Neutralization Of Acid Mine Drainage Research Articles

An evaluation of waste gypsum-based precipitated calcium carbonate for acid mine drainage neutralization

Precipitated CaCO(3) compounds recovered from pulped waste gypsum using some carbonate and hydroxide-based reagents were evaluated for their utilization in acid mine drainage (AMD) neutralization. The neutralization potentials, acid neutralization capacities and compositions of the CaCO(3) compounds were determined and compared with some commercial CaCO(3). It was observed that CaCO(3) recovered from waste gypsum using Na(2)CO(3) significantly neutralized AMD compared with commercial CaCO(3) and that recovered using both (NH(4))(2)CO(3) or NH(4)OH-CO(2) reagents. Moreover, a higher acid neutralization capacity of 1,370 kg H(2)SO(4)/t was determined for CaCO(3) recovered from waste gypsum using Na(2)CO(3) compared with an average of 721 and 1,081 kg H(2)SO(4)/t for ammonium-based CaCO(3) and commercial CaCO(3) respectively. The inorganic carbon content for the CaCO(3) recovered using Na(2)CO(3) and ammonium-based reagents of 49 and 34% respectively confirmed their observed neutralization potentials and acid neutralization capacities, while energy dispersive X-ray fluorescence suggested absence of major oxide impurities, with the exception of residual SO(4)(2-) and Na(2)O which still requires further reduction in the respective compounds.

Characterization and assessment of chemical modifications of metal-bearing sludges arising from unsuitable disposal

Ettringite–gypsum sludge, formed by neutralization of acid mine drainage with lime, has been stored temporarily in the open pit of a uranium mine that floods periodically. The present study characterized samples of this sludge, named according to the time of placement as Fresh, Intermediate, and Old. Standard leaching and sequential extraction procedures assessed the associations and stabilities of U, Zn, Fe, Mn, and other contaminants in the solid phases. Corresponding mineralogical transformations associated with sludge weathering were modeled using PHREEQC. The main crystalline phases were ettringite, gypsum and calcite; the minor constituents were fluorite and gibbsite. This mineral assemblage could be attributed to the incongruent dissolution of ettringite to form gibbsite, calcite, and gypsum. Sequential extractions indicated high contents of U, Ca, SO 4, and Zn in the water-soluble (exchangeable) and carbonate fractions. Thus, the analytical and modeling results indicated that despite being classified as non-toxic by standard leaching protocols, the minerals composing the sludge could be sources of dissolved F, SO 4, Fe, Zn, Mn, U, and Al under various environmental conditions. Decommissioning strategies intended to prevent contaminant migration will need to consider the chemical stability of the sludge in various environments.

Geochemical changes during neutralisation of acid mine drainage in a dynamic mountain stream, New Zealand

Abstract The Mangatini Stream drains a coal mining area in the mountains of northwestern South Island of New Zealand. Abundant rainfall on pyritic rocks yields acid mine drainage (AMD) to the stream, which flows through a steep gorge at discharges that rapidly increase from 100 m3/s during frequent rain events. The AMD is treated with finely ground limestone, which is discharged as a slurry at a point in the middle of the gorge. The limestone slurry mixes and reacts with the AMD during flow ∼4 km downstream over ∼12 h. Neutralisation reactions increase stream pH from near 3 (untreated Mangatini Stream water impacted by AMD) to 5–6 in the first 250 m downstream, although mixing is commonly incomplete in this zone. Large stream discharge volumes in rain events dilute the neutralising material input, thus driving the pH back towards 4 downstream of treatment. More complete neutralisation is achieved 4 km downstream, even in major rain events, and pH can rise to >7. Partial neutralisation is sufficient to remove most of the dissolved Fe(III) (typically ∼30 mg/L) from the Mangatini Stream in the first 10 m, and remaining dissolved Fe is essentially all Fe(II), which decreases over time as it oxidises and precipitates. Dissolved Al in the Mangatini Stream (typically ∼50 mg/L) decreases steadily downstream over ∼100 m in the limestone mixing zone. Precipitated Fe and Al form amorphous oxyhydroxides that are transported as suspended solids and deposited on the stream bed with excess limestone in zones of low flow velocity. Dissolved Zn is removed from solution by adsorption to Fe oxyhydroxide when pH reaches ∼5, but dissolved Ni remains in solution despite the neutralisation process. Gypsum precipitation occurs throughout the limestone mixing zone, resulting in at least 30% decrease in dissolved SO 4 2 - . Minor ettringite forms in the first 100 m, but then probably redissolves. The limestone dosing system is an effective method of neutralising the effects of AMD and removing most dissolved metals in a steep mountain stream with frequent rain events where this dynamic environment places many constraints on treatment options.

