Search

In early 2010, American Recovery and Reinvestment Act funds were available to implement the "shovel-ready" design package for a biochemical reactor (BCR) module that was planned at the abandoned Golinsky Mine site in northern California. The design was based on bench and pilot studies that were documented in previous ASMR papers. The construction site, located near Lake Shasta, is only accessible by boat followed by a 1.6 km (1-mile) trip on a narrow dirt road. During construction, the typically restricted site access was further complicated by the highest lake levels in years which required the relocation of the construction contractor's mobilization site. The construction of the BCR within the footprint of an abandoned limestone quarry required a few minor design modifications. However, the logistics of moving about 1,000-plus tons of organic substrate, drainage gravel, HDPE liner, rip rap, pipes, plus construction equipment safely across Lake Shasta in a coordinated barge and ground transportation program was probably the greatest project accomplishment. The commissioning of the pilot treatment bioreactor in mid-2004 resulted in the drain-down of an acidic mine pool. This action appears to have caused significant improvements in the drainage chemistry of a mine adit adjacent to, but not directly connected to the acidic mine pool. This unintentional outcome allowed the use of the improved mine water source for fire suppression, dust control, and moisture control in earthwork compaction efforts.

Anaerobic passive treatment systems remediating high-strength mine influenced water (MIW) have failed to consistently treat sources with high metals loads and flow rates. For example, the high iron (140 mg/L) and acidity (390 mg/L as CaCO3) of the Klondike-1 discharge near Ashville, PA, caused premature clogging of a vertical flow pond which was filled with a limestone buffered organic substrate (90% spent mushroom compost (SMC) and 10% limestone chips). In this study, continuous-flow columns and pilot-scale field reactors were used to evaluate if treatment of high-strength MIW can be improved using crab shell as a substrate amendment. For the lab study, eight columns were wet-packed with substrate mixtures ranging from 0 - 100% crab shell (with the balance SMC), and fed Klondike-1 water to produce a 16 hr hydraulic residence time (HRT). After determining the best performing substrate mixture in the column test, a pilot-scale field study was initiated in August 2010, in which 1,000 gallon (3,785 L) tanks were filled with a limestone underdrain and an upper substrate layer of: 1) 100% crab shell; 2) 70% crab shell + 30% SMC; or 3) 90% SMC + 10% limestone. A fourth tank containing a sandstone underdrain with a 70% crab shell + 30% SMC substrate layer was installed to determine if similar performance could be achieved without the limestone underdrain. All columns and field reactors also contained sand as a proppant to ensure hydraulic conductivity. Aqueous samples were collected from the columns/reactors over time and analyzed for pH, ammonium, acidity, alkalinity, DOC, anions, and metals. In the column study, an optimum ratio of 70% crab shell + 30% SMC sustained complete iron removal, pH above 5.0, and excess alkalinity generation for twice as long as the traditional SMC and limestone substrate. To date, the field study is still achieving complete iron removal, and other results generally mirror the laboratory findings.

Water chemistry was monitored monthly for ten months from an acid mine drainage (AMD) seep emanating at Stockton Coal Mine within the Mangatini watershed in New Zealand. Metal concentrations of the seep water were Fe (4.31-146 mg/L), Al (7.43-76.7 mg/L), Cu (0.0201-0.0669 mg/L), Ni (0.0629-0.261 mg/L), Zn (0.380-1.39 mg/L), Cd (0.000540-0.00134 mg/L) and Pb (0.0049-0.0056 mg/L), pH was 2.49-3.34 and total acidity (pH 8.3) was 78.5- 626 mg/L as CaCO3. Water chemistry signature prompted laboratory mesocosm studies measuring the effectiveness of sulfate-reducing bioreactors (SRBRs) for generating alkalinity and sequestering metals. Alkaline materials utilized in the SRBRs included industrial waste products such as mussel shells, nodulated stack dust (NSD) derived from the cement industry, and limestone. Organic substrate materials included post peel, a by-product from fence post manufacture, Pinus radiata bark and compost. Seven SRBRs comprised of varying substrate mixes received aerated AMD for nearly four months. AMD was sourced from the pond that collected the seep water. The SRBR containing NSD successfully removed all metals, but effluent was caustic with pH>9. Bioreactors consisting of 20-30% mussel shells were most successful at immobilizing metals and generating circumneutral effluent. Systems containing mussel shells sequestered more than 0.8 moles of metals/m 3 of substrate/day at stable operating conditions and yielded effluent concentrations (removal efficiencies) of 0.120-3.46 mg/L Fe (96.5-99.8%), 0.0170-0.277 mg/L Al (99.5-99.9%), 99.7->99.9%), 99.7%), 98.3->98.9%) and

