BROWSE
HotRot's Unique Rotating Shaft
HotRot’s unique rotating shaft, process control and other design features confer benefits over other in-vessel systems.
Mixing
HotRot regularly mixes the composting waste during processing. Alternative technologies generally rely on premixing to achieve uniformity, which may lead to zones of poor porosity, air channelling and uneven treatment. Unmixed systems potentially exhibit different conditions at sides and edges compared to the vessel centre. HotRot’s mixing prevents this.
Optimal particle size
Small particles typically compost more rapidly than large particles. Faster composting leads to improved microbial activity and disinfection, reduced retention times and lower treatment cost. Unfortunately, small particles generally result in reduced porosity, requiring increased air pressure and energy costs. HotRot’s shaft continually ‘lofts’ the composting material maintaining good porosity, ensuring that HotRot can not only treat fine material, such as sewage treatment plant screenings, that other systems cannot process but that better composting of other materials can be obtained by reducing feed particle size. Processing smaller particles through the system also minimises the need for screening of the final product.
Optimal particle size can be achieved via the integration of shredders and chippers into a turnkey facility.
HotRot 1811 with biofilter, bottom left
Waste balling
In some composting systems wastes may form balls or conglomerates that impede composting. The conglomerates have low porosity that impedes oxygen penetration and slows composting. This is particularly problematic with fibrous and greasy wastes. HotRot’s tines do not lead to ball formation, and tend to break up any conglomerates present in the feed.
Control of residence time
The rotation of the shaft along with feed rate can be used to regulate processing times allowing the quality of the final product to be manipulated. Net forward rotation affects retention time, total rotation controls aeration and mixing. Rapid pre-composting in as little as 10 days can achieve significant mass and volume reductions but the product requires extended maturation and curing. A more stable product can be achieved with composting times of 18-25 days.
Modularity
HotRot systems are modular in design. This allows for flexibility in plant capacity and extension by simply adding additional units. Processing disruption for maintenance may also minimised by incorporating redundancy.
Large Buffer Hopper for 4x HotRot 1811's
Continuous process – low handling
HotRot composting systems are primarily intended to run in a continuous mode (though batch processing is possible). Continuous processing minimises handling and smoothes workloads. Uneven feeding due to 5-day working weeks and similar factors is generally accommodated through the inclusion of buffer storage hoppers.
Sanitisation integrity
Material flows transversely through a HotRot unit and short-circuiting or leachate contamination is avoided. Airflow is drawn from the out-feed end of the unit counter-current to material flow. It is impossible for material that has been disinfected, to be re-contaminated with aerosols arising from unprocessed material. Online temperature, process monitoring and logging provides auditable records of product temperature profiles and feedback control for HotRot operation.
Odour Control
HotRot units are maintained at a negative air pressure as air is drawn through the units. Airtight sealing is not required to prevent fugitive emissions. Odour is typically controlled with a biofilter. Compared to competing systems, the airflow through HotRot is relatively small, minimising the volume of air to be treated.
Safety
HotRot units are fitted with appropriate systems to prevent worker injury, these may include visible and audible warning of shaft rotation, various guards and safety interlocks and safety grills on inspection hatches. The self-contained design means that workers are not exposed to the composting atmosphere during normal operation.
Inspection hatch in the lid of a HotRot 1811
Housing
HotRot is weatherproof and need not be covered. Workers and sensitive components are not exposed to the composting atmosphere.
Power consumption
HotRot’s compact and self-contained design means that air movement is kept to a minimum, significantly reducing power consumption. The shaft rotation is slow and the drive is via a large reduction gearbox. This, combined with the intermittent operation, results in low power requirements.
