Air Technology Systems needed to replace existing Odour Control Units that were in place at Newbury Sewage Treatment Works.
Client – Thames Water
Project Scope & Objectives
Thames Water had two non-functional Odour Control Units (OCU’s) on site that needed to be removed and replaced:
- Bio-scrubber OCU which treated the Picket Fence Thickener (PFT) Area
- Acid Scrubber OCU which treated the Centrifuge Area
Air Technology Systems were employed to decommission and remove these OCU’s and identify, design and provide a replacement Odour Control Solution.
Challenges
- Treating odours from numerous sludge storage and treatment processes across the site.
- Uncertainty about whether the processes of liming sludge was going to remain on site – Important as this would determine the type of abatement selected.
- Odour loads and concentrations had changed from original installation. New basis of design was provided by Thames Water.
- Underground extract ductwork that needed ‘capping off’ and re-routing above ground.
- The largest volume of air to be treated came from the skip room and the capture of odours in this area needed to be improved.
- Thames Water needed a company that was prepared to take on the role of Principle Designer and Contractor and deliver the project complying with CDM regulations 2015 and responsibilities.
- A full Mechanical, Electrical, Instrumentation, Control and Automation (MEICA) package with the addition of Civil and Structural works were to be incorporated into the contract.
- Some assets were in a poor state of repair – the requirement for repair / replacement of the tank lids on both the ‘raw sludge PFT’ and ‘raw sludge buffer’ tanks were identified during one of the pre-start site visits.
Prior to the award of a contract Air Technology Systems proactively engaged with Thames Water and together worked collaboratively to determine the solution that would best meet all of their requirements.
Solution
Air Technology Systems recommended that the two existing OCU’s were replaced with a single multi-stage OCU.
The decision was made that there would be no further ‘liming’ taking place on site, and therefore there was no risk of ammonia odours. This in turn meant that the incorporation of an acid scrubbing stage was not a requirement
Both existing OCU’s were dismantled and removed from site, to be replaced by the new, two stage OCU consisting of:
- Stage 1: 2 x bio-trickling filters treating and removing large volumes of hydrogen sulphide (H2S), mercaptans and other sulphur-based compounds associated with Wastewater and Sludge Treatment.
- Stage 2: 3 x carbon filters to ‘polish’ any remaining odorous compounds and achieve an odour discharge level of <1000OuE/m3 or 50ppb H2S
To ensure efficient treatment of the odours, and minimise the size of the odour control vessels, we used an innovative solution so that only sources of odour classed as ‘high odours’ were treated in the bio-trickling filters and then the carbon filters. The ‘lower odour’ air (which was the largest volume of air) bypassed the bio-filters and was only treated by the carbon filters.
This resulted in an efficient treatment of odour and a lower overall capital and operating cost as the existing OCU footprint was maintained.
ATS replaced or modified much of the existing extract ductwork. Two duct bridges were installed to carry the ductwork across roadways on the site, 1 bridge spanned 16m.
In addition to extract duct modification in the skip room, Air Technology Systems installed their high-velocity nozzle supply system. This Industrial Climate Control System is designed to maximise the ventilation efficiency, it was utilised on this project to ensure increase mixing of air & dilution within the skip room and improving the efficiency of the extract system.
Air Technology Systems also installed a dedicated Form 4 MCC panel to provide automation of the Odour Control System. This was housed in purpose-built GRP Kiosk.
Result
Through the process of collaborative development, the Odour Control Solution designed, supplied, installed, and commissioned by Air Technology Systems was the optimum system to combat the odour challenge.
The solution was fully compliant with all applicable Thames Water Asset Standards and importantly, because Air Technology Systems were communicating directly and effectively with the end user – Thames Water – we were able to introduce & discuss innovative aspects to the solution that were accepted on their merits as well as increasing the speed and efficiency of project delivery.
Henry Crompton, Project Manager for Thames Water commented:
“From initial engagement with ATS, it was apparent that they had a refreshing approach to this project and introduced some clever and constructive ideas. They have taken the role of CDM co-ordinator within their stride and delivered a very professional and most importantly safe installation. Overall, I’m very happy with ATS and hope I get the opportunity to work with them again”
