Problem: Thames Water’s commitment to AMP5 means improvements to process facilities at the Little Marlow Wastewater Treatment Works site. The improvements include the construction of a ventilation plant and an Odour Control System, so Thames Water needed to find a company capable of providing such technology.

Solution: ACWA AIR, has completed a fast-track contract to design, manufacture, install and commission Odour Scrubbing and Activated Carbon Deodoriser technology, with advanced ventilation, for the Little Marlow works. The company surveyed existing technologies at the site and submitted design proposals for a new ventilation system which would not only increase the rate of ventilation within the composting building but reduce atmospheric odour emissions from the air-stream to less than 1000ouE/m3. This lowers odour levels within the building and improves working conditions for plant operatives.

Odour-laden air-stream is carried inside and outside the building through more than 50m of ductwork, extracting contaminated air from the composting building to the new Odour Control System.

The system treats 135,000m3/h of contaminated air, extracted from the Thames Water composting process which is passed through a 4.2m diameter, 13m high scrubber, using sulphuric acid to neutralise ammonia in the air stream. The ammonia sulphate produced in biologically treated so it is clean enough to be discharged into the River Thames.

The relative humidity of the airstream, after the scrubbing process, had to be in the order of 70%, to ensure that the activated carbon deodorisers perform efficiently. This was achieved by an in-line electric heating system. Each of the deodorisers removes hydrocarbons from the air-stream. Air is discharged to atmosphere through a 15m stack.


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