Article

Phytoremediation of BTEX from Indoor Air by Zamioculcas zamiifolia

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Abstract

Zamioculcas zamiifolia has the potential to reduce the concentration of benzene, toluene, ethylbenzene, and xylene (BTEX) from contaminated indoor air. It can remove all four pollutant gases. Benzene, toluene, ethylbenzene, and xylene uptake per unit area of Z. zamiifolia leaf were about 0.96 ± 0.01, 0.93 ± 0.02, 0.92 ± 0.02, and 0.86 ± 0.07 mmol m−2 at 72 h of exposure, respectively. The physicochemical properties of each BTEX may affect its removal. Benzene, a smaller molecule, is taken up by plants faster than toluene, ethylbenzene, and xylene. The toxicity of BTEX on plant leaves and roots was not found. The chlorophyll fluorescence measurement (F v/F m) showed no significantly difference between controlled and treated plants, indicating that a concentration of 20 ppm of each gas is not high enough to affect the photosynthesis of the plants. The ratio of stomata and cuticles showed that 80 % of benzene, 76 % of toluene, 75 % of ethylbenzene, and 73 % of xylene were removed by stomata pathways, while 20, 23, 25, and 26 % of them were removed by cuticles. The BTEX removal efficiency by well-watered Z. zamiifolia was involved with day stomata opening and night closing, while the BTEX removal efficiency by water-stressed Z. zamiifolia can occur both day and night at a slightly lower rate than well-watered plants.

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... Also, the findings proved that BTEX did not cause plant poisoning, and the concentration of 20 ppm of these vapors was not so high that would stop the plant's photosynthesis. About 73-80% of these pollutants were removed through the stomata and about 23-26% by the cuticle (Sriprapat and Thiravetyan 2013). These findings were in agreement with the phytoremediation of formaldehyde by Chamaedorea elegans and Nephrolepis Obliterata due to the plants' growth throughout the test even in fumigation concentrations of 16.4 mg m −3 and 11 mg m −3 respectively (Teiri et al. 2018b, a). ...
... The entry of contaminants into the leaf occurs through an open stoma in the epidermis or via penetration into the wax cuticle (Thomas et al. 2015). Benzene and toluene are mainly absorbed by the plant through the stomata, but some studies have concluded that the stomata have no major role in the removal of volatile organic hydrocarbons (Sriprapat and Thiravetyan 2013;Popek et al. 2018). The cuticle wax layer allows both lipophilic and hydrophilic molecules to penetrate the plant. ...
... Most of the ornamental plants do not need higher light intensity than room natural light, even some of them are vulnerable to higher light intensity than their optimum light level and some others stomata open at night to purify indoor air like Zamioculcas zamiifolia (Sriprapat and Thiravetyan 2013;Torpy et al. 2014). However, in indoor environments with low or without natural light, low energy-consuming lamps or luminescent solar concentrators can be used (Pedron et al. 2021). ...
Article
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In recent decades, indoor air pollution has become a major concern due to its adverse health effects on the inhabitants. The presence of fine particles (PM2.5) and hazardous volatile organic compounds (VOCs), such as formaldehyde and benzene, in indoor air and their proven carcinogenic effects, has raised the attention of health authorities. Their very difficult and expensive removal by chemical and mechanical methods has led researchers to seek an economical and environmentally friendly technique. The use of plants in different ways such as potted plants or green walls is considered as a potential green solution for the improvement of indoor air quality and the health level of its inhabitants. A review of the literature cited in this paper suggests that plants absorb some of the pollutants, such as particles directly and remove some pollutants such as VOCs indirectly through biological transfer or by using microorganisms. This review paper discusses the types of plants that have been used for the phytoremediation of airborne pollutants and the routes and mechanisms for removing the pollutants. Removal pathways of the pollutants by aerial parts of the plants, the growth media along with the roots and their microorganisms in the rhizosphere part were also discussed. Sensitive analysis of extracted data from the literature outlined the most useful types of plants and the appropriate substrate for phytoremediation. Also, it showed that factors affecting the removal efficiency such as light intensity and ambient temperature, behave differently depending on pollutants and plants types.
... Inhalation is account for 95-99% of the benzene exposure. In the United States, daily intake of benzene from the indoor and outdoor air has been estimated between 180 and 1300 μg/day, respectively (Krzyzanowski and Cohen, 2008;Sriprapat and Thiravetyan, 2013). Acute exposure to benzene can cause dizziness, headaches, as well as eye, skin, and respiratory tract irritation. ...
... Nowadays, it has been proven that existing methods have no proper capability to remove the indoor air pollutants due to the problems linked to their very low concentrations (Guieysse et al., 2008). Phytoremediation, the use of plants to remove pollutants from the environment, is an inexpensive and cost-effective technique that is able to remove pollutants at low concentrations (Sriprapat and Thiravetyan, 2013). Many studies have been conducted on phytoremediation of VOCs from different environments (air, soil, and water) (Alavi et al., 2017;Guieysse et al., 2008;James and Strand, 2009;Sriprapat and Thiravetyan, 2013;Suchkova et al., 2014). ...
... Phytoremediation, the use of plants to remove pollutants from the environment, is an inexpensive and cost-effective technique that is able to remove pollutants at low concentrations (Sriprapat and Thiravetyan, 2013). Many studies have been conducted on phytoremediation of VOCs from different environments (air, soil, and water) (Alavi et al., 2017;Guieysse et al., 2008;James and Strand, 2009;Sriprapat and Thiravetyan, 2013;Suchkova et al., 2014). Plants can remove pollutants from the environment through some mechanisms such as phytodegradation, phytostabilization, phytovolatilization, phytoextraction, phytofiltration, and rhizodegradation; however, more than one may be used by the plant simultaneously. ...
Article
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Benzene is a carcinogenic contaminant. It is therefore important to remove it from the environment. In this study, phytoremediation of benzene from polluted air by two plant species (Schefflera arboricola and Spathiphyllum wallisii) was investigated under controlled environment using a Plexiglas chamber. The effect of inlet benzene concentrations of 3.6–29.5 μg/m³, and empty bed residence time (EBRT) of 37.5 and 70 s were tested on the plant efficiency for a period of 36 days. Results showed that the outlet benzene concentration in the control chamber (plant free) was significantly higher than that in the chamber containing the plants. The average removal efficiency (RE) at various inlet concentrations including 3.5–6.5, 10.5–16.3, and 25–30 μg/m³ were 97%, 94%, and 91%, respectively. Also, the average RE at EBRTs of 37.5 and 75 min were 93% and 94% respectively. According to the physiological and morphological tests, no toxicity effects on the plants were found at these concentrations. It can be concluded that the plant's application is a green and environment-friendly technology to remove benzene from the polluted indoor air.
... Volatile organic compounds (VOCs) are present in the indoor spaces. Benzene, toluene, ethylbenzene, and xylene (BTEX) are common VOCs present in both outdoor and indoor air, and also indoor air is a significant source of human exposure to BTEX (5). Indoor sources of benzene are typically newspapers, school books, liquid waxes, fiberglass, adhesives, paints, wooden paneling, paint remover, and nylon carpets (3,4). ...
... In plants' tissues, benzene is converted to nonvolatile organic acids with the aromatic ring cleavage in leaves (24). Several (5,13,20). The Hyrcanian (Caspian) region, which extends throughout the south coast of the Caspian Sea in the northern part of Iran, covers an area of 1 925 125 ha, which has been investigated in many research (25)(26)(27)(28). ...
... R. hyrcanus, and D. racemosa removed benzene after 48 and 72 hours, respectively. In contrast, Zamioculcas zamiifolia lowered the concentration of 80 µL/LBTEX mixture within 14 days (5). It can be due to the effect of different plant species and different leaf areas (5 (20). ...
Article
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Background: Phytoremediation is one of the available and simple techniques for removing benzene, toluene, ethylbenzene, and xylene (BTEX) from indoor air. This study aimed to evaluate phytoremediation of low concentrations of BTEX by Hyrcanian plants including Ruscus hyrcanus and Danae racemosa. Methods: The test chamber was used to evaluate the removal of BTEX. Benzene, toluene, ethylbenzene, and xylene were injected into the chamber using Gastight syringes (Hamilton) to generate the concentration of 10 (benzene), 20 (toluene), 20 (ethylbenzene), and 50 (xylene) µL/L Results: Ruscus hyrcanus was able to remove BTEX (10, 20, 20, and 50 µL/L) from air after 3 days. D. racemosa could uptake BTEX (10, 20, 20, and 50 µL/L) from air after 4 days. Removal efficiency was calculated based on leaf area and volume of the chamber. R. hyrcanus showed the highest removal efficiency ranged from 8.5075 mg/m3 /h.cm2 for benzene to 86.66 mg/m3 /h.cm2 for xylene. The increase in BTEX phytoremediation was assessed after repeated exposures. A significant phytoremediation efficiency was obtained after the third injection of BTEX to the chamber. Afterwards, the effects of BTEX on anatomical and morphological structure of plants were studied. The results of Photomicrography showed that tissue structures of leaves and stems changed. Study of D. racemosa and R. hyrcanus stems showed that vascular bundles also changed. The development of crystal in vacuole of spongy parenchyma was the main anatomical change of R. hyrcanus and D. racemose compared to the control samples. Conclusion: It can be concluded that R. hyrcanus and D. racemosa can be used for phytoremediation of indoor air pollution.
... The first is the static chamber method. The VOC uptake rate was determined as the decrease of VOC concentrations in the chamber (Orwell et al., 2004;Sriprapat and Thiravetyan, 2013). Loss of soluble compounds to condensed water, soil and chamber surfaces is likely to be major problem with this method (Tani and Hewitt, 2009). ...
... The removal of MAHs by plants has been investigated in several studies (for review, see Dela Cruz et al., 2014). In most experiments, their concentrations were controlled at several to several tens of ppmv (=µmol mol − 1 ) levels (Liu et al., 2007;Mosaddegh et al., 2014;Orwell et al., 2004;Sriprapat et al., 2014;Sriprapat and Thiravetyan, 2013;Wolverton et al., 1989), which are 10 3 to 10 4 times higher than their concentrations in urban, sub-urban and rural atmosphere (Garzón et al., 2015;Tiwari et al., 2010). All the above-cited studies, except for Liu et al. (2007), used static chamber method and enclosed whole potted plants; therefore, it is unclear which parts of the potted plants remove MAHs, that is leaves, soils, condensed water, or other parts inside the chambers. ...
... In previous studies, benzene and toluene were fumigated to potted plants in closed chambers at several hundreds of ppbv to several tens of ppmv levels (Liu et al., 2007;Mosaddegh et al., 2014: Orwell et al., 2004Sriprapat et al., 2014;Sriprapat and Thiravetyan, 2013;Wolverton et al., 1989). The concentration range was too high to be extrapolated to the evaluation of plant VOC removal capability in the surrounding atmosphere. ...
Article
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Large amounts of monocyclic aromatic hydrocarbons (MAHs) are emitted into the atmosphere, but it is unclear which compounds among MAHs are effectively removed by the above-ground parts of plants. Although fumigation experiments of MAHs at unrealistically high concentrations (~ppmv) have been conducted, experiments with ambient concentrations have scarcely been conducted. In the present study, MAHs, including benzene, toluene, phenol, benzaldehyde, and benzyl alcohol, with concentrations ranging from several to several tens ppbv, were individually fumigated to four plant species, and the uptake was monitored using proton-transfer-reaction mass spectrometry and gas chromatography-mass spectrometry. No detectable uptake was observed for benzene and toluene, but phenol, benzaldehyde, and benzyl alcohol were significantly taken up by the plants. The uptake rate normalized to fumigated concentration varied from 3 to 50 mmol m⁻²s⁻¹ during the light period, depending on light intensity and compounds. The difference in uptake capability may be attributed not only to different metabolic activities but also to different values of Henry’s law constant, which regulates the partitioning of these compounds into the liquid phase in leaves. The uptake of phenol, benzaldehyde, and benzyl alcohol was affected by stomatal conductance, suggesting that stomatal opening is the main factor regulating the uptake of the three MAHs. This is the first observation that anisole is emitted when phenol is fumigated to Spathiphyllum clevelandii, suggesting that phenol is methylated to anisole within plant leaves. Anisole is more volatile than phenol, meaning that methylation enhances the emission of xenobiotics into the atmosphere by converting them to more volatile compounds. This conversion ratio decreased with an increase in phenol concentration (from 1.3 to 143 ppbv). Considering low reaction rate coefficient of anisole with OH radicals and low conversion ratio from phenol to anisole, it is concluded that plants act to effectively remove oxygenated MAHs from the atmosphere.
