Gold Bioleaching Research Articles

An efficient approach for enhancement of gold and silver bioleaching from spent telecommunication printed circuit boards using cyanogenic bacteria: Prevention of biofilm formation

Environmentally friendly bioleaching of gold and silver from electronic waste using cyanogenic bacteria has emerged as a promising approach. In the process of cyanide bioleaching, cyanide ions produced by cyanogenic bacteria form complexes (such as AuCN and AgCN) with metals in the waste structure and lead to their dissolution. The recovery rate of these valuable elements during bioleaching is influenced by extracellular polymeric substances (EPS). For the first time, this study presents an investigation into the role of EPS from Pseudomonas atacamensis in the bioleaching of gold and silver from spent telecommunication printed circuit boards (STPCBs). The experimental results demonstrate that, after 6 days of bioleaching, gold and silver recoveries reached 22% and 36.2%, respectively. Complementary analyses employing FE-SEM and attachment tests shed light on the interactions between EPS, bacterial attachment to particle surfaces, and biofilm development stages during gold and silver bioleaching. Notably, the most significant bacterial attachment occurred on the fourth day of bioleaching. Zeta potential tests conducted on bacteria and EPS provided insights into the potential absorption of soluble cations such as Au+ and Ag+ by EPS. Furthermore, 250 mg/L polyvinylpyrrolidone (PVP) effectively removed EPS from the particle surfaces, improving gold and silver recovery rates, reaching 26% and 43.2%, respectively. These findings highlight the importance of understanding the role of EPS in bioleaching processes and offer insights into enhancing gold and silver recovery from electronic waste.

Improvement of gold bioleaching extraction from waste telecommunication printed circuit boards using biogenic thiosulfate by Acidithiobacillus thiooxidans

Cyanide usage in gold processing techniques has become increasingly challenging due to its toxicity and environmental impact. It is possible to develop environmentally friendly technology using thiosulfate because of its nontoxic characteristics. Thiosulfate production requires high temperatures, resulting in high greenhouse gas emissions and energy consumption. The biogenesized thiosulfate is an unstable intermediate product of Acidithiobacillus thiooxidans sulfur oxidation pathway to sulfate. A novel eco-friendly method was presented in this study to treat spent printed circuit boards (STPCBs) using biogenesized thiosulfate (Bio-Thio) obtained from Acidithiobacillus thiooxidans cultured medium. To obtain a preferable concentration of thiosulfate among other metabolites by limiting thiosulfate oxidation, optimal concentrations of inhibitor (NaN3: 3.25 mg/L) and pH adjustments (pH= 6–7) were found to be effective. Selection of the optimal conditions has led to the highest bio-production of thiosulfate (500 mg/L). The impact of STPCBs content, ammonia, ethylenediaminetetraacetic acid (EDTA), and leaching time on Cu bio-dissolution and gold bio-extraction were investigated using enriched-thiosulfate spent medium. The suitable conditions were a pulp density of 5 g/L, an ammonia concentration of 1 M, and a leaching time of 36 h, which led to the highest selective extraction of gold (65 ± 0.78%).

Biogenic Production of Thiosulfate from Organic and Inorganic Sulfur Substrates for Application to Gold Leaching