Acid neutralization by dissolution of alkaline paper mill wastes and implications for treatment of sulfide-mine drainage

Metal removal and neutralization of acid mine drainage (AMD) in treatment systems is often controlled by addition of alkaline reagents and metal hydrolysis reactions. To overcome the disadvantage of high cost by conventional treatments, the use of paper mill wastes was evaluated as an alkaline additive to treat AMD at sites within the Iberian Pyrite Belt (IPB) through batch experiments in the laboratory. Paper wastes include three by-products from kraft pulping in a nearby mill: green liquor dregs, slacker grits, and lime mud. When paper mill wastes interacted with AMD, the initial pH increased up to circumneutral values and enhanced greatly the metal removal, reaching average ratios of up to 100% for Al, 98% for Fe, and 66% for Zn (major elements) and 100% for As, Cr, and Cu, 84% for Cd, and 75% for Ni (minor elements). After reaction, gypsum and poorly crystalline Fe-Al oxy-hydroxides and oxy-hydroxysulfates were the main precipitates identified by X-ray diffraction and scanning electron microscopy. Trace metal uptake is mainly attributed to co-precipitation and/or adsorption onto the newly formed Fe-Al precipitates. Geochemical modeling of solutions using the PHREEQC code predicted supersaturation of the observed phases. The experimental results were optimized with the PHREEQC code and combined with the annual production of each waste to quantify the extent of a possible treatment at field-scale. According to our estimations, the system proposed is able to treat effectively an annual total volume of 11.6 hm3, which is equivalent to a mean discharge of 368 L/s. Green liquor dregs alone would be able to treat 86% of the total volume. This result demonstrates the possibility of using alkaline paper mill wastes for treatment and restoration of worldwide natural resources extremely contaminated by AMD such as the IPB.

Nanofiltration of Acid Mine Drainage

Acid mine drainage (AMD) is recognized as one of the more critical environmental problems in the mining industry, with the potential of severe contamination of surface and groundwater, as well as soils. Different conventional methods are used to treat AMD such as lime neutralization, in which lime is added to AMD to raise pH and then precipitate the dissolved toxic heavy metals. In addition to a high concentration of sulphate, the sludge produced by this process has no economic value and has to be disposed of in large areas of land. Nanofiltration (NF) membranes are a new alternative method employed to treat AMD in this work. First, neutralization of AMD collected from the copper mine in Chile using both sodium hydroxide and lime will be investigated to find the optimum formed sludge. Then, three commercial NF membranes (NF99, DK, GE) have been used to filter AMD at two different pressures of 20 and 30 bar and at two different concentrations. The results showed that NF membranes successfully treated AMD w...

Neutralization of acid mine drainage using the final product from CO 2 emissions capture with alkaline paper mill waste

In this study, experiments were conducted to investigate the applicability of low-cost alkaline paper mill wastes as acidity neutralizing agents for treatment of acid mine drainage (AMD). Paper wastes include a calcium mud by-product from kraft pulping, and a calcite powder from a previous study focused on sequestering CO 2 by carbonation of calcium mud. The neutralization process consisted of increase of pH by alkaline additive dissolution, decrease of metals solubility and precipitation of gypsum and poorly crystallized Fe–Al oxy-hydroxides/oxy-hydroxysulphates, which acted as a sink for trace elements to that extent that solutions reached the pre-potability requirements of water for human consumption. This improvement was supported by geochemical modelling of solutions using PHREEQC software, and observations by scanning electron microscope and X-ray diffraction of reaction products. According to PHREEQC simulations, the annual amount of alkaline additive is able to treat AMD (pH 3.63, sulphate 3800 mg L −1, iron 348 mg L −1) with an average discharge of about 114 and 40 L s −1 for calcium mud and calcite powder, respectively. Likewise, given the high potential of calcium mud to sequester CO 2 and of resulting calcite powder to neutralize AMD, paper wastes could be a promising solution for facing this double environmental problem.

