Bioleaching Solution Research Articles

Copper recovery from waste printed circuit boards using pyrite as the bioleaching substrate.

Waste printed circuit boards (WPCBs) can be bioleached for Cu recovery, but lack of substrate for the bioleaching culture. In this study, using pyrite as a bacterial substrate for bioleaching WPCBs and recovering Cu was explored. The results showed that the WPCBs bioleaching using pyrite as the bacterial substrate was feasible. Mechanical crushing was a suitable WPCBs pretreatment method. The optimal WPCBs and pyrite pulp densities were respectively found to be 1.25% (w/v) and 1.0% (w/v), and the suitable nitrogen source ratio ((NH4)2SO4: (NH4)2HPO4) was deemed as 2g/L: 2g/L, achieving a Cu2+ leaching efficiency of 95.60 ± 1.57% in 14 d. Copper in the bioleaching solution can be directly recovery via electrodeposition. The Cu recovery efficiency in 60min was up to 92.19 ± 1.35% under the optimal condition that the initial Cu2+ concentration and pH were respectively set at 7.34g/L and 2.75, and the current density was set at 200 A/m2. Copper was found as the dominant metal in the cathode deposits, existing in the form of Cu and Cu2O. This work provided a novel approach for bioleaching WPCBs and recovering Cu.

Copper from Waste Printed Circuit Boards Was Effectively Bioleached Using Newly Isolated Microorganisms and Subsequently Recovered by Microbial Fuel Cell

Two newly isolated bacterial strains were isolated from activated sludge and identified as Coniochaeta fodinicola (C. fodinicola) and Talaromyces barcinensis (T. barcinensis) by 16S rDNA. C. fodinicola and T. barcinensis were used to bioleach the copper from the waste printed circuit boards (WPCBs) powder, which was obtained by crushing and sorting the printed circuit board substrate after removing components. Results showed that the minimum and maximum Cu2+ leaching rates for C. fodinicola leaching were 3.9% and 89.2%, respectively. The minimum and maximum Cu2+ leaching rates for T. barcinensis leaching were 20.6% and 89.0%, respectively. The bioleaching solution was used as the cathode liquid of a dual chamber microbial fuel cell (MFC), and an X-ray diffraction (XRD) pattern displayed that the Cu2+ in the bioleaching solution was reduced to copper using biological electricity generation.

Recovery of valuable metals from spent lithium-ion batteries using microbial agents for bioleaching: a review.

Spent lithium-ion batteries (LIBs) are increasingly generated due to their widespread use for various energy-related applications. Spent LIBs contain several valuable metals including cobalt (Co) and lithium (Li) whose supply cannot be sustained in the long-term in view of their increased demand. To avoid environmental pollution and recover valuable metals, recycling of spent LIBs is widely explored using different methods. Bioleaching (biohydrometallurgy), an environmentally benign process, is receiving increased attention in recent years since it utilizes suitable microorganisms for selective leaching of Co and Li from spent LIBs and is cost-effective. A comprehensive and critical analysis of recent studies on the performance of various microbial agents for the extraction of Co and Li from the solid matrix of spent LIBs would help for development of novel and practical strategies for effective extraction of precious metals from spent LIBs. Specifically, this review focuses on the current advancements in the application of microbial agents namely bacteria (e.g., Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans) and fungi (e.g., Aspergillus niger) for the recovery of Co and Li from spent LIBs. Both bacterial and fungal leaching are effective for metal dissolution from spent LIBs. Among the two valuable metals, the dissolution rate of Li is higher than Co. The key metabolites which drive the bacterial leaching include sulfuric acid, while citric acid, gluconic acid and oxalic acid are the dominant metabolites in fungal leaching. The bioleaching performance depends on both biotic (microbial agents) and abiotic factors (pH, pulp density, dissolved oxygen level and temperature). The major biochemical mechanisms which contribute to metal dissolution include acidolysis, redoxolysis and complexolysis. In most cases, the shrinking core model is suitable to describe the bioleaching kinetics. Biological-based methods (e.g., bioprecipitation) can be applied for metal recovery from the bioleaching solution. There are several potential operational challenges and knowledge gaps which should be addressed in future studies to scale-up the bioleaching process. Overall, this review is of importance from the perspective of development of highly efficient and sustainable bioleaching processes for optimum resource recovery of Co and Li from spent LIBs, and conservation of natural resources to achieve circular economy.

