Development of a hybrid sewage sludge-rice husk biochar adsorbent for sustainable wastewater treatment in Thailand | |
| Author | Shinwari, Maryam |
| Call Number | AIT Thesis no.EV-26-07 |
| Subject(s) | Biochar--Thailand Sewage sludge Sewage--Purification--Thailand |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Abstract | Excessive discharge of nitrogen (N) and phosphorus (P) from inadequately treated domestic wastewater drives eutrophication across freshwater and coastal ecosystems in developing countries. In Thailand, centralized facilities treat only ~22% of wastewater generated, with influent TN (35–60 mg L⁻¹) and TP (4–8 mg L⁻¹) routinely exceeding Pollution Control Department (PCD) discharge standards of TN < 20 mg L⁻¹ and TP < 4 mg L⁻¹. Municipal sewage sludge and rice husk two abundant waste streams are largely landfilled or openly burned, compounding environmental burdens. This study addresses both challenges by developing a co-pyrolyzed sewage sludge–rice husk biochar composite (SSRH) as a low cost adsorbent for simultaneous ammonium (NH₄⁺–N) and phosphate (PO₄³⁻–P) removal.Three biochar materials sewage sludge biochar (SSB), rice husk biochar (RHB), and a 1:1 co-pyrolyzed composite (SSRH) were synthesized at 500 °C under oxygen-limited conditions. Materials were characterized by BET, BJH, pore analysis, and SEM. Adsorption performance was evaluated through batch kinetic and isotherm experiments using PFO, PSO, Langmuir, and Freundlich models, followed by validation in real domestic wastewater against PCD standards.Despite its lowest BET surface area (91.73 m² g⁻¹), SSRH exhibited hierarchical pore architecture (DFT pore volume: 0.054 cm³ g⁻¹) and a dual-domain morphology integrating porous carbon with reactive mineral phases (Fe/Al/Ca–OH). At 180 min, SSRH achieved 70.20% NH₄⁺–N and 58.00% PO₄³⁻–P removal, outperforming SSB and RHB at p < 0.001. PSO kinetics (R² = 0.995) and Langmuir isotherms (R² = 0.991) best described adsorption behavior, yielding q_max of 32.80 and 5.86 mg g⁻¹ for NH₄⁺–N and PO₄³⁻–P, respectively. In real wastewater (TN = 44.2 mg L⁻¹; TP = 5.5 mg L⁻¹), SSRH alone achieved simultaneous PCD compliance, reducing TN to 18.4 mg L⁻¹ and TP to 2.5 mg L⁻¹. Langmuir predictions matched experimental values within ±0.9 percentage points.Co-pyrolysis of sewage sludge and rice husk yields a multifunctional adsorbent meeting regulatory standards through synergistic porosity and mineral reactivity, offering a scalable circular-economy solution for decentralized wastewater treatment across South and Southeast Asia. |
| Year | 2026 |
| Type | Thesis |
| School | Faculty of Civil and Environmental Engineering (2026) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Environmental Engineering and Management (EEM) |
| Chairperson(s) | Thammarat Koottatep; |
| Examination Committee(s) | Ghimire, Anish;Chongrak Polprasert; |
| Scholarship Donor(s) | PMU-KPCIP-AIT Scholarship; |
| Degree | Thesis (M. Sc.) - Asian Institute of Technology, 2026 |
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