Arsenic Removal Technologies Research Articles

Adsorption behavior of As(III) onto a copper ferrite generated from printed circuit board industry

A copper ferrite generated from the sludge of printed circuit board (PCB) industry was investigated for its As(III) adsorption behavior. The adsorption of As(III) by this copper ferrite exhibited a L-shaped nonlinear isotherm and fitted well the Langmuir isotherm, implying limited binding sites and monolayer sorption occurred on the surface. The K-edge X-ray Absorption Near-Edge Structure (XANES) showed that the adsorbed As(III) could be oxidized to less toxic As(V) by copper ferrite. The maximum As adsorption capacity of the copper ferrite was 41.2mgg−1 at pH 4.2 and decreased dramatically at higher pH (pH>9.2) due to enhanced electrostatic repulsion between As(III) and the adsorbent surface. Desorption of As(III) using four different acid solutions demonstrated that the desorption rate decreased in the order of H3PO4>H2SO4>HCl>HNO3. These results demonstrate that the synthesized copper ferrite is an effective adsorbent for removing As(III) in aqueous solution. The new data obtained reveals informative knowledge for designing an arsenic removal technology in treating contaminated groundwater.

Research Progress on Biological Removal of Arsenic Technology

Arsenic is a toxic element, which is harmful to environment and human health. How to treat arsenic polluted water has become a global environmental concern. Current biological arsenic removal technology was researched base on plants, microorganisms and so on. Biological removal of arsenic technology has high efficiency, low cost, and low secondary pollution, which will be the most promising technology.

New Technology for Arsenic Removal from Mining Effluents

Arsenic is a persistent, toxic, and bioaccumulative element. Water with arsenic contamination has been reported in many parts of the world, and the World Health Organization considers arsenic one of the main contaminants in aqueous waste streams. Ferric co-precipitation treatment process, considered the state-of-the-art (the technology used industrially at present), produces large amounts of secondary waste with low stability, which leads to arsenic eventually being released back to the medium through natural oxidation processes. Current treatment technologies are quite effective at meeting the present environmental legislation discharge criteria (0.2 mg/L - COPAM 10/86 Brazilian Legislation) of removing aqueous oxy anionic contaminants, such as arsenic. An innovative treatment technology was developed for arsenic removal, allowing the reduction of arsenic levels in the effluent generated during the mining processes to a level below the criteria for discharge (reaching 0.1885 mg As/L).

Technological options for the removal of arsenic with special reference to South East Asia

Arsenic contamination in ground water, used for drinking purpose, has been envisaged as a problem of global concern. However, arsenic contamination of ground water in parts of South East Asia is assuming greater proportions and posing a serious threat to the health of millions of people. A variety of treatment technologies based on oxidation, co-precipitation, adsorption, ion exchange and membrane process are available for the removal of arsenic from ground water. However, question remains regarding the efficiency and applicability/appropriateness of the technologies, particularly because of low influent arsenic concentration and differences in source water composition. Some of these methods are quite simple, but the disadvantage associated with them is that they produce large amounts of toxic sludge, which needs further treatment before disposal into the environment. Besides, the system must be economically viable and socially acceptable. In this paper an attempt has been made to review and update the recent advances made in the technological development in arsenic removal technologies to explore the potential of those advances to address the problem of arsenic contamination in South East Asia.

Removing Heavy Metals in Water: The Interaction of Cactus Mucilage and Arsenate (As (V))

High concentrations of arsenic in groundwater continue to present health threats to millions of consumers worldwide. Particularly, affected communities in the developing world need accessible technologies for arsenic removal from drinking water. We explore the application of cactus mucilage, pectic polysaccharide extracts from Opuntia ficus-indica for arsenic removal. Synthetic arsenate (As (V)) solutions were treated with two extracts, a gelling extract (GE) and a nongelling extract (NE) in batch trials. The arsenic concentration at the air-water interface was measured after equilibration. The GE and NE treated solutions showed on average 14% and 9% increases in arsenic concentration at the air-water interface respectively indicating that the mucilage bonded and transported the arsenic to the air-water interface. FTIR studies showed that the -CO groups (carboxyl and carbonyl groups) and -OH (hydroxyl) functional groups of the mucilage were involved in the interaction with the arsenate. Mucilage activity was greater in weakly basic (pH 9) and weakly acidic (pH 5.5) pH. This interaction can be optimized and harnessed for the removal of arsenic from drinking water. This work breaks the ground for the application of natural pectic materials to the removal of anionic metallic species from water.

