COMPOSTING OF BIOLOGICAL WASTE

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ADDED VALUE FROM ORGANIC WASTE

The composting and anaerobic digestion of organic wastes and their return into the cycle of materials as high quality fertilizer and humus is well established worldwide.

As an integral part of the material cycle, our tunnel composting technology makes a valuable contribution to environmental protection and contributes significantly to reducing waste and conserving resources.

  • Collection of organic waste
    Organic waste is generated both in private households and in commercial enterprises. This waste is collected and can be supplied to Waste Tec composting plants.
  • Composting of organic waste and digastate as well as sewage sludge
    In the Waste Tec tunnel composting system, organic waste as well as digestate or sewage sludge can be processed.
  • Production of high quality compost
    After composting in the Waste Tec tunnel composting system and after an appropriate mechanical treatment and optional maturation the organic waste is turned into a high-quality compost.
  • Fermentation of organic waste
    In the absence of oxygen methan is produced in anaerobic digestion plants.
  • Production of biogas for the substitution of fossil fuels
    The methane produced can be used as a substitute for fossil fuels.

Composting

In completely enclosed, process-controlled tunnels compost of the highest quality is produced from compostable organic material, like househould and garden waste, cuttings from trees and bushes, agricultural waste etc. In addition a reliable sanitation of waste is ensured. The closed design avoids the uncontrolled release of emissions and cleans the exhaust air in accordance with legal requirements.

To improve the composting process mechanical treatment steps (shredding, mixing) can be used upstream.

A downstream mechanical treatment guarantees the best possible compost quality.

Different types of waste require adapted pre-treatment steps to optimise the downstream composting process. For example, packaged waste delivered has to be unpacked and wood type waste needs to be shredded and defibrated. By mixing various types of waste a best possible ventilation of the material in the composting system can be ensured.

Special mixing units or the mixture by front end loader are suitable for this purpose.

While optimizing composting of organic waste the composting tunnel, equipped with aeration floor and process control allows maximizing throughput per unit area and minimizing uncontrolled odour emissions. On the basis of its boundary conditions, the client decides on the retention time of the waste in the tunnel and thus on the degree of rotting of the compost produced. Retention times of 7 days (fresh compost) to 28 days (mature compost) are common.

Depending on the legal requirements but also if an intensive rotting of 7 days is applied a windrow maturation outside, in a sheltered area or in a ventilated building is advisable.

In addition to the compost quality solely based on the degree of rotting, the degree of contamination by solid impurities (plastics, stones, glass, etc.) and the chemical burden (such as geogenic loads) originating from the waste is also of a essential importance for the compost quality. The amount of solid impurities in the compost can be reduced by a mechanical treatment.

Screens, classifiers and optical sorters are suitable for this purpose.

Advantages of the WasteTec Tunnel Composting System:

  • Fully enclosed intensive rotting with controlled exhaust air collection and efficient exhaust air purification
  • Quick achievement of the required degree of rotting (RG 2-5) by significantly reduced rotting times
  • Guaranteed sanitation of the compost produced
  • Low space requirement
  • Production of a high quality compost

Digestate and sewage sludge composting

Residues from the fermentation of organic wastes or digested (fermented) sewage sludge normally require a composting before utilisation. The composting transfers the anaerobic digestate into an aerobic environment and in addition (if required) the organic material is sanitised and odour is significantly reduced.

For this composting process the completely enclosed, process-controlled Waste Tec tunnel composting system is perfectly suited. Together with an appropriate mechanical pre- and post treatment compost of the highest quality is produced.

Different fermentation residues require adapted pre-treatment steps to optimize the subsequent composting process.

For the production of a ventilatable substrate the mixture with shredded / defibrated wood type materials  is required in particular. This can be achieved by using special mixing units or front end loaders.

The composting tunnel equipped with aeration floor and process control allows maximizing throughput per unit area and minimizing uncontrolled odour emissions while optimizing composting of digestate respectively sewage sludge.

To produce a high quality compost generally a retention time of 7 days (no sanitation) or 14 days (with sanitation) is sufficient.

In addition to the compost quality solely based on the degree of rotting, the degree of contamination by solid impurities (plastics, stones, glass, etc.) and the chemical burden (such as geogenic loads) originating from the waste is also of a essential importance for the compost quality. The amount of solid impurities in the compost can be reduced by a mechanical treatment.

Screens, classifiers and optical sorters are suitable for this purpose.

Advantages of the WasteTec tunnel composting system:

  • Efficient processing of digestate and sewage sludge
  • Fully enclosed intensive rotting with controlled exhaust air collection and efficient exhaust air purification
  • Guaranteed sanitation of the compost produced (in case of mesophilic fermentation), if required
  • Low space requirement because of short retention times
  • Production of a high quality digestate respectively sewage sludge compost