The spread of arsenic in the environment is more than it was imagined. Currently, it is distributed on a wide scale in the environment. The natural processes that introduce arsenic in surface water include mineral leaching, soil erosion as well as weathering. Industrial arsenic and enriched arsenic geothermal waters significantly contribute to the growth of arsenic amounts in surface waters (Dimitrovski et al 2012, p.14). Arsenic also exists in oxidation states resulting in a variety of compounds. Inorganic form, arsenic contains elements such as carbon. The inorganic types of arsenic mixes are more lethal than natural ones. The inorganic forms of arsenic readily react with body cells, displacing certain elements in the cell and consequently altering the function of the cell.
Arsenic is applied in a variety of ways to produce certain products. It is used in the production of CCA, the common wood preservative in the world. It is also used in the production of alloys that are used in lead-acid batteries as well as semiconductor material manufacture. Additionally, metallic arsenic can be added in alloys that are involved in metal, automotive solder and ammunition production. Arsenic gets into surface water through industrial waste discharge or geothermal waters. Initially, groundwater was regarded as safe but after extensive research, it has been noted that groundwater has started to be contaminated with arsenic (WHO 2008). Arsenic is an inorganic substance that is found in numerous drinking water resources in the world.
In Malaysia, the spread of arsenic contamination is caused by tin mining tools which leach into river waters and groundwater. These waters subsequently contaminate local vegetables as well as fish stocks in Malaysia. In polluted water, arsenic concentration ranges between 0,001 and 0.55mg/l. The maximum arsenic concentration levels that have been reported are 0.125mg/l in sediment and 0.003 and 0.08 mg/l in plant and fish (Howard 2003, P.23). China, Chile, Australia, Hungary, Thailand and the USA are among the countries that reported a serious health hazard from arsenic in drinking water.
The occurrence of cancer of the skin, kidney, bladder and lungs are some of the severe consequences of arsenic intoxication (Mass et al. 2001, p.18). As much as Bangladesh consumes groundwater, the problem of arsenic contamination is not different to Bangladesh. The problem of groundwater arsenic contamination is increasingly soaring in many developed and developing countries. In the Western US, the use of groundwater for drinking purposes has been adversely affected as well as Mexico (Shih 2005, p.39).
The Australia, Europe, Asia, North and South American communities are likewise confronting the issue of arsenic-debased drinking water. The communities in Chile, Brazil, Argentina, Peru and Mexico are also affected (Shevade and Ford 2004, p.21). The arsenic drinking water problem in Mexico and Argentina has been so severe to an extent of achieving state acknowledgement as a public health concern. The impacts of arsenic on drinking water are the worldwide problem and have affected millions of people. It is projected that the affected population is likely to rise in future..
Justification of the Study
The contamination of arsenic in both groundwater and surface water is a global problem which has been reported by several studies in the world. Some of the countries that have been affected include New Zealand, the USA, Italy, Argentina, India and Malaysia. Studies have indicated that arsenic causes numerous damages to human health. The increased consumption of water that contains arsenic contributes to the development of kidney, bladder and liver tumour alongside skin and circulatory system damages.
From these studies, it clear that arsenic contributes to numerous health problems to people and its removal from drinking water will immensely reduce health problems in human. The removal of arsenic in drinking will be achieved through the use of the conventional methods such as ion exchange, adsorption, coagulation and precipitation. Other advanced techniques have been established for the same. Therefore, the removal of arsenic in drinking will be of significance to the health of people.
Severe Health Problems
Over the past three decades, arsenic occurrences in drinking water have been recognized as one of the main public health issues in the world. The irritation of the digestive tract, vomiting, diarrhoea and nausea are some of the symptoms that are related to severe arsenic exposure. The distinct skin abnormalities contributed by acute arsenic consumption include the appearance of small corns on the sole, trunk and the dark or light spots on the skin which progress to skin cancer.
The use of chronic arsenic is related to increase liver, cancer and kidney risks (Choong et al. 2007, p.14). The continuous consumption of low concentration of arsenic can lead to stroke, diabetes mellitus, and hypertension and heart attacks (Liu et al 2010, p.7). Inhalation of arsenic can lead to lung throat and lung irritation and continuous exposure may result in lung cancer and skin conditions.
