Small Drinking Water Research Articles

Application of risk assessment tools to small drinking water systems in British Columbia

A number of risk assessment tools have been developed for drinking water systems, but there is a lack of published independent evaluation of how well the tools incorporate the multiple barrier approach to drinking water safety. Selected risk assessment tools were evaluated by applying the tools to five small drinking water systems serving residential developments in British Columbia. The selected risk assessment tools generally identified hazards and vulnerabilities in the source, distribution, storage and monitoring barriers of the water systems. The risk assessment tools had varying levels of success identifying vulnerabilities in the treatment barrier. In some cases, the existing tools consider the presence or absence of a water system barrier, such as a disinfection process or a monitoring procedure, but do not consider how effective or appropriate that barrier is. A common shortcoming of the risk assessment tools is the failure to identify the need for multiple treatment processes capable of removing or inactivating pathogens, which is particularly important for surface water supplies. In addition to not incorporating the multiple barrier approach into the evaluation of the treatment barrier, none of the risk assessment tools successfully reflected the interconnected nature of the water system barriers.

Virus contamination from operation and maintenance events in small drinking water distribution systems

We tested the association of common events in drinking water distribution systems with contamination of household tap water with human enteric viruses. Viruses were enumerated by qPCR in the tap water of 14 municipal systems that use non-disinfected groundwater. Ultraviolet disinfection was installed at all active wellheads to reduce virus contributions from groundwater to the distribution systems. As no residual disinfectant was added to the water, any increase in virus levels measured downstream at household taps would be indicative of distribution system intrusions. Utility operators reported events through written questionnaires. Virus outcome measures were related to distribution system events using binomial and gamma regression. Virus concentrations were elevated in the wells, reduced or eliminated by ultraviolet disinfection, and elevated again in distribution systems, showing that viruses were, indeed, directly entering the systems. Pipe installation was significantly associated with higher virus levels, whereas hydrant flushing was significantly associated with lower virus levels. Weak positive associations were observed for water tower maintenance, valve exercising, and cutting open a water main. Coliform bacteria detections from routine monitoring were not associated with viruses. Understanding when distribution systems are most vulnerable to virus contamination, and taking precautionary measures, will ensure delivery of safe drinking water.

MTBE in California's Public Drinking Water Wells: Have Past Predictions Come True?

Extensive water quality monitoring data in California are now available for methyl tertiary butyl ether (MTBE) that span the past 16 years. The statewide database includes most of the active (and some inactive) public drinking water wells in the state, most of which have been repeatedly sampled for MTBE during 1995 to 2010. The cumulative detection frequency of MTBE in public drinking water wells in California at any concentration level is approximately 1.6% and 0.9% based on a one-detection criterion and two-detection criterion, respectively. The detection frequency of MTBE is approximately two to three times lower at concentrations above the state drinking water standards. Since 1996, the annual detection frequency of MTBE at any concentration level has ranged from 0.4 to 0.9% (one-detection criterion) and 0.2% to 0.7% (two-detection criterion). Despite repeated sampling, MTBE has been detected in only 1 or 2 years for most public drinking water wells that have ever been found to contain MTBE at any concentration level. The annual average detected concentration of MTBE has ranged from 5 to 16 μg/L (arithmetic mean) and 2 to 5.5 μg/L (median), excluding two outlier samples. MTBE detections are more prevalent in select geographic locations, rather than widespread across the entire state. The cumulative detection frequency for MTBE is approximately 1% for wells that belong to very small and small public drinking water systems (i.e., that serve between 25 and 3,300 people) and is approximately 2% for wells that belong to large and very large public drinking water systems (i.e., that serve >10,000 people). No detections of tertiary butyl alcohol (TBA) were found from 1996 to 2000, although few samples of TBA were collected during this time period. From 2001 to 2010, the cumulative detection frequency of TBA in public drinking water wells in California at any concentration level was approximately 1.4% and 0.2% based on a one-detection criterion and two-detection criterion, respectively. The cumulative detection frequency of tetrachloroethylene (PCE) in public drinking water wells in California is at least six times greater than that of MTBE and TBA, and unlike the trends observed for MTBE and TBA, PCE is often consistently detected in the same wells over time. The results of this analysis can be used to assess historical and current detections of MTBE in public drinking water wells in California. Also, if coupled with other chemical and site-specific information, the results can be used to assess potential future impacts of MTBE on drinking water supplies.

