The system is simple and straightforward:

Structure of the Wendewolf system




  • Operation in batch or continuous mode
  • Ventilated storage of the filter cake in the drying hall
  • Odorless and homogeneous drying process
  • Uniform fine-grained granulate
  • Storage of dry granulate in the drying hall over 80 cm layer thickness
  • Filter cake over 40 cm layer thickness
  • Over 400m³ per hour turning and conveying capacity
  • Sludge cones over 100 cm are leveled without problems
  • No time-consuming backmixing
  • Versatile combination options with waste heat or additional energy
  • Durable, robust and low maintenance

Contact us for more information or a price quote!


Neutralization of unpleasant odors by changing their perceptibility




  • Without additional space requirement
  • Neutralizes odors
  • Reduces perceptibility
  • Reduces insect infestation
  • Maintains low energy costs
  • Maintains simple exhaust paths
  • Increases acceptance

Odor elimination with the ZERODOR

“Odorants are chemical compounds that appeal to the sense of smell and trigger olfactory sensations. They include several thousand individual substances, although it is unclear which structural characteristics determine the odor-carrying properties.”(https://www.lfu.bayern.de/buerger/doc/uw_23_geruchsbelaestigungen.pdf)

…in other words, an odor or fragrance is caused by one or more volatile chemical compounds that are generally present in very low concentrations and are perceived by humans or animals through the sense of smell.

Accordingly, odors or odorous substances are defined as follows:

  • As a compound of molecules or substances
  • As a rule, there is no direct correlation between chemical structure and odor

In addition:

Technical sensors cannot perceive odors in the same way as the human nose

  • The odor detection threshold is the lowest concentration of a particular odor compound that can be perceived by the human sense of smell

Odorous substances in wastewater treatment plants

There are many different odors at wastewater treatment plants that can be perceived by humans or animals.

These substances are mainly:

  • H2S: “Rotten eggs”
  • NH3: “Ammonia” (chicken coop)
  • Mercapthan: “skunk/cheese”
  • Cadaver: “decomposition” (carcass)
  • Trimethylamine: “Fishy”
  • Skatols: “Feces”

Odor treatment methods

There are 3 fundamentally different methods for treating odors in the air or in vapors:

Removal of odorous substances

Biofilters, carbon filters or odor scrubbers remove all or part of the odorous substances by means of a mechanical, biological or chemical process. Since the substances are collected in a filter or liquid, it is necessary to treat these residues and maintain the filter or dispose of or recycle the liquid.
Principle: “Vacuum cleaner bag”

Masking the odors

By using strong, “good” smelling substances, this technology masks the bad odors with “good or not bad” odors. This “masking” of odors is not accepted in many countries.
Principle: “Perfume or deodorant”

Elimination of odors

Conversion of odorous molecules through the use of non-toxic and environmentally friendly reagents, the perceptibility of odors is changed.
Principle: “Noise Cancelling Earphone” the perceptibility is changed



Zerodor: Odor elimination

ZERODOR uses odor elimination technology. It changes the olfactory perceptibility of the odorous substances, the concentration of the molecules is retained, the olfactory perceptibility (the “smellability”) is reduced.

The patented reagent liquids (ZERODOR) were specially developed for the odors that can occur during sewage sludge drying.
The liquids are dosed in the drying halls or at the drying beds and mixed into the odorous air using fans. This leads to an immediate reaction of the odorous substances with the reagents and thus to an immediate elimination of the odors.

Zerodor DGD

Odor removal at the sludge drying beds is carried out using dry steam technology – ZERODOR DGD technology. This means evaporation of an odour-neutralizing reagent under gas pressure.
This technology makes it possible to deodorize an atmosphere that is already saturated with moisture and/or that does not allow a lot of water to be sprayed. The reagent itself does not contain any water.

The Zerodor dosing point

The spray nozzle is installed on the internal fans. The ZERODOR liquid is supplied via a hose, the compressed air via a separate hose.
The nozzle sprays the reagent with a particle size of less than 1 µm. The fan mixes these fine particles with the odorous air. This leads to a fast and efficient reaction of the reactive liquid with the air.

The hoses connect the dosing points on the fans with the central distribution cabinets.

Zerodor Geruchseliminierung

Zerodor distribution cabinet

The liquid is dosed in a distribution cabinet. The distributor pumps and the Zerodor canister are located in this cabinet.

The cabinet is connected to the electrical supply network and the compressed air network.

Installing the dosing points

The nozzles are installed directly on the internal fans.

Zerodor Geruchseliminierung
Zerodor Geruchseliminierung

Each dosing point is supplied with liquid and compressed air.

  • Compressed air requirement: approx. 7Nm3/h
  • Zerodor consumption: approx. 10ml/h

The Zerodor liquid is applied sequentially over the course of the day with a duty cycle of approx. 50%. (2 min on/2 min off).



The reagent (Zerodor)

The reagent -ZERODOR- for sludge drying applications is a special and patented odour neutralizer. This product is not a masking agent.
The active bases of the reagent (aldehydes and ketones) attack the sulphur, amines and mercaptans of the odor molecules nucleophilically.
The reagent molecules combine with the foul-smelling sulfate/mercaptan and ammonia/amine groups, resulting in new neutral combinations that are completely inactive olfactorically and toxically.
It works immediately and achieves excellent results on ammonia odors and gases produced during sludge drying, such as cadaverine, trimethylamine and others.
The ZERODOR reagent has no toxic properties and is classified as safe by accredited test laboratories.

Ohne Zerodor

Odor development over time WITHOUT the use of Zerodor

Mit Zerodor

Odor development over time WITH the use of Zerodor
The perceptible odors are reduced!



Installation of Zerodor

The fans are switched on and off taking into account the specific data of the system (such as temperature, radiation and others).

The dosing pumps are controlled in a separate program cycle and supply the fans with the reagent.

This enables very efficient treatment of odors without affecting the drying process.

The Zerodor system can be easily integrated into existing systems, it does not require any special exhaust air ducting, it does not require any lengthy maintenance and there is no “start-up time”.

Simply switch on and reduce odors immediately!

Zerodor Geruchseliminierung