Abstract:Wastewater generation and treatment is an ever-increasing concern in the current century due to increased urbanization and industrialization. To tackle the situation of increasing environmental hazards, numerous wastewater treatment approaches are used—i.e., physical, chemical, and biological (primary to tertiary treatment) methods. Various treatment techniques being used have the risks of producing secondary pollutants. The most promising technique is the use of different materials as adsorbents that have a h… Show more
“…The scarcity of irrigation water compels farmers to use untreated wastewater and industrial effluents for crop production particularly in developing countries [7,51]. While it is known that wastewater increases crop production due to dissolved nutrients and beneficial impacts on soil properties, it is also a source of heavy metals in soils and growing crops [9,52]. Heavy metals are potentially toxic for plants, animals, and human beings due to their non-biodegradable nature [53][54][55].…”
Untreated wastewater used for irrigating crops is the major source of toxic heavy metals and other pollutants in soils. These heavy metals affect plant growth and deteriorate the quality of edible parts of growing plants. Phytohormone (IAA) and exopolysaccharides (EPS) producing plant growth-promoting rhizobacteria can reduce the toxicity of metals by stabilizing them in soil. The present experiment was conducted to evaluate the IAA and EPS-producing rhizobacterial strains for improving growth, physiology, and antioxidant activity of Brassica juncea (L.) under Cd-stress. Results showed that Cd-stress significantly decreased the growth and physiological parameters of mustard plants. Inoculation with Cd-tolerant, IAA and EPS-producing rhizobacterial strains, however, significantly retrieved the inhibitory effects of Cd-stress on mustard growth, and physiology by up regulating antioxidant enzyme activities. Higher Cd accumulation and proline content was observed in the roots and shoot tissues upon Cd-stress in mustard plants while reduced proline and Cd accumulation was recorded upon rhizobacterial strains inoculation. Maximum decrease in proline contents (12.4%) and Cd concentration in root (26.9%) and shoot (29%) in comparison to control plants was observed due to inoculation with Bacillus safensis strain FN13. The activity of antioxidant enzymes was increased due to Cd-stress; however, the inoculation with Cd-tolerant, IAA-producing rhizobacterial strains showed a non-significant impact in the case of the activity of superoxide dismutase (SOD), peroxidase (POX) and catalase (CAT) in Brassica juncea (L.) plants under Cd-stress. Overall, Bacillus safensis strain FN13 was the most effective strain in improving the Brassica juncea (L.) growth and physiology under Cd-stress. It can be concluded, as the strain FN13 is a potential phytostabilizing biofertilizer for heavy metal contaminated soils, that it can be recommended to induce Cd-stress tolerance in crop plants.
“…The scarcity of irrigation water compels farmers to use untreated wastewater and industrial effluents for crop production particularly in developing countries [7,51]. While it is known that wastewater increases crop production due to dissolved nutrients and beneficial impacts on soil properties, it is also a source of heavy metals in soils and growing crops [9,52]. Heavy metals are potentially toxic for plants, animals, and human beings due to their non-biodegradable nature [53][54][55].…”
Untreated wastewater used for irrigating crops is the major source of toxic heavy metals and other pollutants in soils. These heavy metals affect plant growth and deteriorate the quality of edible parts of growing plants. Phytohormone (IAA) and exopolysaccharides (EPS) producing plant growth-promoting rhizobacteria can reduce the toxicity of metals by stabilizing them in soil. The present experiment was conducted to evaluate the IAA and EPS-producing rhizobacterial strains for improving growth, physiology, and antioxidant activity of Brassica juncea (L.) under Cd-stress. Results showed that Cd-stress significantly decreased the growth and physiological parameters of mustard plants. Inoculation with Cd-tolerant, IAA and EPS-producing rhizobacterial strains, however, significantly retrieved the inhibitory effects of Cd-stress on mustard growth, and physiology by up regulating antioxidant enzyme activities. Higher Cd accumulation and proline content was observed in the roots and shoot tissues upon Cd-stress in mustard plants while reduced proline and Cd accumulation was recorded upon rhizobacterial strains inoculation. Maximum decrease in proline contents (12.4%) and Cd concentration in root (26.9%) and shoot (29%) in comparison to control plants was observed due to inoculation with Bacillus safensis strain FN13. The activity of antioxidant enzymes was increased due to Cd-stress; however, the inoculation with Cd-tolerant, IAA-producing rhizobacterial strains showed a non-significant impact in the case of the activity of superoxide dismutase (SOD), peroxidase (POX) and catalase (CAT) in Brassica juncea (L.) plants under Cd-stress. Overall, Bacillus safensis strain FN13 was the most effective strain in improving the Brassica juncea (L.) growth and physiology under Cd-stress. It can be concluded, as the strain FN13 is a potential phytostabilizing biofertilizer for heavy metal contaminated soils, that it can be recommended to induce Cd-stress tolerance in crop plants.
“…Lignin and cellulose have as primary components –OH and –COOH functional groups that can substitute the H + with As(III), Cd(II), Cr(IV), Hg(II), Pb(II), and Ni(II) as metalloids and metal ions in order to generate complexes, as it was tested for grape and apple wastes, grounds from tea and coffee, nutshells, leaves, algae, rice, and sunflower plants [ 41 ]. In order to enhance the adsorption capacity and reinforce the functional groups potential of these agricultural waste-derived adsorbents, their structure can be modified by different physical and chemical pre-treatments, obtaining carbonaceous materials (biochar), with high surface area and pore volume [ 42 , 43 ].…”
Section: Agri-food Waste Quantificationmentioning
confidence: 99%
“…According to Younas et al, there is a real challenge regarding the treatment methods of wastewaters in correlation with the pollutant sources [ 41 ]. The authors identified two main sources, natural and derived from anthropogenic activities, emphasizing the generation sources for those pollutants that seriously affect the environment and health.…”
Section: Types Of Pollutantsmentioning
confidence: 99%
“…Most research was developed in adsorption capacities and mechanisms with low interest for regeneration studies. In the latest years, this aspect was developed in different studies whilst emphasizing the importance of regeneration and final use disposal of spent adsorbents as potentially dangerous wastes [ 41 ]. The regeneration of the adsorbents could be a valuable benefit, their high potential of reusability leading to cost, disposal, and natural resources reductions.…”
Section: Disadvantages-research Gapsmentioning
confidence: 99%
“…Regarding the evaluation of the adsorption process as a viable option for water treatment, two basic components have to be evaluated, namely efficiency (adsorption capacity) and adsorbent cost [ 41 ]. If agri-food wastes are used as adsorbents, usually, the efficiency is related to a commercial adsorbent (activated carbon).…”
The paper addresses environmental protection by valorizing an important agri-food waste category, namely fruit and vegetables with focusing on the main characteristics regarding consumption, waste quantities, and ways for valorizing these materials. Thus, vast research was undertaken in order to emphasize the main commodities and their potential application as adsorbents for organic and inorganic pollutants. The main methods or treatment techniques applied for the valorization of eco-materials as adsorbents were presented and the principal efficiency results were indicated. The advantages and disadvantages of using these eco-materials as adsorbents in wastewater treatment were revealed and future recommendations were established. According to the international statistics, the most purchased and consumed five commodities were studied regarding waste generations as potential conversion into eco-materials with an adsorbent role for water pollutants. Thus, the performances for adsorbents based on fruit wastes (such as citrus, banana, apples, grapes, mango) and vegetable wastes (such as potatoes, tomatoes, cabbage, carrots, cauliflower, and/or broccoli) were studied and highlighted in this research.
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