Title: Low Cost Design of Arsenic Removal from Groundwater in Bangladesh
1Low Cost Design of Arsenic Removal from
Groundwater in Bangladesh
- Kevin Banahan Jeremy Kozub Jesse Amsel
- Wentworth Institute of TechnologyEnvironmental
Engineering CapstoneSpring 2005
2Overview of Arsenic problem
- Reliance on Surface Water
- Shift to Wells in early 70s
- 8-12 Million Wells
- 35-77 million people in regions where some wells
are known to be contaminated - Maximum concentration recommendation by WHO is
10ug/L - Maximum concentrations in Bangladesh 50ug/L
3Arsenic Pollution Mechanisms
- Arsenic is released by oxidation of pyrite
- Arsenic sorbed to minerals by over application of
fertilizer - Anoxic conditions allow iron oxyhydroxides
release sorbed arsenic to solution
(8FeOOH CH3COO- 15H2CO3 ? 8Fe2 17HCO3-
12H2O)
4Theory of Arsenic Removal
5Chemistry of arsenic removal from groundwater by
sorption
- Synthetic groundwater composition
- H2O As(III) CaCl2 MgCl2 KCl
- Chloride ions will oxidize Arsenite (As III) to
Arsenate (As V) in the presence of atmospheric
oxygen
- H3AsO4 Fe(OH)3 ? FeAsO4.2H2O H2O
6Our Design Considerations
- Low cost
- Simple to make
- Easy to use
- Constructed of local materials
- Takes advantage of native labor
75 Stage Model
Client Statement
- Objectives
- lt50 ppb
- User Requirements
- Family Scale
- Easy to use
- Constraints
- Transport of water
- Design Specifications
- Sorption Isotherms
- Retention time
- Alternatives
- Tea-bag sorbent sack
- Loose sorbent
- Adapted column
- Verification of analytical method
- Refine process to synthesize groundwater
- Saturation experiments
- Regeneration experiments
- Documentations
- Analytical method
- Synthetic groundwater creation method
- Daily laboratory activities
- Experimental data
- Refine chosen design
- Optimize chosen design
- Scale model construction
- Test and evaluate design
- Completion of final design report
- Conclusions
- Suggestions
To develop a low-cost treatment system for the
removal of Arsenic from groundwater in Bangladesh
Design Communication
Final Design
8Conceptual Design
9Sorbent Kinetics
10Breakthrough Curve
11Detailed Design
12Effect of Particle Size on Sorption
Parts per Billion of Ingestible Arsenic (Initial
Concentration 400 ppb)
Arsenic Mass Partitioning
13Column Experiments
- Objective
- Determine Sorptive Capacity in a bench-scale
treatment unit
14Sorption
Material Balance to Determine Sorptive Capacity
15Column Breakthrough
Sorption Curve for Raw Sorbent
16Bangladeshi Technology Transfer
17Recommendations for further work
- Full-scale pilot study
- 10-15 cm diameter about 10 kg of sorbent.
- Model everyday use for a week.
- Soaking scheme for regeneration.
- Lab studies using native materials
- Bamboo, safi cloth
18Acknowledgments
- Dr. Jack Duggan (Design Advisor)
- Dr. Seth Frisbee (Stakeholder)
- Wentworth Professors Larry Decker, Francis
Hopcroft and Henderson Pritchard for technical
assistance
19Thank you