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Arsenic contamination of surface and subsurface waters has been reported in many parts of the world; the problem is particularly severe in Bangladesh. In view of epidemiological problems of arsenic ingestion, it is imperative to look for an effective technology for removal of arsenic in drinking water. Column studies were conducted at the University of Regina using manganese greensand to remove arsenic from drinking water. Iron addition was found to be necessary to achieve effluent arsenic level of 25 μg/L in manganese greensand filtration system. In view of the possible regulatory requirement to achieve arsenic levels of less than 5 to 10 μg/L, further studies were conducted using iron oxide-coated sand (IOCS). Batch studies with IOCS showed that effluent arsenic level could be achieved below 5 to 10 μg/L levels. High adsorption capacity (136 μg/g) of the IOCS showed that the media could be effectively used for achieving less than 5 μg/L of effluent arsenic level in the treatment systems, partic...

This article describes experiments in which iron oxide-coated sand(IOCS) was used to study the removal of both As(V) and As(III) to a level less than 5 μg L-1 in drinking water. Iron oxide-coated sand 2 (IOCS-2) prepared through high temperature coating process was used in batch and column studies to assess the effectiveness and suitability. The isotherm study results showed that the observed data fitted well with the Langmuir model, and the adsorption maximum for IOCS-2 at pH 7.6 was estimated to be 42.6 and 41.1 μg As g-1 IOCS-2 for As(V) and As(III), respectively. In the fixed bed column tests to study arsenic removal from the tap water, good performance ofIOCS-2 was observed in respect of bed volumes achieved and arsenic removal capacity. Five cycles of column tests were conducted to evaluate the performance of IOCS-2, and arsenic wassuccessfully recovered from the media through regeneration and backwash operations. High bed volumes (860 to 1403) up to a breakthrough concentration of 5 μg L-1 were achieved inthe column studies with tap water, and the bed volumes achievedin the studies with natural water (containing arsenic) were 1520.The results of both the batch and column studies showed that ironoxide-coated sand filtration could be effectively used to achieveless than 5 μg L-1 As in drinking water.

Arsenic occurs in both inorganic and organic forms in water. Although various methods have been adopted to remove inorganic species of arsenic from drinking water, not much emphasis has been given to the removal of organic species of arsenic. In the present study column studies were conducted using manganese greensand (MGS), iron oxide-coated sand (IOCS-1 and IOCS-2) and ion exchange resin in Fe3+ form, to examine the removal of organic arsenic (dimethylarsinate) spiked to required concentrations in tap water. Batch studies were conducted with IOCS-2, and the results showed that the organic arsenic adsorption capacity was 8 μg/g IOCS-2. Higher bed volumes (585 BV) and high arsenic removal capacity (5.7 μg/cm3) were achieved by the ion exchange resin among all the media studied. Poor performance was observed with MGS and IOCS-1.

Arsenic, a common toxic element is mainly transported in the environment by water. Arsenic in drinking water is of major concern to many of the water utilities in the world. Numerous studies have examined the removal of arsenic from drinking water through treatment processes such as coagulation-precipitation, reverse osmosis and ion exchange. The focus of research has now shifted to solve the problems using suitable adsorbents to achieve low level As in drinking water for communities with high raw water arsenic concentration. The determination of arsenic species is also essential for a better understanding and prediction of the toxic and carcinogenic nature of the species present in natural water systems. It is generally known that As(III) is more toxic than As(V) and inorganic arsenicals are more toxic than organic derivatives. The objective of this study was to study the arsenic adsorption behaviour on iron oxide-coated sand (IOCS) and ferrihydrite (FH). Batch studies were conducted using these adsorbents with natural water containing 325 μg/L arsenic, and the removal of approximately 90% was obtained. The adsorption capacity of the IOCS and FH used in this study for arsenic was estimated as 18.3 and 285 μg/g, respectively. The experimental data fitted well with the well-known isotherms, namely, Freundlich, Langmuir and BET, indicating a favourable adsorption by these adsorbents. Speciation studies were also conducted with natural water containing arsenic. Particulate and soluble arsenic in water were determined, and As(III) in the sample was determined by passing the sample containing arsenic through anion exchange resin (Dowex 1X8-100; acetate form) packed in the column. Speciation studies with natural water showed that the particulate and soluble arsenic contributed 11.4 and 88.6% of the total arsenic present in the natural water, respectively. In the case of soluble arsenic, As(III) and As(V) were 47.3 and 52.7%, respectively.