... Zamioculcas zamiifolia has been reported to be an efficient plant for the removal of non-polar airborne pollutants such as benzene, toluene, ethylbenzene and xylene (BTEX), which can remove mixed BTEX about 88-99% within 24 h (Sriprapat and Thiravetyan 2013). However, Z. zamiifolia has also been tested for removal of formaldehyde by Khaksar et al. (2016a), who reported an approximate removal of only 55% of 24 mg/m 3 formaldehyde in 36 h. ...
... Effect of exogenous IAA on Z. zamiifolia for removal of toluene and formaldehyde mixture During the first cycle (60 h), we observed that the highest percentage of formaldehyde removal was by Z. zamiifolia with 3 μM and 5 μM IAA (Fig. 2b), and Z. zamiifolia has removed significantly less formaldehyde compared with toluene under the same time. This can be explained as Z. zamiifolia is known to remove non-polar VOCs (toluene) more efficiently (Sriprapat et al. 2014;Sriprapat and Thiravetyan 2013) than polar VOCs (formaldehyde) (Khaksar et al. 2016a). Although, removed percentage of formaldehyde increases in the second and third cycle up to 90%, 81% and 73% in plants with 5 μM, 3 μM and 10 μ IAA sprayed on shoots, respectively (Fig. 2b). ...
... Primarily, exogenous IAA when applied on the shoots of plants is absorbed by the plants through diffusion (Brewer et al. 2009). Z. zamiifolia produced endogenous IAA as a response to stress from airborne pollutants, as benzene (Khaksar et al. 2017a), xylene (Sriprapat et al. 2014) and ethylbenzene (Sriprapat and Thiravetyan 2013). The above results are in consensus with the results we found that for 3 μM, 5 μM and no exogenous IAA conditions, Z. zamiifolia subjected to toluene and formaldehyde has significantly higher endogenous IAA compared with Z. zamiifolia with no pollutant exposure. ...
Article
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Indoor air pollution is of increasing concern for human health. Amongst the volatile organic compounds (VOCs) found indoors, formaldehyde and toluene are two toxic compounds. Indoor plants have an innate capability to remediate indoor airborne pollutants. Zamioculcas zamiifolia is an ornamental plant local to Thailand reported to be very efficient for VOC removal. Indole acetic acid (IAA) was applied to shoots and roots of Z. zamiifolia to enhance the capability for removing a toluene and formaldehyde mixture. We found that 5 μM of exogenous IAA can enhance Z. zamiifolia efficiency about 20% and 40% for toluene and formaldehyde, respectively, after plant was exposed to initial toluene-formaldehyde mixture concentration 20 ppm (1:1) for 3 cycles (156 h). We found that 5 μM of exogenous IAA had a positive effect on the stomatal aperture opening and stomatal conductance. However, 10 μM of exogenous IAA had a negative effect on the opening of stomatal aperture, and thus initially decreased that remediating ability of Z. zamiifolia for formaldehyde and toluene. We investigated the formaldehyde dehydrogenase activity in shoots of Z. zamiifolia and found significantly enhanced FDH activity in plants supplied with exogenous IAA. We concluded that exogenous IAA in optimum amounts could enhance the mitigating ability of indoor plants for airborne air pollutants. However, our research indicated that the application of IAA to roots could have a negative effect on the remediating ability of Z. zamiifolia.
... The entry of the pollutants in the leaf tissue occurs either via the open stomata on the leaf epidermis or by diffusion through the epidermis that is covered by a waxy cuticle (Kvesitadze et al. 2006). Entry through stomata has been assessed by several studies addressing the impact of stomatal density on VOC removal efficiency of various plant species (Treesubsuntorn and Thiravetyan 2012;Sriprapat and Thiravetyan 2013;Sriprapat et al. 2014b). The rates at which indoor plants, such as Chlorophytum Li et al. (2015) comosum and Sansevieria trifasciata, removed ethylbenzene and toluene were not significantly correlated with the number of stomata per leaf (Sriprapat et al. 2014b). ...
... The rates at which indoor plants, such as Chlorophytum Li et al. (2015) comosum and Sansevieria trifasciata, removed ethylbenzene and toluene were not significantly correlated with the number of stomata per leaf (Sriprapat et al. 2014b). Benzene and toluene are taken up mainly through the stomata (Ugrekhelidze et al. 1997;Sriprapat and Thiravetyan 2013), however, few studies concluded that the role of the stomata in VOC removal was insignificant (Schmitz et al. 2000). The alternative route of entry is through the cuticle, which is permeable to both lipophilic and hydrophilic molecules. ...
... Benzene removal through wax adsorption represented 46% of the total benzene uptake by Dracaena sanderiana (Treesubsuntorn and Thiravetyan 2012). Benzene, toluene, ethylbenzene, and xylene removal by Zamioculcas zamiifolia through cuticular adsorption accounted for 20, 23, 25, and 26%, respectively (Sriprapat and Thiravetyan 2013). Treesubsuntorn et al. 2013 investigated the amount and composition of wax materials of different indoor plants and found that the ability of the plant to remove benzene was dependent on the composition of the wax but not on the amount of wax present on leaves. ...
Article
Air quality in homes, offices, and other indoor spaces has become a major health, economic, and social concern. A plant-based removal system for volatile organic compounds (VOCs) appears to be a low-cost, environment-friendly solution for improving indoor air quality. This review presents and assesses VOC removal mechanisms that use plants and their associated microorganisms as well as the factors that influence the rate and efficiency of VOC removal. To increase removal efficiency, it is important to have a thorough understanding of the mechanisms of VOC degradation by plants and their associated microorganisms. The potential of plants and their associated microorganisms, whether present in pots or forced-air systems, to remove VOCs from indoor environments have been supported by a number of studies. Variations in removal efficiency depend on the plant species used, the chemical properties of the volatiles in question, and a cross-section of other internal and external factors. It is thus critical to select the right plants and use methods that reflect in vivo conditions. Indoor plants with superior air-purifying abilities have been extensively studied; however, the low rates of VOC removal efficiency in interior environments entail the need of more studies. For instance, factors that modulate VOC removal by plants, such as air circulation rate, light intensity, moisture status, and season need to be explored. Improving the efficiency of plants and their associated microorganisms for VOC remediation of indoor air is necessary to ensure sustainable and healthy indoor environments.
... The size of a molecule of pollutants is another factor in removal efficiency. In other words, the pollutant with a small size shows higher uptake according to Fick's law [147]. For example, Z. zamiifolia, et al. showed that benzene, toluene, ethylbenzene, and xylene had higher uptake by plants, especially benzene with due to its small size, and xylene while the lowest removal rate. ...
... For example, Z. zamiifolia, et al. showed that benzene, toluene, ethylbenzene, and xylene had higher uptake by plants, especially benzene with due to its small size, and xylene while the lowest removal rate. Also, benzene removal had a higher uptake rate in dark conditions [147,148]. ...
Article
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Urban civilization has a high impact on the environment and human health. The pollution level of indoor air can be 2–5 times higher than the outdoor air pollution, and sometimes it reaches up to 100 times or more in natural/mechanical ventilated buildings. Even though people spend about 90% of their time indoors, the importance of indoor air quality is less noticed. Indoor air pollution can be treated with techniques such as chemical purification, ventilation, isolation, and removing pollutions by plants (phytoremediation). Among these techniques, phytoremediation is not given proper attention and, therefore, is the focus of our review paper. Phytoremediation is an affordable and more environmentally friendly means to purify polluted indoor air. Furthermore, studies show that indoor plants can be used to regulate building temperature, decrease noise levels, and alleviate social stress. Sources of indoor air pollutants and their impact on human health are briefly discussed in this paper. The available literature on phytoremediation, including experimental works for removing volatile organic compound (VOC) and particulate matter from the indoor air and associated challenges and opportunities, are reviewed. Phytoremediation of indoor air depends on the physical properties of plants such as interfacial areas, the moisture content, and the type (hydrophobicity) as well as pollutant characteristics such as the size of particulate matter (PM). A comprehensive summary of plant species that can remove pollutants such as VOCs and PM is provided here. This review will help in making informed decisions about integrating plants into the interior building design.
... Additionally, these systems can use substrates containing a proportion of activated carbon and a range of other materials, to assist with pollutant filtration or substrate microbial growth Torpy et al. 2018). The efficiency with which biofilters can filter out and degrade VOCs from indoor air indicates that they may be used to reduce inhabitant pollutant exposure (Sriprapat and Thiravetyan 2013;Wolverton et al. 1984;Wood et al. 2006;Brilli et al. 2018). ...
... The primary observation of the current work is that plant type does influence the system's capacity for VOC removal. It is well established that potted plants can effectively improve indoor air quality by reducing hazardous VOCs (Ugrekhelidze et al. 1997;Kim and Jeon 2009;Sriprapat and Thiravetyan 2013;Dela Cruz et al. 2014;Kim et al. 2016;Hörmann et al. 2018). However, it is known that the efficiency of VOC removal varies substantially both amongst plant species (Kim et al. 2018;Yoo et al. 2006), and with the molecular characteristics of individual compounds. ...
Article
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Volatile organic compounds (VOCs) are of public concern due to their adverse health effects. Botanical air filtration is a promising technology for reducing indoor air contaminants, but the underlying mechanisms are not fully understood. This study assessed active botanical biofilters for their single-pass removal efficiency (SPRE) for benzene, ethyl acetate and ambient total volatile organic compounds (TVOCs), at concentrations of in situ relevance. Biofilters containing four plant species (Chlorophytum orchidastrum, Nematanthus glabra, Nephrolepis cordifolia ‘duffii’ and Schefflera arboricola) were compared to discern whether plant selection influenced VOC SPRE. Amongst all tested plant species, benzene SPREs were between 45.54 and 59.50%, with N. glabra the most efficient. The botanical biofilters removed 32.36–91.19% of ethyl acetate, with C. orchidastrum and S. arboricola recording significantly higher ethyl acetate SPREs than N. glabra and N. cordifolia. These findings thus indicate that plant type influences botanical biofilter VOC removal. It is proposed that ethyl acetate SPREs were dependent on hydrophilic adsorbent sites, with increasing root surface area, root diameter and root mass all associated with increasing ethyl acetate SPRE. The high benzene SPRE of N. glabra is likely due to the high wax content in its leaf cuticles. The SPREs for the relatively low levels of ambient TVOCs were consistent amongst plant species, providing no evidence to suggest that in situ TVOC removal is influenced by plant choice. Nonetheless, as inter-species differences do exist for some VOCs, botanical biofilters using a mixture of plants is proposed.
... In view of phytoremediation, studies show that the openings (cuticle and stomata) of plant bodies are responsible for potential VOC uptake, predominantly via stomata during the daytime when the stomata are open, unless it is a CAM plant (Weyens et al., 2015). Additionally, the occupied amount of VOCs on the waxy layer determine the potential of cuticular absorption (Treesubsuntorn and Thiravetyan, 2012;Sriprapat and Thiravertyan 2013). Once inserted into the plant system, either the VOCs undergo sequential degradation through the plant itself thereby transforming them into harmless constituents or the excretion and storage method in case degradation fails to occur (Weyens et al., 2015). ...