The most vulnerable populations are infants and children. The indications of the toxic effects of arsenic exposure in children are evidenced on infant birth weight, neurological developments and congenital malformations. In Chile, the deadly, neonatal and post-neonatal mortality dangers have been ascribed by low arsenic levels in drinking water (Author 2004, p.26). According to (Karim 2000, p. 34), the higher incidences of stillbirths, pre-term births and abortions have been related to arsenic in drinking water. To reduce the above risks, it is of importance to involve arsenic in the gauges for drinking water quality. This can only be achieved if appropriate techniques are devised to remove or reduce the amount of arsenic in drinking water.
The chemical composition of arsenic
Arsenic is found in more than 200 different minerals in different oxidation states such as -3, 0, +3 and +5 (Yong 2009, p.21). It additionally happens in different structures in water contingent upon the pH esteem and redox response potential. The common pH value of arsenic ranges between Ph. 5 to 8. The pH value determines the major species that dominate in water and this plays a crucial parameter during the arsenic removal treatments. When As (III) is a hydrolysed, it forms arsenic acid which exists as a free acid or a species that result from dissociation.
On the hand, As (V) can also hydrolyse to H3AsO4 acid but occurs as a non-dissociated acid. In this regard, the quantity of arsenic that can cause severe effects relies upon the physical and also synthetic type of the ingested arsenic. The dissolvable types of arsenic are more harmful as compared to the insoluble forms. More so, the states of oxidation also affect toxicity to humans. The reduced form of arsenic is more toxic than the oxidized form.
2.0 Commonly Used Techniques in the Removal of Arsenic from Water
Different techniques have been developed and implemented in fields and laboratory to expel arsenic from drinking water. The procedures have been characterized in light of the standards include, for example, coagulation, adsorption, ion exchange and layer innovation. In the recent years, the membrane technology has received much more attention as compared to other arsenic removal technique.
Arsenic Removal by Coagulation and Filtration
In this technique, alum and ferric chloride are the main coagulants that are used (Wickramasinghe 2004, p.47). In this case, arsenic is eliminated through sorption onto the fresh precipitate of Al (OH) 3 and Fe (OH) 3 particles. The iron salts remove arsenic in water better than aluminium salts. This method is one of the best methods to remove arsenic species from water. The elimination is more effective in the presence of As (V) but rather unsatisfactory in the presence of As (III). However, this can be necessitated by pre-oxidizing As (III) by H2O2 and chlorine to As (V) (Baskan and Pala 2010, p. 11). The ferric chloride is broadly utilized in the treatment of water because it is of low price and readily available. Ferric chloride has fewer usability risks. The method produces large quantities of arsenic sludge to be discharged.
Arsenic Removal by Membrane Technology
The working principles that are involved in the elimination of arsenic using membrane technology include filtration of the arsenic-bearing particles, exclusion depending on the extent of the hydrated particles or electric aversion by the film. The membrane technology has been regarded as the most effective method in eliminating arsenic from water but it is less satisfactory in arsenic (III) cases. According to studies, the membrane technology can remove 95 per cent of arsenic (V) and approximately 74 per cent of arsenic (III) (Mohan and Pittman 2007, p.19).
The use of reverse osmosis (RO) can offer additional arsenic removal. Nanofiltration process demonstrates a transcendent evacuation of divalent species and can expel arsenic (III) and arsenic (V) species productively through size avoidance. The return osmosis (RO) is another reliable method of eliminating arsenic species. However, the technique is costly to the treatment plants ranging from membrane costs to operating costs. The membranes also produce a bad odour during use and this remains a major disadvantage to such a system.