Efficient metal removal and neutralization of acid mine drainage by crab-shell chitin under batch and continuous-flow conditions

Crab-shell chitin was evaluated as a multifunctional substrate for treating acid mine drainage (AMD) in both batch-microcosms and continuous-flow column tests. In microcosms, crab-shell chitin was able to treat AMD from three different sites with similar results: pH increased from 3.5 to ∼7.5 within 2 days; alkalinity increased at a rate of 37.9 ± 2.2 mg CaCO 3/L day; and sulfate was reduced at a rate of - 13.6 ± 2.6 mg SO 4 2 - / L day . In columns, a hydraulic retention time of 11.2 h was enough to raise the pH from 3.5 to ∼7.5. Alkalinity increased at a rate of 50 ± 20 mg CaCO 3/day, and lasted throughout the duration of the test (125 days, 268 pore volumes (PV)) without showing signs of exhaustion. Metals (Al, Fe, and Mn) were completely removed for 171 PV, and geochemical modeling indicates that they likely precipitated as insoluble hydr(oxides), sulfides, and carbonates. Manganese and iron breakthroughs occurred after 174 and 234 PV, respectively, whereas aluminum breakthrough was never observed. These results demonstrate for the first time that crab-shell chitin can completely remove metals and neutralize the pH of AMD under continuous-flow conditions.

Preliminary Study of Neutralization and Inhibition of Chemolitotrophic Bacteria in an Acid Mine Drainage from Rio Tinto Site

Limestone is commonly used for neutralization of acid mine drainage (AMD). Its main advantages are its lower price, sustained generation of alkalinity and production of low sludge volumes. Nevertheless, armouring of limestone by ferric hydroxides is a problem in oxic limestone drains and in active limestone treatment systems, reducing the efficiency of the process. Due to these disadvantages, there is a permanent search for cheaper and more effective neutralization agents. Many alkaline industrial wastes are gaining importance in the treatment of AMD. The possibilities to use two different industrial by-products, red mud from a bauxite exploitation and low grade magnesium hydroxide from a magnesite mine, as neutralizing and bacterial inhibiting agents, and the comparison with conventional limestone treatment has been studied in this paper. An AMD from Rio Tinto mine site with an initial pH of 2.4 and a ferric concentration of 1 g/L was used. Comparative test were done percolating the AMD in a continuous form with a peristaltic pump through three different columns filled with limestone, red mud and low grade magnesite, during one month and in same conditions of flow rate and amount of each compound used to fill the columns. The evolution of pH, iron and heavy metals, sulphates and microbial populations in the percolate were monitored at different times. The results showed that the best neutralization capacity was obtained with low grade magnesite during the month treatment. By contraire limestone and red mud loosed their neutralization capacity after 10 and 13 days respectively. The control of microbial populations showed that there is an inhibition of chemolithotropic bacteria as long as the materials maintain their neutralization capacity, reverting to the initial conditions when this capacity was loosed.

Removal of phosphorus from agricultural wastewaters using adsorption media prepared from acid mine drainage sludge

Excess phosphorus in wastewaters promotes eutrophication in receiving waterways. A cost-effective method for the removal of phosphorus from water would significantly reduce the impact of such wastewaters on the environment. Acid mine drainage sludge is a waste product produced by the neutralization of acid mine drainage, and consists mainly of the same metal hydroxides used in traditional wastewater treatment for the removal of phosphorus. In this paper, we describe a method for the drying and pelletization of acid mine drainage sludge that results in a particulate media, which we have termed Ferroxysorb, for the removal of phosphorus from wastewater in an efficient packed bed contactor. Adsorption capacities are high, and kinetics rapid, such that a contact time of less than 5 min is sufficient for removal of 60–90% of the phosphorus, depending on the feed concentration and time in service. In addition, the adsorption capacity of the Ferroxysorb media was increased dramatically by using two columns in an alternating sequence so that each sludge bed receives alternating rest and adsorption cycles. A stripping procedure based on treatment with dilute sodium hydroxide was also developed that allows for recovery of the P from the media, with the possibility of generating a marketable fertilizer product. These results indicate that acid mine drainage sludges – hitherto thought of as undesirable wastes – can be used to remove phosphorus from wastewater, thus offsetting a portion of acid mine drainage treatment costs while at the same time improving water quality in sensitive watersheds.

