Decolorization of triphenylmethane dye-bath effluent in an integrated two-stage anaerobic reactor

In the present study, decolorization of a simulated dye waste containing three different triphenylmethane (TPM) dyes--Magenta, Malachite Green and Crystal Violet, was investigated in a laboratory scale, two-stage anaerobic high-rate reactor. The effect of various parameters (influent dye concentration, hydraulic and co-substrate loading rates) on color and COD removal efficiency of the reactor has been studied. It has been shown that the influent dye concentration had little effect on overall COD and color removal efficiency. More than 99% color removal and 96% COD removal efficiency were maintained even at a dye concentration of 500 mg/l and a dye loading rate of 1000 mg/l day. However, a minimum level of glucose as supplementary carbon source is required to maintain the maximum color removal efficiency and it drops appreciably when no glucose is added to the influent. The study also showed that the acidogenic phase of the reaction plays an important role in decolorization of the TPM dyes. In addition, the two-stage anaerobic reactor was observed to have distinct advantages over the single-stage system, as the drop in color and COD removal efficiency of stage 1 are adequately compensated by stage 2 of the reactor especially under high dye loading rates accompanied by low co-substrate loading and under reduced HRTs.     

Application of drastic model and GIS: for assessing vulnerability in hard rock granitic aquifer

Geographic information system (GIS) has become one of the leading tools in the field of hydrogeological science that helps in assessing, monitoring, and conserving groundwater resources. Groundwater is a finite resource, which is being overexploited due to increase in demand over the years leading to decrease in its potentiality. In the present study, DRASTIC model has been used to prepare groundwater vulnerable zone in hard rock aquifer of granitic terrain. The main objective is to determine susceptible zone for groundwater pollution by integrating hydrogeological layers in GIS environment. The layers such as depth of aquifer, recharge, aquifer yield, soil type, topography, vadose zone, and transmissivity are incorporated in the DRASTIC model. The final output of the map shows that around 60% of the area falls under low to no risk of pollution zone. The high risk of pollution zones are mostly present towards the margin of southeastern periphery. The lower part of the basin as well as small area on northern side falls under moderate risk of pollution zone. For the assessment of groundwater pollution zone, 24 groundwater samples have been collected from different vulnerable zones. The chemical analysis of sample shows that the southeastern margin of basin has relatively high concentration of nitrate as compared to other parts of the basin. It is present in high pollution zone as well as moderate pollution zone. The present model can be used for assessment and management of groundwater.     

Heavy metal assessment using geochemical and statistical tools in the surface sediments of Vembanad Lake, Southwest Coast of India

The geochemical distribution and enrichment of ten heavy metals in the surface sediments of Vembanad Lake, southwest coast of India was evaluated. Sediment samples from 47 stations in the Lake were collected during dry and wet seasons in 2008 and examined for heavy metal content (Al, Fe, Mn, Cr, Zn, Ni, Pb, Cu, Co, Cd), organic carbon, and sediment texture. Statistically significant spatial variation was observed among all sediment variables, but negligible significant seasonal variation was observed. Correlation analysis showed that the metal content of sediments was mainly regulated by organic carbon, Fe oxy-hydroxides, and grain size. Principal component analysis was used to reduce the 14 sediment variables into three factors that reveal distinct origins or accumulation mechanisms controlling the chemical composition in the study area. Pollution intensity of the Vembanad Lake was measured using the enrichment factor and the pollution load index. Severe and moderately severe enrichment of Cd and Zn in the north estuary with minor enrichment of Pb and Cr were observed, which reflects the intensity of the anthropogenic inputs related to industrial discharge into this system. The results of pollution load index reveal that the sediment was heavily polluted in northern arm and moderately polluted in the extreme end and port region of the southern arm of the lake. A comparison with sediment quality guideline quotient was also made, indicating that there may be some ecotoxicological risk to benthic organisms in these sediments.     

Antimony sorption at gibbsite-water interface

Antimony (Sb) is extensively used in flame retardants, lead-acid batteries, solder, cable coverings, ammunition, fireworks, ceramic and porcelain glazes and semiconductors. However, the geochemical fate of antimony (Sb) remained largely unexplored. Among the different Sb species, Sb (V) is the dominant form in the soil environment in a very wide redox range. Although earlier studies have examined the fate of Sb in the presence of iron oxides such as goethite and hematite, few studies till date reported the interaction of Sb (V) with gibbsite, a common soil Al-oxide mineral. The objective of this study was to understand the sorption behavior of Sb (V) on gibbsite as a function of various solution properties such as pH, ionic strength (I), and initial Sb concentrations, and to interpret the sorption-edge data using a surface complexation model. A batch sorption study with 20 g L⁻¹ gibbsite was conducted using initial Sb concentrations range of 2.03-16.43 μM, pH values between 2 and 10, and ionic strengths (I) between 0.001 and 0.1 M. The results suggest that Sb (V) sorbs strongly to the gibbsite surface, possibly via inner-sphere type mechanism with the formation of a binuclear monodentate surface complex. Weak I effect was noticed in sorption-edge data or in the isotherm data at a low surface coverage. Sorption of Sb (V) on gibbsite was highest in the pH range of 2-4, and negligible at pH 10. Our results suggest that gibbsite will likely play an important role in immobilizing Sb (V) in the soil environment.     

