Acute biotoxicity assessment of heavy metals in sewage sludge based on the glucose consumption of Escherichia coli.

Yazhu Mi,Xu Zhang,Youbin Si,Xiangyun Tao

doi:10.1098/rsos.181769

Abstract

As a simple and feasible method for acute biotoxicity assessment, personal glucose meter (PGM) can be successfully applied in the early warning of environmental pollutants in sewage. In this paper, the acute biotoxicity of single and joint heavy metals in sewage and real sludge samples was systematically described based on the glucose metabolism of Escherichia coli (E. coli). Results indicated that the biotoxicity order of five single heavy metals in sewage was Hg2+ > As3+ > Cu2+ > Zn2+ > Cd2+. The joint heavy metals of Cu2+ + Zn2+, Cu2+ + Cd2+, and Cu2+ + Hg2+ produced synergistic effects, while Cu2+ + As3+ and Cd2+ + Zn2+ possessed antagonistic effects for the combined biotoxicity. In spiked sludge, Cd2+ and Zn2+ owned higher biotoxicity than Cu2+ and As3+. Notably, the electroplate factory and housing estate sludge respectively showed the highest and lowest inhibition rates as 57.4% and 17.7% under the real sludge biotoxicity assessment. These results demonstrated that PGM was a sensitive and portable method, which could be widely used for acute biotoxicity assessment of heavy metals in sewage sludge.

Highlights

According to the China Environment Statistical Yearbook (2017), approximately 135.20 million cubic metres per day of urban sewage was produced in China in 2016 [1]
When E. coli was suspended with glucose and heavy metal was not added, lots of glucose was consumed in normal metabolism and personal glucose meter (PGM) showed the low glucose concentration as 3.0 mM
If heavy metal existed in the suspended solution, glucose will be less consumed in disturbed metabolism

Summary

Introduction

According to the China Environment Statistical Yearbook (2017), approximately 135.20 million cubic metres per day of urban sewage was produced in China in 2016 [1]. The various applications of sewage sludge administered to agricultural soil can improve the physical, chemical and biological properties of the soil, such as N, P, K and other micronutrients [2,3], and in some cases, can contribute to causing harm to humans and animals after entering food chain [4,5]. Constraints of sewage sludge use on agricultural soil was its high biotoxicity of heavy metals (As, Cu, Cd, 2 Pb, Zn, Hg, etc.) [6]. Concentrations of Zn, Cu, Pb and Cd heavy metals were measured to monitor the instant pollution in the Golden Horn sediment sludge. The total heavy metal concentrations and range of ratios in sludge samples were critical for potential biotoxicity [7]. It is a challenge to rapidly detect biotoxicity of environmental pollutants in sewage sludge

Methods

Results

Discussion

Conclusion