... The potted plants enable the decomposition of VOCs and were reported to reduce benzene by 15% (Lim et al., 2009). Nonetheless, to observe the VOC removal capacity of aerial parts, in a few experiments the aboveground part of the plant was subjected to a physical barrier and isolated from the rest of the substrate, along with the root zone, which showed a positive response independently (Tani et al., 2007;Tani and Hewitt, 2009;Treesubsuntorn and Thiravetyan, 2012;Treesubsuntorn et al., 2013;Sriprapat and Thiravertyan, 2013;Sriprapat et al., 2014a, b). Aydogan and Montoya (2011) set an experiment to observe the efficiency of the formaldehyde-removal capacity of plant root zones and aerial parts separately. ...
... In 2012, D. sanderiana was reported as the best plant for benzene removal compared to other ornamental plant species (Treesubsuntorn and Thiravetyan 2012). Then, Sriprapat and Thiravetyan (2013) showed that Zamioculcas zamiifolia can highly remove benzene, toluene, ethylbenzene, and xylene. Therefore, phytoremediation can be one of the most effective technology for indoor air pollution treatment (Wolverton et al. 1989;Liu et al. 2007;Sriprapat and Thiravetyan 2013;Boraphech and Thiravetyan 2015). ...
... Then, Sriprapat and Thiravetyan (2013) showed that Zamioculcas zamiifolia can highly remove benzene, toluene, ethylbenzene, and xylene. Therefore, phytoremediation can be one of the most effective technology for indoor air pollution treatment (Wolverton et al. 1989;Liu et al. 2007;Sriprapat and Thiravetyan 2013;Boraphech and Thiravetyan 2015). ...
Article
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Benzene-tolerant phyllosphere microorganisms isolated from Dracaena sanderiana were identified as Pantoea sp. B11 and Staphylococcus sp. B12. Inoculating D. sanderiana with these microorganisms growing under 70 and 348 mg/m³ of airborne benzene showed a higher benzene removal efficiency than D. sanderiana without inoculation. Under 348 mg/m³ of benzene, inoculating D. sanderiana with Staphylococcus sp. B12 can remove benzene higher than inoculating D. sanderiana with Pantoea sp. B11 and co-culture between Staphylococcus sp. B12 and Pantoea sp. B11. In addition, individual Staphylococcus sp. B12 had higher ability to bio-remediate benzene than individual Pantoea sp. B11 and co-culture. Staphylococcus sp. B12 can also produce high indole-3-acetic acid (IAA) and harbor 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, which can protect plant from the stress. Photosystem II activity and chlorophyll content of D. sanderiana were decreased clearly under exposure with a 348 mg/m³ of benzene. Inoculating D. sanderiana with Staphylococcus sp. B12 had significantly higher photosystem II activity and chlorophyll content than inoculating D. sanderiana with Pantoea sp. B11 and co-cultures. In co-culture inoculation, Pantoea sp. B11 inhibited growth of Staphylococcus sp. B12, which can probably decrease benzene removal efficiency. Application of Staphylococcus sp. B12 can enhance benzene phytoremediation efficiency in D. sanderiana and protect plant from benzene stress.
... Many plant species have presented high VOC removal efficiency. 13,[22][23][24][25][26] In addition, plants have the ability to transform carbon-based air pollution and use it as a carbon source for plant growth. [27][28][29][30][31] Some native and nonnative microorganisms growing on plants can promote significant VOC removal efficiency. ...
... This might be the effect of the molecular weight of the compound, with benzene and toluene having a lower molecular weight than ethylbenzene and xylene, which means they can easily diffuse to the stomata of plants. 23 For other VOCs such as trimethylamine (TMA) (fishy smell) and formaldehyde, plants also showed the ability to remove these pollutants. In 2015, Sansevieria sp. was reported as a high TMA removal efficiency plant. ...
Conference Paper
Developing countries rapidly grow when green technology, which is referred to as eco-friendly processes or methods, is developed in parallel. Here, some examples of green technology research and development in Thailand will be overviewed. A huge amount of agricultural waste is generated during agricultural processes. Applying these agricultural wastes in order to maximize the benefits for environmental cleanups of water, soil and air has been studied and commercialized. For example: 1) Application of agricultural waste and/or biochar developed from agricultural waste as biological adsorbents for wastewater treatment in some industries, such as textile/dye industries, and printing industries. In addition, this agricultural waste can also be applied in decolorization of sugar syrup from sugar industries; 2) The research on modified biomaterials as adsorbents and packing materials in biofilters would also be presented, and now, pilot scale biofilters have been developed and applied to solve air pollution problems in the field for future commercialization; 3) Some agricultural waste and/or biochar developed from agricultural waste in our laboratory can promote rice growth and improve rice quality via the reduction of Cd uptake and translocation in rice. Phytoremediation technology, in which plants are used to improve the environmental quality in water and air, has also been studied and would be presented. 1) Some species of native Thai plants can effectively remove heavy metals and dye from wastewater. For this research, a constructed wetland for wastewater treatment was developed and applied in a real contaminated site. 2) In air phytoremediation, some plant species harbor highly volatile organic compound (VOC) removal efficiency. In addition, plants do not only absorb organic pollutants, but also they have the innate ability to degrade organic compounds and use them as carbon sources for their growth. In addition, plant growth-promoting (PGP) bacteria inoculation into plants can enhance airborne pollutant removal. From this research, an indoor air phytoremediation system was developed in order to reduce CO2 emissions with high VOC removal efficiency. The high cost of technology transfer is a major problem, especially in developing countries, and green technology research and innovation can overcome this problem along with efficient allocation of resources and technologies.
... Reduction of BTEX levels especially in indoor environments is crucial to protect human health. Sriprapat et al., [188] researched Zamioculcas zamiifolia (Z. zamiifolia) for phytoremediation of BTEX in indoor air. ...
... Overall, to create a safer environment, more efforts need to be done to protect human health and be ecologically sustainable. Table 8 The pros and cons of different removal techniques [12,13,[161][162][163][164][165]180,187,188,[190][191][192][193][194][195]. ...
Article
BTEX are highly toxic environmental compounds that have carcinogenic and mutagenic effects in humans. These components are ubiquitous in environmental samples like water, air, and soil, which increase the risk of human exposure. Therefore, it is necessary to develop rapid, inexpensive, accurate, sensitive, and efficient sample-preparation and analytical methods to detect BTEX, thus reducing the harmful effect of BTEX on the environment and human health. This research reviewed the sources, fate, and distribution of BTEX in the general environment. In addition, a comprehensive summary and comparison of the current determination methods and different removal techniques in various environmental samples is discussed in detail. Also, the analytical and removal challenges and the futuristic development strategies established for BTEX are provided. In conclusion, the current review presents comprehensive evaluation on cutting-edge technologies in the field of BTEX determination and removal.
... As a possible solution to mitigate poor indoor air quality, a large body of research has tested the capacity of potted plants to clean VOCs from the indoor environment (Aydogan and Montoya 2011; Cruz et al. 2014a, b;Hörmann et al. 2017Hörmann et al. , 2018Irga et al. 2013;Orwell et al. 2004;Sriprapat et al. 2014;Sriprapat and Thiravetyan 2013;Teiri et al. 2018;Treesubsuntorn et al. 2013;Treesubsuntorn and Thiravetyan 2012;Wood et al. 2002). The use of plants for indoor air remediation offers an economical and sustainable departure from conventional techniques, such as adsorption filters, photocatalytic oxidation purifiers and ozone generators, that are often expensive, remove a constrained range of VOCs, and can produce harmful by-products ). ...
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Atmospheric pollutant phytoremediation technologies, such as potted plants and green walls, have been thoroughly tested in lab-scale experiments for their potential to remove air pollutants. The functional value of these technologies, however, is yet to be adequately assessed in situ, in ‘high value’ environments, where pollutant removal will provide the greatest occupant health benefits. Air pollution in countries such as China is a significant public health issue, and efficient air pollution control technologies are needed. This work used pilot-scale trials to test the capacity of potted plants, a passive green wall and an active green wall (AGW) to remove particulate matter (PM) and total volatile organic compounds (TVOCs) from a room in a suburban residential house in Sydney, Australia, followed by an assessment of the AGW’s potential to remove these pollutants from a classroom in Beijing. In the residential room, compared to potted plants and the passive green wall, the AGW maintained TVOCs at significantly lower concentrations throughout the experimental period (average TVOC concentration 72.5% lower than the control), with a similar trend observed for PM. In the classroom, the AGW reduced the average TVOC concentration by ~ 28% over a 20-min testing period compared to levels with no green wall and a filtered HVAC system in operation. The average ambient PM concentration in the classroom with the HVAC system operating was 101.18 μg/m³, which was reduced by 42.6% by the AGW. With further empirical validation, AGWs may be implemented to efficiently clean indoor air through functional reductions in PM and TVOC concentrations.
... Early studies on plant air pollution reduction capabilities were carried out by Wolverton et al. (1984Wolverton et al. ( , 1989 for NASA. It was found that potted plants could absorb substantial concentrations of the VOCs formaldehyde, trichloroethylene, and benzene from chamber air (Irga et al., 2013;Orwell et al., 2004;Sriprapat and Thiravetyan, 2013). Subsequent investigative studies demonstrated VOC removal by over 50 plant species . ...
Chapter
The development and subsequent incorporation of the advanced materials and technologies in buildings, with a view to target energy savings, and to fulfill the energy requirements have been gaining impetus during the recent years. The inherent vision lying behind the state-of-the-art technological advancements taking place in the construction sector is to sustain the energy efficiency in both existing and newly developed buildings on a long run. Thermal energy storage (TES), achieved through the phase-change materials (PCMs), is one among a few energy-efficient technologies available. The energy demand at the end-user side can be greatly satisfied using the TES technologies. Using bio-based PCMs in buildings is considered to be an ever-growing as well as an emerging field of interest to wider scientific and engineering communities, worldwide. This chapter is devoted to provide an in-depth understanding of a variety of bio-based PCMs for accomplishing thermal storage and energy efficiency in buildings. The nucleus of this chapter is focused on the TES properties enhancement for a variety of bio-based PCMs through the incorporation of different functional materials thereby; energy efficiency in buildings can be achieved.
... They can be used for relatively less polluted air, their efficiency and decontaminating efficiency cannot be controlled. Still, PPs play their role in controlling air pollution and some plants have been found very proficient in eliminating VOCs, such as formaldehyde Teiri et al. 2018a), toluene (Kim et al. 2011), benzene, ethylbenzene, xylene (Sriprapat and Thiravetyan 2013), and inorganic gaseous pollutants like CO 2 (Torpy et al. 2017) and ammonia (Ortakci et al. 2019), etc. They suffer from certain limitations in addition to the abovementioned, i.e., they need soil which is not least desired in some houses and their maintenance is somehow a challenge. ...
Article
Asymmetrical thiourea of general formula RR’CS where R ≠ R′, were prepared by treating phenyisothiocayanate with iso-butylamine and tert-butylamine and respective thiourea derivatives, isobutylphenylthiourea (1) and tert-butylphenylthiourea (2) were obtained. These ligands were treated with ZnCl2, CdCl2 and HgI2 and neutral complexes bis(isobutylphenylthiourea)dichlorozinc (3), bis(tert-butylphenylthiourea)dichlorozinc (4), bis(isobutylphenylthiourea)dichlorocadmium (5), bis(tert-butylphenylthiourea)dichl-orocadmium (6), bis(isobutylphenylthiourea)diiodomercurry (7), bis(tert-butylphenyl-thiourea)diiodomercurry (8) were obtained. All compounds were structurally characterized with the help of FT-IR and NMR (¹H and ¹³C) spectroscopy. Compounds 2, 3, 5, 7 are crystalline and their structure was confirmed by SC-XRD. Complexes and their starting precursors were evaluated for their antioxidant and enzyme inhibition potentials. Some of the compounds exhibited excellent antioxidant potentials. Molecular docking studies were also carried out for compounds 1–8.
