Research project "Freienhufen"

Experimental investigations to support the switch from fermentation of residual waste to fermentation of biowaste

Client:        Waste disposal association Schwarze Elster

Duration:    April 2017 - March 2018

Contact:       Prof. Dr.-Ing. habil. Christina Dornack

Project description:

The MBT Freienhufen has been operated since 2008 as a treatment plant for residual waste in the waste disposal association Schwarze Elster. Against the background of the introduction of separate biowaste collection in the association area, the operators of the plant intend to convert the plant operation to the exclusive treatment of biowaste. It is expected that the amount of residual waste to be treated will decrease and that a new bio-waste material stream will be created, which can be treated separately in the existing plant.

The facility consists of a mechanical stage and an anaerobic biological stage. Following digestion, the digestate is to be submitted to a rotting process to achieve a rotting grade of IV to V.

Three parts are to be worked out within the scope of investigations:

• Shredding of the biowaste
• Fermentation of the shredded biowaste and the investigation of the seasonal variations on the biogas production
• Preparation of a water balance with the focus on the highest possible process water recirculation

The investigations into the comminution of the biowaste are to realize a mechanical preclusion, so that in the fermentation stage an optimized operation of the plant with regard to the decomposition of organic matter can be realized. The separated lignin-containing components are to be returned to the rotting process as structural material after subsequent fermentation.

The aim of the investigations into the fermentation of biowaste is to develop a concept for the treatment of biowaste so that it can be converted into biogas as efficiently as possible in the existing fermentation stage (wet fermentation). The resulting digestate is to be used as a soil conditioner in agriculture in compliance with the requirements of the Fertilizer Ordinance.

Furthermore, the aim of the investigations is to keep the water consumption for fermentation as low as possible so that a closed water cycle can be realized and only a minimum amount of water has to be treated.

© Axel Zentner