Passive and semi-passive treatment alternatives for the bioremediation of selenium from mine waters (original) (raw)
Related papers
Remediation and Bioremediation of Selenium-Contaminated Waters
Water Encyclopedia, 2005
Selenium (Se) is a trace element that occurs naturally in soils, water, biota, and food. It is nutritionally required, but Se in excess is toxic to aquatic-associated wildlife such as fish and birds. Exposure to Se primarily occurs through the diet, not by direct exposure to water; therefore it is vital to account for the "biogeochemistry" of Se-the complex paths by which it moves from contaminated water up the foodweb. As a consequence, waterborne Se is an inappropriate focus for remediation, and this entry illustrates how such a focus can inadvertently misguide major remediation efforts. In fact, there is no fixed "target concentration" for remediation to achieve, as universally accepted water or tissue threshold concentrations for the protection of wildlife are likely to remain controversial for some time to come. This can stymie the traditional remediation strategies of containment, removal, or treatment. One approach to Se remediation that functions under changing regulatory limits is mitigation of wildlife impacts through "alternative" and "compensation" habitats. Also, strategies that take advantage of the natural biogeochemistry, such as algal volatilization of Se, may provide cost-effective management of contaminated water; however, this approach must be combined with foodweb interruption to prevent Se bioaccumulation.
Bioremediation of selenium-contaminated sediments and water
Biofactors, 2001
Selenium (Se) is a contaminant of agricultural irrigation-drainage water in the western United States, and the cause of wildlife deaths and grotesque deformities. Some approaches in reducing the toxic Se concentrations from contaminated sediments and water have been proposed, but most of these tend to be costly or ineffective. Bioremediation through microbial transformations of toxic Se species into nontoxic forms is being considered as an effective remedial alternative. The microbial reduction of toxic oxyanions of Se {SeO42 and SeO32-} into insoluble Se0 or methylation of these species to dimethylselenide (DMSe) has been accepted as a potential bioremediation strategy for cleanup of Se-contaminated water and sediments. By conducting a series of laboratory, bench-scale and field studies, we have thoroughly investigated the remedial potential of these approaches. It was observed that microorganisms, particularly Enterobacter cloacea, are very active in reduction of Se oxyanions present in irrigation drainage water, into insoluble Se0and, by monitoring various environmental conditions and addition of organic amendments, the process could be stimulated manifold. Similarly, the process of biomethylation of Se in soil sediments and water was found active and highly dependent on specific carbon amendments (pectin and proteins), pH, temperature, moisture, aeration and activators (cofactors). Moreover, Se biomethylation was protein/peptide-limited rather than nitrogen-, amino acid- or carbon-limited. Crude casein and its components were equally stimulatory producing a > 50-fold enhancement in DMSe yield. Methionine and methyl cobalamin stimulated DMSe production by Alternaria alternata, indicating that the coenzyme may mediate the transfer of a methyl group to the Se atom. An acute toxicity test involving inhalation of DMSe by rats revealed that DMSe is nontoxic. Experiments were scaled up from laboratory studies to field plots to verify the feasibility of this bioremediation approach. Based upon the promising results of these studies, a biotechnology prototype was developed which could be applicable for cleanup of polluted sediments and water throughout the western United States.
2013
The removal of selenium (Se) from water using passive technologies at mine sites is challenging as a result of associated high flow rates. However, the chemical and hydraulic conditions of backfilled pits offer a potential means to bioremediate large volumes of water passively. Specifically, the oxidation demand associated carbonaceous waste materials in conjunction with long water residence times within backfilled pits can produce the suboxic conditions required to support the removal of Se from solution through a suite of microbially-mediated processes. Evidence for Se removal is provided from a study of a backfilled pit at a coal mine in Northern Canada. Redox conditions within the saturated backfill are mildly-suboxic, as inferred from low levels of oxygen, nitrate and the presence of dissolved Mn and Fe. Results show pronounced removal of dissolved Se within the saturated backfill, with concentrations decreasing from 40 μg/L (upgradient of saturated zone) to <1 μg/L within t...
Selenium removal by constructed wetlands: role of biological volatilization
Environmental science & …, 1998
Selenium-laden effluents from oil refineries are polluting San Francisco Bay, California. One environmentally friendly way of cleaning up selenium (Se) from effluents is by plant and microbial Se volatilization using constructed wetlands. Using mesocosms, we investigated the role ...