Comparisons between a rule-based expert system and optimization models for sensor deployment in a small drinking water network

In response to the needs for long-term water quality monitoring, one of the most significant challenges currently facing the water industry is to investigate the sensor placement strategies with modern concepts of and approaches to risk management. Most of the previous research mainly focuses on using optimization models to deal with small-scale drinking water networks. Yet the challenge of NP complete when handling large-scale networks can never be overcome. This study develops a rule-based expert system (RBES) to generate sensor deployment strategies with no computational burden as we oftentimes encountered via various types of optimization analyses. Two rules, including the accessibility and complexity rules, were derived to address the characteristics of effectiveness and efficiency required for sensor deployment in these networks. To retrieve the information of population exposure, the well-calibrated EPANET model was applied for the vulnerability assessment leading to the derivation of the accessibility rule whereas the graph theory was employed to retrieve the complexity rule eliminating the need to deal with temporal variability. Comparisons between this new expert system and 14 existing optimization and heuristic models confirm that the newly developed expert system in this paper can always compete with most of the optimization models. With no computational burden, the RBES that is designed to promote health risk management could also be applicable to deal with similar applications in large-scale drinking water distribution networks.

Benefit-Cost Analysis for Drinking Water Standards: Efficiency, Equity, and Affordability Considerations in Small Communities

The federal Safe Drinking Water Act (SDWA), as amended in 1996, enables benefit-cost analysis (BCA) to be used in setting federal drinking water standards, known as MCLs. While BCAs are typically conceived of as a tool to inform efficiency considerations by helping to identify MCL options that maximize net social benefits, in this paper we also illustrate how important equity and affordability considerations can be brought to light by suitably applying BCAs to drinking water regulations, especially in the context of communities served by relatively small water systems. We examine the applicability and relevance of health-health analysis (HHA), and provide an empirical evaluation of the risk tradeoffs that may be associated with the MCL established for arsenic. We find that the cost-associated risks may offset a nontrivial portion of the cancer risk reduction benefits attributed to the MCL (e.g., the additional adverse health impacts from the costs may be roughly half as large as the number of cancer cases avoided). This reveals the relevance of using the HHA approach for examining net benefits of MCLs in small drinking water utilities, and raises issues related to whether and how these cost-associated health risks should be considered in BCAs for drinking water standards.

Piped Drinking Water Sampling Plan for Small Water Systems in Singapore - A Regulator's Perspective

Small piped drinking water systems pose a unique challenge to the regulatory authorities since the owners/operators of such systems often lack technical expertise, resources and organizational controls to effectively operate their treatment systems, unlike the large utilities that have the economy of scale to address these issues in an optimal manner. With the discovery of new non-conventional sources of water and the continuous development of low-cost water treatment processes, the number of small suppliers is likely to grow worldwide in the future, especially in those remote areas/islands where drinking water is not easily available. In order to ensure that these suppliers are able to detect any health risk to the consumers in a timely manner, it is imperative to develop a water sampling plan that is comprehensive enough, yet flexible and practical to implement. This paper highlights Singapore's regulatory experience in prescribing, developing and monitoring the implementation of piped water sampling plans by small water suppliers.

Classification and assessment of water bodies as adaptive structural measures for flood risk management planning

Severe rainfall events have become increasingly common in Europe. Flood defence engineering works are highly capital intensive and can be limited by land availability, leaving land and communities exposed to repeated flooding. Any adaptive drainage structure must have engineered inlets and outlets that control the water level and the rate of release. In Scotland, there are a relatively high number of drinking water reservoirs (operated by Scottish Water), which fall within this defined category and could contribute to flood management control. Reducing the rate of runoff from the upper reaches of a catchment will reduce the volume and peak flows of flood events downstream, thus allowing flood defences to be reduced in size, decreasing the corresponding capital costs. A database of retention basins with flood control potential has been developed for Scotland. The research shows that the majority of small and former drinking water reservoirs are kept full and their spillways are continuously in operation. Utilising some of the available capacity to contribute to flood control could reduce the costs of complying with the EU Flood Directive. Furthermore, the application of a previously developed classification model for Baden in Germany for the Scottish data set showed a lower diversity for basins in Scotland due to less developed infrastructure. The principle value of this approach is a clear and unambiguous categorisation, based on standard variables, which can help to promote communication and understanding between stakeholders.