Arsenate and arsenite removal by FeCl3: Effects of pH, As/Fe ratio, initial As concentration and co-existing solutes

Coagulation is one of the most commonly used technologies for arsenic removal from water and wastewater. Jar tests were carried out to determine the influence of pH, initial As/Fe molar ratio, equilibrium As concentration and co-occurring solutes on the crossover pH, where As(V) removal was equivalent to As(III) by FeCl3 coagulation. As(V) was more effectively removed than As(III) at lower pH values in FeCl3 coagulation process but the opposite was true at higher pH level. Increasing As/Fe ratio from 0.12 to 0.50 progressively lowered the crossover pH from 8.5 to 7.4. The arsenic isotherms revealed that As(V) removal was favored at low pH and low equilibrium concentration yet the opposite was true for As(III). The co-existing solutes had different influences on the crossover pH, depending on their ability to compete for sorption sites and to hinder or facilitate the aggregation of ferric hydroxide flocs. The presence of sulfate broadened the pH range where As(III) removal was better than As(V) removal. However, As(V) removal was always superior to As(III) removal in the presence of Ca2+ and no crossover pH was observed. The results from this study revealed that arsenic speciation, arsenic loading, and pH should be considered when predicting and managing arsenic removal by coagulation.

Adsorption of arsenate on iron(III) oxide coated ethylenediamine functionalized multiwall carbon nanotubes

New criteria in assessing the quality of drinking water reduced the maximum permissible concentration of arsenic from 50μgL−1 to 10μgL−1, and set a requirement for the development of new technologies for arsenic removal. In this paper, ethylenediamine functionalized multiwall carbon nanotubes (e-MWCNT) were loaded with iron(III) oxide in the goethite form, by precipitation of adsorbed Fe3+ and oxidized Fe2+ using base, in that way e-MWCNT/Fe3+ and e-MWCNT/Fe2+ adsorbents, respectively, were obtained. The influence of pH on the As(V) and As(III) removal from drinking water was studied in a batch system, of pH range 3–10 and initial arsenic concentration 0.05–4mgL−1. Time dependent As(V) adsorption and adsorption data can be described by pseudo-second-order kinetic model and by Freundlich isotherm, applying linear and non-linear fitting methods. The maximum adsorption capacities obtained from Langmuir model for As(V) on e-MWCNT/Fe2+ and e-MWCNT/Fe3+ were 23.47 and 13.74mgg−1 at 25°C, respectively. Thermodynamic parameters showed that the adsorption of As(V) was spontaneous and endothermic for both e-MWCNT/Fe2+ and e-MWCNT/Fe3+. Influences of the pH, iron(III) oxide loading and interfering ions were modeled by MINTEQ program, and good agreement between experimental and modeling data was obtained.

A novel two-step coprecipitation process using Fe(III) and Al(III) for the removal and immobilization of arsenate from acidic aqueous solution

Lime neutralization and coprecipitation of arsenate with iron is widely practiced for the removal and immobilization of arsenic from mineral processing effluents. However, the stability of the generated iron-arsenate coprecipitate is still of concern. In this work, we developed a two-step coprecipitation process involving the use of iron and aluminum and tested the stability of the resultant coprecipitates. The two-step Fe–As–Fe or Fe–As–Al coprecipitation process involved an initial Fe/As = 2 coprecipitation at pH4 to remove arsenic from water down to 0.25 mg/L, followed by introduction of iron or aluminum (Fe/As = 2, Al/As = 1.5 or 2). The two-step coprecipitates showed higher stability than traditional Fe/As = 4 coprecipitate under both oxic and anoxic conditions. Leaching stability was enhanced when aluminum was applied in the second step. The use of aluminum in the second step also inhibited microbial mediated arsenate reduction and arsenic remobilization. The results suggest that the two-step coprecipitation process is superior to conventional coprecipitation methods with respect to the stability of the generated arsenic-bearing solid waste. The use of Al in the second step is better than Fe to enhance the stability. This work may have important implications to the development of new technologies for efficient arsenic removal from hydrometallurgical solutions and safe disposal in both oxic and anoxic environment.

