Phytoremediation and Plant-Assisted Bioremediation in Soil and Treatment Wetlands: A Review

Abstract

Phytoremediation is a technology that is based on the combined action of plants and their associated microbial communities to degrade, remove, transform, or immobilize toxic compounds located in soils, sediments, and more recently in polluted ground water and wastewater in treatment wetlands. Phytoremediation could be used to treat different types of contaminants including petroleum hydrocarbons, chlorinated solvents, pesticides, explosives, heavy metals and radionuclides in soil and water. The advantages of phytoremediation compared to conventional techniques are lower cost, low disruptiveness to the environment, public acceptance, and potentiality to remediate various pollutants. The use of plants in conjunction with plant associated bacteria (rhizosphere or endophytic) offers greater potential for bioremediation of organic compounds, and in some cases inorganic pollutants than using plants alone in bioremediation. The implementation of treatment wetlands for phytoremediation of wastewater or polluted water originating from various sources allows removing organic and inorganic pollutants from water in an environmentally friendly and economically feasible way. Presently, different processes of phytoremediation in treatment wetlands are less studied compared to phytoremediation of polluted soils. Further research is needed to advance the understanding of the pollutant removal mechanisms in treatment wetlands with vegetation, and how based on this information to improve treatment wetland design and operational parameters to achieve more efficient treatment processes. This review covers basic processes of phytoremediation with special emphasis on rhizoremediation and plant-microbe interactions in plant–assisted biodegradation in soil and treatment wetlands.

Dynamics of Bacterial Community Abundance and Structure in Horizontal Subsurface Flow Wetland Mesocosms Treating Municipal Wastewater

“…Plant roots modify their surrounding environment by providing additional organic carbon sources as root exudates and dead fine roots, lowering pH value due to the release of organic acids as well as aerating the wetland media [78]. Vegetation is an important external factor in addition to influent parameters that shape the temporal and spatial patterns of microbial community structures in CW media.…”

Phytoremediation and Bioremediation of Pesticide-Contaminated Soil

“…The remediation of pesticides in soil and ground water is important because of public health, the need for healthy productive soils, and for drinking water that is safe to consume. There are several reviews of research on the remediation processes for pesticide contaminated soil [4,13,21,34,40,78,111,114,122,147,163,192,200,214,219,222,223,228,236,262,[274][275][276][277][278][279][280][281]283,284]. The review on physicochemical remediation processes [275] is a very recent addition to the literature, and the review on bioaugmentation [277] was published in 2017.…”

“…There have been several efforts to develop transgenic plants for phytoremediation of pesticide-contaminated soils [284]. The process that plants use may involve 1) addition of a reactive group such as OH to the pesticide, 2) conjugation of another compound to the pesticide through reaction with the reactive group, and 3) integration of the conjugated pesticide into cell-wall components or another part of the plant where the new substance is less toxic [236,283,284]. Atrazine degradation with transgenic plants has been reviewed by Dhankher et al [284].…”

Plant-bacteria synergism: An innovative approach for the remediation of crude oil-contaminated soils

“…Bacteria are ubiquitous -living in the rhizosphere, rhizoplane/ phyllosphere, and plant interior, thus can be considered active players in the cleanup strategy for hydrocarbon remediation (Truu et al, 2015;Pandey et al, 2016a). Microbes having both hydrocarbon-degrading and plant growth promoting (PGP) abilities more actively reduce stress symptoms in plants and detoxify soil pollutants as compared to microorganisms having just contaminant degrading/PGP capabilities (Ma et al, 2011).…”