Multicriteria decision analysis for the selection of a small drinking water treatment system

Research Article| June 01 2010 Multicriteria decision analysis for the selection of a small drinking water treatment system C. Bouchard; C. Bouchard 1Civil Engineering Department, Université Laval, Québec, Canada G1V 0A6 Tel.: +1-418-656-2868 Fax: +1-418-656-2928; E-mail: christian.bouchard@gci.ulavala.ca Search for other works by this author on: This Site PubMed Google Scholar I. Abi-Zeid; I. Abi-Zeid 2Operations and Decision Systems Department, Université Laval, Québec, Canada G1V 0A6 Search for other works by this author on: This Site PubMed Google Scholar N. Beauchamp; N. Beauchamp 1Civil Engineering Department, Université Laval, Québec, Canada G1V 0A6 Search for other works by this author on: This Site PubMed Google Scholar L. Lamontagne; L. Lamontagne 3Computer Science and Software Engineering Department, Université Laval, Québec, Canada G1V 0A6 Search for other works by this author on: This Site PubMed Google Scholar J. Desrosiers; J. Desrosiers 4Direction Production Manicouagan, Hydro-Québec, Baie-Comeau, Québec, Canada G4Z 3B1 Search for other works by this author on: This Site PubMed Google Scholar M. Rodriguez M. Rodriguez 5School of Urban and Regional Planning, Université Laval, Québec, Canada G1V 0A6 Search for other works by this author on: This Site PubMed Google Scholar Journal of Water Supply: Research and Technology-Aqua (2010) 59 (4): 230–242. https://doi.org/10.2166/aqua.2010.071 Article history Received: July 18 2009 Accepted: November 23 2009 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Cite Icon Cite Permissions Search Site Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsThis Journal Search Advanced Search Citation C. Bouchard, I. Abi-Zeid, N. Beauchamp, L. Lamontagne, J. Desrosiers, M. Rodriguez; Multicriteria decision analysis for the selection of a small drinking water treatment system. Journal of Water Supply: Research and Technology-Aqua 1 June 2010; 59 (4): 230–242. doi: https://doi.org/10.2166/aqua.2010.071 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex The selection of a small drinking water treatment system for a hydro-electrical plant is addressed within a multicriteria and participatory decision analysis process. As a first step, based on problem constraints, we identified and retained three water treatment systems alternatives. In close collaboration with the stakeholders, we then defined and obtained weights for criteria that take into account public health, costs, system impacts and perception issues. The ELECTRE II method was used to aggregate the alternatives evaluations in order to obtain a ranking of the three water treatment systems. The process revealed that the system which combines NF and UV disinfection is ranked first for all the different stakeholder weightings. The sensitivity analysis of the aggregation parameters and evaluations reinforced that conclusion. This study provides useful information for conducting similar analysis on industrial or municipal water treatment systems. decision analysis, decision making, drinking water, multicriteria, small systems, water treatment This content is only available as a PDF. © IWA Publishing 2010 You do not currently have access to this content.

Particulate arsenic release in a drinking water distribution system

Trace contaminants have been shown to accumulate in solids found in drinking water distribution systems and can potentially be released to the consumer—s tap water. The objective of this study was to identify and evaluate the source of high arsenic in consumers— tap water at a small drinking water system and assess the effect of the installation of a treatment system for iron/arsenic removal. Before treatment, water samples collected from home taps showed high arsenic concentrations (as high as 299 μg/L) that were attributable to iron solids found in the distribution system. In 29% of the tap water samples, arsenic concentrations in first‐draw water samples were greater than arsenic levels in water entering the distribution system. Color measurements proved to be good predictors of arsenic and iron levels in the tap water, and turbidity was a relatively poor predictive measurement.

Methodology for Bayesian Belief Network Development to Facilitate Compliance with Water Quality Regulations

Limited resources and drinking water quality requirements pose significant challenges to those managing small and rural drinking water distribution systems (WDSs). Real-time monitoring technologies could support regulatory compliance, if shortcomings such as false readings and data corruption could be overcome. Bayesian belief networks (BBNs) are proposed as a means to mitigate technological shortcomings and increase certainty about the state of a given WDS. This paper describes a methodology for the development of BBNs that integrates known system characteristics with real-time monitoring technologies to support the water quality compliance of small or rural WDSs. Expert judgment was used both in the development of the structure of the BBN and in quantifying the required probability relationships. The results of a case study application of this methodology suggest that it is useful in developing a BBN to support decision making for a WDS with limited use of real-time monitoring technology.

