Arsenic removal

In the United States and many other countries, the toxic metalloid arsenic is not allowed in drinking water at levels greater than 10 pg/L, a level that has been exceeded by some water supplies used in the past. Arsenic usually is present in water as arsenic(V), primarily H2ASO4 and HASO4. Groundwater supplies containing the more toxic As(III) form have to be treated with chlorine, ozone. 

The standard method for the removal of dissolved organic material is adsorption on activated carbon, a product that is produced from a variety of carbonaceous materials including wood, pulp mill char, peat, and lignite. The carbon is produced by charring the raw material anoxically below 600°C, followed by an activation step consisting of partial oxidation. Carbon dioxide can be employed as an oxidizing agent at 600-700°C  

These processes develop porosity, increase the surface area, and leave the C atoms in bonding orientations that have affinities for organic compounds. 

The exact mechanism by which activated carbon holds organic materials is still a subject of research. However, one reason for the effectiveness of this material as an adsorbent is its tremendous surface area. A solid cubic foot of carbon particles can have a combined pore and surface area of approximately 10 square miles  

Activated carbon comes in two general types granulated activated carbon, consisting of particles 0.1-1 mm in diameter, and powdered activated carbon, in which most of the particles are 50-100 pm in diameter. Both forms are used to treat water. 

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G. E. Lauf and M. A. Waer, "Arsenic Removal Usiug Potassium Permanganate," presented at the 1993 Water Quality Technology Conference, Miami, Fla., Nov. 1993. 

Arsenic removal from seawater to sediments is mainly governed by pyrite formation in the seafloor sediments. Production rate of sedimentary pyrite is 2.5 x 10 g S/year (Holland, 1978). Therefore, As removal by pyrite from seawater is (1.3-2.9) x lO g/year. This is the same order of magnitude as As input to ocean by river which is equal to 0.7 x 10 g/year. 

Singhakant, C., Koottatep, T., and Satayavivad, J., Enhance arsenic removals through plant interactions in subsurface-flow constructed wetlands, Journal of Environmental Science and Health, Part A, 44 (2), 163-169, 2009. 

Mohan, D. and Pittman, C.U., Arsenic removal from water/wastewater using adsorbents—a critical review, Journal of Hazardous Materials, 142 (1-2), 1-53, 2007. 

Scott NK, Green FJ, Do DH, McLean JS (1995) Arsenic removed by coagulation. J Am Water Works Assoc 87 114-126... 

Thirunavukkarasu OS, Viraraghavan T, Subramanian KS (2003) Arsenic removal from drinking water using iron oxide-coated sand. Water Air Soil Poll 142 95-111... 

Hering, J.G., P.Y. Chen, and J.A. Wilkie. 1997. Arsenic removal from drinking-water by coagulation the role of adsorption and effects of source water composition. Pages 369-381 in C.O. Abernathy, R.L. Calderon, and W.R. Chappell (eds.). Arsenic. Exposure and Health Effects. Chapman Hall, London. 

Arsenic peroxides, 13 404 Arsenic removal, in municipal water treatment, 26 124 Arsenic trioxide, 3 264, 265-266 Arsenic vapor, 3 264, 264t Arsenious acid, presence in water and food, 3 276t... 

Coagulation factor products, 12 139 Coagulation factors, 72 144-145 Coagulation/filtration, for arsenic removal, 3 280t, 281-282... 

Hydrous ferric hydroxide (HFO), for arsenic removal, 3 279, 283-285 Hydrous manganese dioxide, 15 581 Hydrous manganese oxides, 15 585... 

Iron oxide-coated sand (IOCS), for arsenic removal, 3 279, 284-285 Iron oxide control, in industrial water treatment, 26 133 Iron oxide pastes, 19 402 Iron oxide pigments, 19 397-402 production of, 19 385 transparent, 19 412 economic aspects of, 14 557-559... 

Key words Clinoptilolite, ODA-modifier, chromate and arsenate removal, adsorption, isotherm, and breakthrough curve. 

Arsenate removal by ODA-clinoptilolite proceeded almost analogous as chromate removal did, however the front part of the breakthrough curve is fairly shallow and indicates earlier leakage of pollutant into adsorbate (Fig. 

TESTING OF SORPTION MATERIALS FOR ARSENIC REMOVAL FROM WATERS... 

The granular cast iron of the company ERVIN AMSTEEL was chosen to include another type of material, having been described for arsenic removal from water [3,4] before. 

Lackovic J.A., Nikolaidis N. P., Dobbs G. M., Inorganic Arsenic Removal by Zero-Valent Iron, Environmental Engeneering Science 17,2000,29-39. 

Other special features used in the pilot wetland are floating mats and similar installations to assist the sedimentation of iron precipitates to which arsenic is mainly bound. They can be seen in Figure 6. They have proved to significantly increase the effectiveness of iron and arsenic removal by keeping the pond size to a minimum. This is essential under the conditions already described in the Introduction, namely limited space available at most of the sites. 

DETAILS - Arsenic has been in use for centuries. It was a special favorite of the great Renaissance poisoners of the Venetian school. Cesare Borgia s favorite tool was an arsenic compound he called "La Cantarella". First he poisoned a sow with a heavy dose of arsenic, removed its internal organs, ana... 

Yanagese, K., Yoshinaga, T. Kawano, K. 1983. Arsenic removal from geothermal water by coprecipitation with iron(III) hydroxide. Bunseki Kagaku, 32, Till-Til6. 

Table 2.3-1 lists each potential arsenic removal process evaluated in this study along with major evaluation criteria with respect to HP s GaAs processing facility. Because effective liquid solid separation was required, filtration was selected as the process of choice. 

Arsenic Removal Process Form of Arseni c Host Effectively Treated Possible Appli cabi1i ty to Hewlett Packard Potential Waste Reduction Efficiency for Hewlett Packard Operational Characteri sti cs for Hewlett Packard Potential Health and Safety Concerns Potential Costs for HP Relative to Other Listed Procedures Overal1 Potential Effectiveness in Reducing Hazardous Waste... 

The technology to be applied for removing arsenic solids is considered state-of-the-art. A flow diagram of the Installed system is depicted in Figure 3-1. The arsenic removal system will be located within HP s slurry room as indicated in Figure 3-2. This was the same location where pilot studies were carried out. 

L. C. Roberts, S. J. Hug, T. Ruettimann, M. Billah, A. W. Khan, and M. T. Rahman, Arsenic Removal with Iron(II) and Iron(III) Waters with High Silicate and Phosphate Concentrations, Environ. Sci. Technol. 2004, 38, 307. 

Clifford, D.A. and Ghurye, G.L. (2002) Metal-oxide adsorption, ion exchange, and coagulation-microfiltration for arsenic removal from water, in Environmental Chemistry of Arsenic (ed. W.T. Frankenberger Jr.), Marcel Dekker, New York, pp. 217-45. 

Shih, M.-C. (2005) An overview of arsenic removal by pressure-driven membrane processes. Desalination, 172(1), 85-97. 

Thirunavukkarasu, O.S., Viraraghavan, T., Subramanian, K.S. et al. (2005) Arsenic removal in drinking water — impacts and novel removal technologies. Energy Sources, 27(1-2), 209-19. 

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