The water quality of the River Calder will be improved by an £18 million investment in measures to remove phosphorus at Dewsbury wastewater treatment works in the UK.

Phosphorus is a normal part of domestic sewage, entering the sewer system via domestic showers and washing machines due to products such as shampoo and liquid detergent containing phosphorus. It can also run off agricultural fields where fertilisers have been applied and dissolved into soil, which can be difficult to control.

While small amounts of phosphorus are harmless, and an essential part of many ecosystems, the chemical can become damaging to aquatic life if levels are not controlled. On completion of the works, phosphorus concentrations in the treated effluent entering the River Calder will meet new water industry national environment programme (WINEP) targets for England.

Part of the work will involve reconfiguring the primary settlement tanks (PSTs) which are the first stage of treatment. They reduce the velocity of the wastewater flow, allowing heaver solids to settle out for removal.

A number of the 14 existing PSTs will be replaced with three larger tanks and two new primary sludge pumping stations. A new chemical dosing plant will also be added, to help reduce phosphorus levels in the effluent returned to the environment following the treatment process.

Richard Stuart, director of capital delivery, at Yorkshire Water, said, “We are committed to looking at innovative ways to improve the operation of our sites to meet our WINEP targets. This project will make use of a range of measures designed to reduce carbon impact and speed up the length of the works.

“Not only does this provide significant benefits to us and our customers from a cost saving point of view, but the work will also ultimately lead to improved water quality in the Calder by removing phosphorus from treated effluent and provide improved monitoring at the site to ensure compliance.”

The project, which is being carried out by a joint venture between Barhale and Enpure, forms part of Yorkshire Water’s £500 million investment in phosphorous removal, which the company says is part of its ongoing commitment to ensure future facilities meet current and anticipated Environment Agency quality targets.

Yorkshire Water completed another £18 million scheme at Dewsbury wastewater treatment works in 2020 to add anaerobic digestion to the facility. The process converts waste into biogas that can be used to generate heat and electricity.