All Papers

D.G. Kinniburgh, Pauline Smedley

A survey of well waters (n=3534) from throughout Bang- ' ladesh, excluding the Chitt;agong Hill Tracts, has shown that water from 27% of the 'shallow' tubewells, that is wells less than 150 m deep, exceeded the Bangladesh standard for arsenic in drinking water (50 flg L -I). 46% exceeded the WHO guideline value of 10 flg L-I. Figures for 'deep' wells (greater than 150 m deep) were 1% and 5%, respectively. Since it is believed that there are a total of some 6-11 million tubewells in Bangladesh, mostly exploiting the depth range 10-50 m, some 1.5-2.5 million wells are estimated to be contaminated with arsenic according to the Bangladesh standard. 35 million people are believed to be exposed to an arsenic concentration in drinking water exceeding 50 flg L-I and 57 million people exposed to a concentration exceeding 10 flg L -I. There is a distinct regional pattern of arsenic contamination with the greatest contamination in the south and south-east of the country and the least contamination in the north-west and in the uplifted areas of north-central Bangladesh. However, there are occasional arsenic 'hot spots' in the generally low-arsenic regions of northern _Bangladesh. In arsenic-contaminated areas, the large degree of well-to-well variation within a village means that it is diffic'ult to predict whether a given well will be contaminated from tests carried out on neighbouring wells. The young (Holocene) alluvial and deltaic deposits are __ m8-s_caffe_c.ted_whereas_the older alluvial_sediments in the ,I tion' hypothesis in which pyrite oxidation in the zone of water table fluctuation is assumed to release arsenic and ultimately to be responsible for the groundwater arsenic problem. There is no evidence to support the proposition that the groundwater arsenic problem is caused by the recent seasonal drawdown of the water table due to a recent increase in irrigation abstraction. Monitoring of groundwaters at two-weekly intervals at a number of sites, and at different depths, has shown some variation with time but there is as yet no convincing evidence for seasonal changes. Dramatic changes in contamination are not expected within such a short timescale. A monitoring programme should be undertaken at a range of sites to monitor possible long-term changes. In the three contaminated areas studied in most detail, the arsenic concentration increases most rapidly between 10-20 m below ground level. \Vhile arsenic is the single greatest problem in Bangladesh groundwaters, other elements of concern from a health point of view, are manganese, boron and uranium. Some 35% of the groundwaters sampled exceeded the WHO guideline value for manganese (0.5 mg L-I). The spatial pattern of the arsenic and manganese problem areas was significantly different and only 33% of shallow well waters complied with the WHO guideline values for both arsenic and manganese.

Shams Forruque Ahmed, M. Mofijur, Samiha Nuzhat, Anika Tasnim Chowdhury et al.

Emerging contaminants (ECs) in wastewater have recently attracted the attention of researchers as they pose significant risks to human health and wildlife. This paper presents the state-of-art technologies used to remove ECs from wastewater through a comprehensive review. It also highlights the challenges faced by existing EC removal technologies in wastewater treatment plants and provides future research directions. Many treatment technologies like biological, chemical, and physical approaches have been advanced for removing various ECs. However, currently, no individual technology can effectively remove ECs, whereas hybrid systems have often been found to be more efficient. A hybrid technique of ozonation accompanied by activated carbon was found significantly effective in removing some ECs, particularly pharmaceuticals and pesticides. Despite the lack of extensive research, nanotechnology may be a promising approach as nanomaterial incorporated technologies have shown potential in removing different contaminants from wastewater. Nevertheless, most existing technologies are highly energy and resource-intensive as well as costly to maintain and operate. Besides, most proposed advanced treatment technologies are yet to be evaluated for large-scale practicality. Complemented with techno-economic feasibility studies of the treatment techniques, comprehensive research and development are therefore necessary to achieve a full and effective removal of ECs by wastewater treatment plants.

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

Rupa Chakraborty, Anupama Asthana, Ajaya Kumar Singh, Bhawana Jain et al.

