Microbial responses to combined oxidation and catalysis treatment of 1,4-dioxane and co-contaminants in groundwater and soil

Post-treatment impacts of a novel combined hydrogen peroxide (H₂O₂) oxidation and WO_x/ZrO₂ catalysis used for the removal of 1,4-dioxane and chlorinated volatile organic compound (CVOC) contaminants were investigated in soil and groundwater microbial community. This treatment train removed ~90% 1,4-dioxane regardless of initial concentrations of 1,4-dioxane and CVOCs. The Illumina Miseq platform and bioinformatics were used to study the changes to microbial community structure. This approach determined that dynamic shifts of microbiomes were associated with conditions specific to treatments as well as 1,4-dioxane and CVOCs mixtures. The biodiversity was observed to decrease only after oxidation under conditions that included high levels of 1,4-dioxane and CVOCs, but increased when 1,4-dioxane was present without CVOCs. WO_x/ZrO₂ catalysis reduced biodiversity across all conditions. Taxonomic classification demonstrated oxidative tolerance for members of the genera Massilia and Rhodococcus, while catalyst tolerance was observed for members of the genera Sphingomonas and Devosia. Linear discriminant analysis effect size was a useful statistical tool to highlight representative microbes, while the multidimensional analysis elucidated the separation of microbiomes under the low 1,4-dioxane-only condition from all other conditions containing CVOCs, as well as the differences of microbial population among original, post-oxidation, and post-catalysis states. The results of this study enhance our understanding of microbial community responses to a promising chemical treatment train, and the metagenomic analysis will help practitioners predict the microbial community status during the post-treatment period, which may have consequences for long-term management strategies that include additional biodegradation treatment or natural attenuation.

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Multi-metal resistance and plant growth promotion potential of a wastewater bacterium Pseudomonas aeruginosa and its synergistic benefits

Water and soil pollution by toxic heavy metals (HMs) is increasing globally because of increase in population, industrialization and urbanization. It is a burning problem for the public, scientists, academicians and politicians how to tackle the toxic contaminants which jeopardize the environment. One possible solution for pollution abatement is a bioremediation-effective and innovative technology that uses biological systems for treatment of contaminants. Many bacteria synthesize indole-3-acetic acid (IAA) which is a product of l-tryptophan metabolism and belongs to the auxin class of plant growth-promoting hormone. The present study aimed at assessing the resistance pattern of wastewater bacteria against multiple HMs and plant growth promotion activity associated with IAA. A Gram-negative bacterial strain Pseudomonas aeruginosa KUJM was isolated from Kalyani Sewage Treatment Plant. This strain showed the potential to tolerate multiple contaminations such as As(III) (50 mM), As(V) (800 mM), Cd (8 mM), Co (18 mM), Cu (7 mM), Cr (2.5 mM), Ni (3 mM) and Zn (14 mM). The capability of IAA production at different tryptophan concentration (1, 2, 5 and 10 mg mL⁻¹) was determined, and seed germination-enhancing potential was also estimated on lentil (Lens culinaris). Such type of HM-resistant, IAA-producing and seed germination-enhancing P. aeruginosa KUJM offer great promise as inoculants to promote plant growth in the presence of toxic HMs, as well as plant inoculant systems useful for phytoremediation of polluted soils. Hence, P. aeruginosa KUJM finds significant applications in HM-contaminated poor agricultural field as well as in bioremediation of HM-contaminated wastewater system.

     

Potentiality of different isolates of wilt fungus Fusarium oxysporum collected from rhizosphere of tomato against root-knot nematode Meloidogyne incognita

This investigation was undertaken to determine the effect of culture filtrates of different isolates of Fusarium oxysporum f. sp. lycopersici on mortality of Meloidogyne incognita juveniles and egg hatching. It was observed that different concentrations including standard extract (S.E), 1:10 and 1:100 dilutions of all fungal filtrates inhibited egg hatch when compared with control. Minimum mortality and maximum hatching was observed in BRT (showing least mortality) isolate of F. oxysporum, while maximum mortality and minimum egg hatching was recorded in BGT (showing maximum mortality) isolate. Larval mortality was decreased with a decrease in concentration and the least mortality was observed in 1:100 when compared with SE and 1:10. The potentiality of both the isolates (BRT and BGT) against root-knot nematode M. incognita was confirmed by the pathogenicity test on tomato. These observations confirmed that F. oxysporumisolates possesses variability in pathogenicity ranging from pathogenic to bio-control agent. The plants inoculated with BRT isolate failed to show wilt symptoms while plants inoculated with BGT isolate showed wilt indices.     

Combustion,performance, and emission characteristics of diesel engine using oxyhydrogen gas as a fuel additive

Environmental Science and Pollution Research - A lot of research is being carried out to reduce the environmental pollution resulting from compression ignition engines. For this, various gaseous...     

Geospatial strategy for sustainable management of municipal solid waste for growing urban environment

This paper presents the implementation of a Geospatial approach for improving the Municipal Solid Waste (MSW) disposal suitability site assessment in growing urban environment. The increasing trend of population growth and the absolute amounts of waste disposed of worldwide have increased substantially reflecting changes in consumption patterns, consequently worldwide. MSW is now a bigger problem than ever. Despite an increase in alternative techniques for disposing of waste, land-filling remains the primary means. In this context, the pressures and requirements placed on decision makers dealing with land-filling by government and society have increased, as they now have to make decisions taking into considerations environmental safety and economic practicality. The waste disposed by the municipal corporation in the Bhagalpur City (India) is thought to be different from the landfill waste where clearly scientific criterion for locating suitable disposal sites does not seem to exist. The location of disposal sites of Bhagalpur City represents the unconsciousness about the environmental and public health hazards arising from disposing of waste in improper location. Concerning about urban environment and health aspects of people, a good method of waste management and appropriate technologies needed for urban area of Bhagalpur city to improve this trend using Multi Criteria Geographical Information System and Remote Sensing for selection of suitable disposal sites. The purpose of GIS was to perform process to part restricted to highly suitable land followed by using chosen criteria. GIS modeling with overlay operation has been used to find the suitability site for MSW.     

