Powder activated carbon metering - Elimination of man-made trace substances in municipal waste water

HEIDELBERG, Germany - May 9, 2016 - PRLog -- Man-made trace substances in drinking water are a continually growing problem. These compounds, for example from cosmetics and medicines, which are very resistant to biological decomposition, enter our drinking water reserves through waste water.

In many cases, clarification plants have a fourth cleaning stage to remove this category of impurities and some countries, such as Switzerland, it is required by law.

ProMinent supplies two technologies for the removal of these trace substances from municipal waste water. The proven OZONFILT^® systems break down pollutants with ozone.For large-scale elimination with powder activated carbon (PAC), ProMinent has developed a complete system that wets and suspends PAC in a dust-free process and accurately meters it with a multi-screw feeder. The PAC metering system, which consists of a Big Bag emptying unit, a powder storage tank and a multi-screw feeder, will be on show at IFAT 2016 at stand 439/538 in Hall A3.

Tomal^®, a company of the ProMinent Group specialising in dry feeding, has developed a special PAC metering unit which meters powder activated carbon volumetrically and with high precision. Unlike gravimetric metering systems, this technology requires no error-prone, maintenance-intensive weighing equipment.

The emptying station is designed for use with both disposable and reusable bags. The Big Bags are suspended in the frame with the aid of a lifting cross bar. The discharge funnel is matched to the bag size used. A special seal ensures that the bags are emptied into the powder storage tank without producing dust. A vibrator is used as a discharge aid and is monitored by the rotary paddle switch below the outlet. The powder storage tank is used to transfer the powder into the volumetric multi-screw feeder. The self-cleaning screw mechanism guarantees smooth, dust-free and accurate metering of the activated carbon. The powder activated carbon is transported to the wetting funnel with a reproducible accuracy of better than 1%.

Thanks to volumetric metering, exactly the required amount of activated carbon is supplied to the process, resulting in optimum adsorption of the trace substances. There is no over-metering with the associated costs. A Venturi mixer adds the suspension produced to the waste water.

There, the activated carbon adsorbs up to 90% of trace substances and slowly settles in a sedimentation tank. This process can be accelerated by adding flocculants. The resulting sludge of activated carbon and precipitant is then processed.