Gold mining and processing is an activity with large environmental impact due to the low concentration of gold in ore deposits and chemical resistance to most chemicals. Over 75% of gold is leached from ores using cyanide, however less toxic lixiviants have been proposed in the literature. Thiosulfate is one of these alternative reagents, but high reagent consumption has slowed acceptance in mining operations. Reducing the cost and impact of thiosulfate production is a way to reduce the cost of reagent consumption during leaching. The objective of this study was to evaluate the feasibility of leaching gold from ore with biogenic thiosulfate. Biogenic thiosulfate was produced using a marine methylotroph bacterium from three substrates: sodium sulfide, elemental sulfur, and dimethyl sulfide for application in bioleaching. The different substrates were evaluated to determine conversion efficiency from the sulfur source to biogenic thiosulfate and verified by titration and ion chromatography. Optimal conditions for conversion to thiosulfate were determined to be in the range of pH = 7–8, 25–30 °C, with sodium sulfide as a substrate in a sealed system to prevent sulfide from escaping as hydrogen sulfide gas. An oxide gold ore with a grade of 4.02 g/t was selected as a gold source for leaching experiments. The leaching of gold using the biogenic thiosulfate was compared with chemical thiosulfate solutions under experimental conditions of pH = 9.5, 50 mg/L copper, 500 RPM mixing, and 0.1 L/min air. The efficiency of gold bioleaching was measured using flame atomic absorption spectroscopy and fire assay. Gold extraction efficiencies ranging from 20–60% were achieved using the biogenic thiosulfate, and 27–77% with sodium thiosulfate solutions, respectively. It was concluded that the sodium sulfide substrate was best for producing higher biogenic thiosulfate concentrations and leaching efficiency.

Importance of laccase enzyme and triiodide for gold leaching from silicate ore by marine bacterium Acinetobacter sp.

The effect of enzymes and other substances on gold bioleaching was investigated. Acinetobacter sp. had a higher gold leaching performance than two strains of Vibrio sp. because it grew well in nutrient broth (NB) medium containing potassium iodide (KI) and produced high levels of both laccase and triiodide (I3-). Under two-step condition of Acinetobacter sp. in NB medium containing KI 10.9 g·L−1 and 1% (w/v) alkali lignin had the highest efficiency in gold leaching. Plausible mechanisms of gold bioleaching involved in biogenic iodide-iodine lixiviant and laccase reaction mechanisms. Laccase produced by Acinetobacter sp. could directly oxidize insoluble gold to soluble gold and also increase iodide oxidation. Afterward, the gold can be oxidized completely in the biogenic iodide-iodine lixiviant to form gold (I) diiodide [AuI2]- or gold (III) tetraiodide [AuI4]-. Interestingly, it was found that silicate ore could act as an inducer of laccase production. Furthermore, alkali lignin addition could increase gold bioleaching due to it can be used as a substrate for laccase production. Therefore, the two-step condition of Acinetobacter sp. could be applied in gold leaching under mild alkaline pH conditions. The advantage of this technology was safer and more environmentally friendly than cyanidation as a conventional extraction.

Mathematical Model for Scaling up Bioprocesses Using Experiment Design Combined with Buckingham Pi Theorem

Scaling up bioprocesses from the experimental to the pilot or industrial scale involves heuristics and scale relationships that are far from the specific phenomena and are usually not connected to the experimental data. In complex systems, the scaling-up methodology must connect the experimental data with the tools of engineering design. In this work, a two-stage gold bioleaching process was used as a case study to develop a mathematical model of bioprocess scaling that combines the design of experiments with dimensional analysis using the Buckingham Pi theorem to formulate a predictive model that allows scaling up bioprocesses. It was found that the C/N, C/K, and T/C ratios are dimensionless factors that can explain the behavior of a system. Using the Pearson Product–Moment bivariate analysis, it was found that the dimensionless factors C/N and C/K were correlated with the leaching potential of the fermented broth at 1060 cm−1. With these results, a non-linear logarithmic model based on dimensionless parameters was proposed to explain the behavior of the system with a correlation coefficient of R2 = 0.9889, showing that the optimal conditions to produce fermented broth comprised a C/N ratio close to 50 and a C/K ratio close to 800, which allows predicting the scaling of the bioprocess.

