Hydrothermal carbonisation (HTC) has developed considerably over the last 15 years and offers a viable alternative for the utilisation of municipal and industrial organic waste such as sewage sludge. The process takes place in an aqueous environment; therefore, no drying of the waste biomass is required, enabling direct processing. HTC is especially suitable for sewage sludge treatment in combination with the recovery of nutrients like phosphorus. In combination with phosphorus recovery, HTC might contribute decisively. However, the technology has not yet (2022) been able to establish itself as a valorization process for municipal and industrial organic waste such as sewage sludge and is not yet a recognized state of the art. Nevertheless, the HTC technology could gain relevance in the future, especially as an alternative valorization pathway for sewage sludge in rural areas of Germany. During HTC, the waste and biomasses are converted into a lignite-like hydrochar. Significant amounts of HTC process water (HTC-PW) are produced as a by-product. The process water is organically polluted and has to be treated. In Germany, plant operators are obliged to treat industrial wastewater. Either to direct discharge quality, which allows discharge of the treated wastewater into the environment, or to indirect discharge quality, which permits discharge into the public wastewater treatment plant (WWTP). In addition to the large amount of process water and its treatment to the required limits, the organic load and possible persistent and toxic substances pose major challenges for plant operators. As HTC technology advanced, processes for treating the HTC process water were also investigated. Many proven processes from industrial wastewater treatment were transferred for the treatment of HTC-PW. In this review, the most significant treatment options for HTC-PW are presented and the challenges and opportunities for discharging into WWTP are discussed.

Ort: Rostock
Bearbeiter/-in: Zhao, Chao
Zeitraum: 01.04.2023
Professur Abfall- und Stoffstromwirtschaft

Betreuer:

• Tommy Ender
• Dr.-Ing. Jan Sprafke