The typical biofilm thickness on HEWiFILL media in trickling filters is in a range of 1–2 mm, but can be more or less depending on the load scenario of the Filter. Controlling of the biofilm thickness can be done by adjusting the SK-value which is governed by the rotary speed of the distributor.The operator should have an indication of the biomass within the filter in order to counteract in case of a changing biomass content.

The trickling filter performance can go down in case of biomass losses. On the other hand, if too much biomass accumulates in the filter, clogging can occur with a subsequent deterioration of the treatment result.

In addition to a visuell inspection of the top layer media a HEWiPRO control tower allows the operator a better understanding of the biomass growth.The HEWiPRO control tower is installed within the trickling filter media and allows the operator to take representative media samples throughout the filter depth for further assessment and weight monitoring.

The tower consist of a rigid guide-frame made of stainless steel with ~ 40cm x 40cm base area extending throughout the entire packing height.

The frame is filled with media samples of the same type as used for the filter itself. The media samples are installed in a Stainless steel frame for easy pull out by stainless ropes.

Optional, the control tower can be equipped with a load cell for continuous monitoring. This technology allows the operator a permanent reading of the weight without taking the samples out.