Environmental pollution, particularly from heavy metal ions in the wastewater, is one of the most serious concerns of the world. In the pursuit of remedial action, various conventional methods such as ion exchange, chemical precipitation, coagulation, membrane separation, reverse osmosis, and adsorption methods have so far been used for the removal of heavy metal ions. A good variety of adsorbents have been developed to remove different heavy metal ions from wastewater in particular those which have been detrimental to living organisms. Adsorption processes have been very demanding for high removal efficiency of heavy metal ions even at trace levels and they are low cost as compared to conventional methods. It has therefore been crucial to develop low cost and readily available adsorbents for the adsorption of heavy metal ions from wastewater. The adsorbents may be collected from agricultural and animal waste and industrial by-products. All adsorbents, by their intrinsic nature, have functional groups to play the key role in metal ion adsorption. Generally, chemically modified adsorbents enhance the surface area of the adsorbent and exhibit higher adsorption capacity than unmodified adsorbents. In this review, a series of natural waste materials and their modified forms have been evaluated for the removal of various metals from potable and wastewater. The major focus has been an accumulation of comprehensive knowledge on of the use of the low-cost adsorbents for removal of heavy metal ions.

H. M. Solayman, Md. Arif Hossen, Azrina Aziz, Noor Yahida Yahya et al.

Dye wastewater released from several dyes induced industries are harmful towards the living, non-living environment and human. Consequently, existence of dye in water bodies is becoming a rising concern to environmentalists and citizens. Dye wastewater should be treated prior to release in an open water body to minimize its negative impacts. A long term sustainable and efficient treatment methods should be established to reduce and overcome the impacts. Although there have been significant advances in the management and treatment of such effluent using physical, chemical and biological methods. However, due to lack of information on effective dye removal methods, it is difficult to decide on a single unique technique that resolves the prevailing dye wastewater. Therefore, this paper reviews recent research on various (physical, chemical, biological, advanced oxidation process (AOPs) and hybrid) dye removal methods to compare efficiency, evaluation performance, merits and demerits. Among the existing methods, most of them have a common disadvantage which is the generation of secondary pollutes, takes long time and costly. This paper especially highlights AOPs method for dye removal as these are known as one of the promising and most effective dye removal techniques these days. This paper also suggests the application of AOPs methods possess the best performance in terms of faster dye removing as well as cost effective, time oriented and environmentally friendly. Additionally, this paper addressed the difficulties and future prospects of this emerging method that links to sustainable development.

Xinyu Chen, Md Faysal Hossain, Chengyu Duan, Jian Lü et al.

Adsorption is a widely used technology for removing and separating heavy metal from water, attributed to its eco-friendly, cost-effective, and high efficiency. Adsorption isotherm modeling has been used for many years to predict the adsorption equilibrium mechanism, adsorption capacity, and the inherent characteristics of the adsorption process, all of which are substantial in evaluating the performance of adsorbents. This review summarizes the development history, fundamental characteristics, and mathematical derivations of various isotherm models, along with their applicable conditions and application scenarios in heavy metal adsorption. The latest progress in applying isotherm models with a one-parameter, two-parameter, and three-parameter in heavy metal adsorption using carbon-based materials, which has gained much attention in recent years as low-cost adsorbents, is critically reviewed and discussed. Several experimental factors affecting the adsorption equilibrium, such as solution pH, temperature, ionic strength adsorbent dose, and initial heavy metal concentration, are briefly discussed. The criteria for selecting the optimum isotherm for heavy metal adsorption are proposed by comparing various adsorption models and analyzing mathematical error functions. Finally, the relative performance of different isotherm models for heavy metal adsorption is compared, and the future research gaps are identified.

Md. Tamez Uddin, M. A. Islam, Shaheen Mahmud, Md. Rukanuzzaman

The potentiality of tea waste for the adsorptive removal of methylene blue, a cationic dye, from aqueous solution was studied. Batch kinetics and isotherm studies were carried out under varying experimental conditions of contact time, initial methylene blue concentration, adsorbent dosage and pH. The nature of the possible adsorbent and methylene blue interactions was examined by the FTIR technique. The pH(pzc) of the adsorbent was estimated by titration method and a value of 4.3+/-0.2 was obtained. An adsorption-desorption study was carried out resulting the mechanism of adsorption was reversible and ion-exchange. Adsorption equilibrium of tea waste reached within 5h for methylene blue concentrations of 20-50mg/L. The sorption was analyzed using pseudo-first-order and pseudo-second order kinetic models and the sorption kinetics was found to follow a pseudo-second order kinetic model. The extent of the dye removal increased with increasing initial dye concentration. The equilibrium data in aqueous solutions were well represented by the Langmuir isotherm model. The adsorption capacity of methylene blue onto tea waste was found to be as high as 85.16mg/g, which is several folds higher than the adsorption capacity of a number of recently studied in the literature potential adsorbents. Tea waste appears as a very prospective adsorbent for the removal of methylene blue from aqueous solution.