Groundwater arsenic contamination in Brahmaputra river basin: a water quality assessment in Golaghat (Assam), India

Distribution of arsenic (As) and its compound and related toxicology are serious concerns nowadays. Millions of individuals worldwide are suffering from arsenic toxic effect due to drinking of As-contaminated groundwater. The Bengal delta plain, which is formed by the Ganga?CPadma?CMeghna?CBrahmaputra river basin, covering several districts of West Bengal, India, and Bangladesh is considered as the worst As-affected alluvial basin. The present study was carried out to examine As contamination in the state of Assam, an adjoining region of the West Bengal and Bangladesh borders. Two hundred twenty-two groundwater samples were collected from shallow and deep tubewells of six blocks of Golaghat district (Assam). Along with total As, examination of concentration levels of other key parameters, viz., Fe, Mn, Ca, Na, K, and Mg with pH, total hardness, and SO $_{4}^{2-}$ , was also carried out. In respect to the permissible limit formulated by the World Health Organization (WHO; As 0.01 ppm, Fe 1.0 ppm, and Mn 0.3 ppm for potable water), the present study showed that out of the 222 groundwater samples, 67%, 76.4%, and 28.5% were found contaminated with higher metal contents (for total As, Fe, and Mn, respectively). The most badly affected area was the Gamariguri block, where 100% of the samples had As and Fe concentrations above the WHO drinking water guideline values. In this block, the highest As and Fe concentrations were recorded 0.128 and 5.9 ppm, respectively. Tubewell water of depth 180 ± 10 ft found to be more contaminated by As and Fe with 78% and 83% of the samples were tainted with higher concentration of such toxic metals, respectively. A strong significant correlation was observed between As and Fe (0.697 at p < 0.01), suggesting a possible reductive dissolution of As?CFe-bearing minerals for the mobilization of As in the groundwater of the region.     

Green Synthesis of Silver Nanoparticles Using Exopolysaccharides Produced by Bacillus anthracis PFAB2 and Its Biocidal Property

Journal of Polymers and the Environment - Nowadays when control of environmental toxicity is a matter of concern, the focus of the researchers is to find an eco-friendly process. Considering the...     

Chelating resin immobilized sawdust packed chromatographic column: Application to separation and preconcentration of lead ion

Naturally abundant rubber sawdust has been utilized as a stationary support, which after immobilization with a chelating polyelectrolyte (xylenol orange as counterion) gets converted into a suitable column packing material for isolation and enrichment of trace level target analyte, accurately detectable by the technique of differential pulse anodic stripping voltammetry. The sorbent is robust and re-usable in column-chromatography without showing any leaching and interference complications. Its unique lead ion selectivity from multielemental complex matrices (synthetic water sample, blood serum) at optimized column conditions (pH 2.5 and flow rate 0.5?mL?min^?1) mitigates the usual problems of intermetallic and readsorption effects. Effects of flow rate, pH, equilibration time, and other variables are reported. The system has advantageous feature to be used in a single-column ion chromatography with satisfactory performance. A modest attempt has been made to determine lead fractions in human blood serum samples on the bases of selective retention of ionic and labile fractions on complexing resin.     

Remotely-Sensed Active Fire Data for Protected Area Management: Eight-Year Patterns in the Manas National Park, India

The Terai-Duar savanna and grasslands, which once extended along most of the Himalayan foothills, now only remain in a number of protected areas. Within these localities, grassland burning is a major issue, but data on frequency and distribution of fires are limited. Here, we analysed the incidence of active fires, which only occur during the dry season (Nov.–Mar.), within a significant area of Terai grasslands: the Manas National Park (MNP), India. We obtained locations of 781 fires during the 2000–2008 dry seasons, from the Fire Information for Resource Management System (FIRMS) that delivers global MODIS hotspot/fire locations using remote sensing and GIS technologies. Annual number of fires rose significantly from around 20 at the start of the study period to over 90 after 2002, with most (85%) detected between December and January. Over half of the fires occurred in tall grasslands, but fire density was highest in wetland and riverine vegetation, dry at the time. Most burning took place near rivers, roads and the park boundary, suggesting anthropogenic origins. A kernel density map of all recorded fires indicated three heavily burnt areas in the MNP, all within the tall grasslands. Our study demonstrates, despite some technical caveats linked to fire detection technology, which is improving, that remote fire data can be a practical tool in understanding fire concentration and burning temporal patterns in highly vulnerable habitats, useful in guiding management.