Due to the increasing world population, there is a tremendous growth of various industries, which uses many harmful chemicals for the generation of a commodity for public demands but the side products such as contaminants not only affect water bodies but also the air and soil. Dyes have a major demand and application in the textile industries for the dyeing process. About 10–15% of the azo dyes get lost in the effluent during the dyeing process [1] and 50% other reactive dyes reported for use in the textile industry which throw waste into water [2]. Azo dyes are extensively used in the dyeing process. The effluent containing dyes released into the surrounding thereby seriously affecting the atmosphere by destroying the ecosystem, causing water pollution, and reducing light penetration for aquatic life [3].Due to textile dye wastewater, the Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), suspended solid values enhance [4]. So, there is a big challenge to treat textile dyes effluent before released into water bodies.
There are so many physical and chemical strategies, for example, adsorption, coagulation, sedimentation, flocculation, filtration, photodegradation, and chemical oxidation, are accessible for managing contamination produced by textile dyes [5]. These strategies relate to the high expense, low productivity, require huge space and undependable to work. Because of these issues, there is a requirement of the advancement of productive, savvy strategy for the treatment of textile dyes[5].Biological methods are more effective than physical and chemical methods to treat the textile dye wastewater Bioremediation is a very efficient treatment for removing contaminants from textile dyes effluent [6]. Different enzymes and microorganisms were used for removing the dyes from wastewater. Phanerochaete chrysosporium, the most spacious studied white-rot fungus, used to metabolize and decolourise dyes colour and compounds [7]. Biological decolourisation of lignin-containing pulp and paper wastewater using white rot fungi Tictoporia species due to the high oxidative potential of many of the enzymes linked with white rot fungi as ligninase, laccase, Mn-peroxidase [8]. Aspergillus flavipes fungus was reported to decolourise the dye xiron orange [9].From the different bioremediation process, phytoremediation is an energy-efficient, solar-driven process to remove the contaminants from soil, air, water [10]. Phytoremediation is also used to remove pollutants from textile dye wastewater [11].There are various phytoremediation mechanisms as phytoextraction, phytodegradation, rhizofiltration, phytostabilization, phytovolatilization which helps in the dye removal [12]. Due to these different qualities, we can use plants for the treatment of textile dye wastewater. In the present study, the main focus is to screen the potential of ornamental plants for removing the textile dyes from wastewater.
Different ornamental plants are utilised for phytoremediation study such as Marigold, Euphorbia, Bryophyllum, etc. These ornamental plants are widely used as hyperaccumulators for metals for removal of heavy metals from soil, water and air. Euphorbia pithyusa is proved to be as phytostablizer to remediate low trace element concentration in highly contaminated soils [13]. Marigold variety T. erecta has leaf plasticity when exposed to Cr, indicating the presence of the tolerance mechanism to Cr [14]. Decorative plants are also used for the treatment of dye wastewater as Hibiscus sabdariffa is used to treat CR dye [15]. Ipomoea hederfolia plant is reported for treatment of Scarlet red dye [5]. The petunia grandiflora plant reported to remove the triphenylmethane textile dye Brilliant Blue G [16]. The main investigation of this research to find and screen the new ornamental plants which have the ability to decolourise the textile dye waste water. Textile dye effluent treated with wild plants such as Blumea malcolmii [17], Rheum rabarbarum [18], Typhonium flagelliforme [19], Rumex hydrolapathum [20], and Phragmites australis [21].Aquatic plants are having potential to decolourise and detoxifiers of wastewater containing dyes. They are experimented at laboratory scale studies for degradation of dyes in situ [22].Recently, some tested plants areaquatic macrophytes such as Ipomoea aquatic[23], Salvinia molesta [4], Typha angustifolia [24].Garden ornamental and flowering plants such as Glandularia pulchella [25], Petunia grandiflora [16], Portulaca grandiflora [26], Aster amellus [27] and Ipomoea hederfolia [5] have also been observed as potential candidate for degradation of textile dyes. The petunia grandiflora tissue culture plantlets have the potential to decolourise the Brilliant Blue-green dye [16]. Plants and bacterial consortium of Portulaca grandiflora and Pseudomonas putida showed complete decolourisation of a sulfonated diazo dye direct red 5B [26]. Aster amellus Linn used to decolourise a sulfonated azo dye Remazol Red (RR), a mixture of dyes and a textile effluent [27]. Phragmites australis is commonly used in constructed wetlands either for domestic sewage or industrial effluent ts treatment [21]. The aerobic mineralization mechanisms of Acid Orange 7 (AO7) in a Vertical Flow Constructed Wetland (VFCW) planted with Phragmites australis suggested thatAO7 degradation pathway may involve enzymes like peroxidases (POD), known to degrade some recalcitrant contaminants [21].Glandularia pulchella explored to decolourise the dye green HE4B [25], Ipomoea hederfolia ornamental plant able to decolourise the dye mixtures and scarlet red dye [5]. Nerium oleander plant is used to remove fluoride in comparison to Portulaca oleracea and Pogonatherum crinitum [28]. Nerium oleander plant also has ability to phytoextract the Cr and Ni heavy metals [29]. Alcea rosea plant has the potential to remove disperse red 60 and reactive blue 19 dye [30]. The major research work of screened plants is reported on the removal of heavy metals from the soil, as the T. erecta plant was used to remove Ni and Pb from the soil [31]. Comparison of Chrysanthemum indium plant is exhibited with Dahlia and Calendula for the removal of the Cr metal from the soil [32]. C. indium plant is used to remove CR dye in which flower of the plant act as an adsorbent to remove the CR dye [33]. Bryophyllum pinnatum indicated the tendency to remove Co, Pb, Zn from the soil in comparison with other plants such as Telfaira occidentalis, Talinum triangular. Bryophyllum pinnatum is capable to remove the heavy metals such as Cd, Cr, Cu, Ni, Pb, V [34]. Hibiscus plant helps to eradicate the Cadmium from the soil [35]. C. roseus plant used to remove Cr metal from the soil such as roots, leaves and stems [36]. This research study is aimed to assess the textile dyes removal by using selected ornamental plants as T. ammi, B. fedtschenkoi, C. indicum, T. erecta, H. rosa-sinensis, C. roseus to decolourise the MB and the CR dyes. These plants have an efficient root system and plants do not affect the food chain. There is no research work based on textile dye removal by these ornamental plants. Due to less explore of these plants for dyes removal, this research study focussed the ability of screened plants for decolourisation of MB and CR dyes.