Mining Effluents Research Articles

An overview of the application of electrocoagulation for mine wastewater treatment.

One of the challenges of the twenty-first century is related to the discharge and disposal of mine effluents and wastewater resulting from mine dewatering, precipitation, and surface runoff in mines, especially acidic effluents that contain a variety of toxic and heavy metals and are the main sources of surface and groundwater pollution. Various physical, chemical, and biological methods have been developed and used to treat mine effluents. All proposed methods have their own disadvantages that make their use challenging. One of the new methods used for wastewater treatment is the electrical coagulation process, which has attracted the attention of researchers in recent years due to its advantages such as simplicity, environmental friendliness, and low cost. The present review focused on the applications of electrocoagulation for mine wastewater treatment as well as metals recovery. In addition, the main mechanisms, advantages, and weaknesses of electrocoagulation were reviewed.

“They polluted our cropfields and our rivers, they killed us”: Farmers’ complaints about mining pollution in the Katangese Copperbelt

The adverse impacts of mining industries on human health, local biodiversity, and food security are well-documented in the Katangese Copperbelt. However, farmers' perceptions of pollution and their struggles to obtain compensation for the externalities of mining industries are little addressed in scientific and public debates. Drawing on interviews with smallholder farmers, local civil society archives, oral histories, and analysis of satellite images, this article presents a case of farmers of Mulungwishi Valley whose fields and waterways were polluted by mining effluents. While 25% of respondent farmers argued that they had noticed pollution from the beginning of the 2000s, testimonies from civil society, customary authorities, and farmers concurred that the phenomenon has increased since 2010. Particularly between 2013 and 2014, the death of fish in the Mulungwishi River, the coloration of the water, the spread of mining effluents across the valley, and crop failure raised concerns and despair among farmers. Remarkable changes in land cover and use were noticeable. Since a joint impact assessment in 2014 by la Générale des Carrières et des Mines’ (Gécamines) experts and farmers, civil society unsuccessfully continued a struggle to obtain compensation for about 2570 farmers affected by pollution. Despite an absolute silence of the polluter, 88% of these farmers insisted on the depollution of the valley and were willing to accept, if it was offered, financial compensation of $US 2820 per farmer. The decade-long persistence of farmers in asserting these requests debunks the view of farmers as passive or not concerned about environmental pollution. This article will be helpful for stakeholders (victims and polluters) to find common ground when resolving this environmental issue that has resulted in socio-economic difficulties beyond the valley.

Industrial effluents of mining enterprises of the North Caucasus and water resources

Subject of research. The article is devoted to the problem of preserving the quality of the global water resources under the threat of its deterioration caused by industrial effluents polluting the hydrosphere. Research objective is to establish the patterns of changes in water resources state and carry out the ecological detailing of the mechanism for managing water quality and protecting water resources. Methods of research include the generalization and systematization of reported data and literature on the aquatic environment condition in the metallic ore mining regions and methods of mine effluents treatment, laboratory experiments on electrochemical treatment of mineralized effluents to restore their quality, recommendations for improving the management of the aquatic environment state. Research results and scope. A distinctive feature of the problem for regions with mountainous terrain is indicated. The surroundings of mining enterprises were ranked according to metal pollution. The research results on the effluents state at non-ferrous metallurgy facilities are presented. The results of research by the precipitation curve method are summarized. The laboratory experiment results are shown on electrochemical treatment of mineralized effluents and their quality restoration. The direction is indicated of improving the economic efficiency of effluents treatment by increasing by-products output. A technology with the generation of self-neutralizing agents is recommended. It has been established that in the case of heavy metal pollution, the extent of the pollution bubble is determined by the processes of chemicals mixing and dilution. Conclusions. The management of water resources quality and industrial effluents pollution prevention should begin with the establishment of patterns of change in their state as well as with the control mechanism detailing in mountainous terrain.

Phytoefficacy of Eicchornia crassipes (Mart.) Solms-Laub for aqua-remediation of hexavalent chromium in chromite mine effluent of South Kaliapani, Odisha, India.

