What role can small-scale irrigation play in promoting inclusive rural transformation? Evidence from smallholder rice farmers in the Philippines
Higgins, Daniel ; Arslan, Aslihan ; Winters, Paul - \ 2020
Agricultural Water Management 243 (2020). - ISSN 0378-3774
Impact evaluation - Philippines - Rice production - Rural transformation - Small-scale irrigation
We investigate how user-managed small-scale irrigation can influence inclusive rural transformation. Cultivating inclusive rural transformation is key to sustainable growth and poverty reduction in developing countries, but existing research rarely analyses the holistic impacts of rural development projects on this process. We use a combination of quantitative and qualitative data to rigorously measure impacts and uncover the causal pathways of a canal irrigation project for rice farmers in the Philippines, finding that positive impacts were heavily determined by market access and the strength of the local economy. We also find limited impacts for poorer farmers located further downstream on the irrigation canals. Based on these findings, we draw several lessons about the complementary conditions and support that are required in order for irrigation to be an effective tool in promoting inclusive rural transformation in developing countries.
Groundwater quality evaluation using Shannon information theory and human health risk assessment in Yazd province, central plateau of Iran
Amiri, Vahab ; Kamrani, Salahaddin ; Ahmad, Arslan ; Bhattacharya, Prosun ; Mansoori, Javad - \ 2020
Environmental Science and Pollution Research (2020). - ISSN 0944-1344
EWWQI - Groundwater quality - Health risk - Multivariate analysis - Yazd province
This study aims to evaluate the quality of groundwater in the most arid province of Iran, Yazd. It is highly dependent on groundwater resources to meet the domestic, industrial, and agricultural water demand. Position of water samples on the modified Gibbs diagram demonstrates that the interaction with silicates and the increase in direct cation exchange are responsible for the increased salinity of groundwater. Based on entropy theory, the decreasing order of importance of variables in controlling groundwater chemistry is Fe > As > Ba > Hg > NO2 > Pb > K > Cl > Na > Mg > SO4 > NO3 > HCO3 > Ca. The results of entropy weighted water quality index (EWWQI) calculation show that about 34 and 32% of 206 samples in the wet and dry seasons, respectively, are classified as extremely poor quality (ranks 4 and 5). Approximately 60 and 55% of 206 samples in wet and dry seasons, respectively, have excellent, good, and medium quality (ranks 1, 2, and 3). The non-carcinogenic human health risk (NHHR) from intake and dermal contact pathways using deterministic approach show that 36 and 17 samples in both seasons are not suitable for drinking by children. Furthermore, 9 and 2 samples are not suitable for drinking by adults. The results show that children are more vulnerable than adults to these health risks. The non-carcinogenic risks through dermal contact were negligible.
Arsenic in Latin America : New findings on source, mobilization and mobility in human environments in 20 countries based on decadal research 2010-2020
Bundschuh, Jochen ; Armienta, Maria Aurora ; Morales-Simfors, Nury ; Alam, Mohammad Ayaz ; López, Dina L. ; Delgado Quezada, Valeria ; Dietrich, Sebastian ; Schneider, Jerusa ; Tapia, Joseline ; Sracek, Ondra ; Castillo, Elianna ; Marco Parra, Lue Meru ; Altamirano Espinoza, Maximina ; Guimarães Guilherme, Luiz Roberto ; Sosa, Numa Nahuel ; Niazi, Nabeel Khan ; Tomaszewska, Barbara ; Lizama Allende, Katherine ; Bieger, Klaus ; Alonso, David L. ; Brandão, Pedro F.B. ; Bhattacharya, Prosun ; Litter, Marta I. ; Ahmad, Arslan - \ 2020
Critical Reviews in Environmental Science and Technology (2020). - ISSN 1064-3389 - p. 1 - 139.
Environmental and health impacts - geogenic arsenic in Latin America - sources and mobilization
Today (year 2020), the globally recognized problem of arsenic (As) contamination of water resources and other environments at toxic levels has been reported in all of the 20 Latin American countries. The present review indicates that As is prevalent in 200 areas across these countries. Arsenic is naturally released into the environment and mobilized from geogenic sources comprising: (i) volcanic rocks and emissions, the latter being transported over thousands of kilometers from the source, (ii) metallic mineral deposits, which get exposed to human beings and livestock through drinking water or food chain, and (iii) As-rich geothermal fluids ascending from deep geothermal reservoirs contaminate freshwater sources. The challenge for mitigation is increased manifold by mining and related activities, as As from mining sites is transported by rivers over long distances and even reaches and contaminates coastal environments. The recognition of the As problem by the authorities in several countries has led to various actions for remediation, but there is a lack of long-term strategies for such interventions. Often only total As concentration is reported, while data on As sources, mobilization, speciation, mobility and pathways are lacking which is imperative for assessing quality of any water source, i.e. public and private.
