Severn Trent Water.
BIOdek™ plastic trickling filters
2H Water Technologies worked with the process engineering arm of Severn Trent Water over an extensive period evaluating the potential use of a nitrifying trickling filter at Longbridge STW, Warwick. The works utilised a rock media trickling filter plant which met its BOD requirements with the existing filters but not the future ammonia consent.
Various solutions were evaluated including changing some of the rock filters to plastic but as the existing filters were all in good condition, it was decided to add a plastic media tertiary nitrification stage.
This option had various advantages:
The design to handle 440l/s flow with the capability of all the flow being handled by each distributor in an emergency was accommodated in 2 off filters 16.2m diameter with 3.6m media depth of BIOdek FKP615 with 190m2/m3 media to produce a 5mg/l ammonia consent from an ammonia load of 423kg/d at 11.3mg/l.
2H worked with Severn Trent, their contractor Costain, and design engineers MWH to ensure that the tanks, main support structure and distributors were designed to meet the requirements of the media and the process.
“With the Longbridge plant now consistently recording ammonia levels so low that they’re nearly off the scale, installing BIOdek™ plastic trickling filters has proven to be a remarkable success,” said Tom Pawson, Delivery Manager – Waste Water, Severn Trent Water.
The installation of the media and the support system were completed in two weeks as planned keeping the project on schedule.