Selenium Immobilization in a Pond Sediment at Kesterson Reservoir
Journal of Environmental Quality, 1990
Kesterson ReseiVoir, Merced County, CA. a disposal facility for agricultural drain water, became the object of intense scientific investigation following discovery in 1983 that Se-laden agricultural drain water was having serious effucts on the reproductive success of waterfowl. A remedial measure involving permanent flooding with low-Se water, aimed at taking advantage of low Se solubility under reducing conditions, was proposed as a means of limiting Se movement into groundwater and biota. A field experiment was undertaken to evaluate the feasibility of the proposed remedial measure, its impact on the quality of shallow groundwater and for quantifying Se immobilization and transport through a newly-flooded pond bottom soil. Extensive soil water and groundwater sampling demonstrated that although initial soluble Se concentrations in the top 1.22 m (4 ft) of soil typically ranged from approximately 1000 to 3000 J.Lg L-l, Se concentrations declined dramatically after flooding and elevated concentrations below 1.22 m were obseiVed at only one of five sampling sites. Analysis of the temporal and spatial changes in the distribution of dissolved Se and Cr indicated that 66 to 108% of the initial soluble Se present in the top 1.22 m was immobilized shortly after flooding. These estimates were consistent with the low Se concentrations obseiVed in shallow monitoring wells. The extent to which Se immobilization occurred correlated inversely with average pore water velocity. Data presented suggest that reducing conditions in the newly flooded soils lead to the microbially mediated transformation of selenate to less soluble or mobile forms.
Agricultural drainage water treatment at the algal-bacterial selenium removal demonstration facility
1999
A demonstration Algal-Bacterial Selenium Removal (ABSR) Facility has been treating agricultural drainage water in the Panoche Drainage District on the west-side of the San Joaquin Valley since 1997. The goals of the project are to demonstrate the effectiveness of the ABSR Technology for selenium removal, to investigate potential wildlife exposure to selenium at fullscale facilities, and to develop an operational plant configuration that will minimize the life cycle cost for each pound of selenium removed. The Facility consists of a series of ponds designed to promote native microorganisms which remove nitrate and selenium. Previous treatment research efforts sought to reduce selenium concentrations to less than 51lglL, but the ABSR Facility demonstration focuses on providing affordable reduction of the selenium load that is discharged to the San Joaquin River. During 1997 and 1998, the best-performing ABSR plant configuration reduced nitrate over 95% and reduced total soluble selenium mass by 80%. Ongoing investigations at the Facility focus on optimizing operational parameters and determining operational costs and scale-up engineering requirements. The preliminary total cost estimate for a 10 acre-ftlday ABSR facility is less than $200 per acre-ft of treated drainage water. Solutions to Drainage Selenium Problem Agricultural drainage water treatment for selenium removal has been an active area of research for over a decade since the discovery of deformed waterfowl embryos at Kesterson Reservoir in the western San Joaquin Valley (Ohlendorf et ai., 1986). As yet no treatment technology has proven economically feasible for meeting the 5 Ilg/L State Water Resources Control Board objective for selenium discharged to receiving waters such as the San Joaquin River and Mud Slough (SWRCB, 1989; U.S. EPA, 1987). Agricultural drainage discharged into Mud Slough from the Grasslands Basin exceeds this concentration regularly (CVRWQCB, 1999).
Selenium Removal and Mass Balance in a Constructed Flow‐Through Wetland System
Journal of Environmental Quality, 2003
ABSTRACTA field study on the removal of Se from agricultural subsurface drainage was conducted from May 1997 to February 2001 in the Tulare Lake Drainage District (TLDD) of San Joaquin Valley, California. A flow‐through wetland system was constructed consisting of ten 15‐ × 76‐m unlined cells that were continuously flooded and planted with either a monotype or combination of plants, including sturdy bulrush [Schoenoplectus robustus (Pursh) M.T. Strong], baltic rush (Juncus balticus Willd.), smooth cordgrass (Spartina alterniflora Loisel.), rabbitsfoot grass [Polypogon monspeliensis (L.) Desf.], saltgrass [Distichlis spicata (L.) Greene], cattail (Typha latifolia L.), tule [Schoenoplectus acutus (Muhl. ex Bigelow) Á. Löve & D. Löve], and widgeon grass (Ruppia maritima L.). One cell had no vegetation planted. The objectives of this research were to evaluate Se removal efficiency of each wetland cell and to carry out a mass balance on Se. The inflow drainage water to the cells had aver...
