Influence of bioaugmented fungi on tolerance, growth and phytoremediation ability of Prosopis juliflora Sw. DC in heavy metal-polluted landfill soil.

The research aimed to determine the influence of endophytic fungi on tolerance, growth and phytoremediation ability of Prosopis juliflora in heavy metal-polluted landfill soil. A consortium of 13 fungal isolates as well as Prosopis juliflora Sw. DC was used to decontaminate heavy metal-polluted landfill soil. Enhanced plant growth (biomass and root and shoot lengths) and production of carotenoids, chlorophyll and amino acids L-phenylalanine and L-leucine that are known to enhance growth were found in the treated P. juliflora. Better accumulations of heavy metals were observed in fungi-treated P. juliflora over the untreated one. An upregulated activity of peroxidase, catalase and ascorbate peroxidase was recorded in fungi-treated P. juliflora. Additionally, other metabolites, such as glutathione, 3,5,7,2',5'-pentahydroxyflavone, 5,2'-dihydroxyflavone and 5,7,2',3'-tetrahydroxyflavone, and small peptides, which include Lys Gln Ile, Ser Arg Ala, Asp Arg Gly, Arg Ser Ser, His His Arg, Arg Thr Glu, Thr Arg Asp and Ser Pro Arg, were also detected. These provide defence supports to P. juliflora against toxic metals. Inoculating the plant with the fungi improved its growth, metal accumulation as well as tolerance against heavy metal toxicity. Such a combination can be used as an effective strategy for the bioremediation of metal-polluted soil.

Phytoremediation of leachate contaminated soil: a biotechnical option for the bioreduction of heavy metals induced pollution in tropical landfill.

Metal remediation is important considering the environmental pressure due to soil pollution from landfill leachate. Hence, identifying potential plant-based option for remediation, especially the use of bio-/hyper-accumulators, is inevitable. Contamination of soil with heavy metals has been a decades-long concern. This study is therefore aimed to evaluating the metal-remediation potentials of four ornamental plant species-Cordyline fruticosa, Duranta variegated, Tradescantia spathacea, and Chlorophylum comosum-on leachate-contaminated soil. Details of the study involved leachate analysis, soil characterization, and metal-accumulation test on selected plants. Characterization of both landfill soil and leachate has indicated that Pb, Cu, As, Mn, Cr, Zn, Fe, and Ni were higher than the prescribed limits. The high metal reduction efficiency of C. fruticosa on all the studied metals was about 63%, 85%, 77.88%, 77.55%, and 75% for Pb, As, Mn, Zn, and Cr concentrations. The metal removal by the plants was significantly higher as compared to control soil (P < 0.05). The highest removal rate constant witnessed was for Mn (0.023 day-1) and was achieved using C. fruticosa. The results have revealed that C. fruticosa was the most promising plant for the removal of the studied metals. Therefore, it can be concluded that C. fruticosa has potentials to remediate heavy metal-contaminated soil at significant level. The findings will develop investigation into plant-tissue and compartmentalization effect on metal remediation using C. fruticosa.

Microplastics pollution in salt pans from the Maheshkhali Channel, Bangladesh.

Microplastics (MP) were recognized as an emergent pollution problem due to their ubiquitous nature and bioaccumulative potential. Those present in salt for consumption could represent a human exposure route through dietary uptake. The current study, conducted in Bangladesh, reports microplastics contamination in coarse salt prepared for human consumption. Sea salt samples were collected from eight representative salt pans located in the country's largest salt farming area, in the Maheshkhali Channel, along the Bay of Bengal. Microplastics were detected in all samples, with mean concentrations ranging from 78 ± 9.33 to 137 ± 21.70 particles kg-1, mostly white and ranging in size from 500-1000 µm. The prevalent types were: fragments (48%) > films (22%) > fibers (15%) > granules and lines (both 9%). Fourier transform mid-IR and near-IR spectra (FT-MIR-NIR) analysis registered terephthalate (48%), polypropylene (20%), polyethylene (17%), and polystyrene (15%) in all samples. These results contribute to the MP's pollution knowledge in sea salts to understand and reduce this significant human exposure route and environmental pollution source in the future.

Microplastic pollution in wild commercial nekton from the South China Sea and Indian Ocean, and its implication to human health.