Distributed MPC for Large Scale Systems using Agent-based Reinforcement Learning

In the present work, distributed control and artificial intelligence are combined in a control architecture for Large Scale Systems (LSS). The aim of this architecture is to provide a general structure and methodology to perform optimal control in networked distributed environments where multiple dependencies between sub-***systems are found. Often these dependencies or connections represent control variables so the distributed control has to be consistent for both subsystems and the optimal value of these variables has to accomplish a common goal. The aim of the research described in this paper is to exploit the attractive features of MPC (meaningful objective functions and constraints) in a distributed implementation combining learning techniques to perform the negotiation of these variables in a cooperative Multi Agent environment and over a Multi Agent platform to provide speed, scalability, and computational effort reduction. This approach is based on negotiation, cooperation and learning. Results of the application of this architecture to a small drinking water network show that the resulting trajectories of the levels in tanks (control variables) can be acceptable compared to the centralized solution. The application to a real network (the Barcelona case) is currently under development.

Integrating indicators for performance assessment of small water utilities using ordered weighted averaging (OWA) operators

The main objective of this study is to develop a methodology that integrates indicators for performance assessment of small drinking water utilities. The investigation entails 10 water utilities in the Province of Québec (Canada) that use surface water or groundwater under the direct influence of runoff, and apply chlorination as the only treatment before distribution. All 10 water utilities were sampled five times during different months and a total of 50 data sets were collected, which were divided into two groups – training and validation data sets. The assessment of each water utility was done on an arbitrary normalized scale of being ‘problematic’ over a scale of [0, 1], where zero mean fully non-problematic and vice versa. The performance indicators consist of source water, treatment, infrastructure, operational, and maintenance characteristics of utilities that are aggregated using ordered weighted averaging (OWA) operators. The major thrust behind selecting the OWA operator for aggregation of multi-criteria is its capability to encompass a range of operators bounded between minimum and maximum. The small utility performance indicators developed suggest that it is feasible to combine information operational, infrastructure, and maintenance characteristics to establish utility performance. The findings of this study is useful to government bodies in terms of achieving a better understanding and assessment of small utilities’ specific infrastructure needs and subsequent allocation of appropriate resources.

Survey of disinfection efficiency of small drinking water treatment plants: Challenges facing small water treatment plants in South Africa

A survey involving 181 water treatment plants across 7 provinces of South Africa: Mpumalanga, Limpopo, North West, Free State, KwaZulu-Natal, Eastern Cape and Western Cape was undertaken to identify the challenges facing small water treatment plants (SWTPs) in South Africa . Information gathered included ownership and design capacity of the plants, water sources, and various methods of disinfection, equipment currently employed and performance of the treatment plants. In general, the majority (over 80%) of the SWTPs surveyed in the designated provinces were owned by the district municipalities. The designed capacities of these plants varied between 1 and 60 M./d; the smallest capacity was 100 m3/d and the largest 120 M./d. The small water treatment plants abstracted their raw water from either surface or groundwater or a combination of both water sources with greater preponderance for surface water sources (over 86%). Water treatment practices were noted to be the conventional types mainly coagulation, flocculation, sedimentation, filtration and disinfection. Two types of coagulants namely polyelectrolyte (66%) and alum (18%) were commonly used by the water treatment plants across the provinces studied. Rapid gravity filtration, pressure filter and slow sand filtration systems accounted for 60%, 23% and 9% of the filtration systems across the provinces, respectively. The predominant types of disinfectants employed were chlorine gas (69%) followed by sodium (15%) and calcium (14%) hypochlorite. Over 50% of the various SWTPs did not complywith the SANS 241 Class I (< 1 NTU) and Class II (1 to 5 NTU)  recommended turbidity values. The recommended target range of 0.3 to 0.6 mg/. free chlorine residual concentrations at the point of use was not always met by 40% of the plants. Seventy percent of the SWTPs complied with the SANS 241 criteria of microbiological safety of drinking water vis-a-vis total and faecal coliforms. Operational problems affecting the efficiency of small water treatment plants included: inability to appropriately determine the flow rate, chemical dosage and turbidity, lack of chlorine residual at the point of use and lack of water quality monitoring. To produce safe drinking water, appropriate operational practices must be implemented in all small water treatment plants.

