point of use coagulation and flocculation
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Point of Use Coagulation and Flocculation. Turbidity Terminators: Morgan Rog Shubha Bhar Melanie Tan Lindsay Ellis. Comparing Chemical Coagulants. Alternative Coagulants: Plants. Study done by Kenneth Yongabi, Tafawa Balewa University, Bauchi Nigeria - PowerPoint PPT PresentationTRANSCRIPT
Point of Use Coagulation and Flocculation
Turbidity Terminators:
Morgan Rog
Shubha Bhar
Melanie Tan
Lindsay Ellis
Comparing Chemical Coagulants
Coagulant Community/Household Use Advantages Disadvantages Cost* Comments Alum (aluminum sulfate, etc.), alum potash Yes/rare-moderate
Community use common; simple technology
Difficult to optimize without training and equipment Moderate
Proper use requires skill
Iron salts (ferric chloride or sulfate) Yes/rare Same as Alum Same as Alum Moderate
Proper use requires skill
Lime (Ca(OH2)), lime+soda ash (Na2CO3), caustic soda (NaOH) Yes/rare-moderate Same as Alum
Same as Alum; pH control and neutralization a problem; hazardous chemicals
Moderate to high
Softeners; not applicable to many waters
Alternative Coagulants: Plants
• Study done by Kenneth Yongabi, Tafawa Balewa University, Bauchi Nigeria• Medicinal plants could have coagulative properties
Experiment:–Samples from each plant were dried, ground and stored–Alum was added to each sample–Coagulation mixtures added to turbid water samples–Alum was used as a control–The samples sat for 24 hours–Coagulative effect and bacterial counts were recorded–Extracts were tested for E. coli as a fecal contamination indicator
Jatropha Curcas
Results:–Coagulated 60-80% of particles–Decrease bacterial counts–Less effective than Moringa, but still more effective than Alum
• Common plant found in western and southern Africa
• Roots and leaves highly medicinal
• Seeds dried and ground up to determine coagulative properties
Hibiscus subdariffa
• Plant cultivated in Northern Nigeria
• Contains red calyx extract dried and tested for coagulation
Results:–Effective coagulation–Effective disinfectant
•Reduced E. coli and coliform bacterial counts better than Alum
–Leaves water tinted red
Pleurotus tuberregium
• Grown in Cameroon and parts of Nigeria• Mushrooms have medicinal value
Results:–Least effective coagulant–No antimicrobial properties–Still just as effective as Alum
Moringa oleifera
• Originally from India, found in tropics in Asia, S. America, and Africa• Tough plant, easy to grow and cultivate• Drumstick, use dried seeds from pods
• One tree cleans enough water for 5-6 people
• Also contains pterygospermin, antibacterial
Results:–Coagulated 90% of particles–Much better than treatment with just alum–Antimicrobial properties
•Bacterial counts reduced from “Too Numerous to count” to 2700 CFU
Preparation of Moringa Oleifera
Process:
• dry and crush seeds
• make into a paste
• filter
• add paste to turbid water
• stir fast for ½ minute
• stir slowly 5 minutes
• settle 1 hour
Dosage Demand:
< 50 NTU 10-50 mg/L
50-150 NTU 30-100 mg/L
>150 NTU 50-200 mg/L
Pros and Cons of Moringa Oleifera
Advantages:
• Cheap, readily available
• doesn’t alter pH, pH independent
• doesn’t change taste
• biodegradable sludge Disadvantages
• still needs to be disinfected
• possibility of recontamination, no residual
• needs to be fresh
POU Coagulation & Flocculation in Guatemala
The Experiment, by Proctor and Gamble– Households assigned home flocculation-disinfection
system– 4 controls using flocculation disinfectant and bleach– Stir water 30 seconds quickly, stir 5 minutes slow, let
sit ½ hour, filter
• diarrhea 2nd highest cause of death
• water generally kept in open containers
• use bleach to treat water
How it Works:– Cheap flocculation disinfectant contained: ferric sulfate, bentonite, sodium carbonate, chitosan, polyacrylamide, potassium permanganate, and calcium hypochlorite – causes clumps to form and settle with stirring– chlorine residual 3.5 mg/L
Effectiveness of Proctor and Gamble Experiment
Results: •Flocculation-disinfection (top) reduced diarrhea by 24%•Flocculation-disinfection with special container reduced diarrhea by 30%
Helpful Websites
http://www.blackwell-synergy.com/links/doi/10.1111/j.1365-2672.2004.02309.x/pdf
http://murungaexports.ebigchina.com/sdp/181012/4/cp-1011556.html
http://www.treesforlife.org/project/moringa/uses/uses_water_lgscale_article.en.asp
http://www.biotech.kth.se/iobb/news/kenneth04.doc
http://www.ajtmh.org/cgi/content/abstract/69/4/411