the company has invested in water quality and environmental improvements between 2005 and 2010.
Project manager Dave Jones said: “Ten years ago there were no fish in the River Irwell and people would not fish in it.
“The new improvements at the wastewater works should increase the number of fish in the river. But it will also massively improve the environment locally, so walkers, canoeists and anglers will all reap the benefits.”
Mr Jones added: “We’re really excited about this project. These works are very important because they serve over hundreds of thousands of customers across the area, taking their wastewater, treating it and then returning it safely to the River Irwell.”
Reducing the amount of phosphate in the water is the main driver behind the scheme. New legislation states that the amount of phosphate in waste water should be one milligram per litre because it causes water to clog with algae and reduces the amount of oxygen in the water, which results in less aquatic life and fish.
The plant, built in the 1930s and last updated in the 1970s, treats water from a population of half a million — from Bolton, Prestwich, Whitefield and Clifton. The waste water comes from every single toilet flush and rain water.
The old system was designed to take 64 million litres of water a day. Now it can treat 204 million litres a day. The modernisation will increase that to 242 million litres (equivalent to treating the water in an Olympic-sized swimming pool every 15 minutes) as well as reducing pollution.
The first step in the process is to remove the inorganics, such as paper, litter and plastics from the water. Secondly, all the rocks, pebbles and grit will be removed.
Storm tanks are used to store excess water when there are prolonged downpours until the plant can catch up with treating the excess and two new circular storm tanks are being built to counteract the increasing rainfall in the area. Heavy sludge is then removed from the water in six tanks and two new ones are being built. The sludge is reused to create energy.
Mr Jones hopes that the plant will be entirely self-sufficient in electricity by treating more water and so producing more power from gas in the sludge.
Ammonia is then naturally reduced to under 5mg per litre by reusing the sludge removed from the water and exposing it to air. The quality will meet new legislation by using new dosing tanks to remove iron from the water. Eight tanks remove small particles before the water is pumped back into the river. Four 46 metre tanks are being built to improve the quality of this final process. The end result will be cleaner water in our rivers and canals.
Mr Jones said: “We make sure when we build new tanks that we have left enough room for future upgrades. It has been our priority to ensure that the project has not affected the amount of water that we treat daily.”