Assessing the Performance of Biological Filtration As Pretreatment to Low Pressure Membranes for Drinking Water

Although the use of ultrafiltration membranes in drinking water treatment is increasing, fouling remains a major challenge. The objective of this study was to evaluate rapid biological filtration (without coagulant addition) as a pretreatmentto reduce fouling. Surface water was first passed through a pilot scale roughing filter followed by two parallel anthracite/sand biofilters having different contact times, before being fed to the ultrafiltration membrane. As a chemical-free pretreatment, this novel application of biofiltration removes biopolymers (polysaccharides and proteins) that are the most important component of organic matter for fouling, as well as removing particulate matter. Biopolymer removal was influenced by contact time and temperature. The biofilter with the longer contact time led to greater reductions in both hydraulically reversible and irreversible fouling. The extent of hydraulically reversible fouling was related to the membrane influent biopolymer concentration, but the level of hydraulically irreversible fouling was not, indicating that the composition of the biopolymer fraction may have been important. Biofiltration as a simple and robust pretreatment may be particularly suited for small drinking water systems.

Removal of inorganic As5+ from a small drinking water system

The drinking water from a small drinking water system contained arsenic in a concentration of about 50 ?g/L. Chemical analyses showed that the pentavalent form of arsenic was present. Since the MCL value is 10 ?g/L, it was necessary to implement a technological treatment to make the water suitable for drinking. In order to do so, two technologies were suggested: activated alumina and ?-FeOOH (TehnoArz, TA) adsorption media. Experiments using both adsorption media were performed on a laboratory scale. It was possible to remove arsenic to below 1 ?g/L. The maximal adsorption capacity was found to be 12.7 mg of As5+ per gram of ?-FeOOH. Moreover, all the important physico-chemical parameters of the water remained practically unchanged after the treatment. Only a slight release of iron from the media was observed. The Fe-As bond was studied by means of chemical analysis and X-ray powder diffraction. Finally, in addition to showing the capability of arsenic removal by ?-FeOOH, a comprehensive optimization of the technological parameters of the selected technology is provided.

Arsenic Removal by a Colloidal Iron Oxide Coated Sand

A novel treatment process for arsenic removal from contaminated groundwater has been developed for use as a reactive barrier or a small drinking water treatment unit. In this study, modified porous media was made by the deposition of colloidal iron oxide onto sand grains at intermediate pH and ionic strength. Kd values from column experiments were 0.016–0.37 L∕kg for As(III) and 0.023–0.85 L∕kg for As(V) , being lower than those of batch experiments (0.50 and 1.30 L∕kg for As(III) and As(V) , respectively) due to lower availability of surface adsorption sites in the packed column. Media-independent Kd values reflect the enhancement of arsenic adsorption with an increase of colloidal iron oxide coated sand fraction, apparently due to adsorption equilibration during arsenic transport under the same flow column conditions. The heterogeneous composition of two groundwater samples also reduced arsenic adsorption. Therefore, arsenic elution near the initial breakthrough was regulated by available adsorption sur...

Horizontal transport induced by upwelling in a canyon-shaped reservoir

Several processes associated with spatial variations in buoyancy flux and mixing set up local and lake-wide horizontal temperature gradients, that in turn drive slow gravitational currents. These motions can dominate the horizontal transport and re-distribution of biological and chemical material. Here intrusions, indicative of horizontal transport, are identified in field data from a small drinking water reservoir, and the origin and character of the flows investigated using a 3-dimensional (3D) hydrodynamic model. It is shown that a horizontal temperature gradient is set up along the surface layer, due to upwelling shifting the metalimnion closer to the surface towards the upwind region, leading to a spatial variation in entrainment. The flows driven by these gradients form significant mass flux paths, enhancing exchange with the boundaries and controlling the fate of upwelled fluid. Further, the interaction of these currents with other hydrodynamic conditions is explored; namely the interaction with surface wind-driven currents, and the influence of different internal seiches generated by alternative lake bathymetries.

