How does the ENTEC Bio-filter work?

The bio-filters for sewage shafts makes use of a granulate that excels due to the granulation of NEW paper and its raw porous surface is an excellent bearer for micro-organisms.

We fill a cartridge with this granulate and place it in the filter; this filter cartridge has the advantage for the user of being easily exchangeable. The gases which rise up through the sewer shaft have to flow through the cartridge. Absorption of those materials that engender odour and may be harmful takes place by means of micro-organisms that have bonded with the granulate; through this mechanism the inconvenience and irritation caused by those sewage odours does not take place.

The VDI 3477 “Bio-filter“ demonstrates very clearly that hydrogen sulphide (H²S) is easily bio-degradable with the help of bio-filters. In contrast industrial equipment that is in operation and making use of the usual filter materials are cited as having a volume exposure of 5- 255 m³ discharged air/(h*m³ filter material. With a load of 80 – 7,000 mg H²S/ m³ a degradation of 88–99% was achieved.

At the University of Rostock (Germany) research compared our bio-filter granulate with the usual filter materials: the results confirmed our granulate achieved clearly better results in absorbing pollution..Bark mulch and heather (Calluna vulgaris) Heidekraut was compared to our granulate. The filters in the experiment were each loaded with discharged air at the level 100 m³ </(h*m³ filter material) with an average H²S concentration of 200 ppm (parts per million). The filters made with bark mulch and heather managed a degradation result of approximately 50%; in contrast the bio-filter granulate achieved degradation amounting to no less than 100%. The reason for this outstanding result was the optimal through-flow and water accumulation characteristics of the granulate as well as the significantly better supply of nutrients by the organisms. An additional positive outcome concerned acidification of the filter; this process was effectively limited with the help of products created by the reactions.

Our own research shows that concentrations of hydrogen sulphide up to 1,000 ppm in bio-filters can be well handled. In the zone from 1,000 to 2,5000 ppm the degradation rates decreased, and above the level of 2,500 ppm no significant effect was recorded. In the zone between 200 and 500 ppm there was a very striking and rapid degradation of H²S by means of micro-biology. A major factor in the chemical reaction is an optimal oxygen supply since the micro-biological oxidation of H²S causes a high level of oxygen consumption and thinning.

These laboratory results have been confirmed in practical tests. In the United Arab Emirates experiments were carried out on seven bio-filters subjected to passive through-flow; the results showed that with raw gas concentrations of 300-900 ppm of hydrogen sulphide a degradation rate of 89 – 100% was achieved. Scrutiny of the through-flow processes of the seven filters showed that the bio-filters were subjected to an exposure per volume of approximately 75–185 m³/(h*m³ filter material). From that a problem area was revealed for a continually high level of degradation i.e. the marked fluctuations in concentration lead to peaks of loading that nay be difficult to handle..

How does the bio-filter work? / How the bio-filter functions

We construct the granulate with paper as its basis ensures not only excellent flow-through conditions by means of grainy, spherical-shaped  structure; and due to that very low filter resistance compared to the usual filter materials. The outstanding characteristics of the material we have selected, enables us consistently to notch up significantly higher load and exposure figures (load per volume of filter, load per surface of filter) than the usual filter material; this in turn allows us to manufacture it in a very compact size. 

We guarantee the bio-filter granulate for two years. The average service life of this robust material – depending on the manner and length of the load or exposure – can be estimated as 4-5 years.

 Bio-filter Granulate

For five years now the granulate has been used successfully for the elimination of odours emitted by industrial installations and equipment. Furthermore our product has successfully passed rigorous tests carried out under extreme desert conditions (United Arab Emirates).

 Key statistics:  an overview :

Average diameter of particles   2 – 10 mm

Bulk density   390 - 410 kg / m3

Service life: depends on amount of load or exposure