The DRANCO process is an advanced biotechnological process for an environmentally friendly and cost-effective treatment of organic waste, such as municipal waste or other organic wastes. With its long experience and its extended reference list, the DRANCO process is a well-known and reliable anaerobic digestion technology. The DRANCO technology is marketed throughout the world by OWS or by means of license partners.
The advantages of anaerobic digestion of waste are:
- production of renewable energy and reduction of fossil CO2-emissions;
- low odour emissions and in general low emissions towards the environment;
- flexibility towards the waste composition;
- compact installations.
The DRANCO process consists of a thermophilic, one-phase anaerobic fermentation step, which is followed by a short aerobic maturation phase. Mesophilic operation can also be applied for specific waste streams. During the anaerobic digestion phase, the organic material is partially converted into biogas. The process takes place in an enclosed digester during about 20 days. The digested residue is extracted from the digester and stabilised aerobically. The final product is a hygienically safe and stabilised product.
Partial stream digestion of the waste, whereby the digestate is mixed with a part of the organic fresh waste in order to be treated in a subsequent aerobic composting system, is made possible due to the high total solids content of the digestate. This symbiosis between anaerobic digestion and aerobic composting produces energy, shortens the aerobic composting step and prevents wastewater production.
Wastewater can also be prevented by drying the digestate coming from the digester by using the lost heat of the gas engines or by adding shredded green waste in order to dry the digestate in the composting step.
The DRANCO technology can be used for various types of organic waste streams :
- the organic fraction of mixed or residual municipal waste obtained through mechanical separation;
- biowaste and other source-separated organic waste streams;
- dewatered sewage sludge;
- other organic waste streams, including non-recyclable paper, market waste, food waste, industrial waste etc…
The DRANCO Advantages
dry anaerobic digestion - high solids digestion
- high loading rate and biogas productivity
- small digester volumes
- no phase separation in the digester
- no crust formation or sedimentation
- vertical digester with conical outlet
- extraction at the lowest point
- no accumulation in the digester
- low surface requirement
- no mixing, stirring or gas injection in the digester
- no maintenance or failures inside the digester
- less energy consumption for mixing
- intensive recirculation
- well controled external inoculation
- optimum mixing of fresh feedstock with digestate
- thermophilic temperature (48-57°C)
- higher biogas yield
- kill-off of pathogens and seeds
- automated process control
- robust and industrial system
The DRANCO Process Characteristics
- digester loading: 10 to 20 kg COD/m³ reactor per day
- temperature range: thermophilic: 48 to 57°C (or mesophilic: 35 to 40°C)
- retention time in the digester: 15 to 30 days
- biogas production: 100 to 200 Nm³ of biogas per ton of waste
- electricity production: 220 to 440 kWh per ton of waste
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