https://www.u-cursos.cl/usuario/7c1c0bd54f14c0722cefc0fa25ea186d/mi_blog/r/Lectura_clase_ingenieria_ambiental.pdf

Arsenic contamination, consequences and remediation techniques: a review

Remediation technologies for heavy metal contaminated groundwater.

Arsenic and antimony in water and wastewater: overview of removal techniques with special reference to latest advances in adsorption

Due to overgrowth in population, industrialization and civilization, demands for water are increasing geometrically. Therefore, alternative sources of water are required and wastewater treatment and recycling may serve this purpose. Among various water treatment technologies, adsorption onto activated carbon is in the front line due to its universal nature. Activated carbon is the best adsorbent able to capture inorganic, as well as organic, pollutants that contaminate water resources. Inorganic pollutants, especially metal ions, are more dangerous due to their toxic and possibly carcinogenic natures. Also they are most often persistent and difficult to biodegrade. The present article describes the quest to find an economically viable substitute to active carbon adsorbent to remove toxic metal ions. A brief discussion of design of batch and column adsorption experiments, development of inexpensive adsorbents, and experimental conditions of metal ions removal by batch and column procedures is included. Eff...

The Quest for Active Carbon Adsorbent Substitutes: Inexpensive Adsorbents for Toxic Metal Ions Removal from Wastewater

Cadmium is known to be toxic for living organism even if it is present in low levels. Generally it is associated with zinc and copper minerals and is produced as a byproduct of these industries. It enters the environment from electroplating, smelting, alloy manufacturing, pigments, plastic, cadmium-nickel batteries, fertilizers, pesticides, mining, pigments and dyes, textile operations and refining industries. Various ways of cadmium removal are: precipitation, ion exchange, solvent extraction and adsorption. The present review specifically describes various types of adsorbents which have been used for removing cadmium from aqueous solutions. General emphasis has been on the utilization of agricultural, industrial wastes and low cost synthetic oxides as adsorbents. In most of the studies batch mode data has been evaluated by determining the kinetic, isothermic and thermodynamic parameters. A number of studies have also addressed the mechanism of adsorption process employing instrumental techniques such as XRD, FTIR, SEM etc. Modeling of column data has also been reported by some researchers. More attention needs to be given for regeneration/reuse/ safe disposal of the loaded adsorbents wherein the data are insufficient. The engineering aspects also need attention for commercial application of various adsorbents. 

International Journal of Engineering, Science and Technology, Vol. 2, No. 7, 2010, pp. 81-103

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Review on cadmium removal from aqueous solutions

Biosorptive removal of arsenic from drinking water.

The objective of the present work was to investigate the removal of Ni(II) by the fresh biomass (FBM) and chemically treated leached biomass (LBM) of Calotropis procera. The scope of the work included screening of the biosorbents for their metal uptake potential, batch equilibrium, column mode removal studies and kinetic studies at varying pH (2-6), contact time, biosorbent dosages (1-25 g/L) and initial metal ion concentration (5-500 mg/L). The development of batch kinetic model and determination of order, desorption studies, column studies were investigated. It was observed that pH had marked effect on the Ni(II) uptake. Langmuir and Freundlich models were used to correlate equilibrium data on sorption of Ni(II) metallic ion by using both FBM and LBM at 28 o C and pH 3 and different coefficients were calculated. It was found that both biomasses were statistically significant fit for Freundlich model. The biomass was successfully used for removal nickel from synthetic and industrial effluents and the technique appears industrially applicable and viable.

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Biosorptive removal of Ni(Ii) from wastewater and industrial effluent.

Biosorptive removal of cadmium from contaminated groundwater and industrial effluents.

Laboratory measurements of water samples from a range of environments in the Bhilai region demonstrated the ability to identify characteristic features of groundwater quality. This study focusses on geology and hydrology of the studied site to evaluate the ability to locate the source of contamination, either geological or concentration of mine drainage or industrial pollution causing adverse quality of potable water in some areas of this region. Monitoring the groundwater at periodic intervals over a two-year period provided information on the production and transport of pollutant. During analysis of the water samples concentration of redox species such as Fe 2+ and S 2- were found significantly above their detection limits. Anomalous high concentration of ferrous iron Fe 2+ (65 ppm) and sulphide S 2- (24 ppm) witnessed in various areas are indicative of the reducing conditions of the ground water. The majority of bore wells and hand-pump samples clustered towards the Ca-Mg-HCO 3 regime of the phase diagram. In contrast to increased concentrations of Fe 2+ , an increased alkalinity up to 700 ppm has been observed which makes the study significant. A correlation study indicated that the iron and sulphide anomaly is primarily related to point source contamination.

Mineral-Water Interfacial Reactions and Their Effect on Elemental Mobilisation

Iron is essential heavy metal in trace quantities, but its excessive concentration as Fe2+ is present in effluents from steel mills, iron ore mines, and metal processing industries, which pollute the groundwater. Among other conventional methods, sorption by natural biomass is a low-cost alternative for iron sequestration from an aqueous solution. The root of a native weed plant Calotropis Procera was used to optimize the adsorption parameters like pH, contact time, sorbent dose, and initial adsorbate concentration. Competitive adsorption of Fe2+ in the presence of cations (Ni2+, Cd2+, Cr3+, Zn2+, Ca2+, Mg2+, As3+) and anions (Cl-, SO42- , F-) was also studied. Batch adsorption studies were carried out to evaluate adsorption isotherm by Langmuir and Freundlich isotherm models. Leaching of biomass significantly improved iron uptake capacity from 15 mg g-1 to 80 mg g-1. The kinetics of the reaction was fast, with equilibrium conditions attaining in 30 minutes. FTIR study of the biomass revealed the presence of -COOH, -NH groups responsible for the metal binding mechanism. The biomass could be regenerated with 0.1 M HNO3 for further use. Iron removal from simulated acidic water was done under optimum conditions and absorbance was measured by a UV-Visible spectrophotometer.

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Removal of Fe (II) from aqueous solution by Calotropis Procera: Kinetics, isotherm s tudies, and measurement of competitive adsorption with UV-Visible spectrophotometer

Yashu Verma

Papers

Biosorptive removal of arsenic from drinking water.

Biosorptive removal of Ni(Ii) from wastewater and industrial effluent.

Biosorptive removal of cadmium from contaminated groundwater and industrial effluents.

Mineral-Water Interfacial Reactions and Their Effect on Elemental Mobilisation

Removal of Fe (II) from aqueous solution by Calotropis Procera: Kinetics, isotherm s tudies, and measurement of competitive adsorption with UV-Visible spectrophotometer