Synergistic enhancement effect of Ag+ and organic ligands on the bioleaching of arsenic-bearing gold concentrate

Bio-oxidation of arsenic-bearing gold concentrate is generally slow and prone to passivation. To alleviate this concern, it is pivotal to explore the possible catalysts to reduce passivation during bio-oxidation. In the present work, the enhancing effects of Ag+, ethylenediamine tetraacetic acid (EDTA) and oxalate (Ox) on bio-oxidation of arsenic-bearing gold concentrate and the possible mechanisms were investigated by the leaching experiments, thermodynamic calculation, XRD and SEM analyses. Results indicated that the addition of Ag+ and organic ligands could effectively accelerate the bioleaching process. Especially, under the synergistic action of Ag+ and EDTA, the leaching efficiency of As reached the highest value of 87.4% after 10 days. Thermodynamic calculations demonstrated that from the onset of bio-oxidation, the leaching rate was significantly retarded due to the formation of S0, As2S2, As2S3 and jarosite. However, As2S2 and As2S3 could be dissolved in the presence of Ag+ by the formation of Ag2S intermediate that was easily dissolved by Fe3+. Moreover, the addition of EDTA and Ox further facilitated the As extraction, for the possible reason that the presence of organic ligands inhibited the formation of jarosite on the mineral surface by forming corresponding complexes. This possible mechanism was further confirmed by XRD and SEM analyses. Overall, this work demonstrated that organic ligands bind to Ag+ can substantially enhance the efficiency of bioleaching of arsenic-bearing gold concentrate.

Bioleaching of Gold from Silicate Ore by Macrococcus caseolyticus and Acinetobacter calcoaceticus: Effect of Medium, Amino Acids and Growth Supernatant

The aims of this work were to study the gold leaching by the isolated bacteria from silicate ore. Three strains were isolated and identified as Macrococcus caseolyticus, Acinetobacter calcoaceticus, and Bacillus sp. MBEA40. However, only M. caseolyticus and A. calcoaceticus were capable of gold bioleaching. In order to examine only the effect of microorganisms involved in the gold bioleaching process, minimal medium and ethanol mineral salt medium without amino acids were used for culturing M. caseolyticus and A. calcoaceticus, respectively. The result showed that the growth supernatant (in the absence of microorganisms) of both strains might be more suitable to leaching gold from ore than leaching by microorganisms (in the presence of microorganisms) directly. This might be due to the fact that there is no interference of gold absorption and metal toxicity in microorganisms in the long-term operation. The result also confirmed that amino acids/peptides/proteins produced by microorganisms might be involved in gold bioleaching, as shown in the high-performance liquid chromatography (HPLC) results. The Fourier transform infrared spectroscopy (FTIR) study also found that amine groups and carboxylic groups played important roles in gold bioleaching by M. caseolyticus and A. calcoaceticus. In addition, the bioleaching process had significantly higher gold leaching than mixed pure amino acids due to the growth supernatant containing mixed amino acids/peptides/proteins and other compounds. Therefore, the growth supernatant of M. caseolyticus and A. calcoaceticus can be applied in gold bioleaching under neutral pH conditions, which is considered to be a safe, not corrosive, and environmentally friendly leaching process. This study is also needed further study in order to increase the percentage of gold bioleaching and decrease times.

Recovery of Gold and Other Precious Metal Resources from Environmental Polluted E-waste Printed Circuit Board by Bioleaching Frankia

The physicochemical profiling of e-waste was done by AAS, XRD, and SEM with EDX that reveals the composition of valuable metals like Au−, Ag−, Zn−, and Cu−. Thus, the present findings provide the important resource of precious metal in the e-waste (PCBs) as pollutant in the environment and human impact. The native isolates Frankia sp. DDNSF-01 and Frankia casuarinae DDNSF-02 were subjected for bioleaching of gold and precious elements bearing e-waste under one and two-step leaching methods. The two-step bioleaching protocol was found effectual in expression with high level of metal leaching within the culture medium of Frankia metabolites and organic acids which were obtained by the leaching of metals. The presence of organic acids functional groups was determined by FT-IR spectrum and by low pH of growth medium. The AAS analysis quantified the initial concentration of metals and their significant increase brought by the leaching. The initial concentration of precious metal elements was found in the e-waste like Au−, Ag−, Cu−, and Zn− (0.04, 0.05, 0.35, 0.1 mg/g) respectively. Frankia sp. leached out precious metals like Au−, Ag−, Cu−, and Zn− (0.2, 0.14, 0.68, 0.2 mg/g) respectively. Frankia casuarinae leached out precious metals like Au−, Ag−, Cu−, and Zn− (0.25, 0.15, 0.55, and 0.2 mg/g) respectively. The precious metal gold was highly leached out by F. casuarinae than Frankia sp.. The valuable metal copper was significantly increased by Frankia sp. than F. casuarinae. Higher gold recovery, at 75%, was obtained for F. casuarinae and copper 94% recovery by Frankia sp. bioleaching of the biooxidised e-waste at 0.2% low pulp densities. The results were confirmed by XRD and SEM with EDX analysis.