Irrigation infrastructure and farm productivity in the Philippines: A stochastic Meta-Frontier analysis
Bravo-Ureta, Boris E. ; Higgins, Daniel ; Arslan, Aslihan - \ 2020
World Development 135 (2020). - ISSN 0305-750X
Impact evaluation - Irrigation - Philippines - Productivity - Rice - Selectivity bias - Stochastic Production and Meta-Frontiers
Irrigation is a lynchpin of rural development strategies and a key input to improving productivity and farm incomes, the key source of livelihood for the majority of the world's poor. Limited land and growing water scarcity mean that establishing systems to maximise the benefits from every drop is pivotal. In this paper, we analyse the impact of a canal irrigation project for smallholders in the Philippines, focusing on rice, one of the world's most water intensive crops. We contribute to two strands of literature by combining impact evaluation and efficiency analysis methods. Using a dataset for 714 treatment and 440 control farm parcels, we apply Propensity Score Matching and a selectivity-corrected Stochastic Production Frontier to handle biases from both observable and unobservable variables. We then analyse technical efficiency (TE) and frontier output using a shared Stochastic Meta-Frontier. We find that the project had a statistically significant impact on frontier output but not on TE, suggesting that improved irrigation technology increased beneficiaries' production potential, but it did not improve TE likely due to insufficient training and input access. Thus, beneficiaries were unable to take full advantage of their improved production potential, highlighting the need for suitable complementary support in future projects. Heterogeneity analysis reveals that the main beneficiaries were downstream parcels, smaller parcels, those located in the poorer project district, and farmers with lower education, all implying a pro-poor impact. Finally, we find that female-headed households benefitted less from the project, suggesting the need for additional support in future interventions.
Arsenic removal by iron based co-precipitation : Mechanisms in groundwater treatment
Ahmad, Arslan - \ 2020
Wageningen University. Promotor(en): A. van der Wal; P. Bhattacharya, co-promotor(en): H. Bruning. - Wageningen : Wageningen University - ISBN 9789463953740 - 194
Arsenic (As) contamination of groundwater with is a wide-scale problem, affecting health of people around the world. The World Health Organization (WHO) guideline for As in drinking water is currently set at 10 µg/L, however recent studies suggest that As can cause a considerable damage to human health even at concentrations lower than the WHO guideline. As a result, several drinking water companies are making efforts to reduce As concentrations in drinking water to very low concentrations, below 1 µg/L.
Co-precipitation of As with iron(III)(oxyhydr)oxides [Fe(III)(oxyhydr)oxides] is a widely used As removal method in groundwater treatment. Fe(III)(oxyhydr)oxides are produced in an As contaminated water, typically by oxidation of naturally occurring ferrous iron [Fe(II)] in groundwater using oxygen (O2) and/or dosing a ferric iron [Fe(III)] coagulant such as Ferric Chloride (FeCl3). Arsenic strongly adsorbs to the surface of freshly formed Fe(III) precipitates and subsequently the As bearing Fe(III) precipitates are removed by filtration to produce As-safe water. The adsorption efficiency of As onto Fe(III) precipitates and the size of As bearing Fe(III) particles is governed by several interdependent factors such as the conditions of Fe(III)(oxyhydr)oxide generation in water, oxidation state of As, solution pH and the concentration of As and co-occurring ions with respect to Fe in the initial solution. The objective of this thesis is to discern mechanistic understanding of As removal by co-precipitation with Fe(III)(oxyhydr)oxides under different redox, ion composition and filtration conditions and to investigate routes to reduce As in drinking water to very low levels, below 1 µg/L.
