| Industrial-Scale Evaluation of Integrated Sewage Sludge Drying and Pyrolysis: A Case Study in Tehran, Iran |
| کد مقاله : 1673-IWWA |
| نویسندگان |
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الهام توحیدی فر *، سید مهدی حسینی پور Water Engineer, Padyab Tadjhiz Co., Tehran, Iran |
| چکیده مقاله |
| Integrated thermal drying and slow pyrolysis offer a promising approach to sewage sludge volume reduction and resource recovery, although industrial-scale evidence remains limited. This study evaluates an integrated installation at the Firouz Bahram wastewater treatment plant in Tehran, Iran, using physicochemical characterization, mass-balance calculations, energy assessment, and preliminary economic analysis. Sludge moisture decreased from 73.1% in dewatered feed to 35.9% after drying and approximately 1% in the pyrolysis product. Volatile matter decreased from 94.3% to 23.1%, while electrical conductivity declined by 71.3%, from 2,480 to 713 µS/cm. The reported 48-h EC50 increased from 19.5% to 87.5%, indicating potential toxicity reduction under the tested conditions. At an illustrative feed rate of 100 t/day, dry-solids conservation calculations estimated dryer discharge at 41.97 t/day under the recorded moisture condition and 33.63 t/day at the 20% target, representing an approximately 20% reduction. The corresponding volumetric flow of 2.91 m³/h falls within the pyrolysis unit’s nominal capacity of 3–4 m³/h. Project-based estimates suggest that process-gas recovery could offset 50% of the pyrolysis unit’s fuel-equivalent demand, resulting in an estimated external thermal input of 3.89 MW. Under specified financial assumptions, the calculated simple annual return on investment is 27.3%, with a payback period of 3.66 years. However, elevated concentrations of Zn, Cu, Pb, and Cd warrant further assessment before determining biochar suitability for specific applications. Overall, the findings demonstrate the potential of integrated drying–pyrolysis while highlighting the need for synchronized operational measurements and validated product, energy, and economic assessments. |
| کلیدواژه ها |
| Sewage sludge; Thermal drying; Slow pyrolysis; Energy recovery; Techno-economic assessment |
| وضعیت: پذیرفته شده برای ارائه شفاهی |
