Enhancement of Chromium (VI) Reduction in Microcosms Amended with Lactate or Yeast Extract: A Laboratory-Scale Study

Abstract

A laboratory-scale study was carried out to evaluate the groundwater bioremediation potential of hexavalent chromium (Cr(VI)), taking into account the chromate pollution of an industrial site located in Southern Italy (Apulia Region). The reduction of Cr(VI) was studied on laboratory microcosms, set up in different experimental conditions, namely: ABIO (soil and water sterilized), BIO (soil and water not sterilized), LATT (with the addition of lactate), and YE (with the addition of yeast extract). Control test lines, set up by using sterilized matrices and amendments, were employed to assess the occurrence of the pollutant reduction via chemical processes. By combining molecular (microbial abundance, specific chromate reductase genes (ChR) and the Shewanella oinedensis bacterial strain) with chemical analyses of chromium (VI and III) in the matrices (water and soil) of each microcosm, it was possible to investigate the response of microbial populations to different experimental conditions, and therefore, to assess their bioremediation capability in promoting Cr(VI) reduction. The overall results achieved within this work evidenced the key role of amendments (lactate and yeast extract) in enhancing the biological reduction of hexavalent chromium in the contaminated aqueous phase of laboratory microcosms. The highest value of Cr(VI) removal (99.47%) was obtained in the YE amended microcosms at seven days.

Chromium Pollution in European Water, Sources, Health Risk, and Remediation Strategies: An Overview

“…Cr (VI) can be determined in filtered solutions by colorimetric reaction with 1,5 diphenylcarbazide (DPC) at the wavelength of 540 nm [22,77]. Despite its simplicity, the method that uses DPC suffers from the presence of several interferents that can bring to an overestimation or underestimation of the values of Cr (VI), such as Fe (III), Fe (II), Hg, V, sulphides sulphates and organic matter present in the matrix [2].…”

“…In particular, bacteria represent a highly promising and cost-effective resource for chromium removal owing to their high plasticity and widespread presence. They are able to reduce the toxic of chromium Cr (VI) to the less toxic trivalent state, both as a survival mechanism aimed at reducing toxicity around the cell and as a means of deriving metabolic energy for cell growth [22,135]. Other strategies useful for Cr (VI) removal, which take advantage of bacterial resistance to high pollutant concentrations, include bioaccumulation and biosorption [136,137].…”

“…These strategies are also highly efficient for a high content of Cr (VI), but some limitations are related to sludge production, large amount of chemicals required, and consequent risk of secondary pollution [20]. To overcome these issues, bioremediation can represent a valid alternative, particularly with lower and moderate concentrations of Cr (VI) present in large volumes of wastewater [21][22][23]. Bioremediation techniques generally take advantage of the metabolisms of microbes, particularly bacteria, thanks to their high plasticity and widespread presence [24].…”

Isolation and Identification of Chromium Reducing Bacillus Cereus Species from Chromium-Contaminated Soil for the Biological Detoxification of Chromium

“…These untreated chromium-containing pollutants are mostly released into the environment, posing threats to ecosystems [2,5]. There are two common and stable oxidation states of chromium in the environment, namely Cr(VI) and Cr(III) [8][9][10]. Cr(III) is involved in sugar and lipid metabolism and is less toxic to humans [8,11,12], while Cr(VI) is carcinogenic, teratogenic, and mutagenic and is easily absorbed by humans through biomagnification in the food chain [13,14].…”

“…Since the discovery of chromium-reducing bacteria, the use of microorganisms to reduce Cr(III) to the less toxic Cr(VI) has gained more attention [10,20]. Many species have been described to have the ability to reduce hexavalent chromium [20,21,25], such as Acidithiobacillus [26], Acinetobacter [27], Arthrobacter [28], Achromobacter, Bacillus [15], Brucella [20], Desulfovibrio [29], Enterobacter [30], Leucobacter [31], Mirococcus [32], Ochrobactrum [32], Pseudomonas [32] and Thermus [33].…”