Arsenic Removal through Sorption Methods
In the sorption method, activated carbon, hydrous metal and ion exchange resins are the conventional adsorbents used in removing arsenic. The proposed arsenic species removal in the synthetic ion exchange is mostly in chloride form (Kim et al 2004, p.8). The arsenate species of arsenic can be removed by the resin. The exhausted resin regeneration is achieved by adding NaCl solutions. The hydrous metal can be utilized in an expulsion of arsenic in water. At the point when the hydrous metals are in contact with water, its surface has hydroxyl bunches which are liable to protolytic responses. At the zero pH charge, the surface is protonated which require An-adsorption.
The proficiency in arsenic expulsion has been seen in the utilization of iron oxide. Depleted surface recovery can be conveyed by NaOH arrangements pursued by corrosive washing to change the positive surface charge. The utilization of hydrous metal has restricted unsteadiness. In the particle trade technique, half breed materials are presented in the polymer framework. The materials consolidate sorption onto ferric oxide material with quick sorption onto nano-particles. The moderate rate of sorption is one of the hindrances of utilizing hydrous metal oxides or hydroxide.
Arsenic Removal by Precipitation Methods
This kind of method is suitable for removing arsenic in some inorganic arsenic compounds that are insoluble. It is the most common method of removing arsenic from process streams by precipitation. The arsenic (III) sulphide, ferric arsenate and calcium arsenate compounds are produced by adding calcium oxide to the contaminated waters. At pH values exceeding 10.5, a high amount of arsenic precipitate will be formed from the solution. Arsenic (V) can be eliminated by precipitating it with ferric arsenate to arsenic water (Harper and Kingham1992, p.4). However, precipitation forms unstable precipitates which are unsuitable for direct disposal to uncontained sites which can eventually produce arsenic-bearing leachates (Litter et al. 2010, p.17).
Coagulation Followed By Microfiltration (C/MF Process)
The microfiltration water recovery is higher as compared to other membrane advancements. The vitality utilization is likewise moderately lower than different techniques utilized in the arsenic evacuation. Microfiltration, for the most part, expels particulate type of arsenic since it has the vast particulate pore. In this way, microfiltration is anything but a feasible strategy for expelling arsenic since it evacuates a low level of the particulate type of arsenic in the most water source. To enhance arsenic elimination in water, coagulation and flocculation method is recommended to help the microfiltration technology. Studies have indicated that the combination of coagulation and microfiltration improves arsenic removal and the combination is much higher than the separated microfiltration.
The use of Al (III) and Fe (III) salts can increase the concentration of metals in the treated water and anions from the salts. Inorganic arsenic is present as arsenate and arsenite in the natural aquatic environment. The stable form of inorganic arsenic is arsenate which dominates in surface water. Arsenite is a reduced form of arsenic which reduces groundwater (Chwirka et al 2000, p.38). According to (Basu et al 2015, p. 52), it is difficult to eliminate arsenite from groundwater by the coagulation and microfiltration method. However, arsenite can be removed by oxidizing it to arsenate by using oxidants such as chlorine. To remove arsenic in groundwater and surface water, coagulation and microfiltration method should involve an oxidant to necessitate arsenate from the water.
Lime Softening
The use of lime softening is effective for arsenic elimination but a considerable effort should be involved to make it successful. The addition of lime in water serves two purposes in water. As much as it used to eliminate arsenic, it also minimizes water hardness. The process of adding lime in water removes calcium and magnesium ions as well as removes some considerable amounts of arsenic through uptake of metal carbonates and hydroxide.
Contrary to its use, an excellent design is needed to pay attention to the possibility of operation and maintenance costs that may occur, to outweigh the initial savings of installing a cheap physical plant. Arsenic uptake usually rises at higher pH during the process of lime softening, especially when magnesium hydroxide is established at the pH exceeding 10.8. The process of uptake combines co-precipitation, sorption and occlusion of magnesium as well as calcium solids (Kartinen and Martin 1995, p.78).
3.0 Advanced Treatment Methods Hybrid Membrane Systems
The introduction of membrane bioreactors in the treatment of wastewater has offered an alternative to eliminating arsenic from water. The hybrid membrane systems are crucial because they permit phase separation between particles that bind arsenic and the treated water. In this technique contact time, pH effect and other ionic compounds existence should be put into consideration during the design of the membrane bioreactor system for maximum rejection of arsenic (Nguyen et al. 2009, p. 31). However, researches have not yet established the full potential of the technology for arsenic removal. The hydraulic as well as removal performances of the hybrid adsorption technology ought to assess both the potential of the membrane and adsorption technology in arsenic elimination.