Methods for selenium removal from contaminated waters: a review
Environmental Chemistry Letters
Worldwide contamination of waters by metals, metalloids, and organometallic pollutants is a major health issue. In particular , the occurrence of the selenium metalloid at rather high concentrations in the environment, especially in the water compartment, is of increasing concern, notably in developing countries. Selenium is difficult to remove from groundwater and industrial effluents because selenium is often present in complex polycontaminated mixtures, thus inducing competition issues with other anions. Moreover, the efficiency of remediation methods depends on selenium speciation and water parameters, e.g. pH and concentration of competing anions. Here, we review methods for selenium removal from water, wastewater, and industrial effluents. Technologies are based on zero-valent iron, iron-oxyhydroxides, supported materials, nanofiltration, reverse osmosis, chitosan-enhanced ultrafiltration, electrodialysis, and activated granular sludge.
Chemical status of selenium in evaporation basins for disposal of agricultural drainage
Chemosphere, 2007
Evaporation basins (or ponds) are the most commonly used facilities for disposal of selenium-laden saline agricultural drainage in the closed hydrologic basin portion of the San Joaquin Valley, California. However concerns remain for potential risk from selenium (Se) toxicity to water fowl in these evaporation basins. In this study, we examined the chemical status of Se in both waters and sediments in two currently operating evaporation pond facilities in the Tulare Lake Drainage District. Some of the saline ponds have been colonized by brine-shrimp (Artemia), which have been harvested since 2001. We evaluated Se concentration and speciation, including selenate [Se(VI)], selenite [Se(IV)], and organic Se [org-Se or Se(-II)] in waters and sediment extracts, and fractionation (soluble, adsorbed, organic matter (OM)-associated, and Se(0) and other resistant forms) in sediments and organic-rich surface detrital layers from the decay of algal blooms. Selenium in ponds without vascular plants exhibited similar behavior to wetlands with vascular plant present, indicating that similar Se transformation processes and mechanisms had resulted in Se immobilization and an increase of reduced Se species [Se(IV), org-Se, and Se(0)] from Se(VI)-dominated input waters. Selenium concentrations in most pond waters were significantly lower than the influent drainage water. This decrease of dissolved Se concentration was accompanied by the increase of reduced Se species. Selenium accumulated preferentially in sediments of the initial pond cell receiving drainage water. Brine-shrimp harvesting activities did not affect Se speciation but may have reduced Se accumulation in surface detrital and sediments.
Phytoremediation of Selenium-Impacted Water by Aquatic Macrophytes
Journal American Society of Mining and Reclamation, 2019
Stormwater runoff raises concern over potential downstream impacts of selenium (Se) on aquatic ecosystems. Constructed wetland phytoremediation is a sustainable, inexpensive, eco-friendly technology with potential to remove Se from stormwater. The objectives of this study were to: 1) evaluate the bioavailability of Se chemical form and concentration on plant uptake and 2) determine the potential of aquatic macrophytes to improve water quality in a constructed wetland 4. The experiment was arranged as a 2 X 2 factorial nested within a split-split plot design replicated three times. Cattail (CT; Typha angustifolia L.), duckweed (DWD; Lemna minor L.), fanwort (CAB; Cabomba caroliniana A. Gray), soft rush (SR; Juncus effuses L.), muskgrass (MG; Chara spp.), and unplanted controls (UNP) were acclimatized 14 d in 115-L microcosms containing 0.035 m 3 of Catalpa silty clay loam with 26 L of water supplemented with 0.1 N Hoagland's solution. Selenium treatments were applied as a 4-L solution of either sodium selenite (SeO3 2-) or sodium selenate (SeO4 2-) to a total volume of 30 L at 0, 500, or 1000 μg Se L-1. Water samples were collected daily for six days. Plant and soil samples were collected prior to Se application and at three-day intervals post Se application. Water, plant, and soil samples were analyzed for total [Se] by inductively coupled plasma-mass spectrometry. Data were analyzed with PROC GLM at α=0.05. After six days, CT and MG-planted microcosms significantly decreased aqueous [Se] by 75 and 74%, respectively, compared to 61% for UNP. The aqueous fraction of microcosms planted to CAB, DWD, and SR were similar to UNP controls. Plant tissue Se content in CT was significantly less than CAB, DWD, or MG, suggesting CT has the potential to volatilize Se. Given its abundance and efficacy, CT is likely a suitable species for Se removal in constructed wetlands supplied with either selenite or selenate-impacted waters.