Habibun Nabi Muhammad Ekramul Mahmud, A. K. Obidul Huq, Rosiyah Yahya

Water pollution caused by heavy metal ions is becoming a serious threat to human and aquatic lives day by day.

Marzia Sultana, Mahbub Hasan Rownok, Meherunnesa Sabrin, Md. Hafezur Rahaman et al.

Effective and low-cost removal of dye and heavy metals from wastewater still is a great challenge for researchers. Adsorption using activated carbon is widely used in removing these toxic pollutants. Physical, chemical, and biological modifications have been studied for improving activated carbon adsorption performance. Literature suggests that chemical modified activated carbon showed maximum adsorption capacity towards dye and heavy from aqueous solution. Chemical modifications, including acid, base, and impregnation, are studied extensively due to reagent availability, easy modification, and tuning facilities of surface functional groups. However, systematic documentation of chemical modifications on activated carbon is required for dye and heavy metals removal efficiency improvement from wastewater. This review focused on the up to date experimental chemically modified activated carbon that showed improved adsorption capacity towards dye and heavy metals from aqueous solution. The available experimental data recommends that an appropriate treatment strategy of a chemical modification process enhanced dye and heavy metals adsorption capacity of the modified activated carbon. Optimum modification process developed textural or surface functional groups properties of modified activated carbon that improved adsorption or binding capacity toward adsorbate or a particular species. In addition, the adsorption capacity of modified and corresponding activated carbon is compared.

Md. Rabiul Awual, Ismail M.M. Rahman, Tsuyoshi Yaita, Md. Abdul Khaleque et al.

Ratan Dhar, Bhajan Kumar Biswas, G. Samanta, Badal Kumar Mandal et al.

Assia Benhouria, Md. Azharul Islam, Hassina Zaghouane-Boudiaf, Mokhtar Boutahala et al.

Three adsorbents, namely, bentonite–alginate beads, activated carbon–alginate beads, and activated carbon–bentonite–alginate beads (ABA) were prepared for the adsorption of methylene blue (MB). The effects of solution pH (3–11), temperature (30, 40, and 50 °C), initial concentration (25–500 mg/L), and contact time were investigated. Results showed that the maximum monolayer adsorption capacity of ABA beads for the adsorption of MB was 756.97 mg/g at 30 °C. Furthermore, the adsorption kinetics illustrated the suitability of employing the pseudo-second-order kinetic model. The equilibrium adsorption data fitted the Freundlich isotherm well. In addition, the ABA composite exhibited more than 70% adsorption uptake capacity after six regeneration cycles. The outcomes of this study suggest the potential of ABA composite for cationic dye removal.

Md. Munjur Hasan, Mohamed A. Shenashen, Md. Nazmul Hasan, Hussein Znad et al.

With increasing the dye contamination scenes reported around the globe, the highly promising materials are needed to clean up the water to safeguard the human health. In this work, we have investigated the naturally available carbohydrate polymeric biodegradable adsorbent of wheat flour (WF) for the encapsulation of cationic Rhodamine B (RB) dye with high sensitivity and selectivity. The adsorbent was characterized to define the functional groups existing for complexation ability to the RB dye molecules. Adsorption studies were evaluated in batch mode with the function of solution acidity, contact time, initial RB concentration, competing ions existing and reusability with using eluent. The solution acidity was exhibited the key role, and the suitable pH 5.50 was selected based on the high adsorption efficiency and sensitivity nature. Moreover, the adsorption data were highly adjacent with the Langmuir adsorption isotherms model with monolayer coverage. The determined maximum adsorption was 142.26 mg/g, which was comparable with the other forms of adsorbents in the cationic dye adsorption operations. The competing ions were not adversely affected in the RB dye adsorption by the WF adsorbent due to the complexation ability. The WF adsorbent was exhibited the high reusability based on the elution and reuses performances. The adsorbed RB dye elution was evaluated using ethanol and then the WF adsorbent was ready to use for RB dye adsorption after washing with water without significant loss in its functionality. Therefore, the biodegradable natural carbohydrate polymeric WF adsorbent will attract the scientific community as suitable bio-adsorbent for efficient cationic dye removal from contaminated water as well as the production of value-added adsorbent for water treatments for safeguarding the public health.

