The ARMATEC solids feeder has a high energy-saving operating principle. No pre-mixing of the feedstock is required. With different feedstocks, the stratification in the container guarantees very good mixing by the vertical metering unit with milling rollers or metering belt with scraper bars. The solid material is thus discharged with high precision, low energy consumption and low wear of the tools and assemblies. A feed pump conveys the recirculate as a liquid phase to the substrate mixing pump. Thanks to this optimal feeding for the microorganisms, they increase the gas yield and reduce the energy required for mixing, stirring and pumping. The systems for solids dosing on biogas plants or fermenter feeding, which we have developed and continuously perfected, are used internationally and prove their quality every day.