We carried out sampling campaigns at water treatment plants in the Netherlands to gain understanding of the pertinent As removal mechanisms during groundwater treatment. It was found that rapid sand filtration is the most important treatment step for oxidation and removal of As during groundwater treatment. The removal of As is tightly coupled to Fe removal in rapid sand filters and mainly attributed to co-precipitation of As with Fe(III)(oxyhydr)oxides, which are generated by oxidation and subsequent hydrolysis of Fe(II). The As co-precipitation efficiency with Fe(III)(oxyhydr)oxides is much higher in rapid sand filter beds compared to aeration and supernatant storage. This is ascribed to oxidation of arsenite [As(III)] to arsenate [As(V)] in the rapid sand filter beds, potentially executed by manganese oxides (MnO2) and/or As(III) oxidizing bacteria, as both are observed in the coating of rapid sand filter media grains. In the pH range of most groundwaters, As(V) adsorbs to Fe(III)(oxyhydr)oxides much more effectively than As(III).
Typical aeration techniques such as cascades are inefficient in oxidizing As(III) to As(V) before rapid sand filters at water treatment plants, resulting in inefficient As co-precipitation with Fe(III)(oxyhydr)oxides. Nevertheless, dosing a strong oxidant such as potassium permanganate (KMnO4) rapidly accomplishes As(III) oxidation to As(V) and drastically improves As co-precipitation efficiency with Fe(III)(oxyhydr)oxides, resulting in As reduction to very low levels, below 1 µg/L. While no negative effect on the removal efficiency of Fe(II), Mn(II) and ammonium (NH4+) in rapid sand filters is observed due to KMnO4 dosing, the pre-established Fe(II) and Mn(II) removal mechanisms in rapid sand filters are altered due to KMnO4 dosing, generating a need for rapid sand filter media replacement. We also found that dosing of strong oxidants during groundwater treatment impacts the composition and structure of the formed Fe and Mn bearing precipitates. For example, in the absence of competing ions, O2 produces Mn(III)-incorporated moderately crystalline lepidocrocite, sodium hypochlorite (NaOCl) produces Mn(III)-incorporated poorly-ordered hydrous ferric oxide, and KMnO4 produces poorly-ordered MnO2 and poorly-ordered hydrous ferric oxide phases. This diversity of formed precipitates under different redox conditions should be considered in As removal during groundwater treatment.
In this thesis we show that As levels below 1 µg/L can alternatively be achieved by dosing a small amount of FeCl3 in the effluent of rapid sand filter at groundwater treatment plants. The effluent of rapid sand filter predominantly contains arsenate [As(V)] which is much more effectively adsorbed to Fe(III)(oxyhydr)oxides than As(III). In this way use of KMnO4 or other strong oxidants can be avoided at groundwater treatment plants. Nevertheless, the ionic composition of water strongly controls As(V) removal by iron based co-precipitation, by affecting the adsorption efficiency of As(V) with Fe(III)(oxyhydr)oxides and the size of As bearing Fe(III) particles. We show that silicate (SiO4-4) and phosphate (PO4-3) reduce As(V) removal, mainly due to competition with As(V) adsorption to Fe(III) precipitates. Though SiO4-4 en PO4-3 oxyanions are known to strongly reduce Fe(III) precipitate growth, we show that presence of high calcium (Ca) concentrations in groundwater (common in the Netherlands and several other parts of the world) counteracts the negative effects of both SiO4-4 en PO4-3 and promote coagulation of Fe(III) precipitates to form large particles which are easily separated from water by gravitation settling and rapid sand filtration. Despite presence of high Ca concentrations, Natural Organic Matter (NOM) reduces As(V) removal quite drastically, attributed largely to the formation of soluble and colloidal Fe(III)–NOM complexes which are not easily separated by conventional filtration.
In-line dosing of a small amount of FeCl3 in the feed water of ultrafiltration (UF) step (typically used for final polishing and disinfection) is shown to be effective for As reduction to <1 µg/L at water treatment plants which use artificially recharged water as source. In this process, As(V) co-precipitation with Fe(III)(oxyhydr)oxides rapidly reaches equilibrium, thus little contact time before the membranes is required. Moreover, when As bearing Fe(III) precipitates grow to sizes larger than the pore size of UF membranes (expected for most Ca bearing groundwaters) the Fe(III) particles foul the membranes mainly by forming a cake-layer on the surface which is effectively removed with a hydraulic backwash. Thus, we conclude that sustainable long term operation of UF membranes with in-line FeCl3 dosing for As removal is highly viable.
