Paper-Rest-Cycle
Duration: 01.07.2023-30.06.2026
Funding organisation: MWIKE.NRW PROGRES.NRW-RESEARCH, funding code: EFO 0169A
Initial situation:
The paper industry aims to become climate-neutral by 2050. One approach to reducing the use of fossil fuels is the production of biogas from waste materials from the paper industry. In the RE-Papier and Plus RE-Papier projects (funded by Leitmarkt Agentur. NRW) at FH Aachen University of Applied Sciences, an anaerobic process for biogas production from the resulting waste materials was successfully established. Biogas production, to which nutrients are added to optimise the process, produces a fermentation product in addition to the biogas. Its agricultural use as fertiliser is prohibited by the Fertiliser Ordinance. This results in a residue that would have to be disposed of at high cost. In order to implement biogas production economically on an industrial scale in companies, utilisation and purification technologies must be developed for the fermentation product.
The project:
The project aims to determine the optimum recovery of nitrogen and phosphate from the liquid phase of the fermentation products from paper fermentation. An adapted and extended membrane stripping process will be developed for more efficient recovery of nutrients. The fermentation product is first separated with a sequence of sedimentation and subsequent chemical precipitation of the supernatant. The resulting almost solids-free liquid phase contains ammonium, the concentration of which depends on the nitrogen content of the fermentation input streams used.
Nutrient recovery from this liquid phase is being investigated using membrane stripping. In connection with this process, various ammonia acceptors such as phosphoric acid, which have not yet been used, are to be applied. The generation of ammonium carbamate is also being investigated in order to obtain a high-quality undiluted product. The recovery of phosphate is also being analysed within the project. Finally, an overall concept will be developed whereby nitrogen and phosphate can be extracted and bound with the highest possible quality.
Objectives:
The aim of the project is to investigate various treatment methods for fermentation products. Firstly, solid-liquid separation is planned so that the solid material can be delivered to the construction or glass industry. In the next step, the nutrients used in the biogas process are to be recovered from the liquid phase before the water is purified further. The diagram shows the desired circular economy for the optimal utilisation of residual materials from the paper industry, which can be achieved through the successful implementation of nutrient recovery. An overall economic and ecological assessment of the process is also provided.