Predicting the neutralisation of acid mine drainage in anoxic olivine drains

The precipitation of gypsum within anoxic limestone drains subjected to very acidic and sulphate rich acid mine drainage is a problem that can be prevented by initial neutralisation of the drainage using magnesium-rich olivine. The applicability of this concept is limited to the low pH region (i.e. pH < 3) where gypsum precipitation is a potential problem and the olivine dissolution rate is sufficiently fast to be of practical importance. This paper presents a simple finite element model for predicting the performance of olivine drains with respect to the neutralisation of highly acidic solutions under anoxic conditions and low pH. The model is based on the kinetic rate expression for olivine dissolution and the sulphuric acid dissociation equilibrium. To test the model, a series of column experiments were conducted in which olivine sand (0.1–1 mm) was subjected to different solutions of dilute sulphuric acid (0.0025–0.01 M) that was pumped through the column at various flow rates. For practical purposes the synthetic solutions contained no iron. The steady-state effluent pH obtained from each experimental run was used to calculate the relative amount of neutralisation. The neutralisation process, as expressed by the relative neutralisation values, was adequately described by the simple prediction model.

Passive neutralisation of acid mine drainage by fly ash and its derivatives: A column leaching study

Active treatment of acid mine drainage using fly ash (FA) generates solid residues. This work investigated the suitability of using the solid residues (SR) generated from the process for passive treatment of acid mine drainage in a backfill set-up. A column leaching study of the solid residues blended with varying amounts of fly ash (5%, 25%, 40%) and 6% ordinary portland cement (OPC) and fresh fly ash was carried out to assess the neutralisation and contaminants attenuation in AMD with time. All the solid cores acidified in a stepwise fashion, exhibiting three buffer zones (12–10, 9–7.5 and 6–4). Dissolution of CaO in fly ash and solid residues blended with fly ash impacted high pH in the initial leachates while hydrations reactions in OPC blend solid residues contributed to high initial pH. Dissolution of SiO 2(amorphous) and mullite in the solid residues contributed to sustain buffering at pH 7–9.5 for SR and FA blended solid residues. Encapsulation of the solid residue particles by the calcium silicate hydrate gels (CSH) in OPC blended solid residues reduced interaction of particles with SAMD hence the buffering at pH 7–9.5 was not observed. Eventual clean-up of the AMD for all solid cores was dependent on the increase of the pH to alkaline and circum-neutral levels and sustainability of the buffering capacity at circum-neutral pH. It is hypothesized that the duration of the effectiveness of generation of alkalinity and AMD clean-up by the solid residues will greatly depend on the quality of the AMD percolating through. The SR and SR + 6% OPC were observed to be superior in removal of Al, Fe and SO 4 2 - compared to FA and SR + 25% FA. Lowest efficiency was observed in FA and SR + 25% FA cores for all contaminants except for Mn in FA core. This study shows that the solid residues (SR) can successively generate alkalinity over an extended period of time and passively treat AMD. This has positive implications upon the application of the solid residues for backfilling of mine voids. Different solid cores exhibited varying degrees of leachability for various toxic elements. B was the most leached element and the leaching was more pronounced in the SR and SR + FA blends. The SR + OPC core was observed to be superior in retention of Mo and B. Calculation of % toxic trace elements leached based on total composition from XRF data indicated insignificant amounts are leached over the experimental period for SR core. However the pH regime generated will depend on backfill scenario which in-turn will dictate the extent of leaching of toxic trace elements. It is recommended that more studies be carried out on the leachability of the toxic trace elements on a long-term basis before suitability of the SR and SR + FA blends can be fully evaluated.

Effects of Soluble Ferri−Hydroxide Complexes on Microbial Neutralization of Acid Mine Drainage

Heterotrophic respiration of ferric iron by Acidiphilium cryptum was investigated in anoxic microcosms with initial media pH values from 1.5 to 3.5. No organic carbon consumption or iron reduction was observed with an initial pH of 1.5, indicating that A. cryptum may not be capable of iron respiration at this pH. Significant iron reduction was observed at pH 2.5 and 3.5, with different effects. When the initial pH was 3.5, pH increased to 4.7-5.5 over 60 days of incubation with simultaneous production of 0.4 g L(-1) Fe2+. However, at an initial pH of 2.5, no significant change in pH was observed during iron respiration, although the accumulation of soluble ferrous iron was significantly higher, averaging 1.1 g L(-1) Fe2+. The speciation of the ferric iron electron acceptor may explain these results. At pH values of 3.5 and higher, precipitated ferric hydroxide Fe- (OH)3 would have been the primary source of ferric iron, with reduction resulting in net production of OH- ions and the significant increases in media pH observed. However at pH 2.5, soluble complexes, FeOH2+ and Fe(OH)2+, may have been the more prevalent electron acceptors, and the alkalinity generated by reduction of complexed iron was low. The existence of charged ferri-hydroxide complexes at pH 2.5 was verified by voltammetry. Results suggest that initiation of bacterial iron reduction may result in neutralization of acid mine drainage. However, this effect is extremely sensitive to iron speciation within a relatively small and critical pH range.