A huge quantity of toxic hexavalent chromium (Cr-VI or Cr6+) was released into the environment through mine effluent at the South Kaliapani chromite mining area during different mining activities. The present in situ bioremediation approach was conducted to assess the remediation potential of a well-known aquatic weed water hyacinth (Eichhornia crassipes (Mart.) Solms-Laub) for attenuating Cr(VI) from mine wastewater. The study correlates the bio-concentration factors (BCF) of Cr with the reduction percentage. The percent reduction of Cr content in mine effluent was maximum (53.5%) at 100days after treatment (DAT) followed by 40.7% at 75 DAT after passage through 2000 sq. ft area covering four water hyacinth-populated (1350 plants) ponds. Reduction in Cr content of OMC discharged mine effluent varies with plant age as well as with the distance of passage. A constant increase in root biomass was recorded with increased passage distance and days of treatment of contaminated mine effluent. The plants could not survive after 125days of treatment but could show an increasing trend in shoot biomass up to 100 DAT. After 75days of treatment, it was noted that Cr concentration in roots decreased from 200 to 148ppm and from 76 to 21ppm in shoots after passage through the 2000sq.ft area at 100 DAT. Water hyacinth roots exhibit maximum Cr bioaccumulation at 75 DAT, whereas this was highest in shoots at 100 DAT.

Spatiotemporal evolution of U and Th isotopes in a mine effluent highly polluted by Acid Mine Drainage (AMD)

The spatiotemporal evolution of both U and Th isotopes in a mine effluent highly polluted by acid mine drainage (AMD) was evaluated. The acidic tributary, which born from the outflows of an abandoned sulfide mine, flows into the Odiel River. AMD comprises an important source of natural radionuclides, presenting concentrations of 238U and 232Th, two and four orders of magnitude higher, respectively, than the background values of surface continental waters. These natural radionuclides behave conservatively along the mine effluent (pH < 2.5) throughout the hydrological year. Under AMD conditions uranium is in the hexavalent state U(VI) and the main dissolved species are uranyl sulfate complexes. The polluted tributary has a significant impact on the Odiel River acidifying its waters during the low flow season and increasing up to one order of magnitude the activity concentrations of U and Th isotopes. U presented a conservative behavior in the Odiel River during the low flow season (pH ≈ 3), however it is removed from the liquid phase in the wet season (pH ≈ 6), probably due its coprecipitation/adsorption onto Al-phases. Th shows a high sensitivity to small increases of pH, and it is strongly coprecipitated/adsorbed with or onto Fe-oxyhydroxydizes in the river.

In situ modified nanocellulose/alginate hydrogel composite beads for purifying mining effluents.

Biobased adsorbents and membranes offer advantages related to resource efficiency, safety, and fast kinetics but have challenges related to their reusability and water flux. Nanocellulose/alginate composite hydrogel beads were successfully prepared with a diameter of about 3-4 mm and porosity as high as 99%. The beads were further modified with in situ TEMPO-mediated oxidation to functionalize the hydroxyl groups of cellulose and facilitate the removal of cationic pollutants from aqueous samples at low pressure, driven by electrostatic interactions. The increased number of carboxyl groups in the bead matrix improved the removal efficiency of the adsorbent without compromising the water throughput rate; being as high as 17 000 L h-1 m-2 bar-1. The absorptivity of the beads was evaluated with UV-vis for the removal of the dye Methylene Blue (91% removal) from spiked water and energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) elemental analyses for the removal of Cd2+ from industrial mining effluents. The modified beads showed a 3-fold increase in ion adsorption and pose as excellent candidates for the manufacturing of three-dimensional (3-D) column filters for large-volume, high flux water treatment under atmospheric pressure.

