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 Selection Criteria & Recommendation Additional Questions & Information Required

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 http://www.orissa.gov.in/waterresources/AR_water_resources/Pdf_data/water_resources/WR_AR_07-08_Eng.pdf

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

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 http://www.orissa.gov.in/waterresources/AR_water_resources/Pdf_data/water_resources/WR_AR_07-08_Eng.pdf

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/yield of crops Study focuses on treating high fluoride concentrations in ground water http://cgwb.gov.in/gw_profiles/st_Orissa.htm

Defluoridation Methods Common methods include: 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 http://www.un-igrac.org/dynamics/modules/SFIL0100/view.php?fil_Id=131

Preliminary Analysis Green – Most suitable Orange – Average suitability Red – Not suitable

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. http://www.samsamwater.com/library/TP40_22_Technologies_for_fluoride_removal.pdf http://www.un-igrac.org/dynamics/modules/SFIL0100/view.php?fil_Id=131

Adsorption Apparatus (Drinking Water Treatment)

Common Adsorption Materials Dosage Cost Advantage Disadvantage Activated Alumina (Al2O3) 100 mg alumina/mg F (1200 g F/m3) pH of 6.5 $700-$1400 per metric ton 85-95% effective Lots of past experience in this type of technique (therefore lots of literature on how-to) Usable at household & community level Low energy consumption High capacity Periodic regeneration of material required Slightly more expensive than other materials Suitable grade may not be readily available in Odisha Training on handling of materials required Bone Char 1000 g F/m3 pH > 7 Locally available Low cost Good capacity Low efficiency Affected by high alkalinity May not be culturally acceptable (possibly animal bones more acceptable?) For drinking: if improperly prepared, imparts taste and odor to treated water Activated Alumina: http://www.alibaba.com/showroom/activated-alumina-price.html http://www.tradeindia.com/Seller-2840690-AIRON-GAS-TECHNOLOGIES/ http://www.indiamart.com/patalia-chem-industries/activated-alumina-balls.html#activated-alumina-for-flouride-removal Bauxite: http://www.capealumina.com.au/bauxite_aluminium-market-demand.htm#bauxite-pricing Activated Carbon: http://www.alibaba.com/showroom/activated-carbon-price-in-india.html Red Mud: http://redmud.org/home.html

Common Adsorption Materials cont. Dosage Cost Advantage Disadvantage Bauxite (Al(OH)3) “red mud” is a solid waste from refining of bauxite Effective in pH range 5-7, max effectiveness at pH of 6.4; (not effective above pH of 10) $20-$30 per ton Locally available Likely low cost – will need further research into actual cost Adsorption highly dependent on concentrations of other anions (sulphate (SO42-), nitrate (NO3-), and phosphate (PO43-)) due to competition with each other for aluminum based materials. Limited literature available Sujana. Activated Carbon Variable dosage Most effective at pH < 3 >90% effective Usable at household & community level Many interferences Large changes in pH before & after treatment Relatively high cost Medium operator skill level

Common Adsorption Materials cont. Dosage Cost Advantage Disadvantage Coconut Shells & Paddy Husk Charcoal (specific types of activated carbons) Variable dosage Effective at low pH (1.7 in experiment) Low cost Local availability Usable at household and possibly small community level Effectiveness of coconut fiber charcoal significantly increased with zirconium ion impregnation. Not effective at commercial level (depending on size of farm, it may not be appropriate) Varying effectiveness

Selection Criteria & Recommendation Activated Alumina 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 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

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?

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?