Iron –Modified Bamboo Charcoal
The technique is effective in the elimination of arsenic from aqueous systems. The method is exciting for future growth in arsenic removal. The low cost and high adsorption capacity of the BC-Fe discussed by (Wang et al 2013, p.62) demonstrates that the technique is a promising option for end of arsenic in polluted water. This method was orchestrated by placing iron into bamboo charcoal by absorbing the arrangement of ferric salt.
The BC-Fe has a porous surface 277895 m2/g surface territory. After the adsorption qualities of arsenic onto BC-Fe researched at a few pHs, arsenic focuses, contact times and adsorbent dosages in bench tests, it was seen that the relating most extreme balance times pH ranges of arsenite and arsenate expulsion were 4-5 and 3-4 separately. The balance times of arsenite and arsenate adsorption likewise ran between 30 to 35.5 h. in this strategy, the arsenic end depends on the underlying adsorbent fixation and additionally the adsorbent dose.
Electrocoagulation
It is a water treatment technology that comprises electrolytic oxidation of anode materials as well as the in-situ production of coagulant. According to (Kumar et al 2005, p.13), the method achieved over 99.9 per cent arsenic elimination efficiency. The method has been effective in eliminating arsenic from drinking water. It is an alternative to chemical coagulant and the process can oxidize arsenite to arsenate. After the batch electro coagulant experiment conducted, it was observed that arsenic removal in this method is slower at high pH but arsenate removal is fast as compared to arsenite (World Health Organization, 2008).
There are numerous considerations to be followed for the elimination of arsenic from drinking water. Firstly, the expert ought to keenly select the appropriate technology to be used. However, they have to be aware of the total concentration of arsenic in the source water. They should access information from the database or send samples to the laboratory to ascertain the concentration if the information is unavailable. Secondly, the source water quality characterization will be of help to determine the best treatment option. The water qualities in the source are known to hinder arsenic removal performance. Besides, the sustainability of the treatment system should also be considered to know if water quality will be measured in compliance with regulatory agencies. Finally, the safe handling and appropriate disposal of the produced waste from arsenic elimination should be put into the account.
Conclusion
The drinking water contamination of arsenic is a worldwide problem that will become apparent in the future. Most of the developing countries have put their attention on the rural, urban groundwater and agricultural contamination of arsenic contamination in the developed countries. The severe arsenic poisoning does not only cause physical problems but also acute social effects.
The chronic skin lesions caused by arsenic poisoning have accidentally stigmatized families and leading to family isolation. Fossil fuels, wood as well as industrial activities have resulted in air, soil and surface water contamination by arsenic compounds. The only way to prevent or reduce this hazard is to minimize arsenic chemical use, arsenic contamination confinement and ensuring complete enforcement through regulatory bodies. To select the most appropriate technology, the concentrations of arsenic in source water need to be considered. The elimination of arsenic does not only involve removing arsenic in water but also proper disposal of the solid wastes.
References
Author, A., 2004. Metals in PerspectiveGroundwater arsenic contamination and its health effects in the Ganga-Meghna-Brahmaputra plain. Journal of Environmental Monitoring, 6(6), pp.74N-83N.
Baskan, M.B. and Pala, A., 2010. A statistical experiment design approach for arsenic removal by coagulation process using aluminum sulfate. Desalination, 254(1-3), pp.42-48.
Basu, S., Mukherjee, S., Kaushik, A., Batra, V.S. and Balakrishnan, M., 2015. Integrated treatment of molasses distillery wastewater using microfiltration (MF). Journal of environmental management, 158, pp.55-60.
Choong, T.S., Chuah, T.G., Robiah, Y., Koay, F.G. and Azni, I., 2007. Arsenic toxicity, health hazards and removal techniques from water: an overview. Desalination, 217(1-3), pp.139-166.