Md. Azharul Islam, Muthanna J. Ahmed, Waheed Ahmad Khanday, Mohammad Asif et al.

Mesoporous activated carbon was prepared using a hydrochar derived from coconut shell waste through hydrothermal carbonization and NaOH chemical activation process (COSHTC). Three sets of activated carbons were obtained with different hydrochar:NaOH impregnation ratios (1:1, 1:2, and 1:3). Among these ratios, 1:3 (COSHTC3) exhibited the optimum adsorption for methylene blue (MB). COSHTC3 adsorbed MB with an initial concentration of 25-250 mg/L at pH 3-11 and 30 °C. The adsorption isotherm of MB on COSHTC3 demonstrated that Langmuir isotherm could be better applied at a maximum monolayer adsorption capacity of 200.01 mg/g at 30 °C. The data was well fitted to the pseudo-second-order (PSO) kinetic model. These results show that the COSHTC3 prepared from low-cost agricultural waste (coconut shell) with average pore diameter 28.6 Å and surface area 876.14 m 2 /g acts as a better adsorbent for removal of cationic dyes and could pave the way for more low-cost adsorbents for dye removal.

R.M. Waliullah, Ariyan Islam Rehan, Mrs Eti Awual, Adiba Islam Rasee et al.

Md. Azharul Islam, Muthanna J. Ahmed, Waheed Ahmad Khanday, Mohammad Asif et al.

Hydrothermal carbonization of biomass wastes presents a promising step in the production of cost-effective activated carbon. In the present work, mesoporous activated carbon (HAC) was prepared by the hydrothermal carbonization of rattan furniture wastes followed by NaOH activation. The textural and morphological characteristics, along with adsorption performance of prepared HAC toward methylene blue (MB) dye, were evaluated. The effects of common adsorption variables on performance resulted in a removal efficiency of 96% for the MB sample at initial concentration of 25mg/L, solution pH of 7, 30°C, and 8h. The Langmuir equation showed the best isotherm data correlation, with a maximum uptake of 359mg/g. The adsorbed amount versus time data was well fitted by a pseudo-second order kinetic model. The prepared HAC with a high surface area of 1135m 2 /g and an average pore size distribution of 35.5Å could be an efficient adsorbent for treatment of synthetic dyes in wastewaters.

Md. Chanmiya Sheikh, Md. Munjur Hasan, Md. Nazmul Hasan, Md. Shad Salman et al.

Md. Shad Salman, Md. Nazmul Hasan, Md. Munjur Hasan, Khadiza Tul Kubra et al.

Mir Ferdous Chowdhury, Shahjalal Khandaker, Forkan Sarker, Aminul Islam et al.

The release of colored wastewater from industries into surface water bodies creates undesirable consequences to the marine ecosystem and human beings owing to its pernicious effect. Indigo dyes being aromatic compounds with complex structure are one of the most important as well as the largest classes of synthetic dyes commercially employed in the textile denim dyeing process. However, being toxic and hazardous to handle, indigo dye poses a risk of permanently damaging of eyes when it comes into direct contact and can also cause perilous trouble to the respiratory tract of human beings. The manufacturing unit handling with indigo dyes incurs huge costs for this contaminated water treatment due to strict regulatory restrictions. This review is primarily focused on the recent studies dealing with the treatment of indigo dye-containing wastewater. There are various treatment methods for the removal of indigo dye including chemical degradation, bacterial decomposition, adsorption on various adsorbents, electrochemical decolorization, as well as the use of employing nanocomposite and activated low-cost charcoal materials. A brief insight into indigo dye removal mechanism and comparison among various methods of wastewater treatment along with their advantages and disadvantages are discussed alongside suggestions for further actions that might be taken into consideration for the improvement of the treatment process from both economic and technological viewpoints.