Based on the present work, three groundwater treatment plants in the Netherlands have received an upgrade with KMnO4 dosing for reducing As to below 1 µg/L. Another treatment plant, which makes use of artificially recharged groundwater, will receive an upgrade with FeCl3 dosing before the polishing UF step.
Mobility and redox transformation of arsenic during treatment of artificially recharged groundwater for drinking water production
Ahmad, Arslan ; Heijnen, Leo ; Waal, Luuk de; Battaglia-Brunet, Fabienne ; Oorthuizen, Wim ; Pieterse, Brent ; Bhattacharya, Prosun ; Wal, Albert van der - \ 2020
Water Research 178 (2020). - ISSN 0043-1354
Arsenic - Co-precipitation - Drinking water - Fe(III)(oxyhydr)oxides - Rapid sand filtration
In this study we investigate opportunities for reducing arsenic (As) to low levels, below 1 μg/L in produced drinking water from artificially infiltrated groundwater. We observe that rapid sand filtration is the most important treatment step for the oxidation and removal of As at water treatment plants which use artificially recharged groundwater as source. Removal of As is mainly due to As co-precipitation with Fe(III)(oxyhydr)oxides, which shows higher efficiency in rapid sand filter beds compared to aeration and supernatant storage. This is due to an accelerated oxidation of As(III) to As(V) in the filter bed which may be caused by the manganese oxides and/or As(III) oxidizing bacteria, as both are found in the coating of rapid sand filter media grains by chemical analysis and taxonomic profiling of the bacterial communities. Arsenic removal does not take place in treatment steps such as granular activated carbon filtration, ultrafiltration or slow sand filtration, due to a lack of hydrolyzing iron in their influent and a lack of adsorption affinity between As and the filtration surfaces. Further, we found that As reduction to below 1 μg/L can be effectively achieved at water treatment plants either by treating the influent of rapid sand filters by dosing potassium permanganate in combination with ferric chloride or by treating the effluent of rapid sand filters with ferric chloride dosing only. Finally, we observe that reducing the pH is an effective measure for increasing As co-precipitation with Fe(III)(oxyhydr)oxides, but only when the oxidized arsenic, As(V), is the predominant species in water.
Mechanisms of arsenate removal and membrane fouling in ferric based coprecipitation–low pressure membrane filtration systems
Ahmad, Arslan ; Rutten, Sam ; Waal, Luuk de; Vollaard, Peter ; Genuchten, Case van; Bruning, Harry ; Cornelissen, Emile ; Wal, Albert van der - \ 2020
Separation and Purification Technology 241 (2020). - ISSN 1383-5866
Arsenic removal - Coprecipitation - Groundwater treatment - Iron chloride - Microfiltration - Ultrafiltration
Ferric based coprecipitation–low pressure membrane filtration is a promising arsenic (As) removal method, however, membrane fouling mechanisms are not fully understood. In this study we investigated the effect of feed water composition and membrane pore size on arsenate [As(V)] removal and membrane fouling. We observed that As removal efficiency was independent of the membrane pore size because the size of the Fe(III) particles was larger than the pore size of the membranes, attributed to a high calcium concentration in the feed water. Arsenic coprecipitation with Fe(III) (oxyhydr)oxides rapidly reached equilibrium before membrane filtration, within 1 min. Therefore, As removal efficiency was not improved by increasing residence time before membrane filtration. The removal of As(V) was strongly dependent on feed water composition. A higher Fe(III) dose was required to reduce As(V) to sub-µg/L levels for feed water containing higher concentration of oxyanions such as phosphate and silicate, and lower concentration of cations such as calcium. Cake-layer formation was observed to be the predominant membrane fouling mechanism.
Arsenic reduction to <1 µg/L in Dutch drinking water
Ahmad, Arslan ; Wens, Patrick van der; Baken, Kirsten ; Waal, Luuk de; Bhattacharya, Prosun ; Stuyfzand, Pieter - \ 2020
Environment International 134 (2020). - ISSN 0160-4120
Arsenic removal - Drinking water - Groundwater - Health risk assessment - Lung cancer - WHO guideline
Arsenic (As) is a highly toxic element which naturally occurs in drinking water. In spite of substantial evidence on the association between many illnesses and chronic consumption of As, there is still a considerable uncertainty about the health risks due to low As concentrations in drinking water. In the Netherlands, drinking water companies aim to supply water with As concentration of <1 μg/L – a water quality goal which is tenfold more stringent than the current WHO guideline. This paper provides (i) an account on the assessed lung cancer risk for the Dutch population due to pertinent low-level As in drinking water and cost-comparison between health care provision and As removal from water, (ii) an overview of As occurrence and mobility in drinking water sources and water treatment systems in the Netherlands and (iii) insights into As removal methods that have been employed or under investigation to achieve As reduction to <1 µg/L at Dutch water treatment plants. Lowering of the average As concentration to <1μg/L in the Netherlands is shown to result in an annual benefit of 7.2–14 M€. This study has a global significance for setting drinking water As limits and provision of safe drinking water.
