Background
Severn Trent operate Spernal WWTP, a medium sized sewage treatment plant in the Spernal Ash, Redditch, Warwickshire. The site has a Dry Weather Flow of 1,150 m3/hr and operates Primary settlement, an activated sludge plant, fixed film filters, Humus settlement tanks, and sand filters.
The Overall Objective
During sand filter refurbishment, the site would need a contingency plan to ensure compliance with the discharge consent. The temporary solution would be used to treat purely inert solids from the sites fixed film (Non-ASP) process. The required solution would be taking the place of the existing sand filter and would need to be sized to treat an incoming flow of up to 575 m3/hr (half the works FFT). The solution would be treating purely inert solids from the sites fixed film (Non-ASP) process.
Solution
Siltbuster worked closely with Severn Trent and started the project process by collecting samples and subjecting them to laboratory scale performance and analysis at Siltbuster’s in-house laboratory – a Siltbuster standard, time-efficient and proven procedure to find the best treatment system for the job. The most effective solution was to install a modular system of a flow split tank or a 4-way manifold, which would then distribute all the effluent from site HSTs to be split evenly to 4 D100 DAF (Dissolved Air Flotation) units. The flow to each of D100 DAF units would be up to a maximum of 41l/s, but for maximum treatment efficiency 27.8 l/s.
During the commissioning of the temporary units, it was observed that the 4-way manifold would be the best option for the required flow to be pumped forward to the DAF units.
Treated effluent from each D100 DAF was discharged by gravity back into the final effluent channel.
