Treatment of Oil-containing Eastewater from the Bogie Cleaning of Trams

Cause

In a municipal transport company, the bogies of the trams are regularly cleaned and then serviced. During cleaning with high-pressure nozzles using drinking water and cleaning agents, oil-containing wastewater is produced, whereby the hydrocarbons are emulsified in the water. Weil Wasseraufbereitung was commissioned to design and install a treatment plant to remove the hydrocarbons from the wastewater.

Ultrafiltration system for treating oil-containing wastewater

After high-pressure cleaning, the oil-containing wastewater enters a buffer tank where coarse impurities settle to the bottom. Depending on the level, a submersible pump pumps the excess oily water (emulsion) through a filter (100 µm) into a treatment tank.
In treatment mode, the wastewater is removed from the treatment tank by a centrifugal pump and channeled through a cartridge filter (50 µm) and then into the ultrafiltration modules (UF modules). The concentrate flowing out of the modules is recirculated back into the treatment tank. The oil- and hydrocarbon-free filtrate is channeled via a flow meter into the on-site final inspection chamber, from where it flows into the sewage system. Due to the permanent removal of clean water from the emulsion, the oil and hydrocarbon concentration in the treatment tank increases during treatment. As a result, the filtrate capacity of the system continuously decreases until maximum concentration of the oil and minimum filtrate capacity are achieved.

The oil-containing concentrate can then be drained from the treatment tank and disposed of. The high concentration minimizes the disposal volume and the high oil/hydrocarbon content means that the waste can still be thermally recycled.

The UF modules are then rinsed and cleaned with special membrane cleaners so that the filtrate performance is restored.

The used cleaning solution is treated and concentrated together with the next batch of oil-containing wastewater in the ultrafiltration process

The entire process is controlled via a PLC with visualization and operates fully automatically until cleaning is required. Cleaning itself is semi-automatic, with operational personnel receiving instructions for preparing the cleaning solution from the panel displays. This process includes prompts and necessary confirmations to prevent incorrect operations.