Towards Engineered Hydrochars: Application of Artificial Neural Networks in the Hydrothermal Carbonization of Sewage Sludge

Abstract

Sewage sludge hydrochars (SSHs), which are produced by hydrothermal carbonization (HTC), offer a high calorific value to be applied as a biofuel. However, HTC is a complex processand the properties of the resulting product depend heavily on the process conditions and feedstock composition. In this work, we have applied artificial neural networks (ANNs) to contribute to the production of tailored SSHs for a specific application and with optimum properties. We collected data from the published literature covering the years 2014–2021, which was then fed into different ANN models where the input data (HTC temperature, process time, and the elemental content of hydrochars) were used to predict output parameters ((higher heating value, (HHV) and solid yield (%)). The proposed ANN models were successful in accurately predicting both HHV and contents of C and H. While the model NN1 (based on C, H, O content) exhibited HHV predicting performance with R2 = 0.974, another model, NN2, was also able to predict HHV with R2 = 0.936 using only C and H as input. Moreover, the inverse model of NN3 (based on H, O content, and HHV) could predict C content with an R2 of 0.939.

Preparation and Application of a Hydrochar-Based Palladium Nanocatalyst for the Reduction of Nitroarenes

“…FE-SEM images of CWH showed an irregular but porous surface morphology (Figure 2a,b). Hydrochars are typically amorphous materials with a low degree of crystallinity [14,15]. Following the deposition of Fe 3 O 4 , it was observed that CWH's surface morphology was not affected, but only covered by Fe 3 O 4 particles (Figure 2c,d).…”

Indicators for resource recovery monitoring within the circular economy model implementation in the wastewater sector

“…Sewage sludge valorization is an important element for CE implementation in the wastewater sector (Klavins et al, 2021). According to the latest publications (Kapetanakis et al, 2021;Knötig et al, 2021;Xiong et al, 2021), hydrochar produced from thickened sewage sludge shows satisfactory fuel properties in terms of higher heating value and reduced ash content.…”