Removal of Heavy Metals from Industrial Acidic Effluents Using Electroless Plating

Acid mine drainage (AMD) is one of the biggest issues faced by the mining and mineral processing industries in terms of removing heavy metals from the effluents. The present study investigated the effects of glyoxylic acid, hydrazine and dimethylamine borane as reducing agents and the effect of using Ni, Fe, basic oxygen furnace slag (BOFS) and granulated blast furnace slag (GBFS) as seeding materials to remove metals from acidic effluents respectively. The experiments were conducted using acidic mine effluent in a 0.5 L batch reactor using different seeding materials and reducing agents respectively. The study is the first of its kind to examine and compare all four seeding materials using different reducing agents respectively. X-ray diffraction (XRD) patterns, scanning electron microscope (SEM), and a Fourier Transform Infrared (FTIR) spectrometer were used to analyse the seeding material before and after Electroless plating.. The study suggests that BOFS is a effective seed together with hydrazine reducing agent that yielded a 99.9% removal of Fe (III), whilst Ni and Fe powder failed to seed effectively. During reduction precipitation, nucleation and breakage were identified as the predominant particulate processes based on particle size distribution (PSD) evolution and its moments. There were significant mineral phases formed, such as bownmillerites Ca2(Al, Fe)2O5, which formed by replacing Si with Al and Fe in all tetrahedral coordinations between Al, Fe and Si, suggesting chemisorption being a dominant mechanism.

Biochar-Assisted Bioengineered Strategies for Metal Removal: Mechanisms, Key Considerations, and Perspectives for the Treatment of Solid and Liquid Matrixes

Biochar has drawn the scientific community’s attention during the last few years due to its low production value and unique physicochemical properties, which are helpful for numerous applications. The development of biotechnological processes for the remediation of heavy metal environmental pollution is one central research avenue in which biochar application has shown promising results, due to its positive effect on the bacteria that catalyze these activities. Biochar stimulates bacterial activity through adsorption, adhesion, electron transport, and ion exchange. However, before biochar implementation, a complete understanding of its potential effects is necessary, considering that those interactions between biochar and bacteria may help improve the performance of biological processes designed for the remediation of environmental pollution by metals, which has been historically characterized by limitations related to the recalcitrance and toxicity of these pollutants. In this review, the key biochar–microorganism interactions and properties of unmodified biochar with the potential to improve metal bioremediation in both solid (mine tailings, polluted soils) and liquid matrixes (metal-laden wastewaters) are summarized. Knowledge gaps regarding the mechanisms involved in remediation strategies, the effect of long-term biochar use and the development of improved biochar technologies and their combination with existent remediation technologies is summarized. Additionally, an up-to-date summary of the development of biochar-assisted bioengineered strategies for metal passivation or removal from solid and liquid matrixes is presented, along with key perspectives for the application of biochar-based biotechnologies at full scale during the treatment of mining effluents in the real scale.

Schoenoplectus californicus as Potential Remover of Metal Elements from Mine Effluents: A Laboratory Assessment

AbstractAcid mine drainage (AMD) is one of the most significant environmental challenges facing the mining industry worldwide. For this reason, many methods for AMD treatment are developed, being wetlands a good option for metal elements removal from these mining effluents. The efficiency of Peruvian native plants such as Schoenoplectus californicus (S. californicus) to remove metal elements in effluents through artificial wetlands is studied. Batch removal tests are carried out with different effluents containing copper, zinc, lead, and iron. For iron‐metal binary effluents, copper, zinc, and lead are removed by 82%, 75%, and 88%; while in the effluent containing all metals, the removal rate is 90% and 92% for copper and lead, respectively. According to the preliminary results, it is concluded that iron interferes more in the removal of zinc and lead than in copper from binary effluents. The use of S. californicus turns out to be an efficient, attractive, and economical alternative for the treatment of effluents contaminated with copper, zinc, lead, and iron.

Investigating the effect of Eh and pH on binding forms of Co, Cu, and Pb in wetland sediments from Zambia.