Leaching characteristics of encapsulated controlled low-strength materials containing arsenic-bearing waste precipitates from refractory gold bioleaching

We report on the leaching of heavy elements from cemented waste flowable fill, known as controlled low-strength materials (CLSM), for potential mine backfill application. Semi-dynamic tank leaching tests were carried out on laboratory-scale monoliths cured for 28 days and tested over 64 days of leaching with pure de-ionised water as leachant. Mineral processing waste include flotation tailings from a Spanish nickel-copper sulphide concentrate, and two bioleach neutralisation precipitates (from processing at 35 °C and 70 °C) from a South African arsenopyrite concentrate. Encapsulated CLSM formulations were evaluated to assess the reduction in leaching by encapsulating a ‘hazardous’ CLSM core within a layer of relatively ‘inert’ CLSM. The effect of each bioleach waste in CLSM core and tailings in CLSM encapsulating medium, are assessed in combination and in addition to CLSM with ordinary silica sand. Results show that replacing silica sand with tailings, both as core and encapsulating matrix, significantly reduced leachability of heavy elements, particularly As (from 0.008–0.190 mg/l to 0.008–0.060 mg/l), Ba (from 0.435–1.540 mg/l to 0.050–0.565 mg/l), and Cr (from 0.006–0.458 mg/l to 0.004–0.229 mg/l), to below the ‘Dutch List’ of groundwater contamination intervention values. Arsenic leaching was inherently high from both bioleach precipitates but was significantly reduced to below guideline values with encapsulation and replacing silica sand with tailings. Tailings proved to be a valuable encapsulating matrix largely owing to small particle size and lower hydraulic conductivity reducing diffusion transport of heavy elements. Field-scale trials would be necessary to prove this concept of encapsulation in terms of scale and construction practicalities, and further geochemical investigation to optimise leaching performance. Nevertheless, this work substantiates the need for alternative backfill techniques for sustainable management of hazardous finely-sized bulk mineral residues.

Review on Chromobacterium Violaceum for Gold Bioleaching from E-waste

Electronic waste, such as printed circuit boards, are an important secondary resource if processed with environment-friendly technologies for obtaining precious metal, such as gold. The gold bioleaching from electronic waste was recently getting paid attractive attention because its available deposit is limited. This review was focused on Chromobacterium violaceum (C. Violaceum), which was a mesophilic, gram-negative, and facultative anaerobe. C. violaceum has the ability of producing CN− which can dissolve gold from the metallic particles of crushed waste printed circuit boards. This article also provided an overview of cyanide-generation mechanism and the optimal conditions for C. violaceum to achieve maximum amount of cyanide generation. The past achievements and recently scenario of recovery studies carried out on the use of some other microorganisms were compared with C. violaceum. And recently some researchers proposed that combined C. violaceum with chemical methods or other mechanism such as iodide, Pseudomonas aeruginosa and Pseudomonas fluorescens which can reinforce the cyanide generation and improve gold-leaching efficiency. The factors affected the microorganisms on cyanide generation were summarized and the proper conditions were also discussed in this article. And present researches of C. violaceum in gold bioleaching had made good progress which the reported leaching efficiency of gold was over 70%.

