Arsenic treatment considerations

Chen, Hsiao-wen; Frey, Michelle; Clifford, Dennis; McNeill, Laurie S.; Edwards, Marc

doi:10.1002/j.1551-8833.1999.tb08601.x

Cited by 116 publications

(71 citation statements)

References 27 publications

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“…Enhanced coagulation, is intended to improve natural organic matter (NOM) removal, but is also in many cases the least-cost option for water utilities to comply with the new As MCL [6,7]. Early bench, pilot, and demonstration scale studies have shown that As(V) can be efficiently removed during coagulation with ferric chloride and alum even when present at low or high concentration in influent waters [8,9].…”

Section: Introductionmentioning

confidence: 99%

Effect of aluminum speciation on arsenic removal during coagulation process

Liu

Chen

et al. 2012

Separation and Purification Technology

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a b s t r a c tThe effect of Al speciation on arsenate [As(V)] removal during coagulation process was investigated from the viewpoint of Al hydrolysis species transformation. The As(V) removal efficiency of preformed Al 13 was compared with that of in situ formed Al 13 considering various Al dosages and pH values. The mechanisms of As(V) removal by Al salt coagulation were explored, and adsorption ability of the flocs formed from Al 13 species were evaluated. The results showed that As(V) removal efficiency was positively correlated with the content of Al 13 species during coagulation process. Weak acidic condition (pH 5-7) is the optimal pH range to remove As(V) because Al 13 species, especially for AlCl 3 , is largely in situ formed from the transformation of monomeric Al species. Through regulating Al speciation, pH adjustment could improve As(V) removal and AlCl 3 could benefit most from this. In contrast, the improvement induced by pH control for polyaluminum (PACl) was slighter because Al speciation of PACl was less dependent upon water pH. This present study confirmed that adsorption on formed hydroxide flocs was the most active mechanism for As(V) removal by Al based coagulants. The flocs generated from in situ formed Al 13 presented better As(V) adsorption ability than the flocs generated from preformed Al 13 . These findings are important to understand the coagulation mechanisms of arsenic removal by Al based coagulants.

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Section: Introductionmentioning

confidence: 99%

Effect of aluminum speciation on arsenic removal during coagulation process

Liu

Chen

et al. 2012

Separation and Purification Technology

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“…The aforementioned patterns of behaviour of arsenic in waters were also observed in another temperate low-contaminated river, the Adour by Point et al (2007). The relationship between dissolved and particulate arsenic was highly dependent on flow but during annual average flow it was 1:1, as described in one third of 49 groundwater sources in USA (Chen et al, 1999).…”

Section: Discussion 41 the Fluvial Reservoirmentioning

confidence: 55%

Land–ocean contributions of arsenic through a river–estuary–ria system (SW Europe) under the influence of arsenopyrite deposits in the fluvial basin

Costas

Prego²,

Filgueiras³

et al. 2011

Science of The Total Environment

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Abstract. Water was sampled monthly from September 2005 to August 2006 at 14 stations distributed throughout the coastal system of Anllóns-Laxe, from where 30 surface sediment samples were also taken. After filtration through 0.22 m polycarbonate filters, dissolved inorganic and total arsenic (UV oxidation) concentration was determined by HG-AFS. After microwave digestion, the arsenic in SPM and sediment was determined by AAS. Ultra-clean procedures were adopted during sampling, handling and analysis and the analytical accuracy was checked using CRM. Spatial distribution of As in water (0.2-4.0 g L -1 ), SPM (21-169 mg kg -1 ) and sediment of the river reservoir was altered by the presence of arsenopyrite deposits in the middle fluvial basin that increases 2.1±0.5 and 1.7±0.5 times the concentrations of inorganic dissolved (DI-As) and particulate (P-As) arsenic, respectively. At the termination fluvial zone As fluxes can be calculate to be: [DI-As]=7.09 Q -0.69. The Anllóns River exports to its estuary 460 kg a -1 of dissolved (<7% as organic) arsenic annually. It is higher (i.e. 0.83 kg s -1 km -2 of DI-As) than that of most of European rivers. In the estuary reservoir, the influence of arsenopyrite is also evident as the river concentration of DI-As, which was lower than in seawater during the wet season and higher during the dry season. Arsenic has non-conservative behaviour, as in other European estuaries, but the Anllóns shows an ambivalent pattern: as it usually gain DI-As during the wet season and loses it during the dry season, while P-As seems to behave contrary to the DI-As. When the fluvial arsenic reaches the ria its concentration varies due to the estuarine processes. In the wet season DI-As increases its concentration by one third while in the dry season it decreases by one fifth and the annual contribution to the ria is 10% higher than the fluvial output. In the case of P-As more data are necessary to quantify its behaviour; however, the estuarine sediments are contaminated by arsenic. In the ria reservoir DI-As levels were similar to those of the ocean, DO-As comprises 9-22% of the inorganic, P-As ranges from 3 to 40 mg kg -1 , and As-sedimentary can classified as uncontaminated (4-18 mg kg -1 ), except in the fishering ports. The ria circulation, reinforced by upwelling favours the exportation of arsenic to the ocean. In the Anllóns-Laxe system as a whole, the freshwater-saline interface processes do not lead to a decrease in the dissolved fluvial arsenic flux to the ocean.

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“…Removal efficiency with reverse osmosis units has been shown to be lower when arsenic is present as As (III) (Chen et al 1999;USEPA 2000;Walker et al 2008).…”

Section: Significance Of Trivalent Arsenic (As (Iii) )mentioning

confidence: 99%

Arsenic, As(III), and tungsten in Nevada County's private water supplies

Walker

Fosbury

2009

Journal of Water and Health

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In parts of the western United States groundwater used for drinking water contains high concentrations of metals, including arsenic. In a rural county in Nevada, USA, we measured concentrations of arsenic and tungsten and the proportion of arsenic occurring in trivalent form (As (III) ) in tap water samples from private domestic wells in 307 households. The proportion of arsenic occurring as As (III) ranged from 0 to 100% (ave. 21%, median 1% This suggests that householders in this area were likely to be exposed to both metals simultaneously, given that 253/307 of the respondents (82%) reported consuming tap water.

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Arsenic treatment considerations

Cited by 116 publications

References 27 publications

Effect of aluminum speciation on arsenic removal during coagulation process

Effect of aluminum speciation on arsenic removal during coagulation process

Land–ocean contributions of arsenic through a river–estuary–ria system (SW Europe) under the influence of arsenopyrite deposits in the fluvial basin

Arsenic, As(III), and tungsten in Nevada County's private water supplies

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