This study investigated binding forms of cobalt (Co), copper (Cu), and lead (Pb) in 28 sediment samples from inlet to outlet of three Zambian wetlands receiving mining effluents. Use was made of a modified Tessier metal binding fractions procedure. Due to storage artefacts, the original aim of investigating the effects of redox potential (Eh) changes, starting from extremely low Eh, was suspended. Instead, use was made of the new, not often explored opportunity for replicate sample division into three categories of varying redox potential and pH. Additionally, in line with the original research aim, two sediments from each wetland were investigated for their response to increasing Eh. The results showed overall high trace metal contents, with a need for remedial actions for Co and Cu in the first, Cu in the second, and Pb in the third wetland. Rather independent of Eh and pH, Co was often found in the residual fraction (F5), as well as in the oxidizable (F4) and reducible (F3) fraction. Cu was generally dominant in F5 and F4 fractions, with low F3 prevalence, indicating a high organic matter affinity. Pb distribution among binding forms showed small variations within and across wetlands, F5, F4, and F3 fractions dominating. In the above observations, statistical analysis showed that, among the 28 sediment samples across wetlands, the influence of Eh and pH on binding forms were generally found to be not significant, being 'overruled' by other sedimentological factors. With increasing Eh, the decrease in the oxidizable (F4) fraction was smaller than expected in eight of 18 tests. The Risk Assessment Code (RAC) method, based on the exchangeable fraction (F1) plus carbonate fraction (F2), showed that some sediments turned from "unsafe" to "safe," and vice versa, with increasing Eh. The "total metals method" does not show bioavailability, whereas RAC does not use the metal contents. Thus, the two methods should be used together to improve the prediction of potential toxicity.

Removal of antimony from model solutions, mine effluent, and textile industry wastewater with Mg-rich mineral adsorbents

Naturally occurring layered double hydroxide mineral, brucite (BRU), was compared with hydromagnesite (HYD) and a commercial Mg-rich mineral adsorbent (trade name AQM PalPower M10) to remove antimony (Sb) from synthetic and real wastewaters. The BRU and HYD samples were calcined prior to the experiments. The adsorbents were characterized using X-ray diffraction, X-ray fluorescence, and Fourier transform infrared spectroscopy. Batch adsorption experiments were performed to evaluate the effect of initial pH, Sb concentration, adsorbent dosage, and contact time on Sb removal from synthetic wastewater, mine effluent, and textile industry wastewater. Several isotherm models were applied to describe the experimental results. The Sips model provided the best correlation for the BRU and M10. As for the HYD, three models (Langmuir, Sips, and Redlich–Peterson) fit well to the experimental results. The results showed that the adsorption process in all cases followed the pseudo-second-order kinetics. Overall, the most efficient adsorbent was the BRU, which demonstrated slightly higher experimental maximum adsorption capacity (27.6 mg g-1) than the HYD (27.0 mg g-1) or M10 (21.3 mg g-1) in the batch experiments. Furthermore, the BRU demonstrated also an efficient performance in the continuous removal of Sb from mine effluent in the column mode. Regeneration of adsorbents was found to be more effective under acidic conditions than under alkaline conditions.

Potential for water and metal recovery from acid mine drainage by combining hybrid membrane processes with selective metal precipitation

Acid mining drainage has a serious impact on the environment. Forward osmosis allows the concentration of acid mine waters to favor the formation of enrichment sludges and subsequent selective metal precipitation. In this work, a methodology was proposed to treat mining effluents from the Iberian Pyrite Belt. Forward osmosis experiments were performed using different osmotic pressures from 0.5M to 2.5M NaCl to evaluate water fluxes and recovery. The water recovery obtained was in the range of 50-80%, and the flux remained above 5 (L•m−2•h−1). Four combined processes were modelled to determine the feasibility of eliminating water and precipitating metals. Furthermore, a new hybrid membrane process was proposed to recover at least 75% of water with recovery yields of Al, Fe, Cu, Zn and Mn of greater than 70%. A water production cost of 2.01 $/m3 and a specific energy consumption of 8.03 kWhe/m3 were estimated for the hybrid process.