Two-step bioleaching of copper and gold from discarded printed circuit boards (PCB)

An effective strategy for environmentally sound biological recovery of copper and gold from discarded printed circuit boards (PCB) in a two-step bioleaching process was experimented. In the first step, chemolithotrophic acidophilic Acidithiobacillus ferrivorans and Acidithiobacillus thiooxidans were used. In the second step, cyanide-producing heterotrophic Pseudomonas fluorescens and Pseudomonas putida were used. Results showed that at a 1% pulp density (10g/L PCB concentration), 98.4% of the copper was bioleached by a mixture of A. ferrivorans and A. thiooxidans at pH 1.0–1.6 and ambient temperature (23±2°C) in 7days. A pure culture of P. putida (strain WCS361) produced 21.5 (±1.5)mg/L cyanide with 10g/L glycine as the substrate. This gold complexing agent was used in the subsequent bioleaching step using the Cu-leached (by A. ferrivorans and A. thiooxidans) PCB material, 44.0% of the gold was mobilized in alkaline conditions at pH 7.3–8.6, and 30°C in 2days. This study provided a proof-of-concept of a two-step approach in metal bioleaching from PCB, by bacterially produced lixiviants.

A Feasibility Study of Arsenopyrite-Bearing Gold Bioleaching and its Characterization

Gold concentrates are mainly composed of arsenopyrite and pyrite. Leptospirillum ferriphilum has been found to be a dominant iron-oxidizing bacterium in the biooxidation of arsenopyrite-bearing gold concentrates. The present study demonstrated the capability of the bacterium Leptospirillum ferriphilum in oxidizing arsenopyrite within 6 days as evidenced by X-ray diffraction (XRD) analyses.

Bio-Oxidation and Biocyanidation of Refractory Mineral Ores for Gold Extraction: A Review

Bioleaching has emerged as a green technology with promising applications in mining industries in the context of recovery of precious metals from mineral ores. The authors synthesize the current knowledge available in the bioleaching of gold (Au) from ores by bringing together historical developments and recent endeavors. In addition, the role of the microbial community in the bio-oxidation of refractory ores for removal of base metal impurities and in the recovery of Au based on biocyanidation is reviewed. They also address the future research directions in the bioleaching of Au in order to make further advances toward practical industrial applications.

Influence of surfactants on bioleaching of arsenic-containing gold concentrate

To shorten the bioleaching cycle of arsenic-containing gold concentrate, surfactants were used to promote the interaction between bacteria and ore to increase the arsenic leaching rate. Three different kinds of surfactants were used to evaluate the effects of surfactants on the growth of bacteria and arsenic leaching rate of arsenic-containing gold concentrate. The mechanism underlying surfactant enhancement was also studied. Results show that when relatively low-concentration surfactants are added to the medium, no significant difference is observed in the growth and Fe2+ oxidation ability of the bacteria compared with no surfactant in the medium. However, only the anionic surfactant calcium lignosulfonate and the nonionic surfactant Tween 80 are found to improve the arsenic leaching rates. Their optimum mass concentrations are 30 and 80 mg/L, respectively. At such optimum mass concentrations, the arsenic leaching rates are approximately 13.7% and 9.1% higher than those without the addition of surfactant, respectively. Mechanism research reveals that adding the anionic surfactant calcium lignosulfonate improves the percentage of bacterial adhesion on the mineral surface and decreases the surface tension in the leaching solution.

