“Organic waste is valuable”

The Rhein-Main Deponie GmbH (RMD) is located in the middle of Germany, between Wiesbaden and Frankfurt. This municipal utility specializes in using organic waste, and is the largest producer of renewably generated energy in the region.


In addition to an anaerobic digestion system, landfill and biogas utilization plant, the Rhein-Main-Deponiepark in Flörsheim operates a biomass power plant and photovoltaic system. Currently the anaerobic digestion plant processes about 50,000 tonnes of biogenic waste each year. A Komptech shredder and screener kick off the anaerobic digestion process.

The RMD was moving towards renewable energy sources even before the renewable energy law was passed. They first used the landfill gas from municipal landfills to generate environment-friendly power, later adding the anaerobic digestion plants in Flörsheim and Neu-Anspach. “The basis for the construction of the anaerobic digestion plants was the long-term acceptance and disposal of the organic waste in the MTK and HTK districts,” explains Thomas Richter, RMD’s Biogas and Green Waste Department Manager. The goal was to utilize organic waste effectively, i.e. both for material reclamation and energy production while keeping transport distances short, and offering it all at a fair price to local communities, said the Richter, a degreed chemical engineer.


Processing with Komptech machines

The first anaerobic digestion plant was built in 2008. For organic waste processing RMD chose a stationary solution from Komptech, consisting of a Crambo and star screen. About six months ago they replaced the machines with new ones. A big part of the reason was the new organic waste legislation with its tighter quality requirements, which made new equipment necessary. Richter: “The first system was fully depreciated after only ten years. Its 14-year service life was naturally a stroke of luck for us, and proof of the outstanding quality of its component parts.” RMD wrote a modification into the bid tender for the new system. It needed to have higher throughput, removal of foreign matter from organic waste, and lower screen overflow. Star screening is ideal for the application in question, and Komptech cooperates exclusively with Anlagenbau Günther in this area.

“Our focus is on the generation of renewable energy, and organic waste processing is a key part of that.”

Thomas Richter

Customer-specific modifications

The new setup consists of a Crambo 3400 pre-shredder, two-stage star screen, magnetic separator, film suction and rolling item separator for heavy items. Christian Hüwel, who is in charge of “Stationary Technology” projects at Komptech Germany, explains: “The shredder and the screen determine the quality of the process. As a low-speed shredder, the Crambo is one of the best machines available for prepping organic waste, since instead of chopping up the plastic bags that the waste unfortunately often comes in, it only opens them. This makes it easier to separate out the plastic later. On top of that, the machine is tough, and is powered by an electric motor in the stationary version. This significantly reduces the maintenance effort.”

Reduction of screen overflow

Instead of a screen with uniform star size, RMD uses two screens in stairstep sequence. Material that doesn’t land on the conveyor after the first screening goes on to film suction and then to a second star screen. There, the organic waste is processed again and the remaining clumps are broken up. This new screening solution significantly reduces screen overflow, and disposal costs for the overflow have been cut almost in half. Matthias Sternstein, in charge of sales at Anlagenbau Günther, says, “This success is due to the excellent project description on the customer side. Since RMD contributed its experience from its years of practical applications, we were able to make a precise contribution in teamwork with Komptech.”

RMD Operations Director Heiko Scriba is visibly happy with the new solution: “What we have here is a system made up of different components that is perfectly attuned to our daily work. If problems come up, Komptech is always right there to help. That’s the dependability we need.”


New organic waste legislation requires plant operators to treat only organic waste whose foreign material content does not exceed certain limits. This is especially the case for film and hard plastic. At the same time, the amount of care taken by private citizens in organic waste disposal leaves much to be desired. Therefore, a new Komptech system was a necessary and important investment for RMD.

Anaerobic digestion plants account for a third of the company’s revenue. Costs for disposal of contraries rose by around 400 percent from 2015 to 2020.

Every year, from 50,000 tonnes of organic waste RMD generates around 10 million kilowatt hours of current, which is fed into the electricity grid, as well as heat, which is marketed to Hochheim as district heating. The fermentation solids are turned into some 17,000 tonnes of RAL-certified compost. The liquid fermentation products, around 20,000 tonnes, go from interim storage to use in agriculture, likewise under quality control. The biomass power plant at the Flörsheim-Wicker location burns about 115,000 tonnes of waste wood every year and sells the current thereby produced. Richter: “We’ve made a name for ourselves regionally with this energy concept, and even get requests for advice from other countries.”