Bioleaching of valuable metals from spent LIBs followed by selective recovery of manganese using the precipitation method: Metabolite maximization and process optimization

Despite the increased demand for resource recovery from spent lithium-ion batteries (LIBs), low Mn leaching efficiencies have hindered the development of this technology. A novel process was devised to enhance the dissolution of metals by producing citric acid using a molasses medium by Penicillium citrinum. This investigation used response surface methodology to investigate the influence of molasses concentration and media components on citric acid production, which demonstrated that molasses (18.5% w/w), KH2PO4 (3.8 g/L), MgSO4.7H2O (0.11 g/L), and methanol (1.2% (v/v)) were the optimum values leading to the production of 31.50 g/L citric acid. Afterward, optimum inhibitor concentrations (iodoacetic acid: 0.05 mM) were added to accumulate citric acid, resulting in maximum bio-production (40.12 g/L) of citric acid. The pulp density and leaching time effect on metals dissolution was investigated in enriched-citric acid spent medium. The suitable conditions were a pulp density of 70 g/L and a leaching duration of 6 days, which led to the highest dissolution of Mn (79%) and Li (90%). Based on the results of the TCLP tests, the bioleaching residue is non-hazardous, suitable for safe disposal, and does not pose an environmental threat. Moreover, nearly 98% of Mn was extracted from the bioleaching solution with oxalic acid at 1.2 M. XRD, and FE-SEM analyses were utilized for further bioleaching and precipitation mechanism analysis.

Bioleaching of indium from spent light-emitting diode monitors and selective recovery followed by solvent extraction

The spent light emitting diode (LED) monitors are one of the fastest-growing waste streams that could provide indium, an essential element for the industry. This study presents a comprehensive strategy for indium extraction from spent LED monitors, including bioleaching followed by solvent extraction, stripping, and precipitation. Effects of A. thiooxidans and A. ferrooxidans inoculum percentage in mixed culture, pulp density, and time on indium, aluminum, and strontium bioleaching were investigated. In this regard, at optimized inoculum percentages (1.5 and 0.5% (v/v) of A. ferrooxidans and A. thiooxidans, respectively) and pulp density (60 g/L) at initial pH of 2, approximately 100% indium recovery was obtained in 18 days. The solubilized indium in the bioleaching solution has been extracted by the organic solvent of 20% (v/v) D2EHPA in kerosene. Following extraction, the stripping step was carried out to recover indium rather than iron selectively. The effect of two-phase contact time and aqueous to organic phase volume ratio in the extraction step and the acid type and concentration in the stripping step on indium and iron recovery percentages have been evaluated. For indium extraction, the optimum ratio of aqueous to organic phase volume and time were determined as 1 and 30 min, respectively, recovering 91.5% of indium. Using 5 M sulfuric acid has also resulted in an efficient stripping process. Finally, sodium hydroxide performed indium precipitation and a final precipitate of 94% (w/w) indium was obtained.

Morphology, Phase and Chemical Analysis of Leachate after Bioleaching Metals from Printed Circuit Boards.

The article presents the assessment of solutions and dried residues precipitated from solutions after the bioleaching process of Printed Circuit Boards (PCB) utilizing the Acidithiobacillus ferrooxidans. The obtained dried residues precipitated from bioleaching solution (leachate) and control solution were tested using morphology, phase, and chemical composition analysis, with particular emphasis on the assessment of crystalline and amorphous components. The analysis of the dried residues from leachate after bioleaching as well as those from the sterile control solution demonstrated a difference in the component oxidation—the leachate consisted of mainly amorphous spherical particles in diameter up to 200 nm, forming lacy aggregates. In the specimenform control solution larger particles (up to 500 nm) were observed with a hollow in the middle and crystalline outer part (probably Fe2O3, CuFeS2, and Cu2O). The X-ray diffraction phase analysis revealed that specimen obtained from leachate after bioleaching consisted mainly of an amorphous component and some content of Fe2O3 crystalline phase, while the dried residue from control solution showed more crystalline components. The share of the crystalline and amorphous components can be related to efficiency in dissolving metals during bioleaching. Obtained results of the investigation confirm the activity and participation of the A. ferrooxidans bacteria in the solubilization process of electro-waste components, with their visible degradation–acceleration of the reaction owing to a continuous regeneration of the leaching medium. The performed investigations allowed to characterize the specimen from leachate and showed that the application of complementary cross-check of the micro (SEM and S/TEM) and macro (ICP-OES and XRD) methods are of immense use for complete guidance assessment and obtained valuable data for the next stages of PCBs recycling.