Two-Step Bioleaching and Spent Medium Leaching of Gold from Electronic Scrap Material Using <i>Chromobacterium violaceum</i>

Rapid technological advancement and the relatively short life time of electronic goods have resulted in an alarming growth rate of electronic waste which often contains significant quantities of toxic and precious metals. Compared to conventional chemical recovery methods, bioleaching has been shown to be an environmentally friendly process for metal extraction. In this work, gold bioleaching from electronic scrap material (ESM) was examined using batch cultures of the bacterium Chromobacterium violaceum which produces cyanide as a secondary metabolite. Gold was bioleached via gold cyanide complexation. The ESM was pretreated using nitric acid to dissolve the base metals (mainly copper) in order to reduce competition for the cyanide ion from other metals present in ESM. ESM was added to the bacterial culture after it reached maximum cyanide production during early stationary phase. Spent medium bioleaching using bacterial cell- free metabolites showed a higher gold recovery of 18%, compared to that of two-step bioleaching of 11% at 0.5% w/v pulp density of ESM. Gold bioleaching was further enhanced to 30% when the pH of the spent medium was increased to shift the equilibrium in favor of cyanide ions production. Spent medium bioleaching of pretreated ESM yield a higher gold recovery compared to two-step bioleaching at a pulp density of 0.5% w/v.

Electrochemical Behavior of Carbon Paste Electrode with Gold-Bearing Pyrite in Bioleaching

The dissolution of gold-bearing pyrite plays an important role in bioleaching of gold. This paper describes a fundamental study on the electrochemical behavior and reaction mechanisms of gold-bearing pyrite leaching in the form of Carbon Paste Electrode (CPE) with and without microorganisms using Cyclic Voltammetry (CV) and polarization curve. A two step process was suggested from Cyclic voltammetry. Electrode passivation by elemental sulphur was observed below 700mV (vs. SCE), elemental sulphur was then oxidized to sulphate when the electrode potential further increased from 700mV. The polarization current density of CPE and the oxidation rate of pyrite are further enhanced by the presence of microorganisms. Analyses of EDS and XPS confirmed the formation of elemental sulphur and sulphate. This electrochemical method successfully showed its simplicity and reliability to measure oxidation rate of gold bearing pyrite.

Evaluation of bioleaching factors on gold recovery from ore by cyanide-producing bacteria

The present study was conducted to investigate the gold bioleaching factors from ore by cyanide producing bacterium Chromobacterium violaceum. The optimal condition for cyanide production by C. violaceum was pH 9 and 5g/L of glycine in YP medium in 2-days of incubation. In shake flask culture, gold bioleaching from the ores by C. violaceum was determined with various experimental protocols such as particle size, pre-grown C. violaceum, pH, and biooxidative treatment. The three types of low grade ores viz., R, S, and H were used. The gold bioleaching efficiencies were recorded as 0%, 50%, and 5% for ores R, S, and H, respectively, when C. violaceum culture was used without any pretreatment (protocol 1). In the experimental protocol involving grinding and pre-grown C. violaceum, leaching efficiencies increased to 60%, 100%, and 40% for ore R, S, and H samples, respectively. Especially, the bioleaching efficiency of ore S enhanced to almost 100% with pre-grown C. violaceum (protocol 2) and that of ore R increased to 53% (i.e., 96% of cyanidable gold) with grinding (protocol 3) due to their mineralogical characteristics of the ores. For refractory gold (i.e., ore R) grinding as pretreatment was needed, and for ore S (almost all of the gold was cyanidable) cyanide production was activated by using pre-grown bacteria. Biooxidation with Acidithiobacillus ferrooxidans and pH adjustment (i.e., 9–11) did not affect the bioleaching efficiencies. The mineralogical cause of gold refractoriness was analyzed by automated SEM that showed most of gold in the ore was entrapped in pyrite and silica. The results indicated that gold bioleaching by C. violaceum from low grade ore can be enhanced by grinding and pre-grown microbe; use of appropriate experimental condition is important according to the mineralogical characteristics.

