Kinetics, Isotherms and Adsorption–Desorption Behavior of Phosphorus from Aqueous Solution Using Zirconium–Iron and Iron Modified Biosolid Biochars

Md Aminur Rahman,Dane Lamb,Mohammad Mahmudur Rahman,Anitha Kunhikrishnan

doi:10.3390/w13233320

Md Aminur Rahman, Dane Lamb + Show 2 more

Open Access

https://doi.org/10.3390/w13233320

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Journal: Water	Publication Date: Nov 23, 2021
Citations: 10	License type: CC BY 4.0

Affiliation: RMIT University, University of Newcastle Australia

Abstract

Excessive discharge of phosphorus (P) to aquatic ecosystems can lead to unpleasant eutrophication phenomenon. Removal and recovery of P is challenging due to low C/N ratios in wastewater, hence the development of efficient removal and recovery of P strategies is essential. In this study, zirconium–iron (Zr–FeBC) and iron modified (Fe–BC) biosolid biochars were examined to investigate their capacity for the removal of P by batch experiments. The influence of solution pH, biochar dose, initial P concentration, ionic strength, interfering ions and temperature were also studied to evaluate the P adsorption performance of biochars. The P experimental data were best described with pseudo-second order kinetics and the Freundlich isotherm model. The maximum P adsorption capacities were reached to 33.33 and 25.71 mg g−1 for 24 h by Zr–FeBC and Fe-BC at pH 5 and 4, respectively. Desorption studies were performed to investigate the reusability, cost-effectiveness and stability of the adsorbents Zr–FeBC and Fe-BC. The adsorption–desorption study suggests that both examined biochars have considerable potentiality as adsorbent candidates in removing as well as recovery of P from wastewaters. Results also reveal that the regenerated Zr–FeBC and Fe–BC could be utilized repetitively in seven adsorption–desorption cycles using NaOH as a desorbing agent, which greatly reduces the P-removal cost from wastewaters. Thus, P enriched biochar could potentially be used as fertilizer in the agriculture sector.

Highlights

Phosphorus (P) is one of the essential primary nutrients controlling soil fertility, plant growth and agricultural productivity [1]
The pH of biochars indicated that the modified Zr–FeBC and Fe–BC are acidic characteristics whereas BC and
Kinetic data suggested more than a single step could control adsorption using batch experiments

Summary

Introduction

Phosphorus (P) is one of the essential primary nutrients controlling soil fertility, plant growth and agricultural productivity [1]. The quality of water may deteriorate and cause eutrophication when excess (due to the emission of wastewater discharge or runoff system) P is present in aqueous systems [2,3]. Excess P in aquatic systems may occur from excessive fertilization in agricultural systems or release from point sources, such as municipal waste treatment plants, industrial sources (e.g., cheese factories, abattoirs) and animal husbandry (e.g., dairy and piggery operations). The effective recovery and utilization of P from wastewater sources is critical for the continued productivity of agricultural systems. P removal and recovery for beneficial reuse is of critical importance globally, given the limitation of P sources into the future [4,5]

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