Experimental study and parameters optimization of microalgae based heavy metals removal process using a hybrid response surface methodology-crow search algorithm

N Sultana,S A Razzak,B Haq,M M Hossain,M Ezzudin Mohammed,S M Zakir Hossain,M F Irfan,M O Faruque

doi:10.1038/s41598-020-72236-8

Abstract

This study investigates the use of microalgae as a biosorbent to eliminate heavy metals ions from wastewater. The Chlorella kessleri microalgae species was employed to biosorb heavy metals from synthetic wastewater specimens. FTIR, and SEM/XRD analyses were utilized to characterize the microalgal biomass (the adsorbent). The experiments were conducted with several process parameters, including initial solution pH, temperature, and microalgae biomass dose. In order to secure the best experimental conditions, the optimum parameters were estimated using an integrated response surface methodology (RSM), desirability function (DF), and crow search algorithm (CSA) modeling approach. A maximum lead(II) removal efficiency of 99.54% was identified by the RSM–DF platform with the following optimal set of parameters: pH of 6.34, temperature of 27.71 °C, and biomass dosage of 1.5 g L−1. The hybrid RSM–CSA approach provided a globally optimal solution that was similar to the results obtained by the RSM–DF approach. The consistency of the model-predicted optimum conditions was confirmed by conducting experiments under those conditions. It was found that the experimental removal efficiency (97.1%) under optimum conditions was very close (less than a 5% error) to the model-predicted value. The lead(II) biosorption process was better demonstrated by the pseudo-second order kinetic model. Finally, simultaneous removal of metals from wastewater samples containing a mixture of multiple heavy metals was investigated. The removal efficiency of each heavy metal was found to be in the following order: Pb(II) > Co(II) > Cu(II) > Cd(II) > Cr(II).

Highlights

This study investigates the use of microalgae as a biosorbent to eliminate heavy metals ions from wastewater
This research examined the performance of a microalgae biomass for efficiently eliminating heavy metals from an aqueous solution
The second-order model developed was interpreted with ANOVA in terms of significant factors and their interactions

Summary

Introduction

This study investigates the use of microalgae as a biosorbent to eliminate heavy metals ions from wastewater. The biosorption process via active or dead organisms/biomasses is a cost-effective method for the removal of heavy metals from industrial wastewater [10,11,12]. In this approach, the biomass serves as a substrate with a range of functional groups with a nearly consistent distribution of binding sites. Most research on this topic has attempted to identify effective and readily available dead biomasses or biosorbents for eliminating heavy metals [13,14,15,16] These biosorbents include algae, fungi, yeast, bacteria, and agricultural waste [13,15,16,17,18]. There are only few studies available in the literature dealing with heavy metals removal using microalgae, which grows very rapidly and can act as a bisorbent for heavy metals

Methods

Results

Conclusion