... Early studies on plant air pollution reduction capabilities were carried out by Wolverton et al. (1984Wolverton et al. ( , 1989 for NASA. It was found that potted plants could absorb substantial concentrations of the VOCs formaldehyde, trichloroethylene, and benzene from chamber air (Irga et al., 2013;Orwell et al., 2004;Sriprapat and Thiravetyan, 2013). Subsequent investigative studies demonstrated VOC removal by over 50 plant species . ...
Chapter
The human population is spending more time in the indoor environment. This coupled with tightly sealed buildings, increased insulation, and reduced ventilation has resulted in indoor air pollution emerging as a global issue as evidence for it being a significant cause of morbidity and mortality increases. Currently, the main form of air filtration technology is centered on mechanical filtration and dilution. However, conventional indoor air filtration methods have a limited range of pollutant application. Alternatives in the form of biological filtration are a rapidly growing field of research with the demand and development of these biological systems supporting a growing industry aimed at maximizing their efficiency and effectiveness.
... However, most experiments have been conducted on individual pollutants, not on mixed pollutants. Only a few studies have considered the case of complex mixed pollutants; for example, Sriprapat and Thiravetyan (2013) reported that Zamioculcas zamiifolia efficiently removed mixed pollutants of benzene, toluene, ethylbenzene, and xylene (BTEX). In real situations, mixed pollutants contaminate indoor air, so application of phytoremediation technology for mixed pollutant removal requires more evaluation. ...
Article
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Botanical biofilters have been proposed as an effective technology for indoor air remediation. Plants, including Sansevieria trifasciata and Chlorophytum comosum, which remove VOCs effectively, can also reduce CO2 emission since S. trifasciata and C. comosum are CAM and C3 plant species, respectively. Therefore, a botanical biofilter using these plants together shows potential for use in contaminated sites. Herein, the potential of this mixed plant botanical biofilter was evaluated as a method of phytoremediation for multi-pollutants from cigarette smoke. The results showed that the combination of S. trifasciata and C. comosum in a botanical biofilter was highly effective in removing VOCs and PM2.5. In addition, this botanical biofilter can also successfully remove formaldehyde, acetone, benzene, and xylene, with low CO2 emission under indoor conditions of moderate light intensity (50 μmole PAR m⁻² s⁻¹). The system was also installed in a large volume room (24 m³) to test phytoremediation of multi-pollutants from cigarette smoke. The results showed that this mixed plant botanical biofilter can remediate indoor air pollution effectively under both light and dark conditions continuously for three cycles. The mixed plant botanical biofilter developed showed potential for use in real contamination sites.
... The entry of the pollutants in the leaf tissue occurs either via the open stomata on the leaf epidermis or by diffusion through the epidermis that is covered by a waxy cuticle 16 . Entry through stomata has been assessed by several studies addressing the impact of stomatal density on VOC removal efficiency of various plant species 17,18 . The alternative route of entry is through the cuticle, which is permeable to both lipophilic and hydrophilic molecules. ...
Article
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Plant based biofilters associated with microorganisms have been gaining popularity in controlling odorous compounds like volatile organic compounds (VOCs) as they are cost effective and an environment friendly alternative to conventional air pollution control techniques. In this context, here, we tried to evaluate the performance of potted plants based Claire's biofilter for biodegradation of benzene. A sealed perspex chamber with lid and fan was designed to ensure minimum leakage, proper aeration and distribution of benzene inside the chamber. Five different ornamental indoor plants were placed inside the chamber sequentially and exposed to a concentration of 5 ppm benzene for 30 h each. The leakage of benzene was checked beforehand. Epipremnum aureum (Money plant) showed maximum benzene degradation in the aforementioned time period with a removal efficiency of 98%. The µ max and K s values for 100 ppm concentration of benzene were calculated to be 0.284 h-1 and 0.427 g/m 3 , respectively.
... Since it shows high environmental and pest tolerability, it does not need much attention in cultivation. As an advantage for an indoor plant, Z. zamiifolia contributes to purify indoor air very effectively (Guieysse et al., 2008;Sriprapat and Thiravetyan, 2013;Sriprapat et al., 2014;Tarran et al., 2007). There is only one species with a specific set of features in the genus Zamioculcas (Burchett et al., 2008;Wong, 2009). ...
Article
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Zamioculcas zamiifolia (Lodd.) Engl. is an export-oriented, potted foliage plant used for indoor scaping. Since it shows high environmental and pest tolerability, it does not need much attention in cultivation. Thus, the aim of present study was to develop stable, novel mutants of Z. zamiifolia induced by colchicine (a mutagenic chemical) treatment. Three leaflet types (rooted leaflets with tuber, tuber initiating leaflets without roots and freshly harvested leaflets) were applied separately with four concentrations of colchicine ranging from 0 to 0.4% to induce mutations in a 70% shaded greenhouse. The experiment was conducted for three generations. Results showed that at 0.4% and 0.04% colchicine, plant size decreased in some leaflets, thus producing extreme dwarf and semi dwarf plants, respectively, which are suitable to be used as table-top, miniature ornamental plants. Some leaflets at 0.004% colchicine produced yellow and light green variegated leaflets. According to our knowledge, this is the first report of producing Z. zamiifolia plants with variegated leaves using colchicine. Other than molecular breeding, which is costly and takes a longer period, conventional breeding cannot be employed to generate new plants, since there is only one species under this genus. As such, use of chemical mutagens such as colchicine would provide a rapid means of developing new plant types of this species with attractive morphological features since there is a very narrow range of variants available in the world.
... Since it shows high environmental and pest tolerability, it does not need much attention in cultivation. As an advantage for an indoor plant, Z. zamiifolia contributes to purify indoor air very effectively (Guieysse et al., 2008;Sriprapat and Thiravetyan, 2013;Sriprapat et al., 2014;Tarran et al., 2007). There is only one species with a specific set of features in the genus Zamioculcas (Burchett et al., 2008;Wong, 2009). ...
Article
Full-text available
Zamioculcas zamiifolia (Lodd.) Engl. is an export-oriented, potted foliage plant used for indoor scaping. Since it shows high environmental and pest tolerability, it does not need much attention in cultivation. Thus, the aim of present study was to develop stable, novel mutants of Z. zamiifolia induced by colchicine (a mutagenic chemical) treatment. Three leaflet types (rooted leaflets with tuber, tuber initiating leaflets without roots and freshly harvested leaflets) were applied separately with four concentrations of colchicine ranging from 0 to 0.4% to induce mutations in a 70% shaded greenhouse. The experiment was conducted for three generations. Results showed that at 0.4% and 0.04% colchicine, plant size decreased in some leaflets, thus producing extreme dwarf and semi dwarf plants, respectively, which are suitable to be used as table-top, miniature ornamental plants. Some leaflets at 0.004% colchicine produced yellow and light green variegated leaflets. According to our knowledge, this is the first report of producing Z. zamiifolia plants with variegated leaves using colchicine. Other than molecular breeding, which is costly and takes a longer period, conventional breeding cannot be employed to generate new plants, since there is only one species under this genus. As such, use of chemical mutagens such as colchicine would provide a rapid means of developing new plant types of this species with attractive morphological features since there is a very narrow range of variants available in the world.
... Most of these research has focused on treating benzene in indoor air by C3 plants and has found that they have potential to improve indoor air quality [11][12][13][14][15]. However, few studies have focused on the benzene removal efficiency of crassulacean acid metabolism (CAM) plants [16], which is a type of effective phytoremediation plant and a common ornamental plant in indoor environments. Noticeably, the concentrations used in these tests were several orders of magnitude greater that those in real-life homes. ...
Article
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The concentration of benzene in indoor air has received appreciable attention due to its adverse health effects. Although phytoremediation has been considered as an eco-friendly method to remove benzene, it is unclear how to select plants with a high removal rate. In this study, we evaluated the benzene removal efficiency of four common ornamental plants, Epipremnum aureum, Chlorophytum comosum, Hedera helix and Echinopsis tubiflora, and we also explored the factors impacting benzene removal efficiency. The removal efficiency of all plants in this study averaged at 72 percent. The benzene absorption rates of Epipremnum aureum, Hedera helix and Chlorophytum comosum were 1.10, 0.85 and 0.27 µg·m−3·cm−2, respectively. This is due to the different transpiration rates and chlorophyll concentrations in the plants. The benzene removal efficiency of crassulacean acid metabolism plant (Echinopsis tubiflora) was 23% higher than C3 plant (Epipremnum aureum) under dark conditions. This can be attributed to the fact that the characteristic of Echinopsis tubiflora stomata is different from Epipremnum aureum stomata, which is still open under dark conditions. Therefore, Echinopsis tubiflora can take up more benzene than Epipremnum aureum. For different initial benzene concentrations, the benzene removal efficiency of Echinopsis tubiflora was always great (50–80%), owing to its high rate of transpiration and concentration of chlorophyll. Our findings indicate that transpiration rate and chlorophyll concentration can be used as reference parameters to facilitate ornamental plant screening for indoor air quality improvement.
... Additionally, the energy costs will rise due to the higher air conditioning needs required to heat or cool the intake air. Conversely, there are suitable biological technologies with the potential to detoxify organic compounds, such as some plants that efficiently and cost-effectively remove contaminants from the air (Sriprapat and Thiravetyan, 2013). ...
Article
Currently, the population spends most of the time in indoor environments, which makes Indoor Air Quality (IAQ) very important for health and comfort. As vegetation can act as a biofilter capturing air pollutants, this study aims to assess the effectiveness of a living wall module in the removal of the Total Volatile Organic Compounds (TVOCs) for IAQ improvement. An airtight glass chamber was used to release contaminants, monitoring the TVOCs both with the chamber empty (control) and with a small Fytotextile® living wall module planted with Nephrolepis exaltata L. A substantial reduction of TVOCs was observed when the living wall was inside the chamber. In few hours, TVOCs levels were reduced below the recommended limit (following Spanish regulations). More tests are recommended considering different plant species and other variables related to the IAQ.
... Many studies report the accumulation of several pollutants indoors such as benzene, toluene, ethylbenzene, xylene, and formaldehyde (Chikara et al. 2009). High BTEX, formaldehyde, ozone, and trimethylamine concentrations are frequently found in indoor conditions (Treesubsuntorn et al., 2012;Sriprapat and Thiravetyan 2013;Boraphech and Thiravetyan 2015;Chen et al. 2018;Li et al. 2019). Taking in these compounds in high concentration can affect human systems such as the nervous and respiratory systems. ...
Article
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High-rise residential developments are rapidly increasing in urban areas. Smaller residential units in this high rise bring a reduction in windows, resulting in poor indoor air ventilation. In addition, materials used in interiors can emit volatile organic compounds (VOCs), which can significantly affect human health. Since people spend 90% of their time indoors, an evaluation of indoor air quality is especially important for high-rise residential buildings with an analysis of determining factors. This study aims to measure the concentrations of VOCs, formaldehyde, and particulate matter (PM2.5 and PM10) in 9 high-rise residential buildings in Bangkok by using the accidental sampling method (n = 252) and to investigate possible important determining factors. The results show that the average concentrations of VOCs, formaldehyde, PM2.5, and PM10 in 9 high-rise residential buildings were at good to moderate levels in the indoor air quality index (IAQI) and that high pollutant concentrations were rarely found except in new constructions. Moreover, it was found that the age of buildings shows strong correlations with all pollutants (p value < 0.0001). Old buildings showed significantly lower pollutant concentrations than new and under-construction buildings at a 95% confidence level. The findings from this investigation can be used as part of sustainable well-being design guidelines for future high-rise residential developments.
