Abul Hussam

A simple and effective arsenic filter based on composite iron matrix: Development and deployment studies for groundwater of Bangladesh

Drinking groundwater contaminated with naturally occurring arsenic is a worldwide public health issue. This work describes the research, development and distribution of a filter used by thousands of people in Bangladesh to obtain arsenic-free safe water. The filter removes arsenic species primarily by surface complexation reactions: = FeOH + H2AsO4 − → = FeHAsO4 − + H2O (K = 1024) and = FeOH + HAsO4 2− → = FeAsO4 2 − + H2O (K = 1029) on a specially manufactured composite iron matrix (CIM). The filter water meets WHO and Bangladesh standards, has no breakthrough, works without any chemical treatment (pre- or post-), without regeneration, and without producing toxic wastes. It costs about

Voltammetric methods for determination and speciation of inorganic arsenic in the environment - a review.

40/5 years and produce 20–30 L/hour for daily drinking and cooking need of 1–2 families. The spent material is completely non toxic-solid self contained iron-arsenate cement that does not leach in rainwater. Approved by the Bangladesh Government, about 30,000 SONO filters were deployed all over Bangladesh and continue to provide more than a billion liters of safe drinking water. This innovative filter was also recognized by the National Academy of Engineering – Grainger Challenge Prize for sustainability with the highest award for its affordability, reliability, ease of maintenance, social acceptability, and environmental friendliness, which met or exceeded the local governments guidelines for arsenic removal.

Arsenic Removal with Composite Iron Matrix Filters in Bangladesh: A Field and Laboratory Study

The measurement of inorganic arsenic in the environment has received considerable attention over the past 40+ years due to its toxicity and prevalence in drinking water. This paper provides an overview of voltammetric techniques used since 2001. More than fifty papers from refereed analytical chemistry journals on the speciation and measurement of inorganic arsenic (As(III) and As(V)) in practical and environmental samples are included. The present review shows that stripping voltammetry is a sensitive and inexpensive technique. The new approaches include development of novel measurement protocols through media variation, development and use of new boron doped diamond electrodes modified with metals, nano Au-modified electrodes on carbon or carbon nano-tubes, novel rotating disc and vibrating electrodes to enhance mass transfer, and modified Hg(l) and thin film Bi on carbon for cathodic stripping voltammetry are discussed. Although, majority of the papers were of exploratory in nature, the trend towards developing a commercial standalone instrument for field use is still in progress.

Electrochemical measurement and speciation of inorganic arsenic in groundwater of Bangladesh

The main arsenic mitigation measures in Bangladesh, well-switching and deep tube wells, have reduced As exposure, but water treatment is important where As-free water is not available. Zero-valent iron (ZVI) based SONO household filters, developed in Bangladesh, remove As by corrosion of locally available inexpensive surplus iron and sand filtration in two buckets. We investigated As removal in SONO filters in the field and laboratory, covering a range of typical groundwater concentrations (in mg/L) of As (0.14-0.96), Fe (0-17), P (0-4.4), Ca (45-162), and Mn (0-2.8). Depending on influent Fe(II) concentrations, 20-80% As was removed in the top sand layer, but As removal to safe levels occurred in the ZVI-layer of the first bucket. Residual As, Fe, and Mn were removed after re-aeration in the sand of the second bucket. New and over 8-year-old filters removed As to <50 μg/L and mostly to <10 μg/L and Mn to <0.2 mg/L. Vertical concentration profiles revealed formation of Fe(II) by corrosion of Fe(0) with O2 and incorporation of As into forming amorphous Fe phases in the composite iron matrix (CIM) of newer filters and predominantly magnetite in older filters. As mass balances indicated that users filtered less than reported volumes of water, pointing to the need for more educational efforts. All tested SONO filters provided safe drinking water without replacement for up to over 8 years of use.