Chanda, C.R., Lodh, D., Saha, K.C., Mukherjee, S.K. and Roy, S., 2000. Groundwater arsenic contamination in Bangladesh and West Bengal, India. Environmental health perspectives, 108(5), p.393.
Chwirka, J.D., Thomson, B.M. and Stomp III, J.M., 2000. Removing arsenic from groundwater. Journal?American Water Works Association, 92(3), pp.79-88.
Dimitrovski, D.V., Bozinovski, Z.L., Lisichkov, K.T. and Kuvendziev, S.V., 2012. Arsenic removal through coagulation and flocculation from contaminated water in Macedonia. Zaštita materijala, 53(1), pp.57-61.
Harper, T.R. and Kingham, N.W., 1992. Removal of arsenic from wastewater using chemical precipitation methods. Water Environment Research, 64(3), pp.200-203.
Howard, G., 2003. Arsenic, drinking-water and health risk substitution in arsenic mitigation: a discussion paper. World Health Organization, Geneva.
Karim, M.M., 2000. Arsenic in groundwater and health problems in Bangladesh. Water Research, 34(1), pp.304-310.
Kartinen Jr, E.O. and Martin, C.J., 1995. An overview of arsenic removal processes. Desalination, 103(1-2), pp.79-88.
Kim, Y., Kim, C., Choi, I., Rengaraj, S. and Yi, J., 2004. Arsenic removal using mesoporous alumina prepared via a templating method. Environmental science & technology, 38(3), pp.924-931.
Kumar, P.R., Chaudhari, S., Khilar, K.C. and Mahajan, S.P., 2004. Removal of arsenic from water by electrocoagulation. Chemosphere, 55(9), pp.1245-1252.
Litter, M.I., Morgada, M.E. and Bundschuh, J., 2010. Possible treatments for arsenic removal in Latin American waters for human consumption. Environmental Pollution, 158(5), pp.1105-1118.
Liu, C.P., Luo, C.L., Gao, Y., Li, F.B., Lin, L.W., Wu, C.A. and Li, X.D., 2010. Arsenic contamination and potential health risk implications at an abandoned tungsten mine, southern China. Environmental Pollution, 158(3), pp.820-826.
Mass, M.J., Tennant, A., Roop, B.C., Cullen, W.R., Styblo, M., Thomas, D.J. and Kligerman, A.D., 2001. Methylated trivalent arsenic species are genotoxic. Chemical research in toxicology, 14(4), pp.355-361.
Mohan, D. and Pittman Jr, C.U., 2007. Arsenic removal from water/wastewater using adsorbents—a critical review. Journal of hazardous materials, 142(1-2), pp.1-53.
Nguyen, V.T., Vigneswaran, S., Ngo, H.H., Shon, H.K. and Kandasamy, J., 2009. Arsenic removal by a membrane hybrid filtration system. Desalination, 236(1-3), pp.363-369.
Shevade, S. and Ford, R.G., 2004. Use of synthetic zeolites for arsenate removal from pollutant water. Water Research, 38(14-15), pp.3197-3204.
Shih, M.C., 2005. An overview of arsenic removal by pressure-drivenmembrane processes. Desalination, 172(1), pp.85-97.
Wang, W., Wang, X., Wang, X., Yang, L., Wu, Z., Xia, S. and Zhao, J., 2013. Cr (VI) removal from aqueous solution with bamboo charcoal chemically modified by iron and cobalt with the assistance of microwave. Journal of Environmental Sciences, 25(9), pp.1726-1735.
Wickramasinghe, S.R., Han, B., Zimbron, J., Shen, Z. and Karim, M.N., 2004. Arsenic removal by coagulation and filtration: comparison of groundwaters from the United States and Bangladesh. Desalination, 169(3), pp.231-244.
World Health Organization, 2008. Guidelines for drinking-water quality: second addendum. Vol. 1, Recommendations. World Health Organization.
Yong, J.W., Ge, L., Ng, Y.F. and Tan, S.N., 2009. The chemical composition and biological properties of coconut (Cocos nucifera L.) water. Mole
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