BIOdek Trickling Filter Solves United Utilities’ Consent Problems at its Ulverston WWT Plant
A Trickling Filter system designed, built and installed by 2H Water Technologies is helping United Utilities meet consents at its wastewater treatment plant in Ulverston, Cumbria.
The Trickling Filter project is part of an AMP6 programme which commenced in 2014 when United Utilities appointed C2V+, a Volker Stevin and Jacobs joint venture, as one of four Construction Delivery Partners (CDP).The contract included all water and wastewater treatment design and construction activities across North West England for the current capital investment period –i.e. 2015-2020.
The site already had three existing plastic media trickling filters successfully providing secondary treatment to reduce BOD and ammonia levels. However, early in 2019, it was determined that this set-up was not capable of meeting the Ulverston plant’s future BOD and ammonia consents (25mg/l and 20mg/l respectively).
“We discussed various ways in which the use of the current Trickling Filter assets could be maintained but optimised to greatest effect. In the end, we agreed that reducing flows and loads to the three existing Trickling Filters would improve overall performance.” explained Richard Manning, Managing Director, 2H Water Technologies.
“We calculated that by designing a new Trickling Filter to treat 40% of incoming flows and loads, the three legacy Trickling Filters could each treat 20% of the remaining effluent with far greater effect. 2H was confident that the blended effluent from all four Trickling Filters would comfortably achieve the required consents.”
The 2H Water Technologies solution included:
PLANT: Design, Build and Install
- BIOdek KFP619 polypropylene(PP) crossflow media with a specific surface area of 150m2/m3
- PIERdek support system
- Rotary distributor
CONSULTANCY AND TRAINING
In conjunction with United Utilities own staff, 2H carried out operator training and demonstrated essential maintenance activities.
Bespoke is Best
Because space is limited at the Ulverston wastewater treatment plant,size was an important factor in the design process.While the Trickling Filter had to be compact to ensure it would be easily accommodated onsite, it also had to be capable of treating nearly half the flows and loads generated at the Ulverston plant.2H responded by sizing the new Trickling Filter at 15.370m diameter with a packed media depth of 5.185m.
2H recommended using BIOdek KFP619 polypropylene (PP) crossflow media in the new Trickling Filter because it offered the best combination of surface area and open area (97% void) for the treatment of the incoming BOD and ammonia loads.
The PIERdek media support system, designed and built by 2H, eliminated the need for a civil, concrete build support system in the base of the tank.
C2V+ carried out the civil works for the Trickling Filter base, distributor support column and installed the delivery pipework. The company also handled the supply and installation of the new filter’s glass coated steel tank.
When the tank was in place, 2H completed the installation of the PIERdek support system, installed the BIOdek media, and set-up the rotary distributor.
The rotary distributor was designed to deliver a range of flows at the optimal wetting rate for process requirements. Every element was precision-built to ensure consistent and reliable operation. For example, the motor control ensures the distributor always delivers the correct flushing intensity while the speed of rotation can be modified to enable specific flushing cycles and ensure a healthy biomass is maintained on the BIOdek media. And, in the event of one of the other Trickling Filters being out of service, the 2H design allowed for the rotary distributor to handle any additional flow.
The distributor was commissioned as soon as power was available and flows underway. The commissioning process included pan tests to prove even distribution of flows over the top surface area of the media.
The fourth BIOdek Trickling Filter has been live, and delivering reliable, high-quality wastewater treatment since Summer 2019. However, the installation process didn’t always run smoothly.
“It’s a rare project that doesn’t encounter a few bumps on the road to completion, and the Ulverston installation was no exception. Handled badly, even minor problems can have a disproportionately negative effect, not only on the project but also on relationships between each of the contractors as well as the client.” Richard Manning explains.
“As far as the Ulverston project is concerned, we had an issue with a supplier which resulted in a some of the parts needed for the PIERdek support system being delayed. Because we believe in collaboration – and honesty – we made a point of keeping CV2+ aware of every development, good and not so good. We were able to discuss the problem openly with CV2+ and, as a result, agreed an approach that mitigated the potential for delay and ensured our working relationship remained cordial and productive.”