Application of Klebsiella oxytoca Biomass in the Biosorptive Treatment of PAH-Bearing Wastewater: Effect of PAH Hydrophobicity and Implications for Prediction

Dong Zhang,Hongting Zhao,Meiqing Jin,Li Lu,Ting Lü,Jun Lin

doi:10.3390/w10060675

Abstract

Biosorption has been widely recognized as a promising method to treat wastewater. However, few studies have investigated the impact of pollutants’ properties on wastewater treatment, as well as the underlying mechanisms and future predictions. In this study, the effects of pollutants’ hydrophobicity on the biosorptive removal of polycyclic aromatic hydrocarbons (PAHs) were evaluated. The results showed that the inactive biomass of Klebsiella oxytoca effectively removes PAHs from aqueous solutions with a high biosorption capacity, high biosorption affinity, and short equilibrium time. The biosorption of seven PAHs achieved equilibrium rapidly (less than 2 h) and fitted well to the pseudo-second-order kinetic model. Sorption occurred with a predominantly linear partition process to the biomaterial with Kd values of 363.11, 1719.5, 2515.5, 7343.3, 6353.4, 22,806, and 19,541 L·kg−1 for naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, pyrene, and fluoranthene, respectively. An increase in temperature led to a decrease in the biosorption affinity, and the bacterial biosorption of PAHs was spontaneous and exothermic. Furthermore, a positive correlation was observed between the sorption affinity and the octanol partition coefficient (Kow) (logKd = 1.011logKow − 0.7369), indicating that hydrophobicity is the main factor influencing the biosorption efficiency. These results suggest that biosorption is an efficient and predictable treatment for micropollutant-bearing wastewater.

Highlights

Hydrophobic organic compounds (HOCs) have become an increasing concern with respect to their potential mutagenicity, carcinogenicity, and teratogenicity associated with their persistence and bioaccumulation potential [1,2,3]
Naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, pyrene, and fluoranthene were selected as representative polycyclic aromatic hydrocarbons (PAHs) to model HOCs and were purchased from Acros Organics (Pittsburgh, PA, USA) with purities >98%
Several characteristic werethe identified in the bacterial biomass, and differences were found characteristic peaks were identified in the bacterial biomass, and no obvious differences were found in the peak shift upon biosorption of PAHs, e.g., phenanthrene (PHEN)

Summary

Introduction

Hydrophobic organic compounds (HOCs) have become an increasing concern with respect to their potential mutagenicity, carcinogenicity, and teratogenicity associated with their persistence and bioaccumulation potential [1,2,3]. In the bioremediation process microorganisms play roles as biosorbents that uptake pollutants and bioreactors that degrade them [6]. As one process in bioremediation, biosorption is considered the crucial step and plays a vital role in both the removal and biodegradation of HOCs [1,6,7,8,9]. Our previous results indicated that the biosorption of HOCs even governs their biodegradation process due to low bioavailability of HOCs [10]. Microorganisms with higher sorption affinity for organic pollutants may have the advantage of obtaining more “food”, resulting in higher biodegradation efficiency, especially for those micropollutants with relatively low water solubility, and bioavailability

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Conclusion