Task

In a large city in north-eastern Europe, characterised by extensive industry, the need was recognised to implement comprehensive monitoring of discharges into the wastewater treatment plant.

Repeated incidents of illegal discharges of various substances had caused considerable problems for the sewage treatment plant. In order to identify the polluters, sampling points were to be installed throughout the city.

One particular challenge was that some of the sampling points were located more than 70 metres below street level. Nevertheless, for safety reasons and to optimise the operability of the devices, it was necessary to convey the samples to the surface.

Only explosion-proof components were allowed to be installed in the sewer.

Our solution

We designed a two-stage system with pressure-vacuum conveying. With this combination, we were able to achieve conveying heights of over 70 metres without any problems – and with a representative sample quality.

Function

Two successive pressurised conveying systems are controlled via a sampling device positioned on the surface. These systems are used to transport the sample fluid upwards in two stages from a depth of over 70 metres. The sampling station is equipped with a downstream measuring container that allows the integration of measuring electrodes.

In addition to the measurement, samples are bottled in parallel.

All components in the channel system were realised without electrical components. Due to the customer’s concerns regarding the functionality of our concept, we carried out tests in a quarry in advance and documented them on video.