Marine biota, especially commercially important species, serves as a basis for human nutrition. However, millions of tons of plastic litter are produced and enter the marine environment every year, with potential adverse impacts on marine organisms. In the present study, we investigated the occurrence and characteristics of microplastic (MP) pollution in the digestive tracts of 13 species of wild nektons from 20 stations sampled in the South China Sea (SCS) and the Indian Ocean (IO), and assessed the human health risks of MPs. The detection rate of MPs ranged from 0.00% to 50.00% from the SCS, which was dramatically lower than that from the IO (10.00-80.00%). The average abundance of MP was 0.18 ± 0.06 items g wet weight-1 (ww-1) in the SCS, which was significantly lower than that in the IO with a concentration of 0.70 ± 0.16 items g ww-1. Most MPs were fibers in type, black in color, and polyester (PES) in polymer composition in both the SCS and IO. Interestingly, distinct profiles of MP pollution were found between the benthic and pelagic nektons: 1) The predominant MP composition was PES in the benthic nektons, whereas polyamide (PA) accounted for a larger part of the total MP count in the pelagic nektons within the SCS; 2) The abundance of MP in the benthic nektons (0.52 ± 0.24 items individual-1) was higher than that in the pelagic nektons (0.30 ± 0.11 items individual-1). Accordingly, the mean hazard score of MPs detected in the benthic nektons (220.66 ± 210.75) was higher than that in the pelagic nektons (49.53 ± 22.87); 3) The mean size of the MP in the pelagic nektons (0.84 ± 0.17 mm) was larger than that in the benthic nektons (0.49 ± 0.09 mm). Our findings highlight the need to further investigate the ecological impacts of MPs on wild nekton, especially commercially important species, and its potential implications for human health.

Stabilized landfill leachate treatment by coagulation-flocculation coupled with UV-based sulfate radical oxidation process.

In this work, the feasibility of coagulation-flocculation coupled with UV-based sulfate radical oxidation process (UV/SRAOP) in the removal of chemical oxygen demand (COD) of stabilized landfill leachate (SLL) was evaluated. For coagulation-flocculation, ferric chloride (FeCl3) was used as the coagulant. The effect of initial pH of SLL and COD:FeCl3 ratio on the COD removal was evaluated. The result revealed that COD:FeCl3 ratio of 1:1.3 effectively removed 76.9% of COD at pH 6. The pre-treated SLL was then subjected to UV/SRAOP treatment. For UV/SRAOP, the sulfate radical (SR) was generated using UV-activated persulfate (UV/PS) and peroxymonosulfate (UV/PMS). The dosage of oxidant and reaction time were found to be the main parameters that influence the efficiency of COD removal. On the other hand, the effect of initial pH (3-7) and the type of oxidant (PS and PMS) was found to have no significant influence on COD removal efficiency. At optimum conditions, approximately 90.9 and 91.5% of COD was successfully removed by coagulation-flocculation coupled with UV/PS and UV/PMS system, respectively. Ecotoxicity study using zebrafish showed a reduction in toxicity of SLL from 10.1 to 1.74 toxicity unit (TU) after coagulation-flocculation. The TU remained unchanged after UV/PS treatment but slightly increased to 1.80 after UV/PMS treatment due to the presence of residual sulfate ion in the treated effluent. In general, it can be concluded that coagulation-flocculation coupled with UV/SRAOP could be a potential water treatment method for SLL treatment.

Removal of organic matter from stabilized landfill leachate using Coagulation-Flocculation-Fenton coupled with activated charcoal adsorption.

The treatment of stabilized landfill leachate (SLL) by conventional biological treatment is often inefficient due to the presence of bio-recalcitrant substances. In this study, the feasibility of coagulation-flocculation coupled with the Fenton reaction in the treatment of SLL was evaluated. The efficiency of the selected treatment methods was evaluated through total organic carbon (TOC) removal from SLL. With ferric chloride as the coagulant, coagulation-flocculation was found to achieve the highest TOC removal of 71% at pH 6. Then, the pretreated SLL was subjected to the Fenton reaction. Nearly 50% of TOC removal was achieved when the reaction was carried out at pH 3, H2O2:Fe2+ ratio of 20:1, H2O2 dosage of 240 mM and 1 h of reaction time. By coupling the coagulation-flocculation with the Fenton reaction, the removal of TOC, COD (chemical oxygen demand) and turbidity of SLL were 85%, 84% and 100%, respectively. The ecotoxicity study performed using zebrafish revealed that 96 h LC50 for raw SLL was 1.40% (v/v). After coagulation-flocculation, the LC50 of the pretreated SLL was increased to 25.44%. However, after the Fenton reaction, the LC50 of the treated SLL was found to decrease to 10.96% due to the presence of H2O2 residue. In this study, H2O2 residue was removed using powdered activated charcoal. This method increased the LC50 of treated effluent to 34.48% and the removal of TOC and COD was further increased to 90%. This finding demonstrated that the combination of the selected treatment methods can be an efficient treatment method for SLL.

Drivers of sustainable waste management in Asia.

Drivers of sustainable waste management are defined as groups of related factors that influence the development (or lack thereof) of industry. There has been no attempt to reasonably list the drivers that influence sustainable waste management in Asia. In this review, four groups of drivers of sustainable waste management, specifically of Asia, are explained. The four groups of drivers consist of three human elements (human, economic and institutional) and the environment as a single driving group. Typically, the first three groups have been very influential, with the environment driver, noticeably, only considered when preceded by other groups of drivers. The interconnectedness of the drivers and neglect of the environment driver is discussed. It is concluded that while the essence of the four groups of drivers can be found all over Asia, each driving group must be investigated in a local context and all information combined to devise sustainable waste management policies or strategies.