The use of limestone, lime and MnO 2 in the removal of soluble manganese from acid mine drainage (original) (raw)

The Application of MnO2 in the Removal of Manganese from Acid Mine Water

Water, Air, & Soil Pollution, 2013

In recent years, much attention has been devoted in developing inexpensive or alternative systems for treating acid mine drainage (AMD). Manganese is a common component of AMD, and it is traditionally removed by precipitation. However, in order to meet the standard limits for discharging, usually <1 mg L −1 , it is necessary to raise the pH above 10 which implies in high consumption of reagents and a final pH that does not meet the required value for discharging. This study investigated the removal of manganese from an acid mine effluent and laboratory solutions by using an industrial residue consisted of manganese dioxide (MnO 2). The pH of the acid effluent is around 2.7, and the manganese concentration is approximately 140 mg L −1. Batch experiments assessed the influence of pH and the efficiency of manganese dioxide (MnO 2) in the Mn +2 removal. In the presence of MnO 2 , the metal concentration meets the discharging limit at pH range of 6.8 to 7.2. Experiments carried out with columns packed with MnO 2 assessed the influence of the flow rate on the process. Best results were obtained for columns fed with mine water neutralized with limestone at pH 7.0 and a residence time of 3.3 h. The maximum manganese loading capacity for MnO 2 was around 14 mg g −1. RAMAN spectroscopy showed that the MnO 2 is essentially constituted of pyrolusite. In addition, the solid hausmannite (Mn 3 O 4) was observed on the surface of the MnO 2 residue after its contact with the Mn +2 solution.

Treatment of mine water to remove manganese

1985

Typical acid mine water contains 1-8 mg/L Mn, but concentrations of 50-100 mg/L are not uncommon. At present, most mine operators with manganese problems use excess alkalinity to raise the pH of water to 10 or higher to facilitate manganese oxidation and precipitation. Excess alkalinity, although it increases treatment costs 20-100 pct, was determined by the Bureau of Mines to be less expensive than NaOCl and KMnO/sub 4/ (chemical oxidants). However, laboratory tests indicate that the manganese precipitated by excess alkalinity is easily resolubilized, while that produced by the oxidizing agents is relatively stable. The Bureau also studied two novel approaches to the manganese problem. One was an inexpensive pipeline treatment system device known as the ILS, which was developed by the Bureau to aerate and neutralize mine water. At three mines with influent Mn concentrations of 10-68 mg/L, use of the ILS reduced Mn concentrations to less than mg/L at pH values of only 6.8-7.3. Anoth...

Chemical and biological approach to remove Mn from aqueous solution

Environmental Technology & Innovation, 2019

Many approaches have been proposed to remove manganese from public supply waters as well as from acid mine drainage. This study investigated the removal of high levels of soluble Mn (II), similar to forms found in acid mine drainage in Brazil, by using a manganese oxide (MnO2) residue from the electrowinning process and a Bacillus cereus strain isolated from mine water, immobilized or not in calcium alginate. Experimental data for manganese removal by MnO2 showed that a pseudo-second-order kinetic model conformed well to the equilibrium adsorption data and the Langmuir isotherm was suitable to describe this adsorption process. Thermodynamic analysis showed that the adsorption of Mn (II) using MnO2 was spontaneous and endothermic under the experimental conditions. The manganese removal by Bacillus cereus was 75% and by the MnO2 residue was 96% at the end of nine days. The removal using MnO2 and Bacillus cereus together reached 96%. Immobilization of MnO2 and Bacillus cereus using alginate biopolymer was also investigated. After nine days, the removal by Bacillus cereus reached 93% and Bacillus cereus + MnO2 reached 92%, both immobilizing in alginate. The immobilization promoted fewer changes in pH, which ranged from 7.5 to 8.5 during the experiments. The use of MnO2 alone or the use of Bacillus cereus immobilized in alginate are two interesting alternative to remove high levels of manganese, however, only the last alternative is capable of maintaining an alkaline pH necessary to the process.

Manganese removal in groundwater treatment: practice, problems and probable solutions

Water Supply, 2009

Most drinking water production plants use rapid sand filters for the removal of manganese from groundwater. The start-up of manganese removal on newly installed sand media is slow, taking several weeks till months. Reducing this period in order to prevent the loss of water during this phase has become an issue of concern. In this study pilot and bench scale experiments were conducted to investigate the mechanism, influence of operational conditions (e.g. filtration rate, manganese loading) and measures that enhance manganese removal capacity of the sand media. Other filter media were investigated with the objective of finding suitable substitutes for the sand. The development of the adsorptive/catalytic coating the sand media in a pilot plant was very slow, notwithstanding the relatively high pH of 8. Low manganese concentration and more frequent backwashing resulted in a longer start up period of the manganese removal. It can not be excluded, that nitrite has a negative effect as w...