Innovative bio-acid leaching method for high recovery of critical metals from end-of-life light emitting diodes

The main objective of this work is to introduce a new green recycling process for recovering valuable metals from electronic waste. One of the fastest-growing electronic waste streams is end-of-life light emitting diodes (LEDs). Due to environmental risk and a worldwide shortage of metals, recycling and recovering their valuable metal is an urgent task. In this study, an innovative bio-hydrometallurgical method for the extraction of valuable metals from end-of-life LED lamps is proposed. The present study evaluated a direct multi-step regulation strategy of waste content to enhance the bio-acid leaching of LED at a high pulp density (40 g/L) using a culture of sulfur-oxidizing bacteria Acidithiobacillus thiooxidans (A. thiooxidans). Through a step-wise feeding strategy (10 g/d), the extraction of the metal was further improved due to balancing of A. thiooxidans population and stabilization of pH, ORP, and sulfuric acid concentration in the bioleaching solution. By comparing the results of multi-step and one-stage contact bioleaching, with multi-step contact bioleaching, Cu, Ni, and Ga extraction yields increased from 67%, 92%, and 39% to 100%, 100%, and 75%. Furthermore, this study demonstrates that the presence/addition of EPS did not only adsorb metal ions but also increased diffusion barriers, thus diminishing metal ion transfer from LED into bioleaching solution for an extended period of time. The multi-step non-contact bio-acid leaching method enhanced strategic critical element leaching yields to 100% from end-of-life LEDs. The final product, enriched in Au and Ag, could be used as a secondary source of precious metals.

Investigations on Strategic Element Recovery by an Underground Membrane Pilot Plant from In-Situ Extracted Bioleaching Solutions

Focusing on the selective extraction of the critical raw materials indium and germanium from real bioleaching solutions, extended studies have been carried out using Europe’s first underground hybrid membrane pilot plant (TRL6). In order to transfer former laboratory experiments to pilot scale, NF99 (Alfa Laval) was used for the evaluation of membrane permeance and ion retention. A performance test of microfiltration (MF) and nanofiltration (NF) showed high permeances with low root-mean-square deviation under feed variation (5.2% for MF, 4.7% for NF). Depending on the feed load, a significant permeance drop of up to 57% for MF (3 bar) and 26% for NF (10 bar, 1.1 m s−1) was observed. The NF retention performance showed that, without regular chemical cleaning, the selectivity between the target elements degraded. By introducing acidic-basic cleaning steps, it was possible to keep the retention behavior at an approximately constant level (In 91.0 ± 1.3%; Ge 18.2 ± 5.5%). In relation to the specified target, the best results could be achieved at low pressure (7.5 bar) and a maximum overflow velocity of 1.1 m s−1, with a retention of 88.4% for indium and 8.8% for germanium. Moreover, the investigations proved the functionality and long-term stability of the underground membrane device.

Copper recovery from tailings through bioleaching and further application of bioleached tailings residue: Comprehensive utilization of tailings

Severe environmental pollution and resources waste were caused by tailings. For the sake of making comprehensive utilization of tailings, tailings bioleaching for copper recovery and further application of bioleached tailings residue to make cemented tailing backfill materials were investigated. Such study clarified the potential possibility of bioleached tailings residue in cleaner production and economic benefits, which should contribute to a good reference for comprehensive utilization of tailings. Results showed that adding tailings and bacteria at appropriate interval during tailings bioleaching, particularly adding bacteria both at initial inoculation and day 10, can improve copper recovery (5.46%) and bacteria concentration (7.39 × 107 cells·mL−1). Better performances with high compressive strength (3.82 MPa) and low water-holding capacity of cemented tailings backfill (CTB) specimens using bioleached tailings residue was obtained. 16S rDNA analysis illustrated that bacteria community structure was differentiated significantly during bioleaching experiment. Leptospirillum ferriphium accounted for the highest proportion of bacteria community structure throughout bioleaching process among all the samples. Furthermore, possible reaction mechanism was put forward suggesting the possible role of precipitation including KFe3(SO4)2(OH)6 and (KH3O)Fe3(SO4)2(OH)6 formed by Fe3+ hydrolysis can contribute to performance of CTB specimens. Moreover, adding tailings and bacteria at appropriate interval was beneficial to removal of excessive hazardous ions, such as Fe3+ and SO42− from bioleaching solution.