Electrochemical investigation of microemulsions

The presence of arsenic in groundwater above the maximum permissible limit of 50 mug l(-1) has threatened the health of more than 50 million people in Bangladesh and neighboring India. We report here the development of an inexpensive anodic stripping voltammetric (ASV) technique for routine measurement and speciation of arsenic in groundwater. The measurements are validated by more expensive atomic absorption, atomic emission and other techniques. To understand the present situation in Bangladesh, we measured As(III) in 960 water samples collected from 18 districts. A random distribution of 238 samples was used to measure both As(III) and As(V). The results from the present study indicate that most toxic form of inorganic arsenic, As(III), has the broad range of 30-98%. It shows 60% of the samples have 10 mug l(-1) and 44% of the samples have 50 mug l(-1) or more As(III). The fractional distribution pattern shows significant skew towards high percent occurrence which may indicate a progressive reduction process with a single source or a single mechanism for the formation of As(III). For direct consumption, this is possibly one of the most toxic groundwater known today. Speciation distribution at groundwater pH value shows H(3)AsO(3) is the predominant species including H(2)AsO(4)(-) and H(2)AsO(4)(2-) whose distribution is significantly pH dependent. This is also supported by E(h)-pH measurements. The depth distribution for Kushtia shows most of the As(III) is located within 100-200 ft deep aquifers. Similar fractional distribution of As(III) is found in deeper aquifers and may indicate contamination by leakage from upper aquifer. This study clearly demonstrates the aquifer environment is reductive and conducive to the formation of As(III) species.

Contending with a Development Disaster: SONO Filters Remove Arsenic from Well Water in Bangladesh (Innovations Case Discussion: SONO Filters)

Abstract Two electrochemical techniques, cyclic voltammetry and rotating disk voltammetry, were successfully applied to characterize oil-in-water microemulsions. Diffusion coefficients of microemulsion droplets were determined using ferrocene as the hydrophobic electroactive probe. Microemulsions containing n-octane as the oil, cetyltrimethylammonium bromide as the surfactant, n-butanol as the cosurfactant, and NaBr as the electrolyte were investigated. The diffusion coefficients are compared with values obtained from quasielastic light scattering measurements. The differences observed between electrochemical and light scattering measurements are due to the different modes of diffusion probed by these techniques. The electrochemical techniques yield values of the self-diffusion coefficients, whereas light scattering techniques yield mutual-diffusion coefficients. The diffusion coefficients are strongly affected by interactions between the microemulsion droplets. Compared to light scattering, the electrochemical approach provides a faster and less expensive tool for characterizing microemulsions. Electrochemical techniques do not require any prior information of physical properties except viscosity, and are also applicable to opaque systems.

Chemical Fate of Arsenic and Other Metals in Groundwater of Bangladesh: Experimental Measurement and Chemical Equilibrium Model

ishing with it. Instead, engaging with science for the public good requires one to solve problems in a manner acceptable to the people whom research breakthroughs will benefit. This premise has guided my thinking for at least the last fifteen years of my career, during which time I have joined with many other concerned scientists and physicians in mitigating the effects of arsenic laden ground water in the Ganges river delta region of South Asia. I originally come from Kushtia, Bangladesh, an area very much affected by this problem and where much of my family still lives, but for over twenty years I have taught and researched at George Mason University in Virginia, where I specialize in analytical chemistry. Since 1997, I have worked closely with my brother, Dr. A.K. Munir, on the problem of arsenic poisoning, a matter of great urgency that hundreds of thousands of people throughout Eastern India, Bangladesh, and Nepal face every day when they satisfy their most simple of needs by drinking a cup of water. Beginning in the late 90’s with the development of detection systems to measure the trace amount of arsenic in the groundwater, my brother and I then began experiments with filtration systems that could remove arsenic from ground water

SOLID PHASE MICROEXTRACTION: MEASUREMENT OF VOLATILE ORGANIC COMPOUNDS (VOCs) IN DHAKA CITY AIR POLLUTION

Abstract The presence of toxic level of inorganic arsenic in groundwater used for drinking in Bangladesh and neighboring India is unfolding as one of the worst natural disaster in the region. The purpose of this work is to ascertain the chemical fate of arsenic and other metals in groundwater of Bangladesh. A combination of techniques was used to measure 24 metals, 6 anions, Eh , pH, dissolved oxygen, conductivity, and temperature to understand the distribution of components which were then used in computational chemical equilibrium model, MINEQL+, for detailed speciation. It was found that the fate of arsenic and its speciation were inextricably linked to the formation of hydrous ferric oxide (HFO) and its kinetic. The HFO induced natural attenuation removes 50–75% of total arsenic in first 24 h through a first order kinetics. Adsorption on HFO is the predominant mode of removal of arsenic, iron, manganese, and most trace metals. The equilibrium model points to the presence of excess active sites for the removal of arsenic. MINEQL+ shows that significantly higher concentration of HFO forming iron is required to remove arsenic below maximum contamination level (MCL) of 50 µg/L than predicted by stoichiometry. The practical implication of this work is the prediction of water quality based on models.

