Waste Treatment by Dry Digestion
The patented Linde single-stage dry anaerobic digestion process is an example of the dry digestion process.
Linde states that it can be operated in thermophilic or mesophilic mode and has been developed for the anaerobic treatment of solid substrates with dry matter (TS) contents between 15 and 45%.
The digestion principle is based on a plug flow reactor principle, which has a horizontally orientation.
The most outstanding feature of this dry digester is that it is constructed as a horizontally arranged unit within a concrete tube which looks similar in scale and geometry to common aerobic in-vessel composting designs. This is reported to give it extreme “sturdiness”, which might also be described as robustness, we assume.
Within the essentially plug flow reactor vessel, several electric motor driven agitators of are aligned externally with their drive shafts perpendicular to the side walls, and arranged in series along the length of the vessel.
This method of mixing/agitation provides for the net horizontal plug-flow movement, gradually toward the discharge end from the fed hopper/tank, and the use of these mixers is reported to prevent the formation of floating scum and settlement of material, with a high degree of reliability.
A sturdy conveyor frame is fixed to the digester bottom which will reliably transfer the sediments to the fermenter discharge.
All components such as feeding unit, agitator drive units, digestion residue discharge units and the gas system are easily accessible for maintenance and normally installed in individual housings.
The organic material treated is fed into the digester by a compact feeding unit. If required, the TS content in the input is adjusted as desired at the same time.
At the digester end the digestion residue is discharged from the reactor through a low-wear (and presumably low maintenance discharge system.
In addition to the treatment of bio-wastes, green wastes and organic industrial wastes this process can very well handle residual wastes and mixed refuse (otherwise nowadays known as BMW - Biological Municipal Waste) with high TS contents.
Process Features and Advantages
The following features and advantages over other systems are reported by Linde:-
- high biogas production rate through large gas discharge area, low digester filling level and several agitators (low-speed units)
- low space requirement
- use of small compact digesters because material needs not be diluted
- low heat requirements and low wear through minimised material flow
- no or very low process water consumption depending on material characteristics
- low energy demand in material handling, conveying and fermentation through the use of low-speed units only and staggered operating times
- flexible adjustment to fluctuating throughput rates through a variable filling level in the digester
- high VSS degradation through quasi-continuous plug flow.
The information on this page is provided courtesy of Linde.
Other suppliers of Dry Digestion Processes are Bekon (Hot-Rot) and HAASE/Clarke Energy.
|
