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Defluoridation by Adsorption

Defluoridation by Adsorption. Presented By: Emily Stewart, Rachel Sparks, Sajeev E . M . , & Erin Kennedy. Agenda. Problem Statement Groundwater Situation in Odisha Defluoridation Methods Preliminary Analysis Specifics on Adsorption Technique Common Adsorption Materials

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Defluoridation by Adsorption

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  1. Defluoridation by Adsorption Presented By: Emily Stewart, Rachel Sparks, SajeevE.M., & Erin Kennedy

  2. Agenda • Problem Statement • Groundwater Situation in Odisha • Defluoridation Methods • Preliminary Analysis • Specifics on Adsorption Technique • Common Adsorption Materials • Selection Criteria & Recommendation • Additional Questions & Information Required

  3. The Problem • India’s economy dependent on agriculture • There has been a shift from seasonal to year-round cropping to address food security • Groundwater used to supplement irrigation • Quality and quantity of groundwater degraded by natural and human activities • Detrimental effect on the quality of crops and public health

  4. Solution Methodology • Define area of study • Amount of groundwater used for irrigation • Extraction methods • Chemical composition of water • Type and intensity of cropping • Effects of contaminated water on crops and health • Suggest point/on-farm treatment methods

  5. Groundwater in Odisha • Total usable groundwater resource= 12.6 BCM (12.6x1012 L), 2007-2008 • Around 390,000 groundwater structures employed for irrigation,2004 • Dug well (92%) • Shallow tube well (4%) • Filter point tuber well (3%) • 4.7 BCM of groundwater was used for irrigation in 2001 • Projections indicate groundwater use for irrigation could rise to 9.4 BCM by 2050

  6. Groundwater in Odisha cont. • Groundwater affected by: • High fluoride concentration (>1.5 mg/L) • High iron concentrations (>1 mg/L) • High nitrate concentrations (>45 mg/L) • Presence of these pollutants in groundwater causes health issues and affects the quality/yieldof crops • Study focuses on treating high fluoride concentrations in ground water

  7. Defluoridation Methods • Common methodsinclude: • Adsorption and ion exchange • Precipitation • Membrane filtration process • Distillation • Membrane filtration and distillation are advanced and not deployable in developing countries • Conduct preliminary analysis to select treatment method

  8. Preliminary Analysis • Green – Most suitable • Orange – Average suitability • Red – Not suitable

  9. Adsorption Through Ion Exchange • Process involves passage of water through a contact bed where fluoride is removed by ion exchange or surface chemical reaction with solid bed matrix • Water is filtered down through column packed with an ion exchange resin • When adsorbent becomes saturated with fluoride ions (F-), material must be backwashed (recharged) with a mild acid or alkali solution to clear and regenerate it • Exchange reaction: • AB + CF AF +CB where A and C are cations and B and F are anions • Double replacement occurs with the fluoride anions exchanged leaving the remaining water with less fluoride.

  10. Adsorption Apparatus (Drinking Water Treatment)

  11. Common Adsorption Materials

  12. Common Adsorption Materials cont.

  13. Common Adsorption Materials cont.

  14. Selection Criteria & Recommendation Activated Alumina • Reasons • Used mostly for drinking water, but seems feasible to increase capacity for irrigation • Relatively low cost • Effective (85-95%) at pH of 6.5 • Material available locally • Easy to implement • Socially acceptable, but training necessary on handling of chemicals • Key Selection Criteria • Use of treated water • Cost of method • Effectiveness • Problems due to break point • Effect of other chemicals • Size and capacity of method • Quality of water (high pH issues and other chemicals) • Social acceptance

  15. Additional Questions/Info Required • Chemical composition of groundwater? Effect of interference due to other contaminants? • Factors affecting fluoride uptake capacity: • Grade of activated alumina • Particle size • Water chemistry: pH, alkalinity, fluoride concentration (effective range of process), temperature • Exact source of irrigation water at specific farms? Groundwater or surface water or both? • Does Odisha (and specifically the local community we are working with) treat water for irrigation? How much do they treat water for drinking water requirements?

  16. Additional Questions/Info Required • What volume of treated water is needed? • Irrigation water rotation between surface and treated groundwater may still be a possible option. • What time is available/acceptable for treatment? • Additional costs: apparatus materials, regeneration chemicals, maintenance tools/materials, preliminary treatment chemicals, testing equipment? • Type and intensity of crops? • Further information on exact effect of fluoride on crops: stunting growth/damaging of crops or indirect damage to health from human consumption of crops?

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