Production of Hydrochar from Tea Waste for Fuel Through Hydrothermal Carbonization
Keywords:
hydrochar, tea residue, hydrothermal carbonization, soil amendmentAbstract
The objective of this study was to identify an effective approach for managing high-moisture tea waste from the tea beverage industry by comparing hydrothermal carbonization (HTC) and dry carbonization (CT) processes for producing hydrochar and char. Experiments were conducted at temperatures of 230–270 °C for 90 and 180 minutes, with a water-to-tea waste ratio of 5:1 (w/w). The percentage yield, higher heating value (HHV), elemental composition (ultimate analysis), physical properties (proximate analysis), and functional groups (FTIR) were analyzed. Results indicated that HTC at 250 °C for 90 minutes achieved an HHV of 5727.7 cal/g, the highest energy recovery efficiency (ERE) of 94.5%, and greater carbon retention and energy densification (ED) compared to CT at 270 °C under the same conditions. In contrast, CT exhibited higher ash content and a lower abundance of carbonyl (C=O) functional groups than HTC. FTIR analysis revealed that HTC reduced C–O and aliphatic C–H functional groups, while increasing CHx and C=O groups with rising temperature, corresponding to dehydration and decarboxylation reactions. This comparison highlights HTC as a suitable process for wet feedstocks such as tea waste, as it reduces drying requirements, operates at lower temperatures, and produces a product with superior energy performance and chemical properties compared to CT. Therefore, HTC has strong potential for further development into solid fuels, adsorbents, and soil conditioners.
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