Arsenic (III) oxidation of water applying a combination of hydrogen peroxide and UVC radiation

Arsenic is toxic to both plants and animals and inorganic arsenicals are proven carcinogens in humans. The oxidation of As(III) to As(v) is desirable for enhancing the immobilization of arsenic and is required for most arsenic removal technologies. The main objective of this research is to apply an Advanced Oxidation Process that combines ultraviolet radiation and hydrogen peroxide (UVC/H(2)O(2)) for oxidizing aqueous solutions of As(III). For that purpose, a discontinuous photochemical reactor (laboratory scale) was built with two 40 W tubular germicidal lamps (λ = 253.7 nm) operating inside a recycling system. The study was made beginning with a concentration of 200 μg L(-1) of As(III), changing the H(2)O(2) concentration and the spectral fluence rate on the reactor windows. Based on references in the literature on the photolysis of hydrogen peroxide, arsenic oxidation and our experimental results, a complete reaction scheme, apt for reaction kinetics mathematical modelling, is proposed. In addition, the effectiveness of arsenic oxidation was evaluated using a raw groundwater sample. It is concluded that the photochemical treatment of As(III) using H(2)O(2) and UVC radiation is a simple and feasible technique for the oxidation of As(III) to As(v).

Treatment and remediation methods for arsenic removal from the ground water

Globally, ground water is contaminating by arsenic continously, which needs economic treatment and remediation technologies. Physical, chemical and biological treatment methods have been developed, that include different kinds of filters, bucket type units, fill and draw, kalshi etc. The remediation methods discussed are air oxidation, reactive barriers, utilisation of deeper aquifers and sanitary protected dug wells. To the best of our knowledge no technology is available capable to remove arsenic from water at efficient, economic and commercial levels. Therefore, fast, efficient and economic arsenic removal technologies are required. Attempts have been made to suggest the future technologies of arsenic removal.

Novel, bio-based, photoactive arsenic sorbent: TiO 2-impregnated chitosan bead

A novel sorbent for arsenic, TiO 2-impregnated chitosan bead (TICB), has been synthesized and successfully tested. Kinetic plots, pH dependence, isotherm data, and bead morphology are reported. Equilibrium is achieved after 185 h in batch experiments with exposure to UV light. The TICB system performs similarly to the mass equivalent of neat TiO 2 nanopowder. The point of zero charge (pzc) for TICB was determined to be 7.25, and as with other TiO 2-based arsenic removal technologies, the optimal pH range for sorption is below this pH pzc. Without exposure to UV light, TICB removes 2198 μg As(III)/g TICB and 2050 μg As(V)/g TICB. With exposure to UV light, TICB achieves photo-oxidation of As(III) to As(V), the less toxic and more easily sequestered arsenic form. UV irradiation also results in enhanced arsenic removal, reaching sorption capacities of 6400 μg As/g TICB and 4925 μg As/g TICB, where arsenic is initially added as As(III) and As(V), respectively. Because the TICB system obviates filtration post-treatment, TICB is superior to TiO 2 nanopowder from the perspective of implementation for decentralized water treatment.

As(III) removal using an iron-impregnated chitosan sorbent

An iron-impregnated chitosan granular adsorbent was newly developed to evaluate its ability to remove arsenic from water. Since most existing arsenic removal technologies are effective in removing As(V) (arsenate), this study focused on As(III). The adsorption behavior of As(III) onto the iron-impregnated chitosan absorbent was examined by conducting batch and column studies. Maximum adsorption capacity reached 6.48 mg g −1 at pH = 8 with initial As(III) concentration of 1007 μg L −1. The adsorption isotherm data fit well with the Freundlich model. Seven hundred and sixty eight (768) empty bed volumes (EBV) of 308 μg L −1 of As(III) solution were treated in column experiments. These are higher than the empty bed volumes (EBV) treated using iron-chitosan composites as reported by previous researchers. The investigation has indicated that the iron-impregnated chitosan is a very promising material for As(III) removal from water.

