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Problems With Pneumatic Systems in Water Treatment Plants

Pneumatic wastewater transport systems are systems used in water and sewage treatment. The system uses compressed air instead of electrical energy to transport and filter the water or wastewater. Increasing pressures from the compressed air allow the influent (entry) and effluent (exit) pneumatic valves to open and close. Although the pneumatic system offers high performance with no electrical energy costs, there are some problems that a water or wastewater treatment facility should consider before installing this type of system.

Air Blockage
- Air blockage in a pneumatic system can occur when the movement of air cannot pass causing the system to not function. The pneumatic system works like a vacuum cleaner in that the motor spins at a high speed creating a low pressure inside the vacuum. Liquids will move from an area of high pressure to an area of low pressure. The air then enters a filter and removes any particles. If the filter is not cleaned on a regular basis, the movement of air is blocked. To avoid blockage, pneumatic systems need to be cleaned regularly for filtration to occur.
Pneumatic Bursting
- Pneumatic bursting occurs in pneumatic systems from repeated impacts onto the pipe from compressed air or air delivered through air supply hoses. Pneumatic bursting is a common problem in pneumatic systems and, if this occurs, pipe replacement is required. Usually in this case, trenchless pipe replacement is required in which a new pipe with the same or slightly bigger diameter is replaced along the existing pipe.
Line Breaks
- Pneumatic plugs are used to divert wastewater flow around a break in a pipe to a downstream manhole. The pneumatic plugs are inserted in a pipe line at a manhole upstream from where the break occurred. The problem with pneumatic plug systems is that they have to be inserted downstream of the manhole. If it is inserted upstream or where pressure is greater, the plug can deflate and get pushed into another line resulting in stoppage of a working line. In addition, the plug can pop out of place resulting in leakage or further line breaking.
Sulfide Removal
- Pneumatic systems are used to prevent the production of hydrogen sulfide. Wastewater moves by gravity into a receiving tank. The influent valve closes and the effluent valve opens. Compressed air enters the receiving tank which is discharged pneumatically into the pressure sewer. The increased velocity of water combined with the sewer prevent the formation of anaerobic material, further preventing the formation of hydrogen sulfide. The problem with this design is that it is extremely expensive for water or wastewater treatment facilities, especially for treatment plants with millions of gallons of water or wastewater treatment daily.

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