Treatment of manganese in acid and neutral mine drainage using modified dolomite

International Journal of Environmental Impacts: Management, Mitigation and Recovery

The treatment of manganese [Mn] in acid mine drainage (AMD) and neutral mine drainage (NMD) is prone to variation in performance, which depends on several factors, including pH, Mn and dissolved oxygen (DO) concentrations, catalysis by Mn-/iron [Fe]-solids, presence of ligands, and bacteria. Notwithstanding the recent technological and scientific advancements, Mn removal is notoriously difficult and still challenging because of its complex chemistry and high solubility. Precipitation of Mn(II), in AMD and NMD, occurs in the form of oxides, with prior oxidation to Mn(III) and Mn(IV), or as carbonates and sulphides. However, most treatment systems have limited efficiency in simultaneously treating Mn and other metals in AMD/NMD, necessitating secondary treatment for Mn removal. Modification of natural or residual materials was found efficient for the treatment of NMD. In this context, this study evaluated the performance of half-charred dolomite (1 h at 750°C) in batch testing (solid: liquid ratio of 3 g:400 mL) for Mn treatment in AMD and NMD. Results showed that modified dolomite treated more than 98% Mn in synthetic NMD (pH 6.1-6.3, up to 1 g/L Mn), at final pH of 9.7-10.6. Similar efficiency (98%) in Mn removal was also found for synthetic AMD (pH 3.6, up to 100 mg/L Mn and 1 g/L Fe, Mn:Fe molar ratio 1:10), while Fe was completely treated, at final pH of 9.7-9.8. In addition, Mn removal was 99.5% within the first 2 h (when pH increased to 8.0), while after 4 h, the efficiency was up to 99.9% (at final pH of 9.6). DO also decreased (from 8 to 2.2 mg/L), at initial Mn concentrations of 1 g/L, and dropped (from 8 to 0.7 mg/L), when Fe concentrations increased to 1 g/L (Mn:Fe molar ratio 1:10). Based on these findings, half-charred dolomite seems a promising option for the treatment of Mn in both AMD and NMD.

A Review on Studies and Research on Manganese Removal

http://ijshr.com/IJSHR\_Vol.1\_Issue.2\_April2016/IJSHR006.pdf, 2016

Water treatment is one of the key areas in the pollution engineering. Removal of organic and inorganic matter is essential for environmental conservation. Various conventional treatment techniques include physical, chemical and advanced treatment processes. The removal of metal ions from wastewater is widely investigated research area. Manganese and iron are two such heavy metals. Manganese removal is difficult because of its high solubility. Various chemical and biological methods can be used for manganese removal. These methods include biosorption, adsorption, biological methods, chemical methods and precipitation. Current review summarizes research and studies on manganese removal.

Oxidative Precipitation of Manganese from Dilute Waters

Mine Water and the Environment, 2016

Various metals may be removed from mine water by precipitation of their hydroxides. However, over the pH range of 7-9, it is more efficient to oxidize Mn II to Mn IV than to precipitate Mn II as its hydroxide. Chlorine (or hypochlorite) can be used to do this, but its use may not be appropriate for mine waters that will be recycled as process solutions or discharged into a receiving body. Consequently, there has been interest in reducing chlorine use or its total replacement by non-chlorinated oxidants, such as oxygen and peroxygens, for treatment of mine water. In this work, we report the results of a comparative investigation of the following oxidants: NaClO (as reference), O 2 ; H 2 O 2 ; Caro's acid (H 2 SO 5), and the combination of H 2 O 2 with NaClO, with initial [Mn] = 10 mg/L, at 25°C, with 100 and 300 % excess oxidant above the stoichiometric requirement. It was found that the reaction pH has to be greater than 8 to obtain effective precipitation. It is possible to reach a final [Mn] below 1.0 mg/L in 60 min of batch reaction time, using either NaClO, Caro's Acid, or a combination of NaClO ? H 2 O 2. Using only O 2 or H 2 O 2 was ineffective.

Significance of MnO2 Type and Solution Parameters in Manganese Removal from Water Solution

International Journal of Molecular Sciences

A very low concentration of manganese (Mn) in water is a critical issue for municipal and industrial water supply systems. Mn removal technology is based on the use of manganese oxides (MnOx), especially manganese dioxide (MnO2) polymorphs, under different conditions of pH and ionic strength (water salinity). The statistical significance of the impact of polymorph type (akhtenskite ε-MnO2, birnessite δ-MnO2, cryptomelane α-MnO2 and pyrolusite β-MnO2), pH (2–9) and ionic strength (1–50 mmol/L) of solution on the adsorption level of Mn was investigated. The analysis of variance and the non-parametric Kruskal–Wallis H test were applied. Before and after Mn adsorption, the tested polymorphs were characterized using X-ray diffraction, scanning electron microscope techniques and gas porosimetry analysis. Here we demonstrated the significant differences in adsorption level between MnO2 polymorphs’ type and pH; however, the statistical analysis proves that the type of MnO2 has a four times ...

Removal of manganese from water supplies intended for human consumption: a case study

Desalination, 2007

In the Volcano Etna area (Sicily) a substantial part of groundwater, used for potable purpose, has concentrations of metals (vanadium, iron and manganese) higher than the maximum contaminant levels (MCLs) set by European and National regulations (European Directive 98/83 and D.Lgs. 31/2001). Specifically, high levels of manganese, up to 1810 µg/l, significantly exceeding the maximum contaminant level (MCL = 50 µg/l), were detected in groundwaters currently used as drinking water supply upwelled from the Etna Volcano aquifer. The paper presents the results of the manganese removal process by potassium permanganate oxidation followed by flocculation, settling and filtration. Batch tests were carried out varying pH, oxidant doses and polyelectrolytes. Two different filters (35 µm and 0.45 µm mesh) were tested as a final step of the treatment. Significant removal (up to 95%) was achieved by addition of polyelectrolytes at pH 8.5, with a 0.5 stoichiometric dose of oxidant and final filtration through 35 µm mesh filter.

Removal of Mn(II) from the acid mine wastewaters using coal fired bottom ash

IOP Conference Series: Materials Science and Engineering

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