engleski

Gasification of sewage sludge as a sustainable circular economy perspective

Sewage sludge (SS) is a by-product of wastewater treatment that needs to be further processed. There are numerous processes for treating SS, and nowadays much attention is paid to the gasification process. Gasification of SS produces synthesis gas or syngas, and the sewage sludge ash (SSA) remains as a non-hazardous waste that needs to be disposed of properly. In this paper, the gasification of SS is studied in a semi-industrial pilot plant consisting of a rotary reactor. The gasification process was preceded by drying the SS in an integrated tubular rotating structure with built-in worm conveyors, to increase the dry matter (DM) content in the SS (>90 wt%). The released hydrogen-rich syngas from the gasification process of SS has calorific value of approximately 8830 kJ/Nm³ (equal to 2.45 kWh / Nm³) due to the high content of combustible gases H₂ (41.5 vol%) and CH₄ (3.2 vol%). The paper also investigates the incorporation of SSA generated in the process of gasification as a partial substitute for clay. In the production of clay bricks, 5 wt% of clay was replaced by SSA. The obtained results show that the use of SSA in the construction industry is feasible and justified. By incorporating SSA at 5 wt%, the new brick product achieves 7.5 % higher compressive strength compared to the control brick.

sewage sludge, gasification, syngas, sewage sludge ash, brick production, circular economy

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