No abstract

The present paper puts forth the complete characterization of effluents produced at various leather processing stages of three selected tannery industries, and of composite effluents at three selected monitoring points (P 1 , P 2 and P 3 ) located at Hazaribagh leather industrial zone in Bangladesh. The analysis results show that the effluents possess extremely high values of TSS, EC, TDS, TS, BOD 5 and COD, and high concentrations of SO 4 2− , Na, Cl , BOD 5 , COD, Na, Cr, As, Cd and Pb in the collected composite tannery effluents, at all monitoring points, were also above the standard disposal limits. The pollutant levels observed at the three monitoring points were in the order P 1 >P 2 >P 3 indicating pollution level decreasing with distance. The study also revealed that the concentrations of various metal ions in the sludge were very high, and the concentrations of Cr and Na ions in particular were about 10,000 and 6000 mg/kg, respectively. The concentrations of chemicals in the sludge were in the order: Cr>Na>Ca>S>Mg>P>Cu>TN>Zn>Organic compound>Pb>As>Cd. So, it is concluded that the leather industrial effluent was highly polluted and not suitable for irrigation or any other uses.

Industrial effluent containing textile dyes is regarded as a major environmental concern in the present world. Crystal Violet is one of the vital textile dyes of the triphenylmethane group; it is widely used in textile industry and known for its mutagenic and mitotic poisoning nature. Bioremediation, especially through bacteria, is becoming an emerging and important sector in effluent treatment. This study aimed to isolate and identify Crystal Violet degrading bacteria from industrial effluents with potential use in bioremediation. The decolorizing activity of the bacteria was measured using a photo electric colorimeter after aerobic incubation in different time intervals of the isolates. Environmental parameters such as pH, temperature, initial dye concentration and inoculum size were optimized using mineral salt medium containing different concentration of Crystal Violet dye. Complete decolorizing efficiency was observed in a mineral salt medium containing up to 150 mg/l of Crystal Violet dye by 10% (v/v) inoculums of Enterobacter sp. CV–S1 tested under 72 h of shaking incubation at temperature 35 °C and pH 6.5. Newly identified bacteria Enterobacter sp. CV–S1, confirmed by 16S ribosomal RNA sequencing, was found as a potential bioremediation biocatalyst in the aerobic degradation/de-colorization of Crystal Violet dye. The efficiency of degrading triphenylmethane dye by this isolate, minus the supply of extra carbon or nitrogen sources in the media, highlights the significance of larger-scale treatment of textile effluent.

The main objective of this study was to identify and isolate arsenic resistant bacteria that can be used for removing arsenic from the contaminated environment. Here we report a soil borne bacterium, B1-CDA that can serve this purpose. B1-CDA was isolated from the soil of a cultivated land in Chuadanga district located in the southwest region of Bangladesh. The morphological, biochemical and 16S rRNA analysis suggested that the isolate belongs to Lysinibacillus sphaericus. The minimum inhibitory concentration (MIC) value of the isolate is 500 mM (As) as arsenate. TOF-SIMS and ICP-MS analysis confirmed intracellular accumulation and removal of arsenics. Arsenic accumulation in cells amounted to 5.0 mg g(-1) of the cells dry biomass and thus reduced the arsenic concentration in the contaminated liquid medium by as much as 50%. These results indicate that B1-CDA has the potential for remediation of arsenic from the contaminated water. We believe the benefits of implementing this bacterium to efficiently reduce arsenic exposure will not only help to remove one aspect of human arsenic poisoning but will also benefit livestock and native animal species. Therefore, the outcome of this research will be highly significant for people in the affected area and also for human populations in other countries that have credible health concerns as a consequence of arsenic-contaminated water.

We isolated and identified Salmonella organisms from ovaries of dead layer birds and from inner content of laid eggs of different poultry farms. The thirty eight ovarian swabs for bacteriology, visceral organs (liver, lung, spleen, egg follicles and intestine) of 38 dead birds for pathological study from 15 layer farms and 45 laid eggs (5 eggs/farm) from reported 9 Salmonella infected farms constituted samples of the study. Samples were subjected to isolation and identification of the causal agent followed by gross and histopathological study of the affected visceral organs. Seventeen of 38 ovarian swabs (44.7%) were Salmonella positive. The percentage of Salmonella Gallinarum, Salmonella Pullorum and paratyphoid causing Salmonella were 70.6%, 17.6% & 11.8%, respectively. About 53% livers of Salmonella affected birds were enlarged, congested, friable and bronze coloured with white necrotic foci. About 59% egg follicles were congested, hemorrhagic, discoloured with stalk formation and 70.6% intestines showed hemorrhagic to catarrhal enteritis. At histopathology, 76.5% livers were congested with formation of multifocal nodules and 82.4% egg follicles were congested with huge leukocytic infiltration. Infiltration of heterophils in intestinal mucosa was found in 47.1% cases. Four Salmonella isolates were found from 9 laid egg samples (5 eggs content comprised as 1 sample) and isolation rate was 44.4% reporting transovarian transmission in poultry Salmonellosis.