Waste Treatment by Dry Digestion

The Strabag patented technology previously known as "Linde" single-stage dry anaerobic digestion process is an example of the dry digestion process.

Strabag 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.

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 Strabag:-