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Composting logo

WTT specializes in composting of organic waste. Composting is the natural process of recycling organic matter, such as leaves and food scraps, into a valuable fertilizer that can enrich soil and plants. Organic waste that is converted to compost can be used by local farmers or for other agricultural applications. In addition, it can also be turned into refuse derived fuel.

The WTT in-vessel composting technology is an advanced and robust system that ensures maximum process efficiency and minimal emissions.

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“What I really liked in working with WTT is the practical approach, the direct consultation structure and keeping the customer perspective in mind. And they do what they promise.“

Alfred Charles

MBT Manager, Veolia, Southwark

Why Compost

Recycle Nutrients

Compost and anaerobic digestion plants support recycling of major plant nutrients, some of them are infinite!

Improve Soil

Compost can improve soil by increasing organic matter levels, creating better soil productivity and supports ecosystems.

Produce Biogas

Biogas can be produced with anaerobic digestion plants, which can be used for the production of electricity or to replace natural gas.

Reduce GHG Emissions

The plants support the reduction of greenhouse gases that would be emitted when waste is going to landfill.

Replace Peat

The use of specialty compost and digestate products can replace horticultural peat use.

Sequester Carbon

Compost supports the soil to sequester carbon and reduces the need for inorganic nitrogen fertilizers.

Composting Made Easy

WTT’s biological tunnel process is individually controlled in order to provide each batch with a tailor-made treatment. WTT’s fully automated process allows the operator to set process parameters to adapt different waste categories and seasonal influences. Its modular construction and versatile control software interface allows the same facility to treat organic waste optimally in short a period of time, maximizing processing efficiency and keeping environmental conditions strictly under control.

Key Features

in vessel

In-Vessel Composting

WTT designs in-vessel technologies, this means that the composting process takes place in completely closed (concrete) vessels; so called tunnels. Over the past 25 years WTT has built over 1300 tunnels. Throughout this time, WTT has continuously improved the design and identi capital and operating costs. One of the major advantages of composting in tunnels is that it is fast. The tunnels are individually controlled with forced aeration to process organic waste into compost. Each composting tunnel has its own aeration system, water and heating modules and is accompanied with the required instrumentation. Process and odour control is optimal, resulting in homogenic pasteurizations and degradation of organics. The whole configuration is included into a skid for faster installation, easier transport to site and simplified commissioning. The complete tunner system is remotely actuated and controlled by a SCADA visualization system. This allows site operators to set process parameters to be able to adapt to different waste streams and seasonal fluctuations.

High Quality – High Efficiency

  • Robust concrete tunnels with efficient aeration system in floor
    Climate control system on modular skids, control over all parameters
    WTT fans to ensure optimal operation at minimal energy usage
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Bio-drying is comparable to composting in terms of aerobic degradation, the main difference lies in the retention time, and thus the final utilization and product obtained. Composting produces compost that can be both a nutrient source and a conditioner in agricultural applications. Bio-drying reduces the moisture content of waste to increase its caloric value. In WTT’s design, residual process heat can be reused and then transported via a hot water circuit to accelerate the drying of the waste. By using the heat from hot water into the air the moisture of the waste will be removed more efficiently and saves energy.

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Control System

WTT provides a control system that allows operators to automatically monitor the process. The supervisory control and data acquisition (SCADA) system gives instantly access to information and the digital monitoring makes data more accurate and up-to-date, which improves decision-making. The experts of WTT have extensive experience with biological processes and know how to run a site using SCADA under a wide variety of circumstances. This experience has taught us how to optimize the setpoints and how to set up SCADA in such a way that the processes on site are running most efficient and with best results.

  • High quality and reliability
  • User friendly
  • Fully automated with seasonal recipes
  • Detailed trending of variables
  • Energy management
  • Batch tracking and reporting to proof permit compliance
  • WTT remote monitoring enables support from our engineers
feed your soil

Feed Your Soil

Compost is the single most important ingredient for a healthy and productive soil:

  • It provides essential organic matter to the soil
  • Compost aids nutrient retention, reducing fertilizer cost
  • It helps to enhance soil structure and decrease erosion
  • Water retention is improved, giving better drought resilience
  • Compost naturally suppresses plant diseases
  • Compost increases the potential for carbon sequestration

View Past Client Projects


The Olper Entsorgungszentrum includes 9 composting tunnels. The facility treats 58.000 t/a of fresh biowaste. All composting tunnels are equipped with a fully automated ventilation and irrigation system. The process itself is controlled and visualized by a SCADA system located in the control room. After the in-vessel composting phase, the waste is fed by wheel loader to the compost refining line.


Ca. 40.000 t/a of waste coming from the tunnels is fed to the mechanical post-treatment line. The waste passes a series of treatment steps by which ferrous, non-ferrous, and inert materials are extracted. The material is sieved at 70mm, and in a second sieving step at 15mm. The final quality compost product is 0-15mm. All fractions are transported by conveyors to indoor storage bunkers, awaiting further transport of site. In 2017, a NIR machine was included in the mechanical line. This machine can remove foils and plastics from the waste, thereby ultimately contributing to a cleaner compost fraction at the end of the process. The addition saved significant time and money to the operator and thereby improved the biological process


9 composting tunnels, compost refining line, facility air treatment, control and visualization

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