In partnership with a major water company, Veolia Water Technologies UK (VWT UK) has supplied and installed its AnoxKaldnes™ Moving Bed Biofilm Reactor (MBBR) solution as well as its Hydrotech Disc Filter at one of its wastewater treatment plants.
This tertiary water treatment, installed downstream of the existing plant, was designed and specified to ensure ammonia, solids and biological oxygen demand (BOD) discharge requirements were met.
To improve the quality of water courses and protect aquatic life, stricter discharge limits were introduced by the regulator Ofwat and the Government’s Water Industry National Environment Programme (WINEP). Specifically, the permitted ammonia level in water discharged from water treatment plants was reduced. As a result, many water treatment facilities had to be upgraded to meet these new standards.
One such site is located in a semi-rural area and discharges its water into a small nearby river. The current plant was not capable of meeting the tightened limits of 1.3mg/l of ammonia, 60mg/l of solids and 40mg/l of biological oxygen demand, so additional treatment steps were required. However, the space available on the site was limited, which had to be considered when selecting a solution.
Following a competitive tender process, VWT UK was selected based on its experience undertaking similar projects, its ability to provide a complete, proven solution – eliminating the need for multiple suppliers – and the total footprint of the plant.
VWT UK recommended its AnoxKaldnes™ Moving Bed Biofilm Reactor (MBBR) technology for ammonia and BOD removal, combined with its Hydrotech Disc Filter to capture the suspended solids. VWT UK worked closely with the water company and the contractor responsible for the project to design a plant configuration that would make efficient use of space and allow safe access for maintenance.
MBBR is a longstanding and proven technology first developed in the 1980s and today is in use on thousands of sites globally. An aerobic wastewater treatment method, MBBR uses active biofilm carriers made from plastic with large surface areas on which bacteria can grow with optimal culture conditions. The carriers are kept in constant motion within the tanks using aeration, allowing the bacteria to break down the ammonia effectively. The large surface area of the carriers in the AnoxKaldnes™ MBBR systems enable the reliable treatment of a large quantity of wastewater, all while maintaining a very small footprint.
VWT UK designed the system to operate in its patented alternating flow configuration to allow the tight ammonia consent to be met. In this configuration, two MBBR tanks are operated in series with gravity transfer between the tanks, so that the second tank receives lower concentrations of ammonium (NH4-N).
Following the MBBR stage, VWT UK installed its Hydrotech Disc Filter to provide wastewater filtration. First introduced 30 years ago, and since developed to improve its efficiency, the Hydrotech Disc Filter uses polyester woven cloth filters mounted on multiple discs to provide a large filter area in a small footprint.
Since its installation, the system has reliably delivered the required levels of treatment to help ensure the discharged water complies with the revised standards, and even exceed the target performance.
Matt Langdon, Business Development Manager at VWT UK said:
“This project demonstrates some of the key advantages of MBBR and our AnoxKaldnes™ solution in particular. MBBR is very flexible in its design and VWT UK can employ many different configurations, media types and additional technologies to meet a client’s specific requirements. This is only possible because of our extensive experience designing and operating MBBR systems in the UK as well as globally.”