Optimized bioengineered copper recovery from electronic wastes to increase recycling and reduce environmental impact

The electronic and electrical industries' long-term development requires not just efficient energy use at all phases of manufacturing, but also the recycling of end-of-life electric and electronic parts. Nonetheless, rapid innovation, miniaturization, and value have resulted in a huge accumulation of e-waste, raising environmental issues. This study delves into the recycling potential of various types of electronic waste (LCD scrap, laptop-computer scrap, user scrap, motherboard scrap, and hard-drive scrap). The research utilizes e-waste scrap and extracts the copper from comminuted scrap by placing it in small columns to simulate small sections of heaps to demonstrate the viability of metal recovery from e-waste. Different grades (according to values of Cu and other precious metals) of e-waste were acquired and tested. The initial bio-leaching solution, for copper extraction, consists of ferric ions, generated by A. ferrooxidans-assisted oxidation of Fe2+. To maximize the Cu recovery, the factors that were examined for column-leaching were initial Eh, pH, and flow-rate using the statistical design of experiments. 96% Cu recovery was accomplished in 72 h utilizing the optimum conditions, demonstrating that metals in e-waste may be efficiently leached using appropriate bio-oxidation and subsequent processing.

Purification of Zinc from the Bioleaching Solution of a Bulk Lead–Zinc Concentrate by Precipitation and Solvent Extraction

Purification of Zinc from the Bioleaching Solution of a Bulk Lead–Zinc Concentrate by Precipitation and Solvent Extraction

Development of polyethyleneimine-starch fibers stable over the broad pH range for selective adsorption of gold from actual leachate solutions of waste electrical and electronic equipment

Polyethyleneimine (PEI)-starch fibers were fabricated as adsorbents for the selective recovery of gold from waste electrical and electronic equipment (WEEE). They were prepared by a simple method of spinning a mixture of PEI and starch in a glutaraldehyde solution, which is a crosslinking agent. The PEI-starch fibers were stable over the broad pH range, thereby suggesting that they are highly applicable for various types of wastewater. The characterization and adsorption mechanism of the PEI-starch fibers were investigated by BET, FT-IR, XRD, and XPS analyses. According to the Langmuir model, the maximum Au(III) uptake by the PEI-starch fibers was estimated to be 1055.59 ± 63.78 mg/g at pH 1.0. The adsorbed Au(III) was sequentially reduced to Au(I) and then Au(0) owing to electron transfer when N–C and C–OH present in the PEI-starch fibers were oxidized to NC and CO, respectively. Moreover, PEI-starch fibers were stable in WEEE-leached aqua regia (diluted to pH 1.0) and bioleaching solution (pH 9.3) and showed excellent selectivity for gold.

Zinc extraction from a bioleaching solution by emulsion liquid membrane technique

Zinc separation from a bioleaching solution of a low-grade lead/zinc sulfide ore was performed by emulsion liquid membrane (ELM) technique. To study the extraction efficiency, the effect of key parameters including contact time, stirring speed, treat ratio, initial zinc concentration in the external phase, D2EHPA, Span80 and stripping agent concentration are studied and optimized. Maximum zinc extraction (≈71 %) was achieved at 20 min contact time, 150 rpm, 10 % (v/v) D2EHPA, 5 % (v/v) Span 80, 1.5 M sulfuric acid in the internal phase, and Vex/Vem = 5:1. The results showed that osmotic pressure gradient is responsible for water transport from the external phase into the internal phase and emulsion swelling in most cases. Anexcessive shear force, extra concentration of emulsion components and longer contact time trigger emulsion breakage and globule rupture.