Safety of Continuous Postoperative Pulse Oximetry Monitoring Without Obstructive Sleep Apnea Screening in > 5000 Patients Undergoing Bariatric Surgery
Veldhuisen, Sophie L. van; Arslan, Ibrahim ; Deden, Laura N. ; Aarts, Edo O. ; Hazebroek, Eric J. - \ 2020
Obesity Surgery 30 (2020). - ISSN 0960-8923 - p. 1079 - 1085.
Bariatric surgery - Continuous pulse oximetry - Morbid obesity - Obstructive sleep apnea - Perioperative care
Introduction: Obstructive sleep apnea (OSA) is common but often undiagnosed in obese patients undergoing bariatric surgery, and is associated with increased risk of cardiopulmonary complications. The aim of this study is to evaluate the safety of continuous postoperative pulse oximetry (CPOX) without preoperative OSA screening in bariatric patients. Methods: Retrospective, single-center cohort study of all consecutive patients who underwent bariatric surgery between 2011 and 2017. All patients were postoperatively monitored with CPOX and received oxygen supplementation. Patients with no history of OSA (the “CPOX” only group) were compared with patients with adequately treated OSA as a reference group. The primary outcome was the incidence of cardiopulmonary complications within 30 days after surgery. Secondary outcomes included overall 30-day complications, mortality, intensive care unit (ICU) admissions, readmissions, and length of stay. Results: In total, 5682 patients were included, 89.6% (n = 5089) had no history of OSA, 10.4% (n = 593) had adequately treated OSA. Cardiopulmonary complications occurred in the CPOX group and OSA group in 0.6% (n = 31) and 0.8% (n = 5), respectively (p = 0.171). No mortality occurred due to cardiopulmonary complications. In both groups, one patient required ICU admission for respiratory failure (p = 0.198). Non-cardiopulmonary complications occurred in 6.4% in the CPOX group and 7.8% in the OSA group (p = 0.792). Mortality, ICU admissions, readmissions, and length of stay were not significantly different between groups. Conclusions: These data suggest that CPOX monitoring without preoperative OSA screening is a safe and effective strategy in perioperative care of bariatric patients. Future studies are needed to assess whether this strategy is also cost-effective.
Impact of phosphate, silicate and natural organic matter on the size of Fe(III) precipitates and arsenate co-precipitation efficiency in calcium containing water
Ahmad, Arslan ; Rutten, Sam ; Eikelboom, Martijn ; Waal, Luuk de; Bruning, Harry ; Bhattacharya, Prosun ; Wal, Albert van der - \ 2020
Separation and Purification Technology 235 (2020). - ISSN 1383-5866
Arsenic removal - Drinking water - Ferric chloride (FeCl) - Groundwater treatment - Natural organic matter (NOM)
Removal of arsenic (As) from water by co-precipitation with Fe(III) (oxyhydr)oxides is a widely used technique in water treatment. Nevertheless, As removal efficiency appears to be sensitive to the composition of the water matrix. The aim of this study was to gain a deeper understanding of the independent and combined effects of silicate (Si), phosphate (P), natural organic matter (NOM) and calcium (Ca) on arsenate [As(V)] co-precipitation efficiency and the size of Fe(III) precipitates. We found that, in complex solutions, containing multiple solutes and high levels of Ca, (variations in) Si and P concentrations reduce As(V) removal to some extent, mainly due to a decreased adsorption of As(V) onto Fe(III) precipitates. On the other hand, NOM concentrations reduced As(V) removal to a much greater extent, due to possible formation of mobile Fe(III)–NOM complexes that were difficult to remove by filtration. These findings have a great significance for predicting As(V) removal as a function of seasonal and process-related water quality changes at water treatment plants.
