Dye house wastewater treatment through advanced oxidation process using Cu-exchanged Y zeolite: a heterogeneous catalytic approach

Catalytic wet hydrogen peroxide oxidation of an anionic dye has been explored in this study. Copper(II) complex of NN'-ethylene bis(salicylidene-aminato) (salenH2) has been encapsulated in super cages of zeolite-Y by flexible ligand method. The catalyst has been characterized by Fourier transforms infra red spectroscopy, X-ray powder diffractograms, Thermo-gravimetric and differential thermal analysis and nitrogen adsorption studies. The effects of various parameters such as pH, catalyst and hydrogen peroxide concentration on the oxidation of dye were studied. The results indicate that complete removal of color has been obtained after a period of less than 1h at 60 degrees C, 0.175M H2O2 and 0.3g l(-1) catalyst. More than 95% dye removal has been achieved using this catalyst for commercial effluent. These studies indicate that copper salen complex encapsulated in zeolite framework is a potential heterogeneous catalyst for removal of color from wastewaters.     

Heavy metal pollution exerts reduction/adaptation in the diversity and enzyme expression profile of heterotrophic bacteria in Cochin estuary, India

Over the past three decades heavy metal pollution has increased substantially in Cochin estuary, south west coast of India. Here we studied the distribution, diversity and enzyme expression profile of culturable microbial population along a pollution gradient. The distribution of resistance against 5 mM concentration of Zn, Co, Ni and Cu was observed among 90-100% of bacterial isolates retrieved from highly polluted Eloor, whereas it was less than 40% in Vypin and Munambam. Similarly, there was a difference in the distribution and diversity of bacterial phyla with predominance of Proteobacteria in Eloor and Firmicutes in Munambam and Vypin. We observed that 75-100% of the organisms retrieved from Eloor had low levels of expression for hydrolytic enzyme. In conclusion, the heavy metal pollution in Cochin estuary brought in reduction/adaptation in the distribution, diversity and enzyme expression profile of bacteria, which may impart adverse impacts on ecosystem functioning.     

Conversion of chromium-containing solid wastes into value-added products through a plasma-assisted aluminothermic process

Chromium-containing solid wastes have been generated by chemical and leather/tanning industries, and the management and proper disposal of the same wastes have been challenging tasks. A significant fraction of these wastes contains chromium compounds with chromium present in the hexavalent (Cr⁺⁶) form, which is hazardous to human beings, animals, and ecosystems. Since these wastes are discarded largely without proper treatments, soil and groundwater get contaminated and they can cause several health issues to human beings. Conventional methods developed to convert hazardous Cr⁶⁺ to Cr³⁺/Cr metal either generate secondary toxic wastes and unwanted by-products and/or are time-consuming processes. In this work, a plasma-assisted aluminothermic process is developed to convert the toxic waste into non-toxic products. The waste was mixed with aluminium powder and subjected to transferred arc plasma treatment in a controlled air atmosphere. Chemical analysis and Cr leachability studies of the waste material prior to plasma treatment have shown that it is highly toxic. Analysis of the products obtained from the plasma treatment showed that Cr and Fe present in the waste could be recovered as a metallic mixture as well as oxide slag, which were found to be non-toxic. Easy separation of the metallic fraction and the slag from the treated product is one of the merits of this process. Besides converting chromium-containing toxic waste to non-toxic materials, the process is rapid and recovers the metals from the waste completely.

     

Influence of sludge characteristics on coagulant recovery from water treatment sludge: a preliminary study

Journal of Material Cycles and Waste Management - This study investigated the effect of raw water quality and coagulant type and dosage on the efficiency of aluminium recovery from water treatment...     

