removing toxic chemicals from drinking water using …...- clare tawney, managing editor, waterlines...
TRANSCRIPT
Removing toxic chemicals from drinking water using biochar
Josh Kearns, PhD student
Environmental Engineering, University of Colorado
Visiting Researcher, North Carolina State University
Director of Science, Aqueous Solutions
[email protected] | (+1) 720 989 3959 | Skype: joshkearns
While microbial pathogens typically represent the most immediate threat to human health, a wide variety of toxic chemicals threaten the safety of drinking water worldwide.
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Therefore, to provide safe drinking water we must address both biological and chemical contaminants.
Long term chronic exposure to trace quantities (ppt to ppb levels) of synthetic toxins such as pesticides, pharmaceutical residues, fuel compounds, manufacturing additives, and disinfection by-products can lead to
cancer birth defects reproductive disorders developmental impairment endocrine disruption neurological dysfunctions damage to internal organs other toxic effects
outline
• A toxic tour: examples of synthetic organic chemical threats to water quality – pharmaceutical residues – manufacturing additives: flame retardants – agrichemical runoff: pesticides & herbicides
• Low cost treatment using biochar adsorbent
– small scale biochar production: cookstoves & drum ovens – laboratory data for removal of select contaminants from surface
water – integration of char in a multi-barrier approach to treatment – cost comparison with other common treatment technologies
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Ningxia Tairui Pharmaceutical Co. Yinchuan, China
“Waste flowing out of a treatment plant near Hyderabad in India pollutes the region's waters with some of the highest levels of pharmaceuticals ever detected in the environment.”
-- Nature, 2009.
pharmaceutical residues
runoff from livestock facilities
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one example (of many): halogenated flame retardants in furniture, clothing and textiles, insulation, carpets, vehicles, electronics…
-- environmentally persistent, accumulate in fatty tissue, blood, seminal fluid, breastmilk
-- known, probable or possible carcinogens, endocrine disruptors, neurotoxins, cause developmental and/or reproductive impairment, thyroid disruption, memory and learning problems, etc.
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manufacturing additives
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e-waste recycling in China & Africa
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http://www.youtube.com/watch?v=pFeHnk_HGFA#t=60
recycled e-waste in
USA plastic imports…
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pesticides, herbicides…
1962 Union Carbide Ad in Scientific American
"I wouldn’t expect that herbicide would be a big risk in most developing countries.”
- Clare Tawney, Managing Editor, Waterlines Journal, in an email dated Sept. 5, 2012.
• >300 million tonnes of synthetic organic contaminants (SOCs) produced annually, including >5 million tonnes of pesticides “constitute a major impairment to water quality on a global scale.” -- Schwarzenbach et al., 2006, Science 313, 1072
• “Pesticide pollution” appears twice in the Top Ten in The World’s Worst Toxic Pollution Problems Report -- Blacksmith Institute/Green Cross Switzerland, 2011
• Exposure to trace quantities of SOCs can lead to cancer, diseases of the endocrine and reproductive systems, and damage to the liver, kidneys, or central nervous system, and other toxic effects -- Centers for Disease Control and Prevention, 2009/2013
• Around 75% of the pesticides used in S/SE Asia are banned or heavily restricted in the West due to ecological and human health effects -- Pesticide Action Network, 1997
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Toxic chemical contaminants are a major blind spot and Achilles’ heel for the WASH sector attempting to provide safe drinking water.
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500 μm
char made from longan wood
500 μm
high temperature chars can exhibit
extensive micro-porosity and large internal surface area
… and thereby make effective adsorbents for trace organic pollutants
activated carbon
brick beehive kiln steel drum/adobe kiln
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gasifier cookstove
gasifier drum oven
Sorption of select organic water contaminants by biochars...
