Phytoremediation Potential of Freshwater Macrophytes for Treating Dye-Containing Wastewater

Fertilization as the most critical factor affecting yield response and agronomic efficiency of phosphorus in Chinese rice production: evidence from multi-location field trials

BACKGROUND

Efficient utilization of phosphorus (P) has been a major challenge for sustainable agriculture. However, the responses of fertilizer rate, region, soil properties, cropping systems and genotypes to P have not been investigated comprehensively and systematically.

RESULTS

A comprehensive analysis of 9863 fertilizer-P experiments on rice cultivation in China showed that rice yield  increased first and then fell down with the addition of P fertilizer, and the highest yield of 7963 kg ha-1 was observed under 100% P treatment. Under 100% P treatment, the yield response of applied P (YRP ) and agronomic efficiency of applied P (AEP ) were 12.8% and 30.1 kg ha-1 , respectively. Lower soil pH (< 5.5) and organic matter (< 30.0 g kg-1 ) were associated with lower YRP and AEP . By contrast, soil available P < 25.0 mg kg-1 resulted in decreased YRP (15.3 to 11.4%) and AEP (32.3 kg kg-1 to 26.2 kg kg-1 ), whereas soil available P > 25.0 mg kg-1 maintained the relatively stable YRP and AEP . Also, the YRP and AEP were significantly higher for single-cropping rice compared to other cropping systems. Moreover, the rice genotypes such as 'Longdun', 'Kendao' and 'Jigeng' had higher YRP and AEP than the average value. Overall, the fertilizer-P rate was the primary factor affecting YRP and AEP , and the recommended P fertilizer rate can be reduced by 9-21 kg P ha-1 compared to existing expert recommendations.

CONCLUSION

The present study highlights the role of fertilizer-P rate in maximizing the YRP and AEP , thereby providing a strong basis for future fertilizer management in rice cultivation systems. © 2023 Society of Chemical Industry.

A bibliometric analysis of green technologies applied to water and wastewater treatment

Freshwater scarcity, a problem that has arisen particularly as a result of the progressive environmental damage caused by human consumption patterns, is strongly associated with a loss of living quality and a drop in global socioeconomic development. Wastewater treatment is one of the measures being taken to mitigate the current situation. However, the majority of existing treatments employ chemicals that have harmful environmental consequences and low effectiveness and are prohibitively expensive in most countries. Therefore, to increase water supplies, more advanced and cost-effective water treatment technologies are required to be developed for desalination and water reuse purposes. Green technologies have been highlighted as a long-term strategy for conserving natural resources, reducing negative environmental repercussions, and boosting social and economic growth. Thus, a bibliometric technique was applied in this study to identifying prominent green technologies utilised in water and wastewater treatment by analysing scientific publications considering authors, keywords, and countries. To do this, the VOSviewer software and Bibliometrix R Package software were employed. The results of this study revealed that constructed wetlands and photocatalysis are two technologies that have been considered as green technologies applicable to the improvement of water and wastewater treatment processes in most scientific articles.

Application of Salvinia sps. in remediation of reactive mixed azo dyes and Cr (VI) - Its pathway elucidation

The emerging industrialization has resulted in the rapid growth of textile industries across the globe. The presence of xenobiotic pollutants in textile wastewater threatens the ecosystem. Applying different microbes (bacteria, fungi & algae) has paved the way for phytoremediation - the eco-friendly, cost-effective method. The present study focuses on the phytoremediation of reactive dyes - Reactive red, Reactive Brown & Reactive Black and Cr (VI) in synthetic textile wastewater using Salvinia sps. The mixed azo dyes of each 100 mg/L showed decolourization of 75 ± 0.5% and 82 ± 0.5% of removal of 20 mg/L of Cr (VI) after eight days of incubation in a phytoreactor setup. Chlorophyll analysis revealed the gradual decrease in the photosynthetic pigments during the remediation. The degraded metabolites were analyzed using FT-IR and showed the presence of aromatic amines on day zero, which were converted to aliphatic amines on day four. The GC-MS analysis revealed the disruption of -NN- bond, rupture of -CN- bond, scission of -N-N-bond, and loss of -SO₃H from the Reactive Black dye leading to the formation of an intermediate p-Hydroxy phenylhydrazinyl. The rupture of Reactive red dye resulted in the formation of p-Hydrazinyl toluene sulphonic acid, Naphthyl amine -3,6-disulphonic acid and 8-Hydroxy Naphthyl amine -3,6-disulphonic acid. Decarboxylation, desulphonation, deoxygenation and deamination of Reactive Brown dye showed the presence of different metabolites and metabolic pathways were proposed for the reactive azo dyes which were phytoremediated.