The strontium isotope fingerprint of phosphate rocks mining

High concentrations of metal(loid)s in phosphate rocks and wastewater associated with phosphate mining and fertilizer production operations pose potential contamination risks to water resources. Here, we propose using Sr isotopes as a tracer to determine possible water quality impacts induced from phosphate mining and fertilizers production. We utilized a regional case study in the northeastern Negev in Israel, where salinization of groundwater and a spring have been attributed to historic leaking and contamination from an upstream phosphate mining wastewater. This study presents a comprehensive dataset of major and trace elements, combined with Sr isotope analyses of the Rotem phosphate rocks, local aquifer carbonate rocks, wastewater from phosphate operation in Mishor Rotem Industries, saline groundwater suspected to be impacted by Rotem mining activities, and two types of background groundwater from the local Judea Group aquifer. The results of this study indicate that trace elements that are enriched in phosphate wastewater were ubiquitously present in the regional and non-contaminated groundwater at the same levels as detected in the impacted waters, and thus cannot be explicitly linked to the phosphate wastewater. The 87Sr/86Sr ratios of phosphate rocks (0.707794 ± 5 × 10−5) from Mishor Rotem Industries were identical to that of associated wastewater (0.707789 ± 3 × 10−5), indicating that the Sr isotopic fingerprint of phosphate rocks is preserved in its wastewater. The 87Sr/86Sr (0.707949 ± 3 × 10−6) of the impacted saline groundwater were significantly different from those of the Rotem wastewater and the background saline groundwater, excluding phosphate mining effluents as the major source for contamination of the aquifer. Instead, the 87Sr/86Sr ratio of the impacted water was similar to the composition of brines from the Dead Sea, which suggests that the salinization was derived primarily from industrial Dead Sea effluents with distinctive Sr isotope and geochemical fingerprints.

Development of a Biochar-Based Substrate Added with Nitrogen from a Mining Effluent for the Production of Picea mariana Seedlings

Ammoniacal nitrogen (N-NH3) is one of the pollutants that has adverse effects on the environment and is present in most effluents generated by mining operations. Therefore, mining companies must manage it to keep it below the regulated discharge criteria to avoid environmental contamination. In this context, the present study aims to valorize N-NH3 in the form of ammonium sulphate ((NH4)2SO4) for the manufacture of biochar pellets used as growth substrates for the production of forest seedlings. The biochar was first produced by fast pyrolysis, at 320 °C, and different recipes of pellets were then prepared to evaluate their hardness, binder type and content, humidity and durability. The optimal granule chosen was composed of biochar, corn starch and canola oil. Six combinations of different compositions were then prepared as substrates for black spruce growth: (1) Peat (P); (2) Peat and bulk biochar (PB); (3) Peat and bulk biochar impregnated with ammonium sulfate (PBAS); (4) Peat and biochar pellets impregnated with water (PBPeW); (5) Peat and biochar pellets impregnated with an ammonium sulfate solution (PBPeAS); (6) Peat, biochar pellets impregnated with ammonium sulfate and perlite (PBPeASPer). The effects of these substrates on the growth of black spruce seedlings, as well as fertilizer leaching, were measured. The results show that seedling biomass is equivalent to the control for the granular treatment, but higher biomass was obtained with bulk biochar (PB). This shows that a quarter of peat could be replaced by biochar to obtain similar or even better results of biomass yield and, consequently, solve part of the supply issue. As to plant nutrition, no tendency was observed for the experiments apart from the higher proportion of Ca in spruce needles. The prepared biochar-based pellet substrate appears to not only be advantageous for spruce production but also for other uses such as golf courses, forestry producers and horticultural nurseries using conventional fertilizers and peat as growing media. In addition, these approaches could help the Abitibi-Témiscamingue region in Québec, Canada to build a local circular economy.

