Microbiota-assisted phytoremediation of metal contaminated soils by sunflower

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Biomethane production from phytoremediation derived maize biomass via anaerobic digestion

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The potential of phytoremediation derived maize biomass for the production of biomethane via anaerobic digestion

Maize is an energetic plant with ability for heavy metals removal from contaminated soil. The growth and ability for heavy metals removal by this energetic culture was tested using an industrialised soil contaminated with zinc (Zn) and cadmium (Cd) vs. an agricultural soil. Plants biomass production and metal accumulation was monitored and resulting biomass (roots, stems and cobs) was used for biogas production in several biomethane assays (BMP) in a factorial design with different inoculum to substrate ratios being tested. The biogas produced during the anaerobic digestion was monitored until stable production and its composition was analysed through gas-chromatography. It was possible to observe that maximum methane production seems to be proportional to the amount of anaerobically degradable substrate and is quickly obtained (ca. 8 days after incubation). It was also noticeable that the metals present in the industrial soil were not damaging to the anaerobic biodegradation of the biomass. The production of biomethane from metal contaminated soils’ phytoremediation derived maize biomass appears thus as a possibility to counterpart biogas production in an increasingly demanding status of renewable energy requirementsinfo:eu-repo/semantics/publishedVersio

Microbiota-assisted phytoremediation of metal contaminated soils by sunflower

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Soil microbiota benefits from phytoremediation coupled to metal-resistant rhizobacteria

Phytoremediation is used for requalifying soils contaminated with heavy metals (HM). Sunflower (Helianthus annuus L.) is one of the most studied species for the remediation of HM-contaminated soils. To increase the bioavailability of nutrients and of metals in soils, metal-resistant plant growth promoting rhizobacteria (PGPR), can be associated to phytoremediation strategies. Soil microbiota can benefit from this association, due to the reduced exposure to HMs toxic effect. In this study, next-generation sequencing (NGS) was applied for investigating shifts in soil microbial community after HMs remediation by sunflowers from a soil amended with Cupriavidus sp. strain 1C2. Sunflower was also grown in a non-contaminated soil (control). Actinobacteria were dominant while Proteobacteria was the second most abundant phylum in both soils. Acidobacteria and Nitrospirae were present in higher relative abundance in the control soil. Results have shown that phytoremediation associated to PGPR induced changes in the contaminated soil microbial community: Acidobacterium (Acidobacteria phylum) and Nitrospira (Nitrospirae phylum) bacterial genera increased their abundance at the end of plant growth. These changes did not occur in the control soil, which presented a more stable bacterial community throughout the experiment. This research increases our knowledge on the relationship between soil microbiota and phytoremediation strategies achievements.info:eu-repo/semantics/publishedVersio

The potential for energetic valorization of energetic crops derived from phytoremediation

There are presently more than 3 million contaminated sites all over EU, according to the EEA (report 25186 EN). Heavy metal contamination is of particular concern, as metals are not degradable. Soil remediation is becoming a priority and several methods are constantly being tested an implemented. From these, phytoremediation has proven to be an attractive low cost alternative as it acts by establishing a vegetation cover which will stabilize the target sites. However, the fate of harvested biomass is a common obstacle for its implementation. Nonetheless, it can also represent an opportunity for producing added value products. This work presents a novel integrated strategy comprising the utilization of all plant parts for the generation of energy products. Combinations of sunflower and plant growth promoting microbiota were assessed growing in agricultural and metal contaminated soils. Sunflower seeds were then used for oil extraction, with observable extraction efficiencies of up to 20 ml oil/m 2 ; plant stems were used for bioethanol fermentation with yields of up to 280 ml/m 2 ; finally, biodiesel was then produced via transterification of the extracted oil with the produced ethanol, allowing the complete production of a biofuel from this phytoremediation derived biomass. All the products were characterized and it was possible to observe that the presence of metals in the soils did not affect significantly the metal levels on either the oil, the bioethanol or the biodiesel. Additionally, plant roots were used as carbon and energy source for biomethane assays (BMP) for the production of biogas via anaerobic digestion. Overall, it was possible to conclude that soil contaminated with metals was not found to have an important effect on the anaerobic biodegradability of the sunflower roots. This study reports thus the successful energetic valorisation of plants grown in degraded soils as a whole.info:eu-repo/semantics/publishedVersio

Treatment of wastewaters contaminated with heavy metals using aerobic granules in a sequencing batch reactor

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Phytomanagement of Zn- and Cd-contaminated soil: helianthus annuus biomass production and metal remediation abilities with plant-growth-promoting microbiota assistance

Mining and industrial activity are contributing to the increase in heavy metal (HM) pollution in soils. Phytoremediation coupled to selected rhizosphere microbiota is an environmentally friendly technology designed to promote HM bioremediation in soils. In this study, sunflower (Helianthus annuus L.) was used together with Rhizophagus irregularis, an arbuscular mycorrhizal fungi (AMF), and Cupriavidus sp. strain 1C2, a plant growth promoting rhizobacteria (PGPR), as a phytoremediation strategy to remove Zn and Cd from an industrial soil (599 mg Zn kg−1 and 1.2 mg Cd kg−1). The work aimed to understand if it is possible to gradually remediate the tested soil while simultaneously obtaining significant yields of biomass with further energetic values by comparison to the conventional growth of the plant in agricultural (non-contaminated) soil. The H. annuus biomass harvested in the contaminated industrial soil was 17% lower than that grown in the agricultural soil—corresponding to yields of 19, 620, 199 and 52 g m−2 of roots, stems, flowers and seeds. It was possible to remove ca. 0.04 and 0.91% of the Zn and Cd of the industrial soil, respectively, via the HM accumulation on the biomass produced. The survival of applied microbiota was indicated by a high root colonization rate of AMF (about 50% more than in non-inoculated agricultural soil) and identification of strain 1C2 in the rhizosphere at the end of the phytoremediation assay. In this study, a phytoremediation strategy encompassing the application of an energetic crop inoculated with known beneficial microbiota applied to a real contaminated soil was successfully tested, with the production of plant biomass with the potential for upstream energetic valorisation purposes.info:eu-repo/semantics/publishedVersio

Biofuel production from phytoremediation derived sunflower biomass

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