Reduction of low arsenic concentrations in drinking water to below 1 µg L−1 by adsorption onto granular iron (Hydr)oxides
Jeworrek, A. ; Ahmad, A. ; Hofs, B. ; Mook, J. van; Wal, A. van der - \ 2019
In: Environmental Arsenic in a ChangingWorld. - CRC Press/Balkema - ISBN 9781138486096 - p. 593 - 594.
Arsenic in drinking water should be reduced as much as possible, because it is amongst carcinogenic substances. FerroSorp® Plus, Huijbergen and Spannenburg GIH could reduce As(V) levels in Ouddorp water below the desired 1 µg L−1. Particularly Huijbergen GIH had according to non-linear Freundlich modeling the higher KF value, translating into a potentially higher effective adsorption capacity. One of the characteristics that probably determines the success of a GIH is its physical properties. Since the effective adsorption capacity increases with higher initial As(V) concentrations, Huijbergen GIH is a promising adsorbent to reduce a wide range of arsenic concentrations from drinking water. Therefore, this affordable technology is not only reducing ultra-low arsenic concentrations to even lower concentrations in Ouddorp water but is also promising for developing countries that are seriously affected by high concentrations of arsenic in their drinking water.
Methods for one- and two–dimensional gas chromatography with flame ionization detection for identification of Mycobacterium tuberculosis in sputum
Arslan, F.N. ; Kolk, A.H.J. ; Janssen, Hans-Gerd - \ 2019
Journal of Chromatography. B, Analytical technologies in the biomedical and life sciences 1124 (2019). - ISSN 1570-0232 - p. 204 - 217.
Two simplified methods based on manual thermally–assisted hydrolysis and methylation (THM) GC and GC × GC with flame ionization detection (FID) were developed for the detection of mycobacteria and Mycobacterium tuberculosis (MTB) in sputum. A central composite design was employed to optimize the THM derivatization conditions. For the detection of MTB the known mycobacterial markers tuberculostearic acid (TBSA) and hexacosanoic acid (C26), as well as three MTB specific markers, the mycocerosates, were evaluated. We found that the optimum conditions for THM release of TBSA and C26 differ from those for maximum release of the mycocerosates. Higher reagent volumes, higher temperatures and longer incubation increase the mycocerosates yield. Application of these conditions unfortunately resulted in unacceptable safety hazards. A GC × GC–FID method was developed that allowed accurate detection of mycocerosates even at poor conversion yields of the derivatization reaction. Using spiked sputum samples from non–TB patients, the detection limit of the method based on TBSA and C26 was found to be comparable to that of microscopy, i.e. 104–105 bacteria/mL sputum. To validate the new test, we compared the results we found for fifteen sputum samples from patients from South Africa suspected of having tuberculosis with those of culture, the gold standard method. Based on the presence of TBSA and C26, all eight microscopy and culture positive samples, and even two microscopy negative but culture positive samples were positive by THM–GC–FID. All five microscopy and culture negative sputum samples were also negative for THM–GC–FID, giving a specificity of 100%. Using GC × GC–FID we could detect mycocerosates, the specific markers for MTB in seven out of ten MTB culture positive sputum samples. The five culture negative cases were also negative for mycocerosates in manual THM–GC × GC–FID giving again 100% specificity. The results obtained indicate that the new methods hold great potential for the early diagnosis of TB in developing countries.
Environmental arsenic in a changing world
Ahmad, Arslan ; Bhattacharya, Prosun - \ 2019
Groundwater for Sustainable Development 8 (2019). - ISSN 2352-801X - p. 169 - 171.
Arsenic in Argentina : Technologies for arsenic removal from groundwater sources, investment costs and waste management practices
Litter, Marta I. ; Ingallinella, Ana M. ; Olmos, Valentina ; Savio, Marianela ; Difeo, Gonzalo ; Botto, Lía ; Torres, Elsa Mónica Farfán ; Taylor, Sergio ; Frangie, Sofía ; Herkovits, Jorge ; Schalamuk, Isidoro ; González, María José ; Berardozzi, Eliana ; García Einschlag, Fernando S. ; Bhattacharya, Prosun ; Ahmad, Arslan - \ 2019
Science of the Total Environment 690 (2019). - ISSN 0048-9697 - p. 778 - 789.