Assessing the environmental performance of a novel coal mine brine treatment technique: A case in Poland

Although the energy transition results in decreased use of coal for power production, hard coal extraction will continue due to its importance in steel production and coal mine wastewater will continue generating after mines closure. The coal mining sector produces wastewater which results in environmental burdens and often contains valuable materials that can be treated to eliminate effluent discharge and recover contained materials. The aim of this study is to determine whether the implementation of a novel wastewater treatment technique in an existing coal wastewater treatment plant (WWTP) can improve both environmental performance and resource recovery potential. Our study assesses for the first time the environmental performance of the WWTP of Dębieńsko at the Upper Silesian Coal Basin, in Poland because coal mine effluents need to be treated to eliminate current environmental impacts on surface water bodies (rivers). The existing wastewater treatment system comprises reverse osmosis, evaporation and crystallization technologies. In the case of the novel ZERO BRINE technique, lab performance data is scaled-up and used for nanofiltration, reverse osmosis, electrodialysis and crystallization technologies. The environmental impacts analysis is performed with life cycle assessment (LCA) by considering mid-point impact categories (climate change, terrestrial acidification and fossil resource scarcity) and end-point damages (human health, ecosystems and resources). The functional unit is 1 m3 of coal mine wastewater input and a scenario is developed where the plant functionality concerns salt production. Results show that the implementation of the ZERO BRINE technique can improve the environmental performance of the WWTP for all considered impact categories due to a reduction in electricity consumption by 13% in the entire plant. Climate change, acidification, fossil resources scarcity, human health, ecosystems, and resources were improved by 16%, 13%, 12%, 25%, 21% and 13%, respectively. A sensitivity analysis is performed on the electricity consumption of electrodialysis which shows an additional improvement by 7% on all impacts. The ZERO BRINE technique produces both water and different types of salts. In this case, the multi-functionality of the system is addressed through substitution, while sensitivity analyses are carried out using mass and economic allocation methods.

Beneficiation of Iron Oxides from Cupola Furnace Slags for Arsenic Removal from Mine Tailings Decant Water

Large volumes of ferrous metallurgical slags (FMS) are generated annually as waste materials from metal extraction, purification, casting and alloying processes worldwide. Some attempts have been made to use bulk FMS in metal precipitation and concrete works but little success has been achieved because of unstable precipitates and volume expansion of concrete structures. As a result, significant quantities of FMS are still disposed in landfills. This disposal leads to land conflicts and poor environmental practices. The present study focuses on the characterization and separation of iron oxide from selected bulk FMS (Cupola Furnace Slag - CFS) obtained from Ghana into constituent components for use as engineering materials. Quantitative X-ray diffractometry was used to determine the mineralogy of CFS. Iron oxide morphology and spot composition in the CFS were determined using scanning electron microscopy, combined with energy dispersive spectroscopy. The inductively coupled plasma-optical emission spectrometry was used to ascertain the chemical composition of CFS after acid digestion. Wet low intensity magnetic separation technique was employed for beneficiating iron oxides from the CFS. It is shown that the CFS is amorphous and consist of ferrous and non-ferrous material. Results of the investigation confirmed that ferrous materials in the slags can be separated using magnetic separation technique. The study further confirmed that fine grinding (- 75 µm) liberates the magnetic portions of the slag efficiently, and as such, they can be recovered using a low magnetic field. The recovery was 99.04 % and the concentrates obtained from the beneficiation process consist primarily of pigeonite, quartz, magnetite and jacobsite. The beneficiated concentrates have the capacity to adsorb arsenic from mine effluent. This study has demonstrated that, slags can be utilized as secondary resources rather than a waste.