Use of Iron- and Manganese-Oxidizing Bacteria for the Combined Removal of Iron, Manganese and Arsenic from Contaminated Groundwater

Abstract The problem of groundwater contamination with arsenic has been under extensive discussion, especially in recent years, because of its adverse effects on human health and its widespread presence in groundwater throughout the world. Large drinking water plants in developed countries normally find alternative and arsenic-free water resources, or they apply conventional arsenic removal methods, such as coagulation/filtration, activated alumina and ion exchange. Smaller towns, communities and individual users in rural areas often rely on local water resources and the respective removal methods developed mainly for larger water treatment plants are not easily applicable, because of high operational and capital costs, or they are simply too complicated and their use is sometimes limited by the specific water composition. Consequently, small drinking water systems face the difficult challenge in providing a safe and sufficient supply of drinking water at a reasonable cost. Alternative treatment methods have been developed for application in these cases. In the present paper, the simultaneous removal of arsenic during biological iron and manganese oxidation is reviewed. The method relies on the use of indigenous non-pathogenic iron- and manganese-oxidizing bacteria. Dissolved iron and manganese species often coexist with arsenic in groundwater. Therefore, the application of this method could provide consumers with water of high quality, which is practically free of iron, manganese and arsenic, complying with the respective legislative limits. In this paper the biological oxidation of iron and manganese has been reviewed and recent findings regarding the removal of arsenic have been summarized. Arsenic(III or V) can be removed efficiently from a wide range of initial concentrations with practically limited operational cost, apart from the capital costs for the installation of treatment units. As a result, the use of chemical reagents for the oxidation of trivalent arsenic can be avoided, because As(III) was efficiently oxidized to As(V) by these bacteria (acting as catalysts) under similar conditions, which are usually applied for the removal of iron and manganese by biological means.

Comparative Evaluation of Conventional and Alternative Methods for the Removal of Arsenic from Contaminated Groundwaters

The present paper intends to summarize the recent findings regarding the development of alternative treatment methods applicable to small municipal drinking water systems. Small systems are frequently affected by the new permissible arsenic concentration rules, as imposed by several international organizations-World Health Organization, European Commission, United States Environmental Protection Agency. The innovate treatment methods reviewed are (a) adsorptive filtration, using iron oxide coated sand or polymeric materials; (b) zero-valent iron; (c) solar disinfection, solar oxidation and removal of arsenic (SORAS); (d) iron-based adsorbents, such as granular ferric hydroxide (GFH); (e) biological oxidation and removal of arsenic, accomplished simultaneously with the biological iron oxidation. In addition, other more conventional methods for arsenic removal are also discussed, such as iron or alum coagulation, lime softening, ion exchange, activated alumina and membrane separation processes. The aforementioned methods have been comparatively evaluated and the relevant conclusions have been drawn with respect to the applicability of arsenic treatment methods, depending on certain parameters, such as locally varying water quality characteristics, sustainability, and economic feasibility.

Manganese Amended Activated Alumina for Adsorption/Oxidation of Arsenic

In a laboratory study, manganese amended activated alumina (MAA), prepared by calcining (400°C) manganese acetate-impregnated activated alumina, showed promise as a more effective medium than activated alumina (AA) for use in small municipal drinking water systems or point-of-use treatment, for removing arsenic [As(III) and As(V)] from groundwater. Batch adsorption/oxidation kinetic tests indicated that in fixed-bed operation, with a bed flowthrough time of 10–20min, MAA would be a more effective medium than AA in removing arsenic [As(V), As(III), and As(III) and As(V) (present together)] from groundwater. In three cycles of downflow column test [bed depth 200mm; bed flowthrough time 20min; influent arsenic 1.0–0.6mg∕L As(III) and 0.4mg∕L As(V)], breakthrough bed volumes at the World Health Organization guideline value of 0.01mg∕L for arsenic in drinking water were 580, 550, and 485, and 825, 770, and 695, respectively, for AA and MAA. During regeneration (backwashing with a sodium hydroxide solution), 84–88% (for AA) and 86–89% (for MAA) of the removed arsenic was recovered. Manganese concentration in the MAA column effluent was low (below 0.02mg∕L). A detailed study addressing the effects of some important factors (water pH, concentration and type of competing ions, and fouling by organics) on the process is needed.