酸化マグネシウムによる坑廃水中和処理殿物のフェライト化に関する研究

To reduce the volume of precipitates generated by the neutralization of acid mine drainage (AMD) containing high concentrations of Fe and As, ferritization of the precipitates was attempted by a two-step neutralization process in which magnesium oxide (MgO) was used as the first neutralizer and sodium hydroxide (NaOH) as the second. Batch neutralization experiments with MgO and continuous flow experiments by the two-step neutralization were conducted in laboratories and an AMD treatment plant. The results showed that the precipitates by the neutralization were magnetized in the continuous flow experiments, although there was Al and Si that prevented the generation of ferrite in the AMD. This indicates that ferrite was formed from the precipitates after removing most of the soluble Al and Si by the first neutralization. In addition, aging of the precipitates under reducing conditions and returning the aged precipitates to a ferrite tank were required to form ferrite. The molar ratio of As to Fe in the precipitates reached a constant value at pH>3.5. This suggests the coprecipitation of As and Fe.

04/00487 Neutralisation of acid mine drainage with alkaline industrial residues: laboratory investigation using batch-leaching tests: Doye, I. and Duchesne, J. Applied Geochemistry, 2003, 18, (8), 1197–1213.

04/00487 Neutralisation of acid mine drainage with alkaline industrial residues: laboratory investigation using batch-leaching tests: Doye, I. and Duchesne, J. Applied Geochemistry, 2003, 18, (8), 1197–1213.

Neutralisation of acid mine drainage with alkaline industrial residues: laboratory investigation using batch-leaching tests

This study constitutes a first stage of the elaboration of a concept for setting up capillary barriers composed of reactive tailings and alkaline industrial wastes. The aim of this barrier is (1) short-term mitigation by neutralising acid produced by Fe sulfides and (2) long-term mitigation by stabilisation of secondary products. The alkaline industrial wastes, cement kiln dust (CKD) and red mud bauxite (RMB), are used to produce neutral conditions. A series of time-controlled static leaching experiments were performed. Samples of reactive tailings were prepared containing 0, 2, 5, and 10% alkaline material. The water:solid ratios were also varied (3:1, 6:1, and 20:1) in order to characterise the geochemical balance between liquid and solid phases. The data are used to discern whether mineral solubility controls exist for particular ions. The pH results show that the use of 5% CKD, 10% CKD and 10% (CKD+RMB) allows neutral pH conditions to be maintained in the reactive layer. At these percentages, the concentrations of Al, Fe, Cu, Zn and SO 4 in solution are significantly reduced compared with those obtained with the reactive tailings only. Aluminum concentrations are principally controlled by secondary phases like boehmite and gibbsite; Fe, by goethite and ferrihydrite; Cu and Zn, by hydroxides. Calcium and SO 4 concentrations are controlled by precipitation of gypsum. The concentrations of Na and K are found not to be controlled by mineral solubility.

Seasonal change of mineral precipitates from the coal mine drainage in the Taebaek coal field, South Korea.

The seasonal change of the precipitates from the acid coal mine drainages is remarkable in the Taebaek coal field in the middle eastern part of the Korean peninsula. The mineral precipitates in the creeks show various colors such as brownish yellow, white, and reddish brown, depending on the chemical conditions of stream waters. The brownish yellow precipitate consist maily of schwertmannite, the white one of poorly crystalline Al-sulfate, and the reddish brown one of ferrihydrite. Neutralization of acid mine drainage took place by mixing with unpolluted waters and/or buffering by dissolution of carbonate or aluminosilicates. The main factors leading to the seasonal change of precipitates are precipitation of hydroxide mineral, water mixing from adjacent unpolluted branch streams, and water-rock interaction.