Recovery and Enhanced Upgrading of Rare Earth Elements from Coal-Based Resources: Bioleaching and Precipitation

Rare earth elements (REEs) are of great importance to modern society and their reliable supply is a major concern of many industries that utilize them in metal alloys, semiconductors, electrical equipment, and defense equipment. REEs in the coal waste have been revealed to be an alternative resource for REEs production. In this study, the extraction, recovery, and upgrading of the REEs from coal waste has been realized with the bioleaching and precipitation processes. Reliable and sustainable acid and oxidant production from the oxidation of the pyrite with Acidithiobacillus ferrooxidans to generate acid for leaching were realized in this research. The acidified bioleaching solution was used to extract REEs from coal waste, with 13–14% yields for most REE elements (~72 h of leaching). However, recovery for longer duration tests was significant higher (varies from 40–60% for individual REEs). After extraction, precipitation and separation processes were designed with the aid of Visual Minteq calculations and modeling to concentrate the REEs. With the procedures designed in this research, a final REEs precipitate product containing 36.7% REEs was produced.

Bioleaching of Uranium Tailings as Secondary Sources for Rare Earth Elements Production

Tailings from inactive uranium mine sites represent a potential secondary source of rare earth elements (REEs). For this study, two mine tailings (DT and RAT) from restored uranium sites in Ontario, Canada, were used. Bioleaching experiments were conducted with a mix of native sulfur- and iron-oxidizing bacteria to test the solubilization of REEs, U and Th at different temperatures (20, 30 and 40 °C). The selective recovery of REEs from bioleaching solution was evaluated using different ion exchange resins. The mineralogical characterization revealed that DT tailings were mainly composed of quartz, pyrite, gypsum and silicates, whereas RAT tailings were mainly composed of quartz. The maximum solubilization of heavy and light REEs (HREEs and LREEs, respectively), Th and U reached 54%, 6%, 60% and 51% for RAT after 35 days at pH 2, T = 30 °C and pulp density = 10% (w/v). Higher extraction yields were obtained for DT, with 58% of HREEs, 14% of LREEs, 85% of Th and 89% of U solubilized under the same conditions. The use of Lewatit TP272 resin for the recovery of Sc (94%) and U (99%) followed by the Lewatit SP112 resin for the recovery of Th (57%) and REEs (81% LREEs and 65% HREEs) seemed a promising method for the co-extraction of the key elements from the bioleaching solution.

A novel approach based on solvent displacement crystallisation for iron removal and copper recovery from solutions of semi-pilot scale bioleaching of WPCBs

Bioleaching of copper from electronic waste (e-waste) in the form of high grade waste printed circuit boards (WPCBs) collected from obsoletemobile phones is assessed using a consortium of iron (Fe2+) & sulfur (S°) oxidizing bacteria in a semi-pilot reactor system. Results from the study indicated that the microorganisms were able to grow in the presence of WPCB and efficiently solubilize Cu from it. At a solid/liquid ratio of 10% (w/v)with a particle size of <250 μm, maximum bioleaching efficiency of around 95% Cu was observed in 8 days of leaching under oxidation-reduction potentials (ORP) of >600 mV and pH 1.8. In order to recover the metallic values, electrowinning (EW) of copper from the bioleach solutions was investigated in detail. Direct EW of the bioleach solution yielded low current efficiencies (66.1% over 4 h.), ascribed due to the high concentrations of iron (i.e., 9.1 g/L). As a novel approach, a downstream purification and concentration process was further tested, that involved ferric hydroxide (Fe(OH)3) precipitation and solvent displacement crystallisation (SDC) to eliminate iron and increase the concentration of copper in solution prior to its application for EW. This significantly improved the current efficiency (by ∼22%) during the EW of copper. A process flow-sheet for Cu recovery from WPCBs was developed and the downstream process was found to be profitable even though its margin was small with techno-economic analysis. It is believed that the two-step hybrid process i.e. bioleaching technique followed by the novel approach proposed (i.e., iron precipitation + SDC) can be suitably employed for the extraction of copper from WPCBs.

Bioleaching: Validation of the Extraction of Precious Metals Through Selective Recovery of Iron, Copper and Zinc