Soil carbon storage as influenced by tree cover in the Dehesa cork oak silvopasture of central-western Spain

The extent of carbon (C) stored in soils depends on a number of factors including soil characteristics, climatic and other environmental conditions, and management practices. Such information, however, is lacking for silvopastoral systems in Spain. This study quantified the amounts of soil C stored at various depths (0-25, 25-50, 50-75, and 75-100 cm) under a Dehesa cork oak (Quercus suber L.) silvopasture at varying distances (2, 5, and 15 m) to trees. Soil C in the whole soil and three soil fractions (<53, 53-250, and 250-2000 μm) was determined. Results showed soil depth to be a significant factor in soil C stocks in all soil particle sizes. Distance to tree was a significant factor determining soil C stocks in the whole soil and the 250-2000 μm soil fraction. To 1 m depth, mean total C storage at 2, 5, and 15 m from cork oak was 50.2, 37, and 26.5 Mg ha(-1), respectively. Taking into account proportions of land surface area containing these C stocks at varying distances to trees to 1 m depth, with a tree density of 35 stems ha(-1), estimated landscape soil C is 29.9 Mg ha(-1). Greater soil C stocks directly underneath the tree canopy suggest that maintaining or increasing tree cover, where lost from disease or management, may increase long term storage of soil C in Mediterranean silvopastoral systems. The results also demonstrate the use of soil aggregate characteristics as better indicators of soil C sequestration potential and thus a tool for environmental monitoring.     

Combined geospatial,geophysical and hydrochemical studies on coastal aquifer at Muttom–Mandaikadu area,Tamilnadu, India

A study was conducted in the Muttom–Mandaikadu coastal region, which is among the profitable coastal sectors in Tamil Nadu, to find the groundwater potential as well as its quality by an integrated geospatial, geophysical and geochemical approach. The GIS-based weighted overlay analysis was used to merge five thematic layers to create the groundwater potential zone map. The geophysical resistivity survey was performed in the study area at 26 stations by applying Schlumberger vertical electrical sounding technique. The observed data were inverted to develop a subsurface lithology model and its electrical properties using one-dimensional software AGI Earth Imager. The combined vertical electrical sounding result and remote sensing thematic maps have exposed the potential zone of groundwater in the study area. From the inferred results, it was observed that 20.8% of the area has ample groundwater potential and 7.7% of the area has scanty groundwater potential. The saltwater intrusion zone had been predicted by validating aquifer resistivity with Dar-Zarrouck (D-Z) parameter. From the geophysical and geochemical interpreted results, it was found that aquifers in 34.6% of the study area are vulnerable to saline contamination. The 4-D model with integrated groundwater quantity and quality suggests that the study area's Western part falls under excellent-to-good groundwater potential zone and excellent water quality.

     

Variability of dissolved reactive phosphate and apparent oxygen utilization along the west coast of India

This work focuses on the spatial variability of dissolved reactive phosphate along the west coast of India. In this study, samples of surface and bottom water was collected from each of the 27 sites during a single pre-monsoon transect along the west coast of India to study the variation of dissolved reactive phosphate. Phosphate showed an enrichment pattern with increase in depth of the water column. In addition to this, an offshore increase in phosphate concentrations was noticed for both surface and bottom stations. Almost all the surface stations of this study area were found to be characterized by negative apparent oxygen utilization (AOU) values, and bottom stations of the deeper offshore zone (200 m depth) displayed large positive AOU values. The bottom stations of shallow near coastal waters and the deeper offshore zone are characterized by an inverse relationship between phosphate and dissolved oxygen, whereas at these depths, a direct relation was observed between phosphate and AOU. AOU is calculated as the difference between oxygen saturation value at the in situ temperature and salinity and the actual measured concentration. This oxidative re-mineralization mechanism decreases the observed dissolved oxygen well below the expected theoretical values, which is concordant with the higher concentration of phosphate and high positive AOU values.     

Causes of heavy metal contamination in groundwater of Tuticorin industrial block,Tamil Nadu,India

Environmental Science and Pollution Research - Groundwater is the major freshwater resource in urban and rural areas of India that provides potable water. The quality evaluation of existing...     

Numerical characterization of the plasma arc with various Ar-CO2 mixtures

Environmental Science and Pollution Research - Plasma technology finds applications in many industrial areas. To improve the process efficiency, different plasma forming gases and their mixtures...     

Detection and extraction of endosulfan by metal nanoparticles

One of the most common pesticides in the developing world, endosulfan, can be detected in ppm levels using gold nanoparticles. Endosulfan adsorbs on the nanoparticle surface and upon interaction for a long time, the nanoparticles precipitate from the solution. Interaction with silver is weak, yet adsorption occurs leading to removal of endosulfan from the solution. A multilayer assembly of gold nanoparticles prepared on a glass substrate shows excellent spectrophotometric response suggesting potential applications.