Bioremediation of tannery effluent by Cr- and salt-tolerant bacterial strains

Microorganisms have great potential to control environmental pollution, particularly industrial sources of water pollution. Currently, leather industry is regarded as the most polluting and suffering from negative impacts due to the pollution it adds to the environment. Chromium, one of the hazardous pollutants discharged from tanneries, is highly toxic and carcinogenic in nature. Effective treatment of tannery effluent is a dire need of the era as a part of environmental management. Among all the wastewater treatment technologies, bioremediation is the most effective and environment-friendly tool to manage the water pollution. The present study evaluated the potential of 11 previously isolated bacterial strains, tolerant to high concentrations of salts and Cr for the bioremediation of tannery effluent. Among all the tested strains, Enterobacter sp. HU38, Microbacterium arborescens HU33, and Pantoea stewartii ASI11 were found most effective in reducing biological oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids (TDS), total suspended solids (TSS), and chromium (Cr) 70, 63, 57, 87, and 54%, respectively, of tannery effluent and proliferated well under highly toxic conditions, at 9 days of incubation. The pollutant removal efficacy of these bacterial strains can be improved by extending the incubation period or by increasing the amount of inoculum.     

The influence of personality traits on sustainability-oriented entrepreneurial intentions: the moderating role of servant leadership

Environment, Development and Sustainability - Economic, environmental, and social imperatives make sustainability-oriented entrepreneurship an indispensable phenomenon of the day, yet only sparse...     

Frequency of PPAR-γ, FTO and ABCC8 genetic variation in Pakistani cardiovascular smokers

Environmental Science and Pollution Research - Smoking is considered as one of the major reasons behind genetic variations in cardiometabolic disorders. However, effect of nicotine via smoking on...     

Urban wild meat consumption and trade in central Amazonia

The switch from hunting wild meat for home consumption to supplying more lucrative city markets in Amazonia can adversely affect some game species. Despite this, information on the amounts of wild meat eaten in Amazonian cities is still limited. We estimated wild meat consumption rates in 5 cities in the State of Amazonas in Brazil through 1046 door-to-door household interviews conducted from 2004 to 2012. With these data, we modeled the relationship between wild meat use and a selection of socioeconomic indices. We then scaled up our model to determine the amounts of wild meat likely to be consumed annually in the 62 urban centers in central Amazonia. A total of 80.3% of all interviewees reported consuming wild meat during an average of 29.3 (CI 11.6) days per year. Most wild meat was reported as bought in local markets (80.1%) or hunted by a family member (14.9%). Twenty-one taxa were cited as consumed, mostly mammals (71.6%), followed by reptiles (23.2%) and then birds (5.2%). The declared frequency of wild meat consumption was positively correlated with the proportion of rural population as well as with the per capita gross domestic product of the municipality (administrative divisions) where the cities were seated. We estimated that as much as 10,691 t of wild meat might be consumed annually in the 62 urban centers within central Amazonia, the equivalent of 6.49 kg per person per year. In monetary terms, this amounts to US$21.72 per person per year or US$35.1 million overall, the latter figure is comparable to fish and timber production in the region. Given this magnitude of wild meat trade in central Amazonia, it is fundamental to integrate this activity into the formal economy and actively develop policies that allow the trade of more resilient taxa and restrict trade in species sensitive to hunting.     

Elevated exposure to polycyclic aromatic hydrocarbons (PAHs) may trigger cancers in Pakistan: an environmental,occupational, and genetic perspective

Environmental Science and Pollution Research - Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic compounds which are emitted through incomplete combustion of organic materials, fossil fuels,...     