Municipal wastewater usually contains many substances that may have risks for human health and environment protection. The Canadian Council of Ministers of Environment (CCME) has developed a Canada-wide Strategy for the Management of Municipal Wastewater Effluent (also called MWWE Strategy) for effluent discharged into surface water from wastewater treatment plants. The Strategy requires all municipal wastewater treatment plants in Canada including Saskatchewan that are discharging effluent into fish-bearing waters to achieve National Performance Standards (NPS) and develop site-specific Effluent Discharge Objectives (EDOs). The strategy also helps to better manage the wastewater facilities and to set up the standard for the future new facilities (CCME, 2009).

High quality water is paramount in protecting and maintaining natural ecosystems and the species that depend upon them, ensuring the productivity of industry, sustaining commerce and growth. Safe drinking water is a vital component in the protection of public health and disease prevention and therefore essential for the health and well-being of citizens across the globe. In the province of Saskatchewan, Canada, the quality of drinking water, the conditions of systems that produce it and the protection of source water is one of the top priorities and continues to be an important public health and environmental goal. As such, ensuring safe drinking water is a shared responsibility amongst a number of provincial ministries and agencies including ministries of Environment, Health and Municipal Affairs and Saskatchewan Water Corporation. Key partners outside the provincial government include the federal government through Health Canada and various infrastructure funding initiatives, municipalities and other waterworks owners, the Saskatchewan Urban Municipalities Association, the Saskatchewan Association of Rural Municipalities, the Saskatchewan Water and Wastewater Association, and the Operator Certification Board. This paper includes the results of sampling/research studies that are conducted to determine the levels of Haloacetic acids (HAA5), Trihalomethanes (THMs) and N- nitrosodimethylamine (NDMA) in Saskatchewan municipal distribution systems. This paper also outlines the regulatory framework, water management and activities undertaken by the Government of Saskatchewan, Canada to manage drinking water in the province.

This paper examines the use of granular ferric hydroxide (GFH) to remove both arsenate [As(V)] and arsenite [As(III)] present in drinking water by conducting batch and column studies. The kinetic studies were conducted as a function of pH, and less than 5 mg/l was achieved from an initial concentration of 100 mg/l for both As(III) and As(V) with GFH at a pH of 7.6, which is in the pH range typically encountered in drinking water supplies. In the isotherm studies, the observed data fitted well with both the Freundlich and the Langmuir models. In continuous column tests (five cycles) with tap water using GFH, consistently less than 5 mg/l of arsenic was achieved in the finished water for 38 to 42 hours of column operation, where the influent had a spiked arsenic concentration of 500 mg/l. High bed volumes (1260 and 1140) up to a breakthrough concentration of 5 mg/l were achieved in the column studies. The adsorptive capacities for GFH estimated from the column studies were higher than that of activated alumina reported in the previous studies. Speciation of a natural water sample with arsenic showed the dominance of As(III) species over As(V). Batch and column studies showed that granular ferric hydroxide (GFH) can be effectively used in small water utilities to achieve less than 5 mg As/l in drinking water. Keywords: Adsorption, Drinking water, Arsenic removal, Granular ferric hydroxide, Arsenic speciation (WaterSA: 2003 29(2): 161-170)

Arsenic contamination of surface and subsurface waters is reported in many parts of the world and is considered as a global issue. The enforcement of stringent arsenic standard for drinking water, because of health problems associated with the ingestion of arsenic contaminated water, call for an effective treatment technology for arsenic removal. Since the toxicity of arsenic depends on its speciation, it is essential to determine the individual arsenic species present in drinking water. Further, a better understanding of the occurrence of arsenic, health effects, and available technologies would help in the evaluation of risk and selection of an appropriate cost-effective technology. This article provides an overview of these aspects. Various treatment methods used to remove arsenic from drinking water are also discussed. Keywords: Arsenic; drinking water; exposure; health effects; sources; speciation; treatment methods

Arsenic occurs in both inorganic and organic forms in water. Although various methods have been adopted to remove inorganic forms of arsenic from drinking water, not much emphasis was given for the removal of orgainc forms of arsenic in drinking water. In the present study column studies were conducted using manganese greensand, iron oxide-coated sand (1 and 2) and ion exchange resins in Fe 3+ form, to examine the removal of organic arsenic (dimethylarsinic acid) spiked in tap water. Batch studies were conducted with IOCS-2, and the results showed that the organic arsenic adsorption capacity was 8 μg/g. Higher bed volumes (585) and high arsenic removal capacity (5.69 μg/cm 3 ) were achieved with ion exchange resins among all the media studied. Poor performance was observed with manganese greensand and iron oxide coated sand-1 (IOCS-1).