Bioleaching of Arsenic-Rich Gold Concentrates by Bacterial Flora before and after Mutation

In order to improve the bioleaching efficiency of arsenic-rich gold concentrates, a mixed bacterial flora had been developed, and the mutation breeding method was adopted to conduct the research. The original mixed bacterial flora had been enrichedin acid mine drainage of Dexing copper mine, Jiangxi Province, China. It was induced by UV (ultraviolet), ultrasonic, and microwave, and their combination mutation. The most efficient bacterial flora after mutation was collected for further bioleaching of arsenic-rich gold concentrates. Results indicated that the bacterial flora after mutation by UV 60 s combined with ultrasonic 10 min had the best oxidation rate of ferrous, the biggest density of cells, and the most activity of total protein. During bioleaching of arsenic-rich gold concentrates, the density of the mutant bacterial cells reached to 1.13 × 108 cells/mL at 15 days, more than 10 times compared with that of the original culture. The extraction of iron reached to 95.7% after 15 days, increased by 9.9% compared with that of the original culture. The extraction of arsenic reached to 92.6% after 12 days, which was increased by 46.1%. These results suggested that optimum combined mutation could improve leaching ability of the bacterial flora more significantly.

Gold Bioleaching of Electronic Waste by Cyanogenic Bacteria and its Enhancement with Bio-Oxidation

This work compares gold bioleaching from e-waste containing gold and copper by Chromobacterium violaceum and Pseudomonas fluorescens. The effect of pulp density (ranging from 0.5 to 8%w/v) was examined. Although C. violaceum produced more cyanide than P. fluorescens in the absence of e-waste, P. fluorescens showed higher growth rate, cyanide production and gold leaching efficiency at all pulp densities. Pretreatment with biooxidation of the e-waste using Acidithiobacillus ferrooxidans resulted in the removal in excess of 80% of the copper present in the waste, and increased the gold/copper ratio in the residual solid. Bioleaching the biooxidised e-waste significantly improved gold recovery, especially by C. violaceum, particularly at high pulp density. For example, at pulp densities of 2 and 4% w/v, gold recovery from non-biooxidzed e-waste was 0.22 and 0.14% respectively. Higher gold recovery, at 8%, was obtained for bioleaching of the biooxidised e-waste at both these pulp densities. The ratio of gold/copper in leachates after bioleaching of the biooxidized e-waste was also found to be increased.

Reverse osmosis removal of arsenic residues from bioleaching of refractory gold concentrates

The paper deals with the quality of liquid streams likely to arise from bioleaching of gold-bearing arsenical sulphide flotation concentrate and with purification of leachate after lime neutralisation. Synthetic liquors, based on data from an industrial process, were subjected to filtration, reverse osmosis and/or resin ion exchange processes under designed conditions in a re-circulating system based on equipment provided by Purite Ltd. The distribution of arsenic at low concentrations required by potable water and groundwater regulations was determined comparatively by four analytical techniques: ICP-AES, ICP-MS, Wagtech Arsenator ® and Algaltoxkit F™. Arsenical ferrihydrite precipitated from the synthetic liquors with lime retained most of the arsenic(V) (As <100 ppb). Over 90% of residual As(V) was removed by reverse osmosis thus achieving the WHO standard (As <50 ppb for discharge). Drinking water standards were readily achieved by reverse osmosis and ion exchange employed in sequence. Arsenic(III) was poorly retained by the RO membrane (only 20–55% removal) because of arsenite existed as neutral molecule which readily penetrated through the membrane. Therefore, prior oxidation of As(III) to As(V) is needed. Calcium sulphate dihydrate (gypsum), which precipitated during the filtration process, contained some 30% of this residual arsenic. The plasma techniques were routinely reliable, although only ICP-MS had sufficient sensitivity with good precision at arsenic levels in the range 1–50 ppb. The arsenator was compact, portable and readily applied, and gave semi-quantitative results in the range 10–50 ppb As. The ecotoxicological assessment was inexpensive and suited to the non-specialist laboratory. However, analyses were time consuming and required experience in algal culture. The algae became insensitive to arsenic below 100 ppb. On the basis of these results, ICP-MS was the best available method to assess environmental compliance of discharge streams for arsenic content. However, the algal system could be appropriate, together with occasional umpire analysis by ICP-MS, when site specific regulatory consents allow and/or effluents contain a mixed pollutant load.