Could saponins be used to enhance bioremediation of polycyclic aromatic hydrocarbons in aged-contaminated soils?

Abstract

21Polycyclic aromatic hydrocarbons (PAH) are persistent organic compounds of major concern 22 that tend to accumulate in the environment, threatening ecosystems and health. Brownfields 23 represent an important tank for PAHs and require remediation. 24Researches to develop bioremediation and phytoremediation techniques are being conducted as 25 alternatives to environmentally aggressive, expensive and often disruptive soil remediation 26 strategies. 27The objectives of the present study were to investigate the potential of saponins (natural 28 surfactants) as extracting agents and as bioremediation enhancers on an aged-contaminated soil. 29Two experiments were conducted on a brownfield soil containing 15 PAHs. In a first 30 experiment, soil samples were extracted with saponins solutions (0; 1; 2; 4 and 8 g.L -1 ). In a 31 second experiment conducted in microcosms (28°C), soil samples were incubated for 14 or 28 32 days in presence of saponins (0; 2.5 and 5 mg.g -1 ). CO 2 emissions were monitored throughout 33 the experiment. After the incubation, dehydrogenase activity was measured as an indicator of 34 microbiological activity and residual PAHs were determined. In both experiments PAHs were 35 determined using High-Performance Liquid Chromatography and Fluorimetric Detection. 36The 4 g.L -1 saponins solution extracted significantly more acenaphtene, fluorene, phenanthrene, 37 anthracene, and pyrene than water. PAHs remediation was not enhanced in presence of saponins 38 compared to control samples after 28 days. However CO 2 emissions and dehydrogenase 39 activities were significantly more important in presence of saponins, suggesting no toxic effect 40 of these surfactants towards soil microbiota. 41

Effects of Magnetically Treated Sedum Alfredii Seeds On The Dissolved Organic Matter Characteristics of Cd-Contaminated Soil During Phytoextraction

“…Generally, Cd is present as an oxyanion in soil, and its uptake by S. alfredii could enhance the pH in the rhizosphere because the plant releases OH − in the soil to maintain the charge balance after extracting Cd. Decreased soil pH was caused by increased root secretions, including rhamnolipids, surfactin, and humic and fulvic acids (Davin et al, 2018). The combination of these two processes could determine the nal soil pH during phytoremediation.…”

Use of Slaughterhouse Sludge in the Bioremediation of an Oxyfluorfen-Polluted Soil

“…Currently, one of the most widely used bioremediation techniques among the scientific community is the application of organic matter to polluted soil, because it is a very cheap, effective technique that can be performed in situ (Davin et al 2018). In these cases, organic matter reduces the concentration of contaminant in the soil via two different pathways.…”

Targeting the right parameters in PAH remediation studies

“…A different approach, involving microcosms, was used by our team when studying the effect of commercial saponins on PAH bioremediation in an aged-contaminated soil. In this case, a realistic soil was treated and placed in controlled incubation conditions (Davin et al, 2018). Such intermediate experimental set-ups, even though they might be expensive to run, allow links to be created between highly controlled laboratory studies and complex, but realistic, field studies (Albarano et al, 2020).…”