05610401 to the Indian Institute of Technology Guwahati, for the award of the degree of Doctor of Philosophy in Civil Engineering is a record of the research work done by him under my supervision and direction. Also, I would like to thank the department office staff for their support in administrative work.
IRON REMOVAL IN RURAL AND SEMI-URBAN AREAS OF ASSAM – PRESENT SCENARIO
ARSENIC AND FLUORIDE REMOVAL IN RURAL AND SEMI- URBAN AREAS OF ASSAM – PRESENT SCENARIO
99 4.2.2 Batch Experiments with Binary Metal Ion Systems 103 4.2.3 Batch Experiments with Ternary Metal Ion Systems 104 4.2.4 Continuous Mode Laboratory Scale Column Adsorption Studies 105 4.2.5 Co-precipitation of Metal and Ternary Metal.
BATCH EXPERIMENTS WITH MONO- AND MULTI-METAL ION SYSTEM
CONTINUOUS MODE LABORATORY SCALE COLUMN ADSORPTION STUDIES
PS beds from ternary metal ion system consisting of Fe(II), F− and As(III) ions.
DESIGN OF LABORATORY SCALE FILTER UNIT AND ITS PERFORMANCE TESTING FOR SIMULTANEOUS REMOVAL OF
369 Appendix D Estimation of Bohart and Adams constants K and No 373 Appendix E Detailed design calculations showing predicted and. Appendix F Detailed Design Calculations for Laboratory Scale Filter Unit 383 Appendix G Daily Performance Test of Laboratory Scale Design.
5.119 Experimental and predicted BDST curves for F− adsorption from PS beds at flow rates of 2.5 and 3.5 mL/min from the binary metal ion system consisting of Fe(II) and F−. 5,131 Experimental and predicted BDST curves for F− adsorption from PS beds at flow rates of 2.5 and 3.5 mL/min from the ternary metal ion system consisting of Fe(II), F−, and As(III) .
List of Tables
BDST values for metal adsorption with PS beds of binary-metal ion system consisting of Fe(II) and F−. BDST values for metal adsorption with PS beds of ternary metal ion system consisting of Fe(II), F− and As(III).
List of Abbreviations/Notations
FMBO : Ferric and manganese binary oxide FTIR : Fourier transform infrared spectroscopy GAC : Granular activated carbon.
Abstract
The Freundlich model best represented the equilibrium data obtained for the uptake of Fe(II) and As(III) by PWC and Fe(II), As(III) and F− by PS by both binary metal ion systems and three. For the binary metal ion system consisting of Fe(II)+As(III), the order of penetration of the metal ion was observed as As(III) followed by Fe(II) while for the binary metal ion system that consists of Fe( II)+F-, the order of metal ion penetration was observed as F- followed by Fe(II) for PWC and PS beds.
Chapter – 1
Introduction
- OVERVIEW
- IRON IN WATER
- Environmental Significance
- Sources
- Undesirable Effects of Iron
- FLUORIDE IN WATER
- Environmental Significance
- Sources
- Health Impacts
- ARSENIC IN WATER
- Environmental Significance
- Health Impacts
- ORGANISATION OF THE THESIS
The communities that use indigenous household iron filter units believe that charcoal and river sand (two of the common media used) help reduce the concentration of the iron from the groundwater. Of the various sources of arsenic in the environment, drinking water probably poses the greatest threat to human health (Smedley and Kinniburgh, 2002).
Chapter – 2
Technologies for Arsenic, Fluoride and Iron Removal
LABORATORY SCALE DEVELOPMENTS
- Mono-metal Ion System Comprising of Arsenic
- Mono-metal Ion System Comprising of Fluoride
- Mono-metal Ion System Comprising of Iron
- Binary- and Ternary-metal Ion Systems
The adsorption capacity of Al-SZP1 was found to be very high for As(V) adsorption, equivalent to that of activated alumina, and it appears to be particularly suitable for the removal of As(V) in low concentration (Xu et al ., 2002) ). In the study conducted by Lenoble et al. 2005), As(III) and As(V) removal was achieved using synthesized iron(III) phosphate (either amorphous or crystalline). It was found that the removal of As(III) depends on adsorbent dose, time and initial concentration of the adsorbate.
