Hermann Traxler

Introduction :

This German company was founded in 1972. Thanks to the company facilities, it has possibility of machining and turning equipment with parts up to a diameter of 3 meters, length is 20 meters and weight 25 tons.

Expertise and facilities of the company enable it to not only design and manufacturing the high quality equipment, but also to serve well developed periodical and after-sales services.


Draft Tube

The Draft Tube Mixers

The main products of the company include motor, impeller and connection pipes (draft tube, ascending pipes).
With more than 20 years of experience Hermann Traxler can manage all design, manufacturing, installation and repair requirements comes from clients.

-The Mixers is designed for digesters with capacity from 1,500 up to 15,000 cubic meter.
-The main principle of the best design and selection is based on mixing whole contents of the digester at least 8 times per day, in order to obtain maximum mixing and digestion efficiency.
-Due to vertically installation of the Draft Tube inside the digester with high length (constructed by pipe pieces, each piece is 6 meter), so connection of these tubes/pipes to each other should have different thickness compering with central section to resist against the weight of the upper tubes and vibration stress caused by the sludge movement and stroke of debris around the mixer pipes. So to have different thickness (6 to 15 mm) of this pipes Hermann Traxler recommended strongly Ductile Iron which is more reliable material instead of Stainless steel according the company experience.
-Also Hermann Traxler could increase the mixing efficiency by placing another Bell Mouth in top part of draft tube at impeller position. In order to achieve more efficiency, the gap between impeller and bell mouth shall be so narrow about 5 mm, due to Hermann Traxler well quality products and reliable design, they could keep the narrow gap during long terms of operation according the global references

The shape of digester has a significant impact on the amount of biogas production, so Hermann Traxler company could serve engineering advises to consulting companies in design stage in order to have better design and get more biogas production in digesters.


The Draft Tube Mixers is the best solution for sludge mixing and homogenization according to following reasons:
– More biogas production due to temperature uniformity in whole area of digesters
– Ease of elimination of scum layers at top of sludge by using splash disk
– faster elimination of the foam at top of the digester by changing the rotation direction of mixer (from top to bottom).
– prevention of particle sedimentation at the bottom of digester.


Hamedan WWTP