Hypersaline mining effluents affect the structure and function of stream biofilm

The salinisation of freshwater ecosystems is a global environmental problem that threatens biodiversity, ecosystem functioning and human welfare. The aim of this study was to investigate the potential impact of a realistic salinity gradient on the structure and functioning of freshwater biofilms. The salinity gradient was based on the real ion concentration of a mining effluent from an abandoned mine in Germany. We exposed biofilm from a pristine stream to 5 increasing salinities (3 to 100 g L−1) under controlled conditions in artificial streams for 21 days. We evaluated its functional (photosynthetic efficiency, nutrient uptake, and microbial respiration) and structural responses (community composition, algal biomass and diatom, cyanobacteria and green algae metrics) over time. Then we compared their responses with an unexposed biofilm used as control. The functionality and structure of the biofilm exposed to the different salinities significantly decreased after short-term and long-term exposure, respectively. The community composition shifted to a new stable state where the most tolerant species increased their abundances. At the same time, we observed an increase in the community tolerance (measured as Pollution-Induced Community Tolerance) along the salinity gradient. This study provides relevant information on the salt threshold concentrations that can substantially damage algal cells (i.e., between 15 and 30 g L−1). The results provide new insights regarding the response and adaptation of stream biofilm to salinity and its potential implications at the ecosystem level.

Valorization of coal mine effluents — Challenges and economic opportunities

Coal-mine effluent treatment has the potential to both reduce the environmental impact of the effluent and provide economic opportunities by recovering valuable minerals and clean water. In this study, we modeled a novel treatment process, which includes nanofiltration (NF), two-step crystallization, reverse osmosis (RO), electrodialysis (ED), multi-effect distillation (MED), and a NaCl crystallizer, and performed a techno-economic analysis of its full-scale implementation, using a circular economy approach. We estimated the thermal and electrical energy consumption to be 745.5 kWhth/tonNaCl and 565.1 kWhel/tonNaCl (or 13.6 kWhth and 10.3 kWhel per m3 of feed effluent), respectively. The levelized cost of the NaCl salt that accounts for the revenue from the plant's co-products (Mg(OH)2, CaSO4 and, pure water) was estimated to be 203 USD/tonNaCl. The economic viability of the treatment chain can be improved by using renewable electricity sources, reducing the total expenditure on NF and RO, and integrating alternate technologies into the treatment plant.

Electrochemical Oxidation of Ammonia-Laden Wastewater in the Mining Industry

Ammonia is a common contaminant in municipalities where human waste causes nitrification of local water bodies. In mining, ammonia contamination occurs as a byproduct of biological water treatment, from the use of ammonium nitrate fuel oil in explosives, and from the exposure of ammonia rich soils during the excavation process. In particular, gold mine effluent represents a significant source of ammonia and nitrogen-based contaminants. Current biological and abiotic treatment processes are difficult to employ at the scale required at mine sites due to the high operating costs, or are limited in effectiveness due to a lack of natural resources required to facilitate the treatment. This article evaluates the use of electrooxidation as a cost effective alternative to treating ammonia-laden wastewater in mining applications. Two mixed metal oxide electrodes are assessed in this article: IrO<inline-formula><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula>/Ti and RuO<inline-formula><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula>/Ti anodes. A Monte Carlo simulation is performed to determine a probabilistic range of capital and operating expenditure for a mining operation deploying an electrooxidation wastewater treatment system. The lowest capital cost of operating the electrochemical treatment occurs at a current density of 200 A/m<inline-formula><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula>, where the number of cells required for treatment is minimized.

EFFECTS OF COAL MINING ON FISHES OF MEGHALAYA, INDIA: A REVIEW

Coal mining activities generate huge quantity of effluent containing tremendous amount of several metals, nitrate, sulphate, dissolved, and suspended solids as well as other harmful pollutants. These toxic effluents are regularly being released into the neighbouring ponds, lakes and rivers. Significant discharge of untreated coal mining effluent into the aquatic environment contributes to a variety of toxic effects on aquatic fauna including fish. Coal mining activities specifically in the region of Meghalaya located in North-east India is posing severe threats to the aquatic biota. The purpose of the paper is to pay special emphasis on the fish fauna that lives in this region that has large effluents of acid mine drainage. Many authors have previously described the different histopathological changes in a fish that suffer from severe toxicity of acid mine drainage. This study has been prepared taking into account the various works of different authors and is thus a review of their work. The whole aim of the study is to give a general idea that acid mine drainage from coal mines has tremendous impact on the fish fauna and may completely wipe out the population that thrives therein in the long run.