... ed quicker formaldehyde removal under dark as opposed to light conditions. Several studies have isolated aboveground plant parts from the root zone and substrate with the use of physical barriers, and have concluded that leaves are capable of VOC removal (Lin et al., 2017;Tani et al., 2007;Tani and Hewitt, 2009;Treesubsuntorn and Thiravetyan, 2012;Sriprapat and Thiravetyan. 2013;Treesubsuntorn et al., 2013;Sriprapat et al., 2014aSriprapat et al., , 2014b. While stomatal uptake offers one possible means of VOC removal by the aerial part of the plant, some VOCs are also able to become adsorbed to or diffuse across the cuticle (Baur and Sch€ onherr, 1995; Treesubsuntorn et al., 2013), with some authors suggesting t ...
Article
Indoor air quality has become a growing concern due to the increasing proportion of time people spend indoors, combined with reduced building ventilation rates resulting from an increasing awareness of building energy use. It has been well established that potted-plants can help to phytoremediate a diverse range of indoor air pollutants. In particular, a substantial body of literature has demonstrated the ability of the potted-plant system to remove volatile organic compounds (VOCs) from indoor air. These findings have largely originated from laboratory scale chamber experiments, with several studies drawing different conclusions regarding the primary VOC removal mechanism, and removal efficiencies. Advancements in indoor air phytoremediation technology, notably active botanical biofilters, can more effectively reduce the concentrations of multiple indoor air pollutants through the action of active airflow through a plant growing medium, along with vertically aligned plants which achieve a high leaf area density per unit of floor space. Despite variable system designs, systems available have clear potential to assist or replace existing mechanical ventilation systems for indoor air pollutant removal. Further research is needed to develop, test and confirm their effectiveness and safety before they can be functionally integrated in the broader built environment. The current article reviews the current state of active air phytoremediation technology, discusses the available botanical biofiltration systems, and identifies areas in need of development.
... In some plants the stomata are open in night and close at day time, for example, CAM plants, and they take VOCs along with CO 2 and help in phytoremediation (Winter and Holtum 2014). There are some plants which are recommended for the remediation of indoor air pollutants like Zamioculcas zamiifolia, Agave and cactus by the uptake BTEX (Sriprapat and Thiravertyan 2013). There are several species of plants that have a capability to host the several microorganisms, and they help in the degradation of VOCs. ...
Chapter
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For the vital functioning of soil ecosystem, microbes have always been the superior force in driving many processes. These microorganisms are the main key facilitators in nutrient cycles associated with plant root system by delivering nutrients and suppressing pathogens, thereby sustaining plant health. Their amazing activity and biochemical versatility, especially the roots of growing plants, show great potential for beneficial microorganisms, for the development of biotechnology applications, for the control of plants of wild plants and for increased food crops. In this chapter we review the existing literature on the interaction between plants, microorganisms and soil. The rhizosphere is an arena where the complex rhizosphere community, which includes both microflora and microfauna, communicates with pathogens and influences the outcome of pathogen infection. A number of microorganisms are advantageous to the plants which include nitrogen-fixing bacteria, endo- and ectomycorrhizal fungi and plant growth-promoting bacteria and fungi. Some of the activities include complex systems of communication, in case of symbiosis such as arbuscular microscopic symbiosis, many millions of years old, while others include exudates from the root and other products of the rhizodeposition which are used as substrates for soil microorganisms. Since degradation of organic compounds in the rhizosphere is encouraged by the release of root expressions and enzymes in plants, therefore, biodegradation plays an important role, depending on the contact between the soil and the contaminated substances surrounding the plants. There is a considerable potential in the expanded area of microorganisms to replace synthetic biological chemistry. Since microbial activities are an important and sensitive component of soil, they are also good indicators of soil disorder and ecosystem. Still, an extended use of microorganisms for bioindication purposes and sustainable means of soil management depends on advances in understanding microbial ecology, especially on a field scale. As a result, to enhance the regenerative capacity of soil ecosystems for sustainable agriculture, it is best to understand how to increase the dynamics and potential of soil biology. This will allow new applications of knowledge to address the challenges of pest and diseases and increase global food production and sustainable farming.
... Both hydrophilic and hydrophobic pollutants can adhere to the surface of the cuticular wax and penetrate into the plant when the concentration of pollutants on the leaf surface exceeds the equilibrium value (Kvesitadze et al. 2006). The adsorption of cuticular wax comprises 46% of the capacity of Dracaena sanderiana to remove benzene (Treesubsuntorn and Thiravetyan 2012), and 20%, 23%, 25%, and 26% of the capacity of Zamioculcas zamiifolia Engl. to remove benzene, toluene, ethylbenzene, and xylene, respectively (Sriprapat and Thiravetyan 2013). Formaldehyde can also enter the plant directly through the opened stomata, which play a significant role in the purification of pollutants in the aerial part. ...
Article
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Decorative plants can efficiently purify formaldehyde and improve the quality of indoor air. The existing studies primarily revealed that the aerial and underground parts of plants’ capacity to purify formaldehyde, while the performance of stems is unclear. A formaldehyde fumigation experiment was conducted on Epipremnum aureum and Rohdea japonica in a sealed chamber. Results showed the stems could remove formaldehyde. The efficiency of removal by the stems of each plant was 0.089 and 0.137 mg∙m−3∙h−1, respectively, the rate of purification was 40.0 and 61.6%, respectively. Both were related to plant species and the latter was affected by other factors like exposed area. To further explore the mechanism of phytoremediation, the correlation between the concentration of formaldehyde and CO2 during the experiment was investigated. Results showed when leaves of plants were exposed to formaldehyde, the concentration of CO2 increased with the decrease in concentration of formaldehyde, and the change in concentration of CO2 could be used as an indicator of the degree of decontamination of formaldehyde by the plants.
... The utilization of plants or botanical systems were found to improve the indoor air quality via active botanical biofiltration [2]. However, most of the air pollution health research has focused on single pollutants rather than multiple pollutants [3], although in reality, we breathe in a complex [4]. More in-depth research is required to evaluate the efficiency of phytoremediation technology in removing the mixed pollutants from the indoor environment [5]. ...
... In this experiment, aerial plant parts showed also different removal efficiencies depending on both chemical and biological identity. In another investigation, no difference in the VOC removal efficiency between substances was detected when aerial plant parts of Zamioculcas zamiifolia were exposed to benzene, toluene, ethylbenzene, or xylene (Sriprapat and Thiravetyan 2013). Trials of Yoo et al. (2006) showed that aerial plant parts of S. wallisii Regal have a higher removal efficiency for benzene than foliage of Syngonium podophyllum Schott., followed by H. helix L. In contrast, all three plant species exhibited the same removal efficiency for toluene. ...
Article
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A unique test chamber system, which enables experiments with plants under highly controlled environmental conditions, was used to examine the pollutant removal efficiency of plants. For this purpose, the removal of two different volatile organic compounds (VOC) (toluene, 2-ethylhexanol) from the air by aerial plant parts of two common indoor plant species (Dieffenbachia maculata and Spathiphyllum wallisii) was monitored. While the control over environmental conditions (temperature, relative humidity, CO2 content, and light condition) worked very well in all experiments, control experiments with the empty chamber revealed high losses of VOC, especially 2-ethylhexanol, over the test duration of 48 h. Nonetheless, compared to the empty chamber, a significantly stronger and more rapid decline in the toluene as well as in the 2-ethylhexanol concentrations was observed when plants were present in the chamber. Interestingly, almost the same VOC removal as by aerial plant parts could be achieved by potting soil without plants. A comparative literature survey revealed substantial heterogeneity in previous results concerning the VOC removal efficiency of plants. This can be mainly attributed to a high diversity in experimental setup. The experimental setup used in the current study offers an excellent opportunity to examine also plant physiological responses to pollutant exposure (or other stressors) under highly controlled conditions. For the analysis of VOC removal under typical indoor conditions, to obtain data for the assessment of realistic VOC removal efficiencies by plants in rooms and offices, a guideline would be helpful to achieve more coherent findings in this field of research.
... Several studies have reported the uptake of BTEX by different species such as Poplar, Ruscus hyrcanus, Danae racemosa, Dracaena deremensis, Opuntia microdasy, Canna x generalis, and Zamioculcas zamiifolia (Burken and Schnoor, 1998, Collins et al., 2002, Fooladi et al., 2019, Mosaddegh et al., 2014, Boonsaner et al., 2011, Sriprapat and Thiravetyan, 2013, Wilson et al., 2013. Nonetheless, plants still show negative effects, including chlorosis, holonecrosis, and hydrosis, when exposed to BTEX. ...
Preprint
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Benzene, toluene, ethylbenzene, and xylenes (BTEX) are important environmental pollutants around the world. The uptake and transformation of BTEX by plants are well understood, but not the molecular mechanisms for BTEX stress response. In the current study, we combined transcriptomic and physiology analysis of two Arabidopsis thaliana accessions with contrasting BTEX tolerance and a reverse genetic approach to identify BTEX-tolerance related genes. Physiology and gene expression were analyzed in seedlings exposed for 5 days to BTEX compounds separately and combined. Our results showed reduced root length, high proline accumulation, and decreased chlorophyll content in the susceptible accession (Ct-1) after BTEX exposure, whereas the tolerant accession (Kn-0) did not show a statistically significant difference. RNA-seq revealed 1593, and 717 DEGs in Ct-1, and Kn-0, respectively, under BTEX stress, with 234 genes in common. DEGs were associated with pathways such as “glutathione transferase activity”, “photosynthesis light harvesting in photosystem I”, “cellular response to ethylene”, and “cellular amino acid catabolic process and found to be upregulated in Kn-0 in stress . DEGs partaking to “response to chitin”, “cellular response to hypoxia”, “plant-pathogen interaction”, and “anthocyanin-containing compound biosynthetic process” were noted to be downregulating in stress mitigation. Moreover, compared with the wild type, BTEX sensitivity increased in T-DNA knockout (KO) lines for two genes, including basic region/leucine zipper motif 60 (BZIP60) (At1G42990) and a hypothetical protein (At2G16190). Our study explored mechanisms underlying the stress involving BTEX compounds in Arabidopsis and the identification of genes responsible for BTEX stress tolerance.
... They can be used for relatively less polluted air, their efficiency and decontaminating efficiency cannot be controlled. Still, PPs play their role in controlling air pollution and some plants have been found very proficient in eliminating VOCs, such as formaldehyde Teiri et al. 2018a), toluene (Kim et al. 2011), benzene, ethylbenzene, xylene (Sriprapat and Thiravetyan 2013), and inorganic gaseous pollutants like CO 2 (Torpy et al. 2017) and ammonia (Ortakci et al. 2019), etc. They suffer from certain limitations in addition to the abovementioned, i.e., they need soil which is not least desired in some houses and their maintenance is somehow a challenge. ...
Article
Formaldehyde evolves from various household items and is of environmental and public health concern. Removal of this contaminant from the indoor air is of utmost importance and currently, various practices are in the field. Among these practices, indoor plants are of particular importance because they help in controlling indoor temperature, moisture, and oxygen concentration. Plants and plant materials studied for the purpose have been reviewed hereunder. The main topics of the review are, mechanism of phytoremediation, plants and their benefits, plant material in formaldehyde remediation, and airtight environmental and health issues. Future research in the field is also highlighted which will help new researches to plan for the remediation of formaldehyde in indoor air. The remediation capacity of several plants has been tabulated and compared, which gives easy access to assess various plants for remediation of the target pollutant. Challenges and issues in the phytoremediation of formaldehyde are also discussed. Novelty statement: Phytoremediation is a well-known technique to mitigate various organic and inorganic pollutants. The technique has been used by various researchers for maintaining indoor air quality but its efficiency under real-world conditions and human activities is still a question and is vastly affected relative to laboratory conditions. Several modifications in the field are in progress, here in this review article we have summarized and highlighted new directions in the field which could be a better solution to the problem in the future.