Neutralization of acid mine drainage by Turkish lignitic fly ashes; role of organic additives in the fixation of toxic elements

AbstractLignitic fly ashes from two power plants in western Turkey were employed to neutralize the Acid Mine Drainage (AMD) effluents originating from a pyritic ore from northern Turkey. The AMD was rich in heavy metals with a pH of about 2. The fly ash samples, on the other hand, showed strong alkalinity when mixed with water. The product was an aggregate with basic reactivity in most cases. The fly ashes were able to neutralize large amounts of AMD. When the aggregate was placed in water, notable leaching of toxic metals into solution was observed. When an organic additive, waste motor oil in this case, was added during the mixing step, the leaching of metals into water from the resulting aggregate was practically zero.© 2002 Society of Chemical Industry

Pyrite microencapsulation technologies: Principles and potential field application

In nature, pyrite is initially oxidized by atmospheric O 2, releasing acidity and Fe 2+. At pH below 3.5, Fe 2+ is rapidly oxidized by T. ferrooxidans to Fe 3+, which oxidizes pyrite at a much faster rate than O 2. Commonly, limestone is used to prevent pyrite oxidation. This approach, however, has a short span of effectiveness because after treatment the surfaces of pyrite particles remain exposed to atmospheric O 2 and oxidation continuous abiotically. Currently, a proposed mechanism for explaining non-microbial pyrite oxidation in high pH environments is the involvement of OH − in an inner-sphere electron–OH exchange between pyrite/surface-exposed disulfide and pyrite/surface-Fe(III)(OH) n 3−n complex and/or formation of a weak electrostatic pyrite/surface-CO 3 complex which enhances the chemical oxidation of Fe 2+. The above infer that limestone application to pyritic geologic material treats only the symptoms of pyrite oxidation through acid mine drainage neutralization but accelerates non-microbial pyrite oxidation. Therefore, only a pyrite/surface coating capable of inhibiting O 2 diffusion is expected to control long-term oxidation and acid drainage production. The objective of this study was to examine the feasibility in controlling pyrite oxidation by creating, on pyrite surfaces, an impermeable phosphate or silica coating that would prevent either O 2 or Fe 3+ from further oxidizing pyrite. The mechanism underlying this coating approach involves leaching mine waste with a coating solution composed of H 2O 2 or hypochlorite, KH 2PO 4 or H 4SiO 4, and sodium acetate (NaAC) or limestone. During the leaching process, H 2O 2 or hypochlorite oxidizes pyrite and produces Fe 3+ so that iron phosphate or iron silicate precipitates as a coating on pyrite surfaces. The purpose of NaAC or limestone is to eliminate the inhibitory effect of the protons (produced during pyrite oxidation) on the precipitation of iron phosphate or silicate and to generate iron-oxide pyrite coating, which is also expected to inhibit pyrite oxidation. The results showed that iron phosphate or silicate coating could be established on pyrite by leaching it with a solution composed of: (1) H 2O 2 0.018–0.16 M; (2) phosphate or silicate 10 −3 to 10 −2 M; (3) coating-solution pH ≈5–6; and (4) NaAC as low as 0.01 M. Leachates from column experiments also showed that silicate coatings produced the least amount of sulfate relative to the control, limestone and phosphate treatments. On the other hand, limestone maintained the leachate near neutral pH but produced more sulfate than the control.

PHYSIOLOGICAL AND BEHAVIORAL RESPONSES OF STONEFLY NYMPHS TO ENHANCED LIMESTONE TREATMENT OF ACID MINE DRAINAGE

A new acid mine drainage (AMD) treatment system uses pulsed, fluidized beds of limestone, and carbon dioxide pretreatment of influent AMD, to enhance limestone neutralization of AMD. We conducted laboratory studies to evaluate the behavior and physiology of larval stoneflies ( Pteronarcys proteus, Plecoptera) exposed to effluents produced by the treatment system. Survival, sodium balance, drift, and feeding responses by P. proteus to treated and untreated AMD were examined. P. proteus nymphs exhibited significant losses of whole body sodium in exposures to untreated AMD. Nymphs exposed to treated effluents experienced no loss of whole-body sodium. Nymphs exposed to untreated AMD showed elevated drift rates and depressed feeding rates relative to those of nymphs exposed to treated AMD, and to AMD-free controls. No significant differences in feeding or drift behavior occurred between nymphs exposed to treated effluents and those exposed to AMD-free controls. The treatment system, with and without CO 2 pretreatment, provided water that was not toxic to the test animals, and that allowed normal behavioral and physiological function.

Tests of Organic Matter Additions for the Neutralization of Acid Mine Drainage Influenced Lakes

Tests of Organic Matter Additions for the Neutralization of Acid Mine Drainage Influenced Lakes