Adsorption Based Technologies for Arsenic Removal from Aqueous Environment: A Review

In the present paper we have focussed on some different adsorbents for arsenic removal from aqueous media. Adsorbents were divided categorically in two different classes viz., synthetic adsorbents and natural adsorbents. Some of the synthetic adsorbents are found to be good for As(III) and some are good for As(V) removal. Similar results were also obtained for the natural adsorbents although removal efficiency depends on a number of factors. The efficiency of the adsorbents, merits and demerits were discussed in detail. Finally, we have discussed on some patented technologies and some potential filters.

An Evaluation of Fish Bone Char as an Appropriate Arsenic and Fluoride Removal Technology for Emerging Regions

Abstract Arsenic and fluoride are both contributors to the global water crisis, with significant health problems resulting from drinking water with levels higher than the 0.01 mg/L and 1.5 mg/L World Health Organization standards, respectively. This study evaluates fish bone char as an appropriate fluoride and arsenic removal technology for emerging regions, and investigates differences between fish bone char and cow bone char. The results of batch tests, specific surface area measurements, chemical composition testing, and point of zero charge (PZC) determination show that charring temperature affects the capacity of fish bone char to adsorb fluoride. It was found that 500°C is the best charring temperature based on removal effectiveness and residual water quality. Specific surface area is affected by charring temperature. It was observed that at lower temperatures, such as 300°C, some of the organic material was not removed during charring and the specific surface area was only 25% of what was observed ...

Technical and Social Evaluation of Arsenic Mitigation in Rural Bangladesh

Technical and social performances of an arsenic-removal technology--the sono arsenic filter--in rural areas of Bangladesh were investigated. Results of arsenic field-test showed that filtered water met the Bangladesh standard (< 50 microg/L) after two years of continuous use. A questionnaire was administrated among 198 sono arsenic filter-user and 230 non-user families. Seventy-two percent of filters (n = 198) were working at the time of the survey. Another 28% of the filters were abandoned due to breakage. The abandonment percentage (28%) was lower than other mitigation options currently implemented in Bangladesh. Households were reluctant to repair the broken filters on their own. High cost, problems with maintenance of filters, weak sludge-disposal guidance, and slow flow rate were the other demerits of the filter. These results indicate that the implementation approaches of the sono arsenic filter suffered from lack of ownership and long-term sustainability. Continuous use of arsenic-contaminated tubewells by the non-user households demonstrated the lack of alternative water supply in the survey area. Willingness of households to pay (about 30%) and preference of household filter (50%) suggest the need to develop a low-cost household arsenic filter. Development of community-based organization would be also necessary to implement a long-term, sustainable plan for household-based technology.

Evaluation of simple methods of arsenic removal from domestic water supplies in rural communities

This study looked at two arsenic removal technologies, method Bucket Treatment Unit and removal using citrus lime, lemon and filter. The method Bucket Treatment Unit used zero-valent iron and removal using citrus lime, lemon and filter used photochemical oxidation of arsenic. The citrus lime, lemon and filter setup was found to be ineffective with its current design. The results reviewed that the method Bucket Treatment Unit was more effective and appropriate, but with clogging problems. The method Bucket Treatment Unit had between 68% and 100% arsenic removal efficiency with a 36 L/day flow rate of filtrate. The removal using photochemical oxidation of arsenic only had 8% removal efficiency. The study also reviewed that groundwater resources in the Ashanti Region of Ghana were contaminated with arsenic above the World Health Organization (WHO) standards.

