EKaBioCopyright: © Department of Processing and Recycling (I.A.R.)
Part: Material flow management in bio waste treatment plants with cascade utilization
The recycling of biogenic waste, such as bio waste and green waste from separate municipal collection, is now state of the art with a volume of more than 10 million t/a. The legislator has anchored a nationwide separate collection in the German Kreislaufwirtschaftsgesetz (KrwG), but its practical implementation has not been completed yet. Whereas initially the focus was only on mechanical recycling as fertiliser, the aim is now to use biogenic waste in cascades. The cascade results from a combination of energetic use through anaerobic treatment followed by aerobic processing of the solid fermentation residues into compost. The production of temporarily storable biogas and its use as balancing energy is supported by the specific regulations of the EEG.
The aim of the EKaBio joint project is to change the process control of bio waste treatment plants with cascade use in such a way that maximum energy efficiency is achieved while complying with future standards for exhaust air treatment. The future standards will be prescribed by the amendment of the Technical Instructions on Air Quality Control, in German: TA Luft. This goal is to be achieved by systematic variation of process parameters of the treatment chain with simultaneous maximized gas yield in the anaerobic process. The basis will be large-scale investigations at a plant site in Northern Germany with original waste from the bio waste treatment plant.
The I.A.R. part of the project focuses on the material flow management of the cascade plant. In the first phase of the sub-project, the quantitative and qualitative inventory of all material flows of the cascade plant is carried out, including the delivered bio waste, fermentation residues and screen overflows. In the second phase of the sub-project, the efficiency of both the anaerobic and aerobic treatment stages is to be maximised by controlling the material flows and producing suitable mixtures. The main objective is to achieve a high product yield in the form of compost which can be used as a substitute for fertiliser. For this purpose, the fulfilment of material quality requirements, which are determined by both substrate and process conditions, must be ensured.