Metal Cation and Surfactant-Assisted Flocculation for Enhanced Dewatering of Anaerobically Digested Sludge

Sanjay Shinde, Anteneh Mesfin Yeneneh (), Tahereh Jafary, Khadija Al Balushi, Eugene Hong, Tushar Kanti Sen () and Parveen Fatemeh Rupani
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Sanjay Shinde: Department of Chemical Engineering, Curtin University, Perth 6845, Australia
Anteneh Mesfin Yeneneh: International Maritime College, National University of Science and Technology, Sohar 321, Oman
Tahereh Jafary: International Maritime College, National University of Science and Technology, Sohar 321, Oman
Khadija Al Balushi: International Maritime College, National University of Science and Technology, Sohar 321, Oman
Eugene Hong: Department of Chemical Engineering, Curtin University, Perth 6845, Australia
Tushar Kanti Sen: Chemical Engineering Department, King Faisal University, Al-Ahsa 31982, Saudi Arabia
Parveen Fatemeh Rupani: School of Energy and Power Engineering, Jiangsu University, Zhenjiang 212013, China

Sustainability, 2023, vol. 15, issue 4, 1-16

Abstract: Flocculation and dewatering of anaerobically digested sludge is known to be a major cost factor in the economy of wastewater treatment plants. Hence, several endeavors have been underway in search of affordable and effective alternatives. This study focuses on the effects of different metal cations, including FeCl 3 , CaCl 2 and MgSO 4, on the dewaterability of digested sludge. The effects of these metal flocculants were also investigated in the presence of co-polymers and surfactants, which can be considered the novelty of this study. The polymers and surfactants investigated in this study were emulsion polymer, CTAB and SDS. Sampling and characterization of digested sludge was conducted, and total solid (TS), volatile solid (VS), dewaterability in capillary suction time (CST), total dissolved solids (TDS), chemical oxygen demand (COD), pH and conductivity of the unconditioned digested sludge samples were determined. The dewaterability of FeCl 3 , CaCl 2 and MgSO 4 conditioned digested sludge samples were compared, and MgSO 4 conditioned digested sludge showed better dewaterability compared to the other two metal conditioning agents at a pH of 6.8. The dewaterability was further improved by the addition of emulsion polymer (EMA 8854), cetyltrimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS). Fe Cl 3 was found to perform better under an acidic pH of around 3. The dual conditioning using polymer and CTAB resulted in better dewaterability, with CaCl 2 as metal conditioning agent. Moreover, the effects of pH, metal dose and polymer dose on the dewaterability of digested sludge were also investigated. The effects of metal and polymer conditioning on the particle size of the sludge flocs was also investigated. Optimum dewatering performance was achieved for metal doses of 0.16 v / v , 0.075 v / v and 0.16 v / v for FeCl 3 , CaCl 2 and MgSO 4 , respectively, and a corresponding CTAB dose of 0.1 v / v and EMA dose of 15 kg/TDS were found to be the optimum. SDS as a polymer conditioning agent resulted in the deterioration of dewatering performance.

Keywords: metal cations; surfactants; emulsion polymer; sludge dewatering (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2023
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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