Argentina - Arsenic - Drinking water - Mitigation - Removal technologies
An overview about the presence of arsenic (As) in groundwaters of Argentina, made by a transdisciplinary group of experts is presented. In this second part, the conventional and emerging technologies for As removal, management of wastes, and the initial investment costs of the proposed technologies, with emphasis on developments of local groups are described. Successful examples of real application of conventional and emerging technologies for As removal in waters for human consumption, for medium, small and rural and periurban communities are reported. In the country, the two most applied technologies for arsenic removal at a real scale are reverse osmosis and coagulation-adsorption-filtration processes using iron or aluminum salts or polyelectrolytes as coagulants. A decision tree to evaluate the possible technologies to be applied, based on the population size, the quality of the water and its intended use, is presented, including preliminary and indicative investment costs. Finally, a section discussing the treatment and final disposal of the liquid, semiliquid and solid wastes, generated by the application of the most used technologies, is included. Conclusions and recommendations, especially for isolated rural and periurban regions, have been added.
Characteristics of Fe and Mn bearing precipitates generated by Fe(II) and Mn(II) co-oxidation with O2, MnO4 and HOCl in the presence of groundwater ions
Ahmad, Arslan ; Wal, Albert van der; Bhattacharya, Prosun ; Genuchten, Case M. van - \ 2019
Water Research 161 (2019). - ISSN 0043-1354 - p. 505 - 516.
Drinking water - Filtration - Groundwater treatment - Iron and manganese oxidation and precipitation - Mn and Fe removal - X-ray absorption spectroscopy
In this work, we combined macroscopic measurements of precipitate aggregation and chemical composition (Mn/Fe solids ratio) with Fe and Mn K-edge X-ray absorption spectroscopy to investigate the solids formed by co-oxidation of Fe(II) and Mn(II) with O2, MnO4, and HOCl in the presence of groundwater ions. In the absence of the strongly sorbing oxyanions, phosphate (P) and silicate (Si), and calcium (Ca), O2 and HOCl produced suspensions that aggregated rapidly, whereas co-oxidation of Fe(II) and Mn(II) by MnO4 generated colloidally stable suspensions. The aggregation of all suspensions decreased in P and Si solutions, but Ca counteracted these oxyanion effects. The speciation of oxidized Fe and Mn in the absence of P and Si also depended on the oxidant, with O2 producing Mn(III)-incorporated lepidocrocite (Mn/Fe = 0.01–0.02 mol/mol), HOCl producing Mn(III)-incorporated hydrous ferric oxide (HFO) (Mn/Fe = 0.08 mol/mol), and MnO4 producing poorly-ordered MnO2 and HFO (Mn/Fe > 0.5 mol/mol). In general, the presence of P and Si decreased the crystallinity of the Fe(III) phase and increased the Mn/Fe solids ratio, which was found by Mn K-edge XAS analysis to be due to an increase in surface-bound Mn(II). By contrast, Ca decreased the Mn/Fe solids ratio and decreased the fraction of Mn(II) associated with the solids, suggesting that Ca and Mn(II) compete for sorption sites. Based on these results, we discuss strategies to optimize the design (i.e. filter bed operation and chemical dosing) of water treatment plants that aim to remove Fe(II) and Mn(II) by co-oxidation.
Arsenic in Argentina: Occurrence, human health, legislation and determination
Litter, Marta I. ; Ingallinella, Ana M. ; Olmos, Valentina ; Savio, Marianela ; Difeo, Gonzalo ; Botto, Lía ; Farfán Torres, Elsa Mónica ; Taylor, Sergio ; Frangie, Sofía ; Herkovits, Jorge ; Schalamuk, Isidoro ; González, María José ; Berardozzi, Eliana ; García Einschlag, Fernando S. ; Bhattacharya, Prosun ; Ahmad, Arslan - \ 2019
Science of the Total Environment 676 (2019). - ISSN 0048-9697 - p. 756 - 766.
