Synthesis and evaluation of a novel cross-linked biochar/ferric chloride hybrid material for integrated coagulation and adsorption of turbidity and humic acid from synthetic wastewater: Implications for sludge valorisation

Pamphile Ndagijimana; Hongwei Rong; Luchun Duan; Shitian Li; François Nkinahamira; Jean Claude Hakizimana; Akash Kumar; Moses Akintayo Aborisade; Pancras Ndokoye; Baihui Cui; Dabin Guo; Ravi Naidu

doi:10.1016/j.envres.2024.119134

Synthesis and evaluation of a novel cross-linked biochar/ferric chloride hybrid material for integrated coagulation and adsorption of turbidity and humic acid from synthetic wastewater: Implications for sludge valorisation

Environ Res. 2024 May 22:255:119134. doi: 10.1016/j.envres.2024.119134. Online ahead of print.

Affiliations

¹ School of Civil Engineering, Guangzhou University, Guangzhou, 510006, China.
² Global Centre for Environmental Remediation (GCER), College of Science, Engineering and Environment, The University of Newcastle, Callaghan, NSW, 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (crcCARE), University Drive, Callaghan, NSW, 2308, Australia.
³ University of Technology and Arts of Byumba (UTAB), Faculty of Agriculture, Environmental Management and Renewable Energy, Department of Environmental Management and Renewable Energy, Post.Box:25, Byumba, Gicumbi District Northern province, Rwanda.
⁴ School of Civil Engineering, Guangzhou University, Guangzhou, 510006, China. Electronic address: cuibaihui0306@163.com.
⁵ School of Civil Engineering, Guangzhou University, Guangzhou, 510006, China. Electronic address: dabin@gzhu.edu.cn.

PMID: 38751002
DOI: 10.1016/j.envres.2024.119134

Abstract

The deep removal of organic pollutants is challenging for coagulation technology in drinking water and wastewater treatment plants to satisfy the rising water standards. Iron (III) chloride (FeCl₃) is a popular inorganic coagulant; although it has good performance in removing the turbidity (TB) in water at an alkaline medium, it cannot remove dissolved pollutants and natural organic matter such as humic acid water solution. Additionally, its hygroscopic nature complicates determining the optimal dosage for effective coagulation. Biochar (BC), a popular adsorbent with abundant functional groups, porous structure, and relatively high surface area, can adsorb adsorbates from water matrices. Therefore, combining BC with FeCl₃ presents a potential solution to address the challenges associated with iron chloride. Consequently, this study focused on preparing and characterizing a novel biochar/ferric chloride-based coagulant (BC-FeCl₃) for efficient removal of turbidity (TB) and natural organic matter, specifically humic acid (HA), from synthetic wastewater. The potential solution for the disposal of produced sludge was achieved by its recovering and recycling, then used in adsorption of HA from aqueous solution. The novel coagulant presented high TB and HA removal within 10 min of settling period at pH solution of 7.5. Furthermore, the recovered sludge presented a good performance in the adsorption of HA from aqueous solution. Adsorption isotherm and kinetics studies revealed that the Pseudo-second-order model best described kinetic adsorption, while the Freundlich model dominated the adsorption isotherm.

Keywords: Adsorption; Biochar; Coagulation; Iron (III) chloride; Turbidity and humic acid.