Photocatalytic Degradation of Organic Dyes Contaminated Aqueous Solution Using Binary CdTiO2 and Ternary NiCdTiO2 Nanocomposites

The synergistic effect of binary CdTiO2 and ternary NiCdTiO2 on the photocatalytic efficiency of TiO2 nanoparticles was investigated. The SEM analysis demonstrates spherical TiO2 NPs of different sizes present in agglomerated form. The structural analysis of the nanocomposites reveals a porous structure for TiO2 with well deposited Cd and Ni NPs. TEM images show NiCdTiO2 nanocomposites as highly crystalline particles having spherical and cubical geometry with an average particle size of 20 nm. The EDX and XRD analysis confirm the purity and anatase phase of TiO2, respectively. Physical features of NiCdTiO2 nanocomposite were determined via BET analysis which shows that the surface area, pore size and pore volume are 61.2 m2/g, 10.6 nm and 0.1 cm3/g, respectively. The absorbance wavelengths of the CdTiO2 and NiCdTiO2 nanocomposites have shown red shift as compared to the neat TiO2 due to coupling with Ni and Cd that results in the enhanced photocatalytic activity. The photocatalytic activity demonstrated that TiO2, CdTiO2 and NiCdTiO2 degrade methylene blue (MB) and methyl green (MG) about 76.59, 82, 86% and 63.5, 88, 97.5%, respectively, at optimum reaction conditions.

Microorganism-Templated Nanoarchitectonics of Hollow TiO2-SiO2 Microspheres with Enhanced Photocatalytic Activity for Degradation of Methyl Orange

In this study, hollow SiO₂ microspheres were synthesized by the hydrolysis of tetraethyl orthosilicate (TEOS) according to the Stober process, in which Pichia pastoris GS 115 cells were served as biological templates. The influence of the preprocessing method, the TEOS concentration, the ratio of water to ethanol, and the aging time on the morphology of microspheres was investigated and the optimal conditions were identified. Based on this, TiO₂-SiO₂ microspheres were prepared by the hydrothermal process. The structures and physicochemical properties of TiO₂-SiO₂ photocatalysts were systematically characterized and discussed. The photocatalytic activity for the degradation of methyl orange (MO) at room temperature under Xe arc lamp acting as simulated sunlight was explored. The result showed that the as-prepared TiO₂-SiO₂ microspheres exhibited a good photocatalytic performance.

A review on application of phytoremediation technique for eradication of synthetic dyes by using ornamental plants

Phytoremediation emerges as an innovative and eco-friendly technique to remediate textile dyes with the use of various categories of plants. In recent years, ornamental plants emerge as more attractive and effective substitute in comparison to edible plants for phytoremediation. Regardless of aesthetic value, some ornamental plants can be grown to remediate the sites contaminated with dyes, heavy metals, pesticides, or other organic compounds. In this review, we focus on pioneer research on synthetic dye removal using ornamental plants and evaluate the phytoremediation capability of ornamental plants for treatment of textile effluent. This paper also emphasized specific ornamental plants having high accumulation and tolerance ability for removal of dyes. The mechanisms explored for the phytoremediation of dyes by ornamental plants have also been explained. This review will also be helpful for researchers for exploring more new ornamental plants in phytoremediation technique.