In Ecuador, large gold deposits were discovered in the areas of Nambija and Ponce Enríquez, but they contain metal sulfides that, when exposed to the action of air and water, intervene in a series of physical, chemical and biological phenomena. The oxidation of sulfides to sulfates occurs by the catalytic action of bacteria, in addition to the production of sulfuric acid that dissolves heavy metals such as iron, copper and zinc; a process known as bioleaching. These solutions, with a high level of acidity, are carried away by water currents or runoff, becoming a great contaminant of water and soil of the surrounding sector. Acid mine drains are one of the main problems of environmental pollution; the mining deposits are located in areas of great biodiversity. In these areas there are births of water used for human consumption, agriculture and mining work; the mismanagement of tailings, tailings and sands that are discharged into rivers and streams generate serious environmental damage. The objective of the work is to use selective precipitation to recover iron, copper and zinc from acid solutions produced by bioleaching during the extraction of precious metals at the laboratory level and from acid drainage of natural mine, to comply with environmental regulations regarding the discharge of effluents and reduce the effect of environmental pollution produced by acid mine drains. This investigation presents the conditions for a successful individual recovery of the main base metals contained in a bioleaching solution with high copper, zinc, and iron concentrations by pH-based selective precipitation. Tests were made with standard solutions of known concentrations of copper, iron, lead, and zinc and by titration the concentrations were checked, which allowed to validate the volumetric titration method. The selective precipitation of heavy metals was carried out in three phases using real acid main drainage and bioleaching solutions generated at the laboratory. The first phase in a pH range of 2 to 4 to recover iron; the second phase in a pH range of 4 to 6 to recover copper; and the third phase in a pH range of 6 to 10 to recover zinc. The selective precipitation allowed the heavy metals to be completely removed from the solution or to achieve concentrations below the maximum allowable limit to be discharged to a body of water or public sewer. Validation of SOLBIO 2 and Orenas bioleaching solutions was performed.

Solvent Extraction of Zinc from a Bioleaching Solution by Modification of D2EHPA: Optimization and Thermodynamic Studies

In this work, zinc extraction from an industrial leach solution was investigated by saponified di(2-ethylhexyl)phosphoric acid (D2EHPA). The solution obtained was from a bioleaching process of a low-grade lead-zinc sulfide ore that contained 50 g/L of zinc and 6.3 g/L of iron. The selective and high Zn(II) extraction yield were obtained by modification of D2EHPA in a proposed two-step process. Firstly, a significant amount of iron (87%) was removed as sodium-jarosite via precipitation from the pregnant leaching solution (PLS) prior to zinc extraction, and secondly, the effective parameters involved in zinc extraction including the contact time, saponification degree, type of saponifier, stirring speed, pH, temperature, D2EHPA concentration, and phase ratio (A:O) were investigated. The results obtained showed that 98.4% of zinc could be extracted under the optimum conditions, i.e. 20% D2EHPA, 15% saponification degree, 650 rpm, pH 2, and an A:O ratio of 1:1 at the ambient temperature (25 ± 2 °C) during 90 s; it was 25% higher than using non-saponified D2EHPA under the same conditions. Moreover, while one theoretical step was required for the complete extraction of zinc by saponified D2EHPA, the required number of steps using D2EHPA was about three. Therefore, the advantages of the process would be two-fold: reducing the number of extraction stages and no need for neutralizing the raffinate in every extraction stage.

Simultaneous removal of iron and sulfate from biodesulfurization solutions of a coking coal by jarosite precipitation

Precipitation of iron- and sulfate-bearing prohibitive layers on the surface of coal particles during heap biodesulfurization is a problematic issue due to the decreasing of biodepyritization rate, causing permeability problems in bioheaps, and reducing the caking properties of coking coals. In this regard, the biodesulfurization of Parvadeh high-pyrite coking coal (Tabas, Iran) was conducted using a mixed culture of iron-and sulfur-oxidizing microorganisms and the ferric level of the bioleaching solution was controlled by jarosite precipitation. The main and interaction effects of some critical parameters including temperature, retention time, the molar ratio of ammonia to iron (MR Ammonia: Iron) and seed addition on the removal of iron from the biodesulfurization solution was investigated by jarosite precipitation using a response surface methodology (RSM). The results were evaluated by the analysis of variance (ANOVA). It was found that 98.4 % iron removal and 62.1 % sulfate removal was achieved at the temperature of 95 °C, the retention time of 2.5 h, the MRAmmonia:Iron of 0.8 and seed addition of 40 g/L. Temperature had the most effect of iron removal efficiency. The precipitates were analyzed by SEM/EDS and XRD analyses. A developed flowsheet was proposed to treat the biodesulfurization solution of coals in bioheaps.

Treatment of an in situ recovered bioleaching solution with a hybrid underground membrane pilot plant

Treatment of an in situ recovered bioleaching solution with a hybrid underground membrane pilot plant