EUBCE 2026 - Yusuf KUCUKAGA - Unlocking the Biotechnological Availability of Waste Sludge-Digestates via Integrated Thermochemical-Biological Biorefinery Approach

Unlocking the Biotechnological Availability of Waste Sludge-Digestates via Integrated Thermochemical-Biological Biorefinery Approach

Short Introductive summary

Municipal wastewater treatment generates large quantities of sewage sludge digestate, whose post-stabilization through mesophilic anaerobic digestion and subsequent thermal drying ensures hygienic safety but leaves a highly recalcitrant, non-bioavailable residue. In Istanbul’s metropolitan wastewater network, a single advanced treatment facility processes the domestic wastewater of several million inhabitants under mesophilic conditions (36 ± 2 °C, 20 d sludge age). The resulting digestate exhibits pH 6.5 ± 0.5, alkalinity ˜ 640 mg CaCO3 L?¹, volatile fatty acids ˜ 300 mg L?¹, NH4-N ˜ 150 mg L?¹, and total/volatile solids of 70.5 ± 10.0 g L?¹ and 37.5 ± 10.0 g L?¹, respectively. After thermal drying (˜ 98.5 % TS), this material is typically used as auxiliary fuel in cement kilns or as a feedstock in waste-incineration-plants, an energetically and environmentally costly practice that locks out circular valorization routes. This work proposes a sustainable and innovative approach: converting thermally dried digestate into bioavailable pyrolytic intermediates—biochar, bio-oil, and syngas—followed by anaerobic bioconversion toward biofuels and green chemicals. Pyrolysis experiments ar

Y. Kucukaga, Gebze Technical University, Istanbul, TURKEY
G. Dinc, Gebze Technical University, Istanbul, TURKEY