The solution lay is using low odour air from the lamella area located in the primary treatment works. The existing ductwork system was modified to allow this air to be supplied directly to the new secondary treatment works, via two new centrifugal fans.
The air was supplied to connections on the covers of the BAFF tanks and to the inlet of the BAFF blowers. The blowers then used this low odour air as process air to aerate the BAFF tanks.
All the foul air was then extracted directly from the BAFF tank covers to the existing odour extract facility located in the primary building.
By recycling the air in this way, no new odour control facility was needed for the secondary works.
It was necessary however, to supply building ventilation for the occupants and for any slight leakage from the covers. Supply air enters the system through a fresh air intake louvre and vertical builders work plenum. The air is drawn downwards through a silencer mounted horizontally within the plenum by the supply air-handling unit mounted at low level. This unit filters the air and heats it as required by an electric heater battery before it is discharged by the run/standby fans into the supply air ductwork system.
The building general extract system is located at low level. Air is extracted from the whole of the space via a bellmouth intake mounted at high level. This is then drawn through a silencer and interconnecting ductwork by the main run/standby extract fans. The air is discharged to atmosphere through a common header duct and a series of three roof mounted penthouse type louvers. A silencer is mounted beneath each louvre reducing noise to the required levels.
The MCC ROOM has been provided with duty/slave air conditioning units, which can operate independently or together to provide boost cooling if required. Each package system consists of a DX under ceiling mounted fan coil unit and a matched condensing unit. These are located in an adjacent area below the MCC, and have been specially treated against corrosion attack by trace elements of H2S gas.
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