Arsenic pollution: a global synthesis

List of Figures. List of Tables. Series Editors' Preface. Acknowledgements. List of Abbreviations. Glossary. 1. Introduction . 1.1. Background. 1.2. The Nature of Arsenic Pollution. 1.3. History of Natural Arsenic Contamination. 1.4. Arsenic Pollution. 1.5. Risk, Perception and Social Impacts. 1.6. Water-supply Mitigation. 1.7. Structure and Scope of the Book. 2. Hydrogeochemistry of Arsenic . 2.1. Introduction. 2.2. The Chemistry of Normal and Arsenic-Rich Groundwaters. 2.3. Adsorption and Desorption of Arsenic. 2.4. The Role of Sulphur in Strongly Reducing Groundwater. 2.5. Arsenic and Microbial Activity. 2.6. Arsenic Mobilisation Mechanisms. 2.7. Associations of Arsenic with other Trace Elements. 2.8. Arsenic Pollution and Mining. 2.9. Summary. Annexe 2.1. Analysis of Arsenic in Natural Waters. 3. The Hydrogeology of Arsenic . 3.1. Introduction. 3.2. Arsenic in Rocks and Sediments. 3.3. Arsenic in River Water and Sediment. 3.4. Geo-environmental Associations of Arsenic in Groundwater. 3.5. Geochemical Processes in their Geological Context. 3.6. Behaviour of Arsenic in Aquifers. 3.7. Case Histories of Arsenic-affected Aquifers. 3.8. Implications of Long-term Pumping of Arsenic Contaminated Groundwater. 3.9. Summary and Conclusions. 4. Soils and Agriculture . 4.1. Introduction. 4.2. Arsenic in Soils. 4.3. Irrigation with Arsenic-contaminated Water. 4.4. Arsenic Uptake by plants. 4.5. Options for Arsenic Management. 4.6. Research and Development Needs. 5. Health Effects of Arsenic in Drinking Water and Food. 5.1. Introduction. 5.2. A Short History of the Health Effects of Chronic Arsenic Poisoning. 5.3. Toxicity of Arsenic Compounds. 5.4. Environmental Exposure to Arsenic. 5.5. Acute Arsenic Poisoning. 5.6. Dermatological Manifestations. 5.7. Carcinogenic effects. 5.8. Systemic Non-carcinogenic Effects. 5.9. Social and Psychological Effects. 5.10. Effect of Other Toxic and Trace Elements. 5.11. Geographical differences in Health Effects. 5.12. Case History of Arsenic Exposure in Murshidabad District, West Bengal. 5.13. Diagnosis and Treatment of Arsenicosis. 5.14. Removing Exposure to Arsenic. 5.15. Summary and Recommendations. 6. Water-supply Mitigation . 6.1. Introduction. 6.2. Approaches to Water-supply Mitigation. 6.3. Surveys of Arsenic Affected Areas. 6.4. Exploiting Safe Groundwater Sources. 6.5. Developing Surface Water Sources. 6.6. Arsenic in Water Distribution Networks. 6.7. Socio-economic Aspects of Mitigation. 6.8. Policy and Planning Initiatives. 6.9. Monitoring and Evaluation of Water-supply Mitigation Programmes. 6.10. Summary. Annexe 6.1. Arsenic Survey Procedures. 7. Removing Arsenic from Drinking Water . 7.1. Introduction. 7.2. Water Quality Issues. 7.3. Methods of Arsenic Removal. 7.4. Aquifer Clean-up. 7.5. Disposing of Waste from Treatment Processes. 7.6. Examples and Operational Experience of Arsenic Removal Technologies. 7.7. Costs of Arsenic Removal. 7.8. Guidance for Selecting Treatment Methods and Technologies. 7.9. Case Study of Water Treatment Requirements in Bangladesh. 7.10. Future Needs. 8. Arsenic in Asia . 8.1. Introduction. 8.2. South Asia. 8.3. Southeast Asia. 8.4. China. 8.5. East Asia. 8.6. Western, Central and Northern Asia. 8.7. Suspect Terrain and Research Needs. Annexe 8.1. The British Geological Survey Court Case. 9. Arsenic in North America and Europe. 9.1. Introduction. 9.2. United States of America and Canada. 9.3. Mexico. 9.4. Europe. 9.5. Suspect Terrain and Research Needs. 10. Arsenic in South and Central America, Africa, Australia and Oceania . 10.1. Introduction. 10.2. South and Central America. 10.3. Africa. 10.4. Australasia. 10.5. Arsenic in the Ocean Basins. 10.6. Suspect Terrain and Research Needs. 11. Synthesis, Conclusions and Recommendations. 11.1. Scale and Impact of Arsenic Pollution. 11.2. Chemistry, Cause and Prediction. 11.3. Agricultural Impacts, Prospects and Needs. 11.4. Water-supply Mitigation. 11.5. Sustainability Issues. 11.6. Geographical Perspectives. 11.7. The Politics of Arsenic Pollution and Mitigation. 11.8. Ten Priority Actions. Notes. References. Index