Useful removal capacities between 0.3 and 1.4 mg/g were obtained – the highest capacity being observed for the lowest flow rate and highest initial fluoride concentration. For bimetallic solutions, the IAST-Freundlich multicomponent isotherm best fitted the experimental data among the four isotherm models investigated – the modified Langmuir multicomponent model, the Langmuir partially competitive model, the Freundlich multicomponent model and the IAST-Freundlich multicomponent model.
HOUSEHOLD LEVEL TECHNOLOGIES
- Household Level Technologies for Arsenic Removal
- Household Level Technologies for Fluoride Removal
- Household Level Technologies for Iron Removal
However, the spontaneity of biosorption decreased with increasing metal concentration from 5 to 50 ppm. Filtration was performed with a sand filter placed at the bottom of the lower bucket. The sorbent used was an improved activated aluminum oxide - ActiGuard medium, which differed from activated aluminum oxide by its larger surface area and greater internal porosity.
Positive correlation was observed between arsenic removal capacity of the filter and iron concentration in groundwater. Arsenic removal efficiency of 43 household sand filters was studied in rural areas of the Red River Delta in Vietnam by Berg et al.
- Design based on Bohart-Adams Equation
- Design based on Bed Depth Service Time Approach
- Design based on Batch Adsorption Studies
The adsorptive capacity No can be determined from the slope of the linear graph of t versus x. According to the BDST method, if the value of a is determined for one flow rate, values for other flow rates can be calculated by multiplying the initial slope a by the ratio of the initial and new flow rates. If a laboratory test is performed on the concentration of solute C1, deriving an equation of the form. then, it is possible to predict the equation for the C2 concentration as follows: where a1= slope at concentration C1 a2= slope at concentration C2.
2003) had presented a detailed approach for continuous adsorption column design using granular carbon based on batch adsorption studies. If it is assumed that the mass of adsorbate in the pore space is small compared to the amount adsorbed, then the QCet term in Eq. 2.12) can be neglected without serious error and the rate of absorptive use is given by.
IRON REMOVAL IN RURAL AND SEMI-URBAN AREA OF ASSAM – PRESENT SCENARIO
- Reinforced Cement Concrete (RCC) Filter
- Tin Container Filter
The upper RCC pipe was used to hold the filter media while the lower one stored the filtered water. The filter media was layered in some of the locations visited, while in others the filter media was mixed and then placed in the unit. When interacting with people, it was established that in both villages only sand and gravel were used as filter media.
The order of placement of filter media was significantly different in these original household iron filter units. Locally available sand, gravel and charcoal were used as filter media in all units.
ARSENIC AND FLUORIDE REMOVAL IN RURAL AND SEMI-URBAN AREA OF ASSAM – PRESENT SCENARIO
CONCLUDING REMARKS
The 'Water Technology Initiative' of the Ministry of Science and Technology, Government of India aims to promote research and development activities to provide safe drinking water at affordable cost and in adequate quantity using appropriate scientific and technological interventions. Inability to use available water due to natural contaminants such as arsenic, fluoride and iron has been cited as one of the main challenges related to water scarcity in the country. Arsenic removal technologies have improved significantly over the past few years, but many technologies do not work satisfactorily for natural groundwater.
Therefore, the urgent need of the moment is to assess and improve the native household iron filter. This will ensure drinking and cooking water quality for the rural and semi-urban population on a sustainable basis at an affordable price in this part of the country and also meet the national needs as per initiative of the Ministry of Science and Technology of the Union, The Government of India has been making preparations based on the directive of the Supreme Court of India issued in the very recent past.
Chapter – 3
Objectives and Scope
As a first step in this direction, this work aims to evaluate the potential of wood charcoal (CPWC) – indigenously prepared by rural and semi-urban communities and river sand (RS) for the removal of iron, fluoride and arsenic from synthetic water samples from mono-, binary and ternary of metal ion systems consisting of Fe(II), F− and As(III). The potential of the medium would therefore be assessed by kinetics (batch mode), equilibrium (batch mode) and column (batch mode) studies from individual mono-, binary and ternary metal ion systems containing Fe(II), F − and As(III ). Depending on the iron, fluoride and arsenic removal potential of these media; efforts may be directed towards designing and assembling a suitable laboratory filtration unit for demonstration purposes and evaluating its performance before attempting to use a pilot household unit for field installation and evaluation.
