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Enhanced dewaterability of anaerobically digested sewage sludge using Acidithiobacillus ferrooxidans culture as sludge conditioner
- Murugesan, Kumarasamy, Ravindran, Balasubramani, Selvam, Ammaiyappan, Kurade, Mayur B., Yu, Shuk-Man, Wong, Jonathan W.C.
- Bioresource technology 2014 v.169 pp. 374-379
- Acidithiobacillus ferrooxidans, Fourier transform infrared spectroscopy, X-ray diffraction, bacteria, cell free system, culture filtrates, filtration, iron, minerals, sewage sludge
- Role of Acidithiobacillus ferrooxidans culture in bioacidification and dewaterability of anaerobically digested sewage sludge (ADS) was investigated. A. ferrooxidans culture grown in 9K medium along with Fe2+ produced iron flocculant containing, secondary iron minerals and biopolymeric substances as confirmed by FT-IR, XRD, and SEM-EDX. Bioacidification of ADS was performed using 10% (v/v) A. ferrooxidans culture, isolated cells and cell-free culture filtrate; and dewaterability was assessed using the capillary suction time (CST) and specific resistance to filtration (SRF). Isolated bacterial cells significantly (P<0.05) reduced the sludge dewaterability when supplemented with Fe2+ while the whole culture and cell-free filtrate rapidly acidified the sludge without Fe2+ and showed significant reduction of CST (71.3–73.5%) and SRF (84–88%). Results clearly indicated that the culture and filtrate of the A. ferrooxidans facilitated rapid sludge dewaterability while the cells supplemented with Fe2+ also enhanced dewaterability but required 2–4days.