Frequently Asked Questions about the Passive Pump System (PPS)
What is a Passive Pump System (PPS)?
A Passive Pump System – PPS – is a siphon pipeline with an automatic cleaning function, where natural laws do most of the work, improving and simplifying operation and maintenance.
How does a PPS work?
A PPS consists of a siphon pipeline, a pumping unit (a compressed air–driven mammoth pump), a liquid reservoir, and a technical cabinet housing the compressor, air tank, and control system.
The liquid flows by gravity through the siphon pipeline since the inlet at M2 is higher than the outlet at PE.
Automatic cleaning occurs once per day for about one minute, when the compressed air–driven mammoth pump lowers the pressure line at PE, increasing flow to self-cleaning velocity.
To ensure sufficient flushing volume, a reservoir is installed between M1 and M2 – after each cleaning cycle, the system returns to passive mode.
What is a siphon pipeline?
When a gravity pipeline encounters an obstacle, it is rerouted beneath it using a siphon pipeline.
Such obstacles may include:
- Watercourses
- Road or pedestrian underpasses
- Railway tunnels
- Stormwater culverts
A siphon pipeline requires no external energy, as it relies on gravity. However, it has a weakness: in practice, it is difficult to maintain design flow rates that keep the pipe self-cleaning.
Over time, sediment builds up in the low point of the siphon due to varying flows in the sewer network. When high flow eventually occurs, the pipe may already be clogged — a well-known issue typically solved with a traditional pumping station.
Traditional pumping station – the common response to the siphon pipeline’s limitations
In a traditional pumping station, the outgoing pressure pipe can be laid as a siphon, while the pump ensures sufficient velocity for cleaning. However, this setup has several drawbacks:
- High energy consumption
- Power outages can cause flooding
- Backup power is required to prevent overflow during outages
- If backup power fails, the station must have an overflow outlet, discharging untreated wastewater — often into a nearby watercourse
PPS – the solution that simplifies and improves
This system functions as a siphon pipeline, but without its disadvantages.
A PPS means that:
- Water flows by gravity 99.9% of the time
- Energy consumption is minimal, as cleaning occurs only about one minute per day
- Power outages have no consequences, since the system resumes operation automatically
- The system cannot overflow
- A PPS is not sensitive to ground settlement – the siphon can settle freely without affecting function
However, a PPS cannot raise water levels. For that purpose, a traditional pumping station is the right solution.