Article
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Humans have a close relationship with nature, and so integrating the nature world into indoor space could effectively increase people’s engagement with nature, and this in turn may benefit their health and comfort. Since people spend 80–90% of their time indoors, the indoor environment is very important for their health. Indoor plants are part of natural indoor environment, but their effect on the indoor environment and on humans has not been quantified. This review provides a comprehensive summary of the role and importance of indoor plants in human health and comfort according to the following four criteria: photosynthesis; transpiration; psychological effects; and purification. Photosynthesis and transpiration are important mechanisms for plants, and the basic functions maintaining the carbon and oxygen cycles in nature. Above all have potential inspiration to human’s activities that people often ignored, for example, the application of solar panel, artificial photosynthesis, and green roof/facades were motivated by those functions. Indoor plants have also been shown to have indirect unconscious psychological effect on task performance, health, and levels of stress. Indoor plants can act as indoor air purifiers, they are an effective way to reduce pollutants indoor to reduce human exposure, and have been widely studied in this regard. Indoor plants have potential applications in other fields, including sensing, solar energy, acoustic, and people’s health and comfort. Making full use of various effects in plants benefit human health and comfort.
Article
Benzene, toluene, ethylbenzene, and xylenes (BTEX) are hazardous air pollutants commonly found in outdoor air. Several studies have explored the potential of vegetation to mitigate BTEX in outdoor air, but they are limited to a northern temperate climate and their results lack consensus. To investigate this subject in a subtropical climate, we deployed passive air samplers for two weeks in parks and nearby residences at four locations: three in an urban area and one in a rural area in Alabama, USA. All BTEX concentrations were below health-based guidelines and were comparable to those found in several other studies in populated settings. Concentrations of TEX, but not benzene, were 3-39% lower in parks than at nearby residences, and the differences were significant. Site type (park vs. residential) was a significant predictor of TEX concentrations, while distance to the nearest major road was a significant predictor of BTX concentrations. In and around two of the parks, toluene:benzene ratios fell outside the range expected for vehicular emissions (p<0.01), suggesting that there were additional, industrial sources of benzene near these two locations. The ratio of m-,p-xylene:ethylbenzene was high at all locations except one residential area, indicating that BTEX were freshly emitted. Concentrations of individual BTEX compounds were highly correlated with each other in most cases, except for locations that may have been impacted by nearby industrial sources of benzene. Results of this study suggest that parks can help reduce exposure to TEX by a modest amount in some situations.
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Poor indoor air quality is a health problem of escalating magnitude, as communities become increasingly urbanised and people’s behaviours change, lending to lives spent almost exclusively in indoor environments. The accumulation of, and continued exposure to, indoor air pollution has been shown to result in detrimental health outcomes. Particulate matter penetrating into the building, volatile organic compounds (VOCs) outgassing from synthetic materials and carbon dioxide from human respiration are the main contributors to these indoor air quality concerns. Whilst a range of physiochemical methods have been developed to remove contaminants from indoor air, all methods have high maintenance costs. Despite many years of study and substantial market demand, a well evidenced procedure for indoor air bioremediation for all applications is yet to be developed. This review presents the main aspects of using horticultural biotechnological tools for improving indoor air quality, and explores the history of the technology, from the humble potted plant through to active botanical biofiltration. Regarding the procedure of air purification by potted plants, many researchers and decades of work have confirmed that the plants remove CO2 through photosynthesis, degrade VOCs through the metabolic action of rhizospheric microbes, and can sequester particulate matter through a range of physical mechanisms. These benefits notwithstanding, there are practical barriers reducing the value of potted plants as standalone air cleaning devices. Recent technological advancements have led to the development of active botanical biofilters, or functional green walls, which are becoming increasingly efficient and have the potential for the functional mitigation of indoor air pollutant concentrations. © 2018 Springer Science+Business Media B.V., part of Springer Nature
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Three common plant species (Dieffenbachia maculata, Spathiphyllum wallisii, and Asparagus densiflorus) were tested against their capacity to remove the air pollutants toluene (20.0 mg m⁻³) and 2-ethylhexanol (14.6 mg m⁻³) under light or under dark in chamber experiments of 48-h duration. Results revealed only limited pollutant filtration capabilities and indicate that aerial plant parts of the tested species are only of limited value for indoor air quality improvement. The removal rate constant ranged for toluene from 3.4 to 5.7 L h⁻¹ m⁻² leaf area with no significant differences between plant species or light conditions (light/dark). The values for 2-ethylhexanol were somewhat lower, fluctuating around 2 L h⁻¹ m⁻² leaf area for all plant species tested, whereas differences between light and dark were observed for two of the three species. In addition to pollutant removal, CO2 fixation/respiration and transpiration as well as quantum yield were evaluated. These physiological characteristics seem to have no major impact on the VOC removal rate constant. Exposure to toluene or 2-ethylhexanol revealed no or only minor effects on D. maculata and S. wallisii. In contrast, a decrease in quantum yield and CO2 fixation was observed for A. densiflorus when exposed to 2-ethylhexanol or toluene under light, indicating phytotoxic effects in this species.
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Studies of indoor air quality have prompted serious concerns of occupant's health and human well-being, which might not be fully achieved solely by current ventilation strategies. Environmental exposures to indoor contaminants such as volatile organic compounds (VOCs), and Carbon Dioxide emissions (CO2) levels remain problematic issues that might not be fully addressed through increased levels of ventilation rate only. Living media where plants are able to remove indoor contaminants can provide an effective passive strategy that impact occupant's health, well-being, as well as building's ventilation system efficacy. Despite many studies on horticultural biotechnologies for improving indoor air quality in laboratory settings, active botanical biofilters or functional green walls seem to perform differently in actual indoor spaces rather than being assessed in closed experimental chambers. By introducing the idea of incorporating active botanical green wall systems as an air filtration strategy into double skin facades, a dual benefit might be achieved to improve indoor air quality and the building's energy saving potential by improving thermal performance of the building's envelope. This paper aims at evaluating previous results of biofiltration, botanical air filters, and potted plants by comparing their removal efficiencies to their air chamber volumes based on a meta-analysis of published results. Results are presented through specific defined metrics in which independent variables in the form of, plant species, leaf areas, time, air volume, and chamber geometry are computed to present spatial and technical influences of different experimental conditions in reducing indoor air contaminants. The paper concludes that plants show higher removal efficiencies when placed in enclosed spaces with higher ratio of leave areas to chamber volumes which also increases the rate of filtration. Although plants' latent heat might improve the envelope thermal insulation, air volume and stratification are more significant variables at improving the envelope thermal properties. Further studies are needed to test the impact of enclosed botanical biofilters in field studies and under different climatic and building types to determine the suitability and optimization potential of this strategy for the design of high-performance envelopes.
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Chapter
Nowadays, air pollutants such as particulate matter, volatile organic compounds, carbon monoxide (CO), nitrogen dioxide (NO2), and sulfur dioxide (SO2) can have significant effects on human health and environment. Air pollutants can harm to the human respiratory system; alter the heart rate; enhance blood coagulation; and decrease lung function, chronic obstructive pulmonary diseases, lung cancer mortality, and cardiovascular problems. Therefore, air pollutants can be managed by using conventional physical and chemical technologies depending on the type of pollutants. Phytoremediation is an alternative method based on green technology that can decrease global warming and is environmentally friendly. Phytoremediation is a technology that uses plants to degrade organic pollutants and use them as a carbon source. In nature, plants are always associated with microorganisms, and they help each other to deal with pollutants by increasing hormones and antioxidant enzymes in the plant cell. Understanding of how plant-microbes remove the pollutants can be used to create an active living wall/botanical biofilter to solve the problem of air pollutants. In order to solve air pollution problems, forested areas should be created in the cities/industrial areas.
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Air phytoremediation technology has been reported as a high potential technology for indoor air pollution treatment. Since 1996, NASA has supported this technology for application in the international space station. However, changes in plant physiology and hormone levels under microgravity (μG) conditions might affect air phytoremediation efficiency, especially changes of auxin hormone transportation in plants. In this study, the application of Chlorophytum comosum, high benzene removal plant species, to remove 100 ppm gaseous benzene under μG condition was studied. The experiment was operated for three days in a random positioning machine generate 6.44 × 10⁻⁴ G within 1 h. The results showed that under μG, benzene removal efficiency by C. comosum was significantly increased, with a remove more than 80% within three days under both 24 h light and dark conditions. In contrast, C. comosum growing under normal gravity (1G) can remove about 75% and 50% benzene under 24 h light and 24 h dark conditions, respectively. Surprisingly, μG conditions seem to maintain open stomata of a plant open under both 24 h light and dark conditions, and this plant will normally have closed stomata in the dark. In this case, shoot auxin hormone in the form of Indole-3-acetic acid was highly increased in the plant growing under μG. This result suggested that under μG, auxin hormone might be accumulated in the shoot part of plant. This auxin accumulation effect of maintaining open plant stomata can enhance benzene phytoremediation efficiency since stomata are the major benzene uptake pathway. Therefore, this study is the first report presenting the possibility of applying air phytoremediation technology under μG conditions.
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Indoor air pollutants comprise both polar and non-polar volatile organic compounds (VOCs). Indoor potted plants are well known for their innate ability to improve indoor air quality (IAQ) by detoxification of indoor air pollutants. In this study, a combination of two different plant species comprising a C3 plant (Zamioculcas zamiifolia) and a crassulacean acid metabolism (CAM) plant (Sansevieria trifasciata) was used to remove polar and non-polar VOCs and minimize CO2 emission from the chamber. Z. zamiifolia and S. trifasciata, when combined, were able to remove more than 95% of pollutants within 48 h and could do so for six consecutive pollutant’s exposure cycles. The CO2 concentration was reduced from 410 down to 160 ppm inside the chamber. Our results showed that using plant growth medium rather than soil had a positive effect on decreasing CO2. We also re-affirmed the role of formaldehyde dehydrogenase in the detoxification and metabolism of formaldehyde and that exposure of plants to pollutants enhances the activity of this enzyme in the shoots of both Z. zamiifolia and S. trifasciata. Overall, a mixed plant of Z. zamiifolia and S. trifasciata was more efficient at removing mixed pollutants and reducing CO2 than individual plants.
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Monitoring of air quality and the application of strategies for its improvement are perceived as key areas for reducing environmental pollution. The research on Nature Based Solutions for the mitigation of pollutant concentrations in the air has increasingly developed in the last twenty years. The purpose of this review is to evaluate whether the current knowledge about Nature-Based Solutions provides a quantitative answer of the real benefits of air phytoremediation. To address this question, the literature on air phytoremediation over the last twenty years was analyzed. Altogether, 52 variables were selected, grouped into six categories, to briefly characterize the contents, methodology and outcome of the peer-reviewed articles. Altogether, 413 plant species found in the analyzed studies were recorded. The results show the trends about the most studied pollutants and on the methodologies mostly applied, in relation to the study outcomes. The analysis demonstrated that particulate matter (PMx) was the most frequently examined pollutant, most studies on NBS are based on experiments with exposure chambers, and scaling up the results with models has been limited. Although effective reductions in pollutant concentrations have been shown in the majority of studies, there is a strong fragmentation of the approaches, most studies have looked at a single pollutant and detailed information for model parameterization is only available for a few species. Thus, the review highlights that studies of Nature Based Solutions in air phytoremediation require unification of methodologies, and should consider a broader range of pollutants and plant organisms useful for mitigating the impacts of air pollutants in indoor and outdoor human environments.