Groundwater Arsenic Removal Technologies Based on Sorbents: Field Applications and Sustainability

ABSTRACT A solid phase microextraction (SPME) technique was applied for the sampling of volatile organic compounds (VOCs) in ambient air polluted by two stroke autorickshaw engines and automobile exhausts in Dhaka city, Bangladesh. Analysis was carried out by capillary gas chromatography (GC) and GC-mass spectrometry (MS). The methodology was tested by insitu sampling of an aromatic hydrocarbon mixture gas standard with a precision of ±5% and an average accuracy of 1–20%. The accuracy for total VOCs concentration measurement was about 7%. VOCs in ambient air were collected by exposing the SPME fiber at four locations in Dhaka city. The chromatograms showed signature similar to that of unburned gasoline (petrol) and weathered diesel containing more than 200 organic compounds; some of these compounds were positively identified. These are normal hydrocarbons pentane (n-C5H12) through nonacosane (n-C29H60), aromatic hydrocarbons: benzene, toluene, ethylbenzene, n-propylbenzene, n-butylbenzene, 1,3,5-trimethylbenzene, xylenes, and 1-isocyanato-3-methoxybenzene. Two samples collected near an autorickshaw station contained 783 000 and 1 479 000 µg/m3 of VOCs. In particular, the concentration of toluene was 50–100 times higher than the threshold limiting value of 2000 µg/m3. Two other samples collected on street median showed 135 000 µg/m3 and 180 000 µg/m3 of total VOCs. The method detection limit of the technique for most semi-volatile organic compounds was 1 µg/m3.

Optimizing data-acquisition schedules in physicochemical experiments : Part 1. Principle of the Method and Application to the Firt-Order Decay of an Absorbing Species

Drinking of arsenic-contaminated water for a long time causes illnesses such as hyperkeratosis on the palms or feet, fatigue, and cancer of the bladder, skin, or other organs. The sources of arsenic-safe potable water may be classified into two major categories: alternative sources such as surface water, dug wells, rainwater harvesting, and filter technologies that can be used to remove toxic arsenic species from contaminated water. The aim of this chapter is to provide general descriptions of arsenic removal mechanisms and current literature review on the techniques in treating or removing arsenic from water. Tools involving surface-complexation reactions, sorption equilibrium and kinetics, field applications of arsenic removal technologies, and an evaluation of sustainability based on technical merits and technology verification criteria are presented. A number of arsenic removal technologies are developed by different research organizations as well as business enterprises. Sustainability of simple arsenic removal technologies requires more than production and distribution of the technology. Special emphasis is given to iron-based filters because they appear to be the most successful ones in the field, in terms of cost and performance.Publisher Summary Drinking of arsenic-contaminated water for a long time causes illnesses such as hyperkeratosis on the palms or feet, fatigue, and cancer of the bladder, skin, or other organs. The sources of arsenic-safe potable water may be classified into two major categories: alternative sources such as surface water, dug wells, rainwater harvesting, and filter technologies that can be used to remove toxic arsenic species from contaminated water. The aim of this chapter is to provide general descriptions of arsenic removal mechanisms and current literature review on the techniques in treating or removing arsenic from water. Tools involving surface-complexation reactions, sorption equilibrium and kinetics, field applications of arsenic removal technologies, and an evaluation of sustainability based on technical merits and technology verification criteria are presented. A number of arsenic removal technologies are developed by different research organizations as well as business enterprises. Sustainability of simple arsenic removal technologies requires more than production and distribution of the technology. Special emphasis is given to iron-based filters because they appear to be the most successful ones in the field, in terms of cost and performance.