Influence of operating parameters on the arsenic removal by nanofiltration

Arsenic contamination of surface and groundwater is a worldwide problem in a large number of Countries (Bangladesh, Argentina, Italy, USA, New Zealand, etc.). In many contaminated areas a continuous investigation of the available arsenic removal technologies is essential to develop economical and effective methods for removing arsenic in order to meet the new Maximum Contaminant Level (MCL) standard (10μg/l) recommended by the World Health Organization (WHO).In this work the removal of pentavalent arsenic from synthetic water was studied on laboratory scale by using two commercial nanofiltration (NF) spiral-wound membrane modules (N30F by Microdyn-Nadir and NF90 by Dow Chemical). The influence of main operating parameters such as feed concentration, pH, pressure and temperature on the As rejection and permeate flux of both membranes, was investigated. An increase of pH and a decrease of operating temperature and As feed concentration led to higher As removal for both membranes, whereas higher transmembrane pressure (TMP) values slightly reduced the removal achievable with the N30F membrane. In both cases, the permeate flux increased with temperature and pressure and reached its maximum value at a pH of around 8.Among the parameters affecting the As rejection, feed concentration plays a key role for the production of a permeate stream respecting the limits imposed by WHO.

Evaluating the Mobility of Arsenic in Synthetic Iron-Containing Solids Using a Modified Sequential Extraction Method

Many water treatment technologies for arsenic removal that are used today produce arsenic-bearing residuals which are disposed in non-hazardous landfills. Previous works have established that many of these residuals will release arsenic to a much greater extent than predicted by standard regulatory leaching tests (e.g. the toxicity characteristic leaching procedure, TCLP) and, consequently, require stabilization to ensure benign behavior after disposal. In this work, a four-step sequential extraction method was developed in an effort to determine the proportion of arsenic in various phases in untreated as well as stabilized iron-based solid matrices. The solids synthesized using various potential stabilization techniques included: amorphous arsenic-iron sludge (ASL), reduced ASL via reaction with zero valent iron (RASL), amorphous ferrous arsenate (PFA), a mixture of PFA and SL (M1), crystalline ferrous arsenate (HPFA), and a mixture of HPFA and SL (M2). The overall arsenic mobility of the tested samples increased in the following order: ASL > RASL > PFA > M1 > HPFA > M2.

Improvement of Arsenic Electro-Removal from Underground Water by Lowering the Interference of other Ions

Electrocoagulation (EC) has been evaluated as a treatment technology for arsenic (As) removal. Experiments were developed in an electrochemical reactor with three parallel iron plates. Current densities of 15, 30, and 45 A m−2 were used to treat model water and 45 A m−2 to treat underground water (GW). For both types of water, the EC process was able to decrease the residual arsenic concentration to less than 10 μg L−1. However, the treatment time for As removal from GW was higher. This phenomenon was attributed to the competition of dissolved species present in GW such as silica and calcium with arsenic for the adsorption sites on the ferric oxyhydroxides flocs generated during the EC process. A procedure is proposed to reduce such interference by the addition of a silica adsorption inhibitor compound into the GW achieving a reduction in the process time. The adsorption of arsenic species over adsorbent was found to follow Lagergren adsorption model.