Chitosan-based beads as sustainable adsorbents for wastewater remediation: a review

Environmental Chemistry Letters - Water contamination is increasing worldwide, yet actual methods of water and wastewater treatment are limited, in particular by actual fossil-fuel derived...     

Conceptions of vulnerability in adaptation projects: a critical examination of the role of development aid agencies in Timor-Leste

It is widely acknowledged that Small Island Developing States (SIDS) are particularly vulnerable to climate change and will continue to require external support to adapt to current and future impacts. The international development community plays an important role in supporting SIDS adapt to climatic changes, and calls for increased international commitment have been made. However, how the vulnerability of SIDS to climate change is being conceptualised and, subsequently, how adaptation programmes are conceived and designed by the international development community are yet to be critically explored. Using Timor-Leste as a case study, this study examines the conceptual trends underpinning 32 donor-led adaptation programmes implemented from 2010 to the present date. Results show that donor-led adaptation programmes continue to conceptualise climate change vulnerability as a biophysical issue rather than a consequence of the dynamic interactions between political, institutional, economic and social structures. Adaptation policy responses therefore have limited ability to target more nuanced and broader-scale structures affecting SIDS and may be falling short in their efforts to reduce the vulnerability of SIDS. We argue that it is critical that the international development community re-conceptualise its approach to vulnerability reduction in SIDS. We conclude by highlighting how the Paris Agreement, with its expanding understanding of vulnerability, can act as a useful instrument to promote such changes.     

Identification of hot spots and well managed areas of Pichavaram mangrove using Landsat TM and Resourcesat—1 LISS IV: an example of coastal resource conservation along Tamil Nadu Coast, India

The present work is a multi-temporal satellite based study on the spatial dynamic of an important coastal habitat, the Pichavaram mangrove ecosystem, over a period of 15 years. The Pichavaram mangrove forest near Chidambaram, South India is the second largest mangrove forest in the world. Unsupervised classification, the Iterative Self Organising Data Analysis Technique (ISODATA), has been used to classify the mangrove cover into the open and dense classes. The status of the classes has been monitored using Landsat TM of 1991, 2001, and Resourcesat–1 LISS IV of 2006 satellite data. The study demonstrated that by classifying mangrove ecosystem into just the 3 classes using remote sensing data and by studying their temporal variations, it is possible to get a reasonably accurate picture of the extent and condition of the mangrove ecosystem. The total area of the Pichavaram mangrove showed a net increase of 2.51 km² within a span of 15 years (1991 to 2006). The hot spots that are at a risk of being degraded, and on the other hand, the mangrove areas that are well managed are identified using Geographical Information System (GIS) tools for the restoration and conservation measures.     

Mutagenicity evaluation of industrial sludge from common effluent treatment plant

Sludge from common effluent treatment plant (CETP) receiving effluents from textile industries at Mandia Road, Pali, was analyzed to assess the level of mutagenicity. Mutagenicity assay using Salmonella typhimurium tester strains TA 98 and TA 100 gave positive results, thus suggesting presence of genotoxic contaminants in the samples investigated. Further, mutagenic activity of chemical sludge was found to be lesser than that of biological sludge. This result is very surprising and unexpected as it is indicating that some mutagenic compounds are either being formed or certain promutagenic compounds are being converted into stable mutagenic metabolites during the biological treatment of the wastewater effluents. There have been no previous reports giving similar or contrary results. Most of the previous studies have reported effects of single combined sludge.     

Enhanced antimicrobial activity of the food-protecting nisin peptide by bioconjugation with silver nanoparticles

Nisin is an antimicrobial peptide widely used in the food industry. The efficacy of nisin has decreased due to the development of resistant bacteria. For instance, bacteria such as Staphylococcus aureus have resistance by digesting nisin using the nisinase enzyme. The efficacy of nisin could be improved using bioconjugation with metal nanoparticles. Here we synthesized silver nanoparticles using the extract of Cymbopogon citratus; then, we bioconjugated those silver nanoparticles with nisin to form a nanosilver bioconjugate. Silver nanoparticles and silver bioconjugate were characterized by UV–Vis spectroscopy, nanoparticle tracking analysis, zeta potential measurement and transmission electron microscopy. In vitro antimicrobial efficacy of both silver nanoparticles and silver bioconjugate was evaluated against selected food spoilage microorganisms such as Listeria monocytogenes, S. aureus, Pseudomonas fluorescens, Aspergillus niger and Fusarium moniliforme. Results show that the antimicrobial potential of nisin increased after bioconjugation with silver nanoparticles. Further, we developed agar film containing nanosilver bioconjugate and also evaluated its antimicrobial activity against selected food spoilage microorganisms. The agar film demonstrated maximum activity against P. fluorescens, of 19 mm, and the minimum against F. moniliforme, of 12 mm. Overall, agar film containing nisin and silver nanoparticles can be used against food spoilage microorganisms.