Technology
Presentation of the technology
We invite you to watch a short video that shows the operation of vacuum sewage technology in the ISEKI system.
The principle of operation of vacuum sewage
Through a gravity connection to the sewer, the wastewater enters a well with a valve that separates the two systems: gravity and vacuum. The wastewater from the well is sucked into a network of vacuum channels along with air and then enters the tank of the vacuum station. From the vacuum station, the wastewater is pumped to the treatment plant, and the air is discharged into the atmosphere after treatment.
The vacuum sewer network consists of three main elements:
Interface valve chambers
Vacuum pipework
Vacuum station
Interface valve chamber
Pneumatically operated vacuum valves are installed in the valve chambers.
Wastewater enters the lower section, or wet sump, of the interface valve chamber via gravity connections to the sewer. When the wet sump is filled to a certain level, a vacuum valve, which is usually closed, opens. When the valve is opened, air is sucked into the network along with the wastewater. When the wet sump is empty, the valve closes automatically.
Vacuum pipework
Vacuum pipework is most often made of welded polyethylene pipes with a diameter of 90 mm to 160 mm. Channels in the profile are laid in the form of a “saw” in accordance with the existing terrain.
The principle of operation
Vacuum station
On the territory of the vacuum station, there is a small brick building measuring approximately 5 x 6 m, in which the following devices are located:
- Two to four vacuum pumps
- Control cabinet with PLC for controlling the operation of the devices
- Generator and display for monitoring valves and networks
- Control and measuring equipment
- Mechanical ventilation
The principle of operation
In addition, the following facilities are located on the territory of the station:
Vacuum reservoir
Usually located near the building, below ground level). It is equipped with two piston pumps and level switches that control the operation of the pumps.
The exhaust air filter
A reservoir filled with biological material eliminates odours from the air removed from the sewage system into the atmosphere.
Chamber shutter
A sealed underground reinforced concrete reservoir with automatically controlled shutters located next to the vacuum reservoir.
Structure of the network
Easy and quick construction of a vacuum sewage network
- Shallow and straight trenches, often only 1.4-1.7 m deep.
- Lightweight earthmoving equipment.
- Low costs for backfilling and surface reconstruction.
- Easily bypass obstacles without the need to rebuild existing underground utilities.
- No need to use inspection wells.
- Quick, easy and durable pipe connections by welding.
The construction of a vacuum network is especially recommended in cities with the following characteristics:
- scattered development
- lack of natural slopes
- difficult soil conditions
- high groundwater level
- in narrow streets
- in open water and groundwater protection zones
Advantages of vacuum sewage
- One pumping station for the entire city of up to 3000 inhabitants.
- Possibility to collect wastewater within a radius of 3.5 km from the pumping station.
- Possibility of transporting wastewater uphill.
- Easy avoidance of collisions with territorial obstacles (canals, water flows, existing communications)
- In the absence of power supply to the pumping station, the system has a reserve volume and can function normally for a long period of time (volume in vacuum chambers and connections to the municipal sewerage system).
- Reliability of ISEKI vacuum valves with a relatively large 90 mm diameter, proven over the years.
- The technology meets the requirements of the current PN-EN 16932 standard
In addition, the vacuum sewage network is characterised by:
- Low investment costs
- Small diameter
- Shallow and narrow trenches
- Low operating costs
- High wastewater flow rate (approx. 6 m/s)
- Using bends to change the direction of flow without the need for wells
- Minimising the level of risk to staff health
- Possibility of laying sewer and water pipes in one trench
- No possibility of groundwater entering
- Eliminating the risk of environmental pollution due to leaking pipes
- The ability to bypass obstacles through pipes in any direction
In many cases, vacuum sewage is the only reasonable alternative for sewerage in suburban and rural
areas. In flat areas, with a high groundwater table, and with scattered buildings, the cost of building a
vacuum sewer can be half that of the proposed traditional gravity network solutions with
intermediate pumping stations.
Exploitation
Exploitation of vacuum sewage system
- Low electricity consumption (approx. 20 kWh/resident x year)
- Vacuum valves operate automatically, without the need for electricity.
- Waterproof and robust welded joints for network ducts made of polyethylene pipes.
- Flexible network ducts - easy to install, do not crack during operation.
- No exfiltration (no risk of soil contamination by wastewater).
- No infiltration (groundwater does not enter the sewerage system).
- No blockages in the network pipelines (high flow rate of about 6 m/s).
- Self-cleaning system (no sedimentation and fermentation of wastewater)
- Reducing the formation of gases and unpleasant odours (a small portion of wastewater, approximately 40 litres, is immediately absorbed into the network, and the exhaust air from the system passes through the deodorisation system).
- The vacuum station is fully automatic and does not require constant supervision.
- The vacuum valves that receive wastewater are controlled by a monitoring system that continuously transmits characteristic information about the valve status and event history.
- A basic set of tools is sufficient for routine maintenance.
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