Phosphorus recovery from sewage sludge and other re-gional utilization concepts for biomass
Many biogenic residues, in particular sewage sludge, contain relevant valua-ble substances that are not being utilized optimally so far. An environmental-ly friendly and sustainable approach is the recycling of these raw materials through targeted regional recovery of resources. From 14 to 18 May at IFAT in Munich, Hall B2, booth 215/314, Fraunhofer UMSICHT presents solutions for the treatment and utilization of sewage sludge for the purpose of phospho-rus recovery by means of ultrasound, as well as other regional utilization concepts for biomass, from fuel supply to material utilization.
Sewage sludge is a heterogeneous multi-component mixture consisting mainly of water, organic substances, nitrogen and phosphorus compounds and other residues such as heavy metal compounds or drug residues. In Germany alone, the volume at industrial and municipal wastewater treatment plants in 2015 was just over 1.8 million tons. New legal regulations (amendment of the Sewage Sludge Ordinance), make a rethink of the previous sewage sludge utilization necessary. Fraunhofer UMSICHT is working with project partners to further develop and implement an innovative process for the treatment and subsequent fractionation of sewage sludge components, in particular for phosphorus recovery.
Ultrasonic treatment of sewage sludge
At the heart of the new process chain is an ultrasonic cavitation plant. A special ultrasonic transmitter introduces a very high power input into the medium to be treated. This results in the formation of acoustic cavitation bubbles within the medium through which the ultrasound flows. When these bubbles implode, different physical and chemical effects are produced. The large vibration amplitude that can be achieved with the new ultrasound technique is a crucial influencing parameter here. “Cell digestion and an improved separation characteristic occur, which makes it easier to separate sewage sludge mechanically into different recycling fractions”, explains Lukas Rüller from the Process Engineering department at Fraunhofer UMSICHT. The result is a cellulose-rich fiber fraction, a nutrient-rich gel fraction and an easily fermentable liquid phase, which can each be used for further utilization concepts (ammonium and phosphorus recovery, fermentation, etc.).
Within the framework of the “UltraSep” project, Fraunhofer UMSICHT wants to investigate the technology’s physical and chemical modes of action. Together with BSonic GmbH and Chemisches Laboratorium Dr. Fülling GmbH & Co. KG, a test facility is being designed that will then be constructed as a movable portacabin version. After initial trials, the pilot plant is to be integrated into a wastewater treatment plant and optimized during practical operation.
Replacement for fossil fuels: regional utilization concepts for biomass
Meeting the rising demand for energy in the long term requires technologies that also make use of previously unused sustainable raw materials as energy suppliers, for instance raw materials such as grass and green waste, greenery, crop residues, processing residues from agricultural and forestry production or biowaste. “Against the background of sustainable management, Fraunhofer UMSICHT is driving forward the conversion of non-flammable, low-value raw materials into higher-value products”, says Dr. Esther Stahl, Department of Process Engineering at Fraunhofer UMSICHT.
“Suitable processing steps, such as grinding, drying and compaction processes or hydrothermal carbonation (HTC), result in products that are suitable as CO2 -neutral substitutes for fossil fuels.” After a hygienization step, the fine fraction produced during biomass processing can be used as a soil improver in agriculture. The corresponding hygienization process was developed by Fraunhofer UMSICHT together with Franz-Josef Kipp GmbH & Co. KG. Another thematic focus is the energetic utilization of greenery. In the course of the project “SET-Laub“ (Systematic identification of the emission data during the thermal conversion of diverse greenery waste fractions) the processing and combustion of diverse greenery fractions is analyzed as well as the related emissions. In addition, recommendations for the energetic utilization of greenery are developed. This allows the material flow management of biogenic residues to be optimized, especially at regional level.
IFAT, the world's leading trade fair for water, sewage, waste and raw materials management, will be held in Munich from 14 to 18 May 2018. Fraunhofer UMSICHT will be exhibiting in hall B2, booth 215/314.