Batch kinetics and equilibrium adsorption studies to assess the potential of charcoal and river sand for the removal of iron [Fe(II)], fluoride [F−] and arsenic [As(III)] from mono- [containing Fe(II) ), F− and As(III)], binary- [comprising Fe(II) + As(III) and Fe(II) + F−] and ternary- [comprising Fe(II) + F− + As( III) ] metal ion systems. Continuous laboratory column adsorption studies to assess the potential of charcoal and river sand to take up [Fe(II)], fluoride [F−] and arsenic [As(III)] from mono- [containing Fe(II) , F− and As(III)], binary- [comprising Fe(II) + As(III) and Fe(II) + F−] and ternary- [comprising Fe(II) + F− + As(III) )] metallic ionic systems.
Chapter – 4
Materials and Methods
MATERIALS
- Wooden Charcoal
- River Sand
The energy dispersive X-ray (EDX) analysis of the PWC sample indicated the absence of iron, arsenic and fluoride on the surface of PWC, indicating that ferrous groundwater is not accessible to the woody plant. The specific surface area of PWC was estimated by nitrogen adsorption/desorption at 77K using the BET method (Model: Coulter SA3100, M/S Beckman Coulter, USA). The sand was extracted from the riverbeds of Kulsi and Digharu - which meet the Brahmaputra River upstream, about 50 and 35 km from the IIT Guwahati campus respectively.
Semi-urban and rural populations generally use this sand in indigenous household iron filter units in addition to charcoal prepared by the community. 4.3, while the EDX result showed the presence of iron but the absence of arsenic and fluoride on the sand surface.
METHODS
- Batch Experiments with Mono-metal Ion Systems
- Batch Experiments with Binary-metal Ion Systems
- Batch Experiments with Ternary-metal Ion Systems
- Continuous Mode Laboratory Scale Column Adsorption Studies
- Co-Precipitation of Metal Ions from Binary- and Ternary-metal Ion Systems with Variation in Dissolved Oxygen
- Fabrication and Operation of Laboratory Scale Filter Units for Removal of Iron, Fluoride and Arsenic Simultaneously
Then, samples were taken from the supernatant for analysis of monometal ions remaining in the solution of respective monometal ion systems. Experiments were planned to assess the solubility of monometal ions present in the monometal ion systems [i.e. The detailed experimental conditions used for the monometal ion systems of Fe(II), F− and As(III) are shown in Tables 4.2 to 4.4, respectively.
Batch experiments were designed to investigate metal uptake by PWC and PS from binary metal ion systems comprising Fe(II)+As(III) and Fe(II)+F–. The concentrations of the remaining metal ions in the liquid part of the binary metal ion systems [comprising Fe(II)+As(III) and Fe(II)+F−] were then estimated.
Chapter – 5
Results and Discussion
BATCH EXPERIMENTS WITH MONO- AND MULTI-METAL ION SYSTEM
- Batch Experiments with Mono-metal Ion System Comprising of Fe(II) Ion
- Batch Experiments with Mono-metal Ion System Comprising of F −−−− Ion
The experiments were performed with initial Fe(II) concentration of 5 mg/L by adjusting pH in the range of 2 to 12. The data obtained from this study were useful in selecting a dose of adsorbent to yield a residual Fe(II). concentration of ≤ 0.3 mg/L (from an initial concentration of 5 mg/L) – the regulatory value for drinking water as proposed by WHO (1984) and IS. However, in the case of PWC, the kinetic data appear to follow the second order rate equation for the initial Fe(II) concentration of 5 and 10 mg/L while the kinetic data appear to follow the first order rate equation for the initial Fe(II) concentration of 2.5 mg/L.
In the case of PWC, it was observed that the plots of qt versus t0.5 for initial Fe(II) concentrations of 5 and. In the case of PS, the adsorption was only due to boundary layer diffusion for all three initial Fe(II) concentrations of 2.5, 5 and 10 mg/L.