UAbstract:U Water treatment is often required at active and inactive mine sites to remove heavy metals and other contaminants of concern (COCs) prior to discharging water. Traditional water treatment can be expensive and impractical at some sites due to excessive energy, manual labor, and operations and maintenance (O&M) requirements. Passive treatment has emerged as a way to treat such waters inexpensively by requiring minimal amounts of O&M and little to no external energy. One form of passive treatment technology that has been developed over the last twenty years is the biochemical reactor (BCR), also known as a sulfate reducing bioreactor (SRBR). As its name would suggest, a BCR treats water by way of biological and chemical reactions. A BCR uses a combination of organic substrate materials and microbial activity to remove heavy metals, remove other COCs, and stabilize pH in mining influenced water (MIW). Additionally, a BCR adds hardness, alkalinity, and organic matter to the MIW, all of which are beneficial to overall water quality and aquatic life.

Soudan State Park contains Minnesota's first iron mine and offers tours through parts of the old underground mine workings. The mine began in 1884 as an open pit before switching to an underground operation in 1892. U.S. Steel operated the mine from the 1920's until it closed in 1962. The average mine dewatering discharge is around 60 gallons per minute and contains copper and cobalt in excess of the permit standards of 0.020 mg/L copper and 0.005 mg/L cobalt. Annual average concentrations have varied from 0.083 to 0.5 mg/L copper and 0.006 to 0.026 mg/L cobalt. Despite at least 60 years of discharge, all the copper and cobalt are removed in about a 5-acre portion of a downstream wetland. Copper concentrations in the peat ranged from around 100 to 3380 mg/kg, and cobalt from 20 to 260 mg/kg. Both metals are strongly bound to the peat; less than 0.5% was removed in laboratory extraction tests About 94% of the total copper and 44% of the total cobalt come from one area in the mine. In 1998, DNR proposed to treat this water in an organic substrate/ limestone bed. Remaining low levels of metals in the mine discharge would be removed within the 5 acres of the wetland that already had elevated concentrations. To compensate for the use of the wetland, an equivalent area of wetlands would be restored in a state park in the southern part of the state. This proposal was approved in 1999 and the wetland mitigation was completed. Despite having approval, land ownership issues and some internal reluctance about using a natural wetland stalled construction. In 2002, the Department signed a compliance agreement and installed an ion exchange unit to remove the majority of metals from the largest source. As soon as the unit was installed, a white precipitate appeared in the inflow water and plugged the unit. In 2006, the Department was fined and signed a stipulation agreement. The current proposal is to construct a wetland at the park to treat the entire mine flow. The estimated cost for this proposal is about 4-5 times the original treatment plan developed in 1998.

The barite is mined from the opencast mine and waste overburden is removed and dumped in the nearby areas. The dumps are invariably associated with pockets of soil/carbonaceous tuff overburden or waste rock incorporated into the tailings. The disintegrated soils, the rock waste and tailings are often very unstable and become sources of pollution. Prosopis juliflora is extensively and exclusively developed on these mine tailings. Leaves and twigs of Prosopis juliflora along with their soil samples were analysed for mineral elements viz., Ba, Sr, Mn, B, Cu, Zn, Pb, Ni, Co and Cr. Huge amounts of Ba, Sr, B, Cu, Pb and Zn have been accumulated in both the organs of this plant. Further, this study has given greater scope on the plant-soil relationship in the mining area and their significance in environmental studies. The existence of plants on the mine wastes and metal contaminated soil led to the belief that metal tolerant species grow by natural selection. The biological absorption coefficient (BAC) is used to characterize the absorption of chemical elements by plants from their substrate. The ubiquitous thorny shrub Prosopis juliflora has an extraordinary ecologic amplitude and tolerance for a variety of elements. Hence, it is envisaged that this plant species can be used for reclaiming the tailings in barite mining area of Mangampeta for the purpose of stabilizing the area. Additional

A limestone-buffered organic substrate (LBOS) is used to passively remove iron (140 mg·L -1 ) and aluminum (85 mg·L -1 ) from low pH (

A pilot scale field test on passive treatment systems for metal and sulfate removal from ground water and surface runoff, is being conducted in Butte, Montana. This study is a collaborative effort between Montana Tech and the Atlantic Richfield Company (ARCO) to find solutions for treating metal contaminated water (e.g. Cu, Zn, Cd, and Fe). The field demonstration systems include anaerobic horizontal flow gravel bed wetlands with plants, horizontal flow gravel/organic substrate wetlands with plants, and vertical upflow gravel/organic substrate system without plants. The experimental design for sulfate and metal removal will be presented as well as the hydraulic design criteria used. Results from this test will be used to estimate system economics, long term performance and the life expectancy for these systems. Studies on mesoscale passive treatment systems such as 1.5 in high vertical upflow gravel/organic substrate columns are also presented. The parameters describing system performance are: hydraulic conductivity, volumetric sulfate-reduction rate, and metal immobilization rate.