Probe compound selection criteria from a water treatment perspective:
• environmental relevance - widely occurring
• negative human health impact
• impair water aesthetics
• difficult to remove
2,4-D herbicide possible carcinogen, suspected endocrine disruptor USEPA MCL 70 μg/L WHO Guideline 30 μg/L pKa 2.7
sulfamethoxazole (SMX) antibiotic (humans and livestock) pKa 5.6
warfarin (WFN) anticoagulant, rodenticide pKa 5.1
2-methyl isoborneol (MIB) cyanobacteria metabolite not a health concern musty taste & odor at >10 ng/L
Cl
Cl Cl
Br
chloroform probable carcinogen
BDCM probable carcinogen
CDBM possible carcinogen
bromoform probable carcinogen
trihalomethanes (THMs) disinfection by-products (DBPs) USEPA MCL 80 μg/L total THMs (TTHMs)
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2,4-D herbicide
sulfamethoxazole (SMX) antibiotic (humans and livestock)
warfarin (WFN) anticoagulant, rodenticide
2-methyl isoborneol (MIB) cyanobacteria metabolite taste & odor concern
Cl
Cl Cl
Br
chloroform
BDCM
CDBM
bromoform
trihalomethanes (THMs) disinfection by-products (DBPs)
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Trace contaminant
adsorption capacity relative
to commercial activated
carbon (AC) as a function of
pyrolysis temperature for
low temp (LT, 350 °C),
intermed. temp (IT, 625 °C),
and high temp. (HT, 900 °C)
chars.
LT LT
LT LT
LT
IT IT
IT IT
IT
HT
HT
HT HT
HT
0.1
1
10
100
2,4-D SMX WFN MIB TTHMs
sorp
oncap
acityrela
vetoAC(%)
2,4-D SMX WFN MIB TTHMs
Summary
High temperature (900 oC) gasifier chars can have 50-100% the adsorption capacity of commercial AC for a variety of prevalent toxic organic chemical contaminants.
Intermediate and low temperature chars are substantially less effective adsorbents.
Biochar – in particular, high temperature gasifier char – has great potential as a low-cost adsorbent for use in local water treatment and eco-sanitation.
“Micro” Multi-Barrier Water Treatment Plant
2,000-3,000 L/day
cost: US$ 400, local materials
open-access handbooks available at aqsolutions.org
English, Spanish, Thai, Burmese, and
Karen translations available so far
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This treatment system at a farm
community in northern Thailand has
been in continuous operation since
February 2008. To-date it has
produced over 2.4 million liters of
treated water. Considering the typical
local price for purchasing bottled
water, this corresponds to a cost
savings of over US$ 45,000 - for a
system that has cost less than US$
500 to install and maintain.
“Nano”
Portable/Emergency Water Treatment Plant
300-500 L/day
cost: US$ 125, local materials
open-access handbooks available at aqsolutions.org
English, Spanish, Thai, Burmese, and
Karen translations available so far
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Since March 2012, about 25 of these
systems have been installed in
remote communities, training centers,
school and villages throughout the
Thailand-Burma border region. To-
date these systems have produced
an estimated 3 million liters of
treated water.
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$20 retail, wholesale ??? replacement after 700 L
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$75 retail, $30 “insider” wholesale replacement after 18,000 L
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P&G sachets are now centrally produced in Pakistan and sold to NGOs worldwide for 3.5 US cents per sachet.
Each sachet treats 10 L of water.
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ceramic pot filter $5 - $25 20 L/day replacement 1-2 years Source: UNICEF/UN Water & Sanitation Program, 2007 Use of Ceramic Water Filters in Cambodia unicef.org/eapro/WSP_UNICEF_FN_CWP_Final.pdf
“biosand” filters $15 - $100
(average ~ $70) 20 L/day
replacement ≥ 10 years
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1 2 3 4
Aq portable system 500 L/day $200 initial capital and labor costs $450 maintenance materials and labor for 10 years $100 capital & maintenance drum oven
Total $750
Aq concrete tank system 2,000 L/day $500 initial capital and labor costs $900 maintenance materials and labor for 10 years $100 capital & maintenance drum oven
Total $1,500
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0
2
4
6
8
10
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Lifestraw PURpackets LifestawFamily
ceramicpotfilter
CityofRaleighNC
biosandfilter Aqportablesystem
Aqconcretesystem
centspergallo
n(US-$)
approximatecostcomparisonoftreatmenttechnologies
1.32
1.10
0.73
0.40 0.37
0.160.08
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
PURpackets LifestawFamily
ceramicpotfilter
CityofRaleighNC
biosandfilter
Aqportablesystem
Aqconcretesystem
centspergallo
n(US-$)
Josh Kearns, PhD student Environmental Engineering, University of Colorado
Visiting Researcher, North Carolina State University
Director of Science, Aqueous Solutions
[email protected] | (+1) 720 989 3959 | Skype: joshkearns
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Biochar workshop tomorrow
ECHO Farm A-T Center!