Isolation of Cr(VI) reducing bacteria from industrial e uents and their potential use in bioremediation of chromium containing wastewater

The present study is aimed at assessing the ability of Bacillus sp.JDM-2-1 and Staphylococcus capitis to reduce hexavalent chromium into its trivalent form.Bacillus sp.JDM-2-1 could tolerate Cr(Ⅵ) (4800 μg/mL) and S.capitis could tolerate Cr(Ⅵ) (2800 μg/mL).Both organisms were able to resist Cd2+ (50 μg/mL),Cu2+ (200 μg/mL),Pb2+ (800 μg/mL),Hg2+ (50 μg/mL) and Ni2+ (4000 μg/mL).S.capitis resisted Zn2+ at 700 μg/mL while Bacillus sp.JDM-2-1 only showed resistance up to 50 μg/mL.Bacillus sp.JDM-2-1 and S.capitis showed optimum growth at pH 6 and 7,respectively,while both bacteria showed optimum growth at 37℃.Bacillus sp.JDM-2-1 and S.capitis could reduce 85% and 81% of hexavalent chromium from the medium after 96 h and were also capable of reducing hexavalent chromium 86% and 89%,respectively,from the industrial effluents after 144 h.Cell free extracts of Bacillus sp.JDM-2-1 and S.capitis showed reduction of 83% and 70% at concentration of 10 μg Cr(Ⅵ)/mL,respectively.The presence of an induced protein having molecular weight around 25 kDa in the presence of chromium points out a possible role of this protein in chromium reduction.The bacterial isolates can be exploited for bioremediation of hexavalent chromium containing wastes,since they seem to have the potential to reduce the toxic hexavalent form to its nontoxic trivalent form.     

Highly active photocatalytic coatings prepared by a low-temperature method

Photocatalytic properties of titanium (IV) oxide (TiO₂) in anatase form can be used for various purposes, including photocatalytic purification of water. For such an application, suspended or fixed photocatalytic reactors are used. Those with fixed phase seem to be preferred due to some advantages, one of which is the avoidance of photocatalyst filtration. To avoid leaching and exfoliation of the fixed phase, an immobilization procedure leading to a good adhesion of a catalyst to a substrate is crucial. Within this work, we present physical and photocatalytic characterization results of five commercially available TiO₂ photocatalysts (P25, P90, PC500, KRONOClean 7000, VPC-10) and one pigment (Hombitan LO-CR-S-M), which were successfully immobilized on glass slides by a “sol suspension” procedure. Different mechanical tests and characterization methods were used to evaluate the stability and morphology of the layers. Evaluation of photocatalytic activity was done by tests under UVA and UV–vis irradiation, using a method based on the detection of the fluorescent oxidation product of terephthalic acid (TPA), i.e., hydroxyterephthalic acid (HTPA). Aeroxide® P90 incorporated into the silica-titania binder was the most photocatalytically active layer and, unlike the others, showed significant increase of photocatalytic activity through the entire range of tested UVA irradiation intensities (2.3 mW/cm²–6.1 mW/cm²). The high mechanical stability of some photocatalytic layers allows using them in water photocatalytic purification reactions.     

Effect of biocides on the precipitation of calcium fluoride in the presence of anionic copolymeric inhibitors

The inhibitory efficiency of anionic copolymers and the effect of the biocides sodium hypochlorite, glutaraldehyde, and tris(hydroxymethyl)nitromethane on the precipitation behavior of calcium fluoride (CaF₂) were studied. The efficiency of polymeric inhibitors was traced from conductivity measurements by using half-life (t_1/2) method. X-ray diffraction parameters have been measured for calcium fluoride scale minerals. An anionic copolymer (K-798) acts as one of the best inhibitors for the precipitation process of the calcium fluoride in water as compared to K-775. It is assigned to the fact that the copolymer (K-798) contains both sulfonic acid and sulfonated styrene groups while the polymer (K-775) having only the sulfonic acid group. It was further observed that the biocides have no appreciable effect on the performance of the anionic polymeric inhibitors.     

Geochemical fractionation and spectroscopic fingerprinting for evaluation of the environmental transformation of potentially toxic metal(oid)s in surface–subsurface soils

Environmental Geochemistry and Health - The contamination of soil by toxic metal(oid)s has emerged as a major concern worldwide, particularly in developing countries. A metals behavior in the soil...