Analytical determination - Argentina - Arsenic - Health - Occurrence - Regulations
An overview about the presence of arsenic (As) in groundwaters of Argentina, made by a transdisciplinary group of experts is presented. Aspects on As occurrence, effects of As on human health, regulations regarding the maximum allowable amount of As in drinking water as well as bottled water, and analytical techniques for As determination are presented. The most affected region in Argentina is the Chaco-Pampean plain, covering around 10 million km 2 , where approximately 88% of 86 groundwater samples collected in 2007 exceeded the World Health Organization (WHO) guideline value. In the Salí river basin, As concentrations ranged from 11.4 to 1660 μg/L, with 100% of the samples above the WHO guideline value. In the Argentine Altiplano (Puna) and Subandean valleys, 61% of 62 samples collected from surface and groundwaters exceeded the WHO limit. Thus, it can be estimated that, at present, the population at risk in Argentina reaches around four million people. Pathologies derived from the chronic consumption of As, the metabolism of As in the human body and the effects of the different As chemical forms, gathered under the name HACRE (hidroarsenicismo crónico regional endémico in Spanish, for chronic regional endemic hydroarsenicism) are described. Regarding the regulations, the 10 μg/L limit recommended by the WHO and the United States Environmental Protection Agency has been incorporated in the Argentine Food Code, but the application is still on hold. In addition, there is disparity regarding the maximal admitted values in several provinces. Considerations about the As concentrations in bottled water are also presented. A survey indicates that there are several Argentine laboratories with the suitable equipment for As determination at 10 μg/L, although 66% of them are concentrated in Buenos Aires City, and in the Santa Fe, Córdoba and Buenos Aires provinces. Conclusions and recommendations of this first part are provided.
Benchmarking of Regression Algorithms and Time Series Analysis Techniques for Sales Forecasting
Catal, Cagatay ; Ece, Kaan ; Arslan, Begum ; Akbulut, Akhan - \ 2019
Balkan Journal of Electrical & Computer Engineering 7 (2019)1. - ISSN 2147-284X - p. 20 - 26.
Predicting the sales amount as close as to the actual sales amount can provide many benefits to companies. Since the fashion industry is not easily predictable, it is not straightforward to make an accurate prediction of sales. In this study, we applied not only regression methods in machine learning, but also time series analysis techniques to forecast the sales amount based on several features. We applied our models on Walmart sales data in Microsoft Azure Machine Learning Studio platform. The following regression techniques were applied: Linear Regression, Bayesian Regression, Neural Network Regression, Decision Forest Regression and Boosted Decision Tree Regression. In addition to these regression techniques, the following time series analysis methods were implemented: Seasonal ARIMA, Non-Seasonal ARIMA, Seasonal ETS, Non -Seasonal ETS, Naive Method, Average Method and Drift Method. It was shown that Boosted Decision Tree Regression provides the best performance on this sales data. This project is a part of the development of a new decision support system for the retail industry.
Arsenic in Drinking Water : Is 10 μg/L a Safe Limit?
Ahmad, Arslan ; Bhattacharya, Prosun - \ 2019
Current Pollution Reports 5 (2019)1. - ISSN 2198-6592 - p. 1 - 3.
Arsenic - Drinking Water - Health Effects - Water Utilities
Arsenic (As) is a naturally occurring element in the Earth’s crust. Both anthropogenic and natural processes can release As into sources for drinking water supply. A substantial epidemiological evidence is available to support that the chronic exposure to high concentrations in drinking water (> 10 μg/L) is associated with several detrimental effects on human health including skin lesions  and cancer of the lung , bladder , kidney , and liver . Furthermore, dermatological, developmental, neurological , respiratory , cardiovascular , immunological , and endocrine effects  as a result of chronic exposure to high As concentrations have been reported. However, there remains considerable uncertainty on the chronic risks due to As exposure at low concentrations (< 10 μg/L) and the shape of the dose-response relationship [10, 11]. It is therefore crucial to question whether the 10 μg/L limit ensures protection of human health from the adverse health effects of As.
Zhu, Yong Guan ; Guo, Huaming ; Bhattacharya, Prosun ; Bundschuh, Jochen ; Ahmad, Arslan ; Naidu, Ravi - \ 2018
In: Environmental Arsenic in a ChangingWorld. - Beijing : CRC Press/Balkema (Environmental Arsenic in a ChangingWorld - 7th International Congress and Exhibition Arsenic in the Environment, 2018 ) - ISBN 9781138486096 - p. xlv - xlvi.
Zhu, Yong Guan ; Guo, Huaming ; Bhattacharya, Prosun ; Bundschuh, Jochen ; Ahmad, Arslan ; Naidu, Ravi - \ 2018
In: Environmental Arsenic in a Changing World. - CRC Press/Balkema - ISBN 9781138486096 - p. xlv - xlvi.