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Air pollution by particulate matter (PM) and volatile organic compounds (VOCs) is a major global issue. Many technologies have been developed to address this problem. Phytoremediation is one possible technology to remediate these air pollutants, and a few studies have investigated the application of this technology to reduce PM and VOCs in a mixture of pollutants. This study aimed to screen plant species capable of PM and VOC phytoremediation and identify plant physiology factors to be used as criteria for plant selection for PM and VOC phytoremediation. Wrightia religiosa removed PM and VOCs. In addition, the relative water content in the plant and ethanol soluble wax showed positive relationships with PM and VOC phytoremediation, with a high correlation coefficient. For plant stress responses, several plant species maintained and/or increased the relative water content after short-term exposure to PM and VOCs. In addition, based on proteomic analysis, most of the proteins in W. religiosa leaves related to photosystems I and II were significantly reduced by PM2.5. When a high water content was achieved in W. religiosa (80% soil humidity), W. religiosa can effectively remove PM. The results suggested that PM can reduce plant photosynthesis. In addition, plants might require a high water supply to maintain their health under PM and VOC stress.
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Indoor air pollution is a significant problem today because the release of various contaminants into the indoor air has created a major health threat for humans occupying indoors. Volatile Organic Compounds (VOCs) are pollutants released into the environment and persist in the atmosphere due to its low boiling point values. Various types of indoor activities, sources, and exposure to outdoor environments enhance indoor VOCs. This poor indoor air quality leads to adverse negative impacts on the people in the indoor environment. Many physical and chemical methods have been developed to remove or decompose these compounds from indoors. However, those methods are interrupted by many environmental and other factors in the indoor atmosphere, thus limit the applications. Therefore, there is a global need to develop an effective, promising, economical, and environmentally friendly alternatives to the problem. The use of the plant and associated microflora significantly impact reducing the environmental VOC gases, inorganic gases, particulate matter, and other pollutants contained in the air. Placing potted plants in indoor environments not only helps to remove indoor air pollutants but also to boost the mood, productivity, concentration, and creativity of the occupants and reduces stress, fatigue, sore throat, and cold. Plants normally uptake air pollutants through the roots and leaves, then metabolize, sequestrate, and excrete them. Plant-associated microorganisms help to degrade, detoxify, or sequestrate the pollutants, the air remediation, and promote plant growth. Further studies on the plant varieties and microorganisms help develop eco-friendly and environmentally friendly indoor air purifying sources.
Chapter
Bioremediation is an option to transform toxic heavy metals into a less harmful state using microbes or their enzymes and is an ecofriendly, cost-effective technique for revitalizing wastewater-polluted environments
Chapter
The quality of life on earth is completely dependent on the environment. The aquatic and terrestrial systems are the two major ecosystems on earth. In ancient times, our natural systems were efficient at absorbing and breaking down pollutants and maintaining the quality of our environment. But now, owing to population explosion, rapid industrialization, and urbanization, humans have produced and added a tremendous number of pollutants in enormous volumes to the environment. As a result, our environment has become polluted and unhealthy. There are various types of pollution, e.g., water, air, soil, noise, and thermal. The invention of modern technologies to exploit natural resources has also aggravated the rate of pollution. The problem of environmental pollution can be mitigated in many ways, but the most suitable methods are biological, in which green plants are used. These plants can absorb and degrade pollutants and act as both biomitigators and bioindicators. Aquatic plants can be used to treat water pollution, and terrestrial plants can be grown around industrial and urban areas to treat air pollution. The utilization of plants to treat pollution is known as phytoremediation. This treatment is considered an ecologically sustainable and cost-effective strategy to alleviate water and air pollution. In the present chapter, we discuss the role of higher plant species in mitigating pollution and the mechanisms they use.
Chapter
Human activities have become the source of myriad pollutants and have accelerated the pressure on natural resource depletion. Intensive farming, urbanization, rapid industrialization, and other human activities have resulted in land deterioration and degradation, a polluted environment, and a downturn in crop productivity across various sectors of agriculture. Several alternative methods have been designed and developed, but often, these processes risk environmental damage by producing secondary pollutants. Biological treatment systems have diversified applications, such as the cleanup of site contaminants in soil, water, streams, and sludge. Bioremediation, an efficacious and lucrative eco-friendly management tool, utilizes microorganisms to degrade or reduce the concentration of hazardous wastes at the contaminated site without causing additional deterioration of the environment. This chapter discusses the role of a vast array of microorganisms used in the reclamation of wastewater containing metal pollutants through bioremediation and puts forward thoughts and opportunities for further research in the field.
Chapter
Air pollution is a major cause of concern globally. The origin of airborne pollutants is attributed to the industrial revolution and large‐scale use of fossil fuels. There are numerous evidences from epidemiologic research on the adverse effects of air pollutants on human health, such as chronic obstructive pulmonary diseases, lung cancer, premature mortality. Current mitigation strategies focus mostly on specific technical measures and are not sufficient to meet the challenges posed by the deteriorating environment. Despite several measures undertaken cities like Delhi are severely polluted throughout the year. Ambient air pollution is composed of a high variety of pollutants, mainly including particulate matter (PM), volatile organic compounds (VOCs) like benzene, formaldehyde, and inorganic pollutants (NO x , SO 2 , O 3 ). Many of these outdoor air pollutants are also found indoor, in concentrations that often can be higher than the outdoors. Phytoremediation is an effective plant‐based, environmentally friendly biotechnology to remediate indoor and outdoor air pollutants. Plants are known to scavenge significant amounts of air pollutants via processes like phytostabilisation, phytoaccumulation, phytodegradation phytovolatilisation, and rhizodegradation. Several plant enzymes such as nitroreductase, dehalogenase, laccase, and peroxidase aid these processes. Plants are known to be associated with symbiotic microbes such as fungi and bacteria that alleviate abiotic and biotic stresses in them and enhance their growth. Plant–microbe mutualism also plays an important role during phytoremediation by degrading, detoxifying, or sequestrating the pollutants. Plants and associated microorganisms maintain biodiversity and ecological sustainability of urban green infrastructures, and studies on this symbiosis are imperative for human health and environmental sustainability. The incorporation of green areas comprising plants remediating air pollution among concrete jungles would have a substantial positive influence on the health of urban dwellers. In cities, the uses of plants improve the microclimate and alleviate side effects of climate change, for example, by blocking excessive sun radiation during summer. In addition, plants can also be exploited to intensively reduce carbon footprint by absorbing CO 2 and provide long‐term carbon sequestration. Phytoremediation of air pollutants is still an emerging concept and the potential and suitability of individual species for specific pollutants require basic as well as applied research. The selection of the plant–soil–microbe system would vary depending on the abiotic factors of the region. Phytoremediation is a slow removal process, hence attempts should be made to combine it with other remediation strategies to achieve enhanced rates of decontamination. Policies must be executed to incorporate urban forestry with city planning, particularly for the rapidly urbanising cities of the developing world.
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Nowadays, the human health is closely related to quality of indoor air. This article analyzes the main types of pollution to indoor air and their harms to human health, and on this basis, it sets forth the prevention measures comprehensively and proposes advices to normalize industry standards.
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ZZ (Zamioculcas zamiifolia), a member of the family Araceae, is emerging as an important foliage plant due to its aesthetic appearance, ability to tolerate low light and drought, and resistance to diseases and pests. However, little information is available regarding its propagation, production, and use. This report presents relevant botanical information and results of our four-year evaluation of this plant to the ornamental plant industry.
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We conducted laboratory tests with six species of plants to determine their ability to remove benzene, trichloroethylene (TCE) and toluene from air. The objective of this proof-of-principal study was to evaluate the idea that phytoremediation techniques might be used to lower the concentrations of indoor air pollutants, such as volatile or semi-volatile organic compounds. Plants were exposed to the pollutants singly or in mixtures in an airtight chamber, and concentrations of the pollutants in the chamber were monitored through time to assess plant effects on the pollutants. In several experiments, we measured air temperature and CO2, as well. Lower surfaces of leaves of several of the species we tested were also examined by scanning electron microscopy to determine stomate abundance and size, and to provide information about leaf-surface elemental composition (by X-ray emission spectroscopy). Several of the species demonstrated an extensive ability to remove benzene from air. Gas chromatography methods allowed a reasonably direct, continuous monitoring of the kinetics and overall efficiency of the pollutant-removal process. We found that pollutant removal efficiency varied in response to plant species and the pollutant. Of the pollutants tested, benzene was most efficiently removed from air by Pelargonium domesticum, Ficus elastica and Chlorophytum comosum. Kalanchoe blossfeldiana, a common ornamental plant, appeared to take up benzene selectively over toluene, and TCE was removed efficiently from the air by C. comosum. Pentane, sometimes used as an internal standard in GC/MS, was removed from air by at least four of the species. For C. comosum, TCE appeared to lower the removal rates of benzene and pentane. Low-vacuum scanning electron microscopy provided information on stomate size and density and permitted rapid initial elemental analysis of the plant-leaf surface by X-ray emission spectroscopy. Our results indicate that simple tests for pollutant uptake, morphological and chemical features of plants, and plant detoxification enzyme activity might be used in multivariate fashion to identify plant species capable of removing volatile or semi-volatile pollutants from air.
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The limitations that will govern bioregenerative life support applications in space, especially volume and weight, make multi-purpose systems advantageous. This paper outlines two systems which utilize plants and associated microbial communities of root or growth medium to both produce food crops and clean air and water. Underlying these approaches are the large numbers and metabolic diversity of microbes associated with roots and found in either soil or other suitable growth media. Biogeochemical cycles have microbial links and the ability of microbes to metabolize virtually all trace gases, whether of technogenic or biogenic origin, has long been established. Wetland plants and the rootzone microbes of wetland soils/media also been extensively researched for their ability to purify wastewaters of a great number of potential water pollutants, from nutrients like N and P, to heavy metals and a range of complex industrial pollutants. There is a growing body of research on the ability of higher plants to purify air and water. Associated benefits of these approaches is that by utilizing natural ecological processes, the cleansing of air and water can be done with little or no energy inputs. Soil and rootzone microorganisms respond to changing pollutant types by an increase of the types of organisms with the capacity to use these compounds. Thus living systems have an adaptive capacity as long as the starting populations are sufficiently diverse. Tightly sealed environments, from office buildings to spacecraft, can have hundreds or even thousands of potential air pollutants, depending on the materials and equipment enclosed. Human waste products carry a plethora of microbes which are readily used in the process of converting its organic load to forms that can be utilized by green plants. Having endogenous means of responding to changing air and water quality conditions represents safety factors as these systems operate without the need for human intervention. We review this research and the ability of systems using these mechanisms to also produce food or other useful crops. Concerns about possible pathogens in soils and wastewater are discussed along with some methods to prevent contact, disease transmission and to pre-screen and decrease risks. The psychological benefits of having systems utilizing green plants are becoming more widely recognized. Some recent applications extending the benefits of plants and microbes to solve new environmental problems are presented. For space applications, we discuss the use of in situ space resources and ways of making these systems compact and light-weight.
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Zamioculcas zamiifolia (Araceae), a terrestrial East African aroid, with two defining attributes of crassulacean acid metabolism (CAM) (net CO(2) uptake in the dark and diel fluctuations of titratable acidity) is the only CAM plant described within the Araceae, a mainly tropical taxon that contains the second largest number of epiphytes of any vascular plant family. Within the Alismatales, the order to which the Araceae belong, Z. zamiifolia is the only documented nonaquatic CAM species. Zamioculcas zamiifolia has weak CAM that is upregulated in response to water stress. In well-watered plants, day-night fluctuations in titratable acidity were 2.5 μmol H(+)·(g fresh mass)(-1), and net CO(2) uptake in the dark contributed less than 1% to daily carbon gain. Following 10 d of water stress, net CO(2) uptake in the light fell 94% and net CO(2) uptake in the dark increased 7.5-fold, such that its contribution increased to 19% of daily carbon gain. Following rewatering, dark CO(2) uptake returned to within 5% of prestressed levels. We postulate that CAM assists survival of Z. zamiifolia by reducing water loss and maintaining carbon gain during seasonal droughts characteristic of its natural habitat.
