Acetate biostimulation as an effective treatment for cleaning up alkaline soil highly contaminated with Cr(VI)

Abstract

Stimulation of microbial reduction of Cr(VI) to the less toxic and less soluble Cr(III) through electron donor addition has been regarded as a promising approach for the remediation of chromium-contaminated soil and groundwater sites. However, each site presents different challenges; local physicochemical characteristics and indigenous microbial communities influence the effectiveness of the biostimulation processes. Here, we show microcosm assays stimulation of microbial reduction of Cr(VI) in highly alkaline and saline soil samples from a long-term contaminated site in Guanajuato, Mexico. Acetate was effective promoting anaerobic microbial reduction of 15 mM of Cr(VI) in 25 days accompanied by an increase in pH from 9 to 10. Our analyses showed the presence of Halomonas, Herbaspirillum, Nesterenkonia/Arthrobacter, and Bacillus species in the soil sample collected. Moreover, from biostimulated soil samples, it was possible to isolate Halomonas spp. strains able to grow at 32 mM of Cr(VI). Additionally, we found that polluted groundwater has bacterial species different to those found in soil samples with the ability to resist and reduce chromate using acetate and yeast extract as electron donors.

Recent bioreduction of hexavalent chromium in wastewater treatment: A review

“…Then they were smashed to pass through a 149 micron sieve followed by pyrolysis at 300, 450, and soil with only water as a second control, at alkaline pH range. [165] In the first case 16 mM Cr(VI) was reduced to zero in 25 days with only 18% acetate consumption, however no significant result were found in other two cases. Among four species isolated from the soil only Halomonas sp.…”

Chemical-Assisted Microbially Mediated Chromium (Cr) (VI) Reduction Under the Influence of Various Electron Donors, Redox Mediators, and Other Additives: An Outlook on Enhanced Cr(VI) Removal

“…Yang et al (2020) showed that compost-derived humic acid along with hematite could promote Cr(VI) reduction by strain MR-1, where the quinonoid and acid groups in organic substances exhibited role as electron shuttle and electron donor, respectively. In a microcosm assay, biostimulation of acetate was effective for anaerobic Cr(VI) treatment in highly alkaline and saline soil of long-term contaminated landfill of León (Guanajuato), Mexico, where a haloalkaliphilic isolate, Halomonas, was expected to lead the catalysis of Cr(VI) reduction (Lara et al, 2017). Treatment of Cr(VI)-contaminated soil from tannery site with Pseudomonas sp.…”

“…(RPT) revealed enhancement of Cr(VI) reduction after biostimulation of neem (Azadirachta indica) oil cake (NOC), and the application of NOC further improved soil enzyme properties (Govarthanan et al, 2019). Habitually, indigenous microbial communities of different sites greatly influence the reduction process (Lara et al, 2017).…”

Carbon-dependent chromate toxicity mechanism in an environmental Arthrobacter isolate

“…However, these have not been well addressed in laboratory studies. Similarly, in environments where organic carbon is added to stimulate microbial contaminant remediation [33][34][35][36][37][38] it is imperative to first understand how these organisms respond under environmentally-relevant conditions.…”