Thames Water Invests in Sand Filtration Technology 

Thames Water is investing in tertiary sand filtration technology from Hydro International (UK) as part of its improvement programmes at seven wastewater treatment works to meet improved discharge standards for ammonia levels.

Thames is installing the first 18 DynaSand Oxy vertical sand filters for ammonia reduction at WwTWs in Oxfordshire, Wiltshire and Berkshire as part of its £multi-billion AMP 5 capital investment programme.

The DynaSand Oxy filters selected by Black and Veatch will enable Thames Water to successfully augment the tertiary treatment process at the sites to meet rigorous Environment Agency water quality requirements.

The DynaSand Oxy units are the first to be ordered for Thames Water projects after Hydro International was appointed one of the preferred suppliers for nitrifying continuous flow sand filtration equipment as part of a three-year framework agreement for AMP 5.

The first 18 units will be installed at Marlborough and East Shefford in Wiltshire, Marsh Gibbon in Oxfordshire and Washwater in Berkshire during 2012 with the remaining units being installed in 2013. The DynaSand Oxy filters remove suspended solids and denitrify in a single stage before discharge into the receiving water courses.

“The DynaSand Oxy units help meet Environment Agency consents at the sites,” points out Paul Nolan, Procurement Manager for Black & Veatch at Reading, which is the appointed Programme Delivery Manager. “The sand filter technology selected provides a commercial solution for the client to achieve the required process performance.”

Chris Day, Operations Director with Hydro International’s UK Wastewater Division added: “We are delighted with these contracts which demonstrate Thames Water’s confidence in the DynaSand Oxy process for ammonia reduction and its suitability for retrofitting at plants where space is at a premium.”

Hydro is one of two Framework suppliers for Filtration Equipment - CF Sand filters and NCF Sand filters, throughout the Thames Water region. The framework agreement covers the supply of DynaSand filters used for tertiary and final treatment of sewage effluent, removal of suspended solids or ‘polishing’, as well as the supply of DynaSand Oxy filters for ammonia reduction.

The DynaSand vertical sand filter operates continuously and efficiently using an internal washing process which eliminates the need for water storage tanks, backwash pumps and water collection.

In the DynaSand Oxy process, ammonia is converted into nitrate by autotrophic nitrifying bacteria - Nitrosomonas and Nitrobacter - as the water flows upwards through the filter bed. The bacteria form a layer on the surfaces of the filter grains and the resultant nitrates remain dissolved in the water.