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The effect of water stress on respiration and mitochondrial electron transport has been studied in soybean (Glycine max) leaves, using the oxygen-isotope-fractionation technique. Treatments with three levels of water stress were applied by irrigation to replace 100%, 50%, and 0% of daily water use by transpiration. The levels of water stress were characterized in terms of light-saturated stomatal conductance (g(s)): well irrigated (g(s) > 0.2 mol H(2)O m(-2) s(-1)), mildly water stressed (g(s) between 0.1 and 0.2 mol H(2)O m(-2) s(-1)), and severely water stressed (g(s) < 0.1 mol H(2)O m(-2) s(-1)). Although net photosynthesis decreased by 40% and 70% under mild and severe water stress, respectively, the total respiratory oxygen uptake (V(t)) was not significantly different at any water-stress level. However, severe water stress caused a significant shift of electrons from the cytochrome to the alternative pathway. The electron partitioning through the alternative pathway increased from 10% to 12% under well-watered or mild water-stress conditions to near 40% under severe water stress. Consequently, the calculated rate of mitochondrial ATP synthesis decreased by 32% under severe water stress. Unlike many other stresses, water stress did not affect the levels of mitochondrial alternative oxidase protein. This suggests a biochemical regulation (other than protein synthesis) that causes this mitochondrial electron shift.
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From screening 8 ornamental plants, it was found that Dracaena sanderiana had the highest benzene removal efficiency. In a long-term study, 4 cycles of benzene were studied under both 24 h dark and 24 h light conditions. From the 2nd to 4th cycle, benzene uptake by plants under 24 h light condition had higher intensity than under 24 h dark conditions, and the close of D. sanderiana stomata was found only in 24 h dark condition. At the final cycle, D. sanderiana still survived, and benzene uptake continued. From the calculation, 46% of benzene was taken up by D. sanderiana crude wax, while 54% was predicted to be taken up by the stomata by 72 h.
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Three factors influencing foliar uptake of monocyclic aromatic hydrocarbons (MAHs; benzene, toluene, ethylbenzene, xylenes) in situ were investigated. The first factor, the plant species, was found to determine absorption pattern and concentrations. Secondly, time variation studies showed that response of leaf concentrations to small changes in air concentrations only occurs after several days or weeks, whereas adaptation to a much higher level of air pollution takes several months. Thirdly, MAH leaf concentrations were observed to be dependent on mean air pollution at the sampling site. Bioconcentration factors BCFvs (g m−3 of wet leaf/g m−3 of air) for MAHs in Pseudotsuga menziesii (Mirb.) Franco leaves were determined to range from 2.7 × 104 to 4.7 × 105.
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Photosystem II plays an especially important role in the response of photosynthesis in higher plants to environmental perturbations and stresses. The relationship between photosystem II and photosynthetic CO2 assimilation is examined and factors identified that may modulate photosystem II activity in vivo. Particular attention is given to non-photochemical quenching of excitation energy, photoinhibition, state transitions, protein phosphorylation and biogenesis of photosystem II.
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An experimental method is described to measure foliar uptake and translocation of volatile organic compounds in plants. A flow-through exposure chamber was designed to determine phytoxicity of volatile organic compounds; an air-tight chamber was used for exposure of whole plants to radiolabeled test compound. 14C-toluene uptake by soybean (Glycine max) foliage was measured as an example of the experimental approach. Leaf tissue concentrations of 14C-toluene were measured over a 55.5-hr exposure period during light and dark periods. Photosynthetic rate was not affected by chronic atmospheric exposure to 27 μmole cm−3 hr toluene. During a 55.5-hr exposure to 7.2 μmoles cm−3 hr 14C-toluene (1.94 Bq cm−3), deposition velocities were greatest in the light phases and showed a marked decrease during the dark phases of exposure, suggesting that stomatal uptake as well as surface deposition contributed to toluene uptake. 14C was translocated from foliage to the roots. These data indicate that deposition of volatile organic compounds to vegetation may constitute a mechanism leading to herbivore exposure to volatile hazardous organics at waste sites. The experimental method described can be used to measure foliar uptake and translocation of volatile organic compounds to whole plants under laboratory conditions.
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Phytoremediation—using plants to remove toxins—is an attractive and cost effective way to improve indoor air quality. This study screened ornamental plants for their ability to remove volatile organic compounds from air by fumigating 73 plant species with 150 ppb benzene, an important indoor air pollutant that poses a risk to human health. The 10 species found to be most effective at removing benzene from air were fumigated for two more days (8 h per day) to quantify their benzene removal capacity. Crassula portulacea, Hydrangea macrophylla, Cymbidium Golden Elf., Ficus microcarpa var. fuyuensis, Dendranthema morifolium, Citrus medica var. sarcodactylis, Dieffenbachia amoena cv. Tropic Snow; Spathiphyllum Supreme; Nephrolepis exaltata cv. Bostoniensis; Dracaena deremensis cv. Variegata emerged as the species with the greatest capacity to remove benzene from indoor air.
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A simple model is proposed to account for observed emissions of volatile organic compounds (VOCs) from new carpets. The model assumes that the VOCs originate predominantly in a uniform slab of polymer backing material. Parameters for the model (the initial concentration of a VOC in the polymer, a diffusion coefficient and an equilibrium polymer/air partition coefficient) are obtained from experimental data produced by a previous chamber study. The diffusion coefficients generally decrease as the molecular weight of the VOCs increase, while the partition coefficients generally increase as the vapor pressure of the compounds decreases. In addition, for two of the study carpets that have a styrene-butadiene rubber (SBR) backing, the diffusion and partition coefficients are similar to independently reported values for SBR. The results suggest that prediction of VOC emissions from new carpets may be possible based solely on a knowledge of the physical properties of the relevant compounds and the carpet backing material. However, a more rigorous validation of the model is desirable.
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An experimental method for the determination of the internal diffusion coefficient (D) and partition coefficient (ke) of volatile organic compounds (VOCs) is developed for dry building materials (such as carpet, vinyl flooring, plywood, etc.). The method is used to determine D and ke for four VOCs (toluene, nonane, decane, and undecane ) through the backing material of a carpet specimen, for four VOCs (ethylbenzene, nonane, decane, and undecane) through a floor tile specimen, and three VOCs (cyclohexene, ethylbenzene, and decane) through a plywood specimen. It was found that the values of diffusion coefficients for a given material are inversely proportional to the molecular weights of the VOCs, whereas the value of the partition coefficients are proportional to the vapour pressures of the VOCs. The measured diffusion and partition coefficients are useful for predicting the emission rates of VOCs from building materials.
Article
BTEX is the commonly used term for a group of toxic compounds (benzene, toluene, ethyl benzene, ortho-xylene and meta- and para-xylene), some of which, most notably benzene, are known carcinogens. The aim of this study is to measure the BTEX levels both inside and outside the homes of 352 one-year old children from the Valencia cohort of the INMA study (Spain) and to analyze the determinants of these levels. Passive samplers were used to measure BTEX levels during a 15day period and a questionnaire was administered to gather information on potentially associated factors (sociodemographics, residential conditions, and lifestyle). The average concentrations of benzene, toluene, ethyl benzene, ortho-xylene, and meta- and para-xylene were 0.9, 3.6, 0.6, 0.6, and 1.0μg/m(3), respectively. On average, the indoor levels of all the compounds were approximately 2.5 times higher than those observed outdoors. Factors associated with higher BTEX concentrations inside the home were being the child of a mother of non-Spanish origin, living in a house that had been painted within the last year, living in an apartment, and not having air conditioning. Higher outdoor concentrations of BTEX depend on the residence being situated in a more urban zone, being located within the city limits, having living in a building with more than one story, residing in an area with a greater frequency of traffic, and the season of the year in which the sample was taken. The data thus obtained provide helpful information not only for implementing measures to reduce exposure to these pollutants, but also for evaluating the relation between such exposure and possible health risks for the children in the cohort.
Article
Recent discoveries in the phytoremediation of volatile organic compounds (VOCs) show that vapor-phase transport into roots leads to VOC removal from the vadose zone and diffusion and volatilization out of plants is an important fate following uptake. Volatilization to the atmosphere constitutes one fundamental terminal fate processes for VOCs that have been translocated from contaminated soil or groundwater, and diffusion constitutes the mass transfer mechanism to the plant-atmosphere interface. Therefore, VOC diffusion through woody plant tissues, that is, xylem, has a direct impact on contaminant fate in numerous vegetation-VOC interactions, including the phytoremediation of soil vapors and dissolved aqueous-phase contaminants. The diffusion of VOCs through freshly excised tree tissue was directly measured for common groundwater contaminants, chlorinated compounds such as trichloroethylene, perchloroethene, and tetrachloroethane and aromatic hydrocarbons such as benzene, toluene, and methyl tert-butyl ether. All compounds tested are currently being treated at full scale with tree-based phytoremediation. Diffusivities were determined by modeling the diffusive transport data with a one-dimensional diffusive flux model, developed to mimic the experimental arrangement. Wood-water partition coefficients were also determined as needed for the model application. Diffusivities in xylem tissues were found to be inversely related to molecular weight, and values determined herein were compared to previous modeling on the basis of a tortuous diffusion path in woody tissues. The comparison validates the predictive model for the first time and allows prediction for other compounds on the basis of chemical molecular weight and specific plant properties such as water, lignin, and gas contents. This research provides new insight into phytoremediation efforts and into potential fruit contamination for fruit-bearing trees, specifically establishing diffusion rates from the transpiration stream and modeling volatilization along the transpiration path, including the trunk and branches. This work also has importance in other plant-VOC interactions, such as potential uptake from the atmosphere for hydrophobic compounds and also uptake from vapor-phase soil contaminants.
Article
There is nowadays no single fully satisfactory method for VOC removal from indoor air due to the difficulties linked to the very low concentration (microg m(-3) range), diversity, and variability at which VOCs are typically found in the indoor environment. Although biological methods have shown a certain potential for this purpose, the specific characteristic of indoor air and the indoor air environment brings numerous challenges. In particular, new methods must be developed to inoculate, express, and maintain a suitable and diverse catabolic ability under conditions of trace substrate concentration which might not sustain microbial growth. In addition, the biological treatment of indoor air must be able to purify large amounts of air in confined environments with minimal nuisances and release of microorganisms. This requires technical innovations, the development of specific testing protocols and a deep understanding of microbial activities and the mechanisms of substrate uptake at trace concentrations.
Article
During the transition from a centrally planned economy to a market economy, many countries seem to have experienced some degree of macroeconomic instability. This paper attempts to provide a theoretical explanation of this phenomenon. The paper develops a simple monetary model and shows how macroeconomic stability can be achieved in a rigid centrally planned economy, despite the inherent structural imbalances and irrational price system. On the other hand, the study shows that without hardening enterprise budget constraints, wage and price decontrol tends to destablize the economy and may lead to persistent budget deficits and inflation. The paper also provides a rigorous analysis of household savings and money demand in a shortage economy, and clarifies the somewhat confusing concept of "monetary overhang" in the literature.
How to grow fresh air
  • B C Wolverton
Wolverton B.C. (1996). How to grow fresh air. New York: Penguin Book.
Some application of chlorophyll fluorescence kinetics to plant stress physiology, phytoecology and agricultural modernization
  • S Q Lin
  • C H Xu
  • Q D Zhang
  • L Xu
  • D Z Mao
  • T Y Kuang
  • SQ Lin
Lin, S. Q., Xu, C. H., Zhang, Q. D., Xu, L., Mao, D. Z., & Kuang, T. Y. (1992). Some application of chlorophyll fluorescence kinetics to plant stress physiology, phytoecology and agricul-tural modernization. Chinese Bulletin of Botany, 9, 1–16.
Gaseous deposition of 14C-toluene to soybean (Glycine max) foliage
  • M S Jen
  • M A Hoylman
  • T N Edwards
  • T B Walton
  • MS Jen