Articles & Case Studies

Anglian Water adopt the Hydrok IFAS™system – the first in the UK

Posted: Wednesday 5th September 2012

An extensive upgrade at two of Anglian Water's major Wastewater Treatment Works, one at Bedford and another at Colchester, adopt the Hydrok IFAS system for the refurbishment of the works aeration tanks. Bedford utilised surface aerators and Colchester an ageing aeration system which are to be replaced by the Hydrok solution using a combination of high efficiency fine bubble diffusers and fixed bed IFAS (Integrated Fixed-Film Activated Sludge) system, positioned in modular cages of the media curtains, above the diffusers.

Bedford WwTW at Summer House Hill

The existing two activated sludge plants use surface aerators which are very energy demanding and have limited expansion capabilities. They are at the end of usable life so Anglian Water working with Skanska Jacobs through the @one Alliance and in design consultation with Hydrok made an informed decision to adopt the Hydrok IFAS system for the planned refurbishment. The Hydrok design solution is to combine highly energy efficient fine bubble diffusers with a fixed bed media to create an Integrated Fixed-Film Activated Sludge (IFAS) modular unit system. The outcome of this approach is both a highly energy efficient solution as well as considerably increasing load capacity of the plant.

Bedford ASP 1

2 lanes of 4 zones(cells) each which had been operated with 8 surface aerators.

Hydrok Solution

Install fine bubble diffusers fixed to the base of the tank in both lanes; install new pipework for the aeration process with air supplied from 3 energy efficient Atlas Copco rotary screw blowers. In 2 zones per lane a total of 12 Hydrok IFAS modular cages would be installed above the diffusers. Approximately 35% of the ASP would incorporate the IFAS cages allowing for future additional cages as required by future increased load demand.

Bedford ASP 2

1 tank with 3 lanes, each with 6 surface aerators per lane, 18 in total.

Hydrok Solution

In a phased refurbishment Hydrok’s design incorporated high efficiency fine bubble diffusers on the base of each lane with 12 IFAS modular cage units to be fitted above the diffusers (36 within the ASP), covering 50% of the tanks operational area. This would allow for further expansion of the load capability by introducing more IFAS cages as demand required. The plan is to refurbish each lane one by one maintaining the works operational ability. New pipework and air mains would be manufactured and fitted to supply air from 5 energy efficient Atlas Copco rotary screw blowers.

Refurbishment work of the two Bedford ASPs is due to commence May 2012.

The @one Alliance commented: “Anglian Water have set targets for AMP5 to reduce the capital cost of delivering projects by 20-30% and the embodied carbon associated with delivering the new assets by 50%. It was only possible to meet these targets for the extensions at Bedford Wastewater Treatment Works by working in close collaboration with Anglian Water Operations teams and Hydrok to develop an IFAS technology solution.”

Colchester WwTW

A large scale refurbishment of the existing aeration tanks to increase efficiency and expand load capabilities without the necessity to build new tanks. Hydrok working closely with @one Alliance and MWH contractors designed a solution to refurbish the aeration tanks in stages, thus maintaining the plant's integrity and operational ability whilst refurbishment takes place.

The site has two tanks, tank 1 has 3 lanes and tank 2 has 2 lanes. New pipework and air mains will be fitted fed from 4 energy efficient Atlas Copco rotary screw blowers.

Colchester Tank 1

Tank 1 requires removal of existing liftout diffuser grids and replacing with Hydrok Liftout grids and Hydrok IFAS modular units incorporating high efficiency fine bubble diffusers and fixed bed media. Each lane will be fitted with 8 bespoke Hydrok modular IFAS cages (6m x 2m x 4.5m high) and 2 Hydrok Diffuser Liftout grids ( 6m x 2m x 4.5m).

Due to Operational demands the installation of all equipment will be carried out without interruption of the flows and more importantly, without the need to drain any of the lanes during the refurbishment. Each lane of tank 1 will be refurbished in a staggered schedule. A total of 24 IFAS modular units plus 6 Hydrok Diffuser Liftout grids will be fitted in tank 1. Worked commenced on the first phase of the refurbishment in February 2012 fitting the new air mains in preparation for the first lane installation Sept/Oct 2011.

Colchester Tank 2

Phase 2 of the refurbishment, tank 2, incorporating 2 lanes of a different configuration to tank 1, requires removal of existing liftout diffuser grids and replacement with the Hydrok systems as in tank 1. Each of the 2 lanes will be fitted with 13 Hydrok IFAS modular units (9m x 1.4m x4.5m high) plus 3 Hydrok Diffuser Liftout grids (9m x 2.8m). Once again the lanes will be refurbished in turn to ensure minimum disruption to the plant's operability.

Mark Lunn, Product Manager at Hydrok commented: "We are really excited to be working with the @one Alliance and Anglian Water on the UK's first IFAS plants. This is a fantastic opportunity for Hydrok to install IFAS and High Efficiency diffusers into two of Anglian Water's biggest waste water treatment works. The technology we will be installing will assist with Anglian Water's drive to increase operational efficiencies and reduce their carbon footprint.”

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