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

josh@aqsolutions.org | (+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.

2

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

3

4

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

5

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.

5

manufacturing additives

6

e-waste recycling in China & Africa

7

http://www.youtube.com/watch?v=pFeHnk_HGFA#t=60

recycled e-waste in

USA plastic imports…

8 8

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

9

Toxic chemical contaminants are a major blind spot and Achilles’ heel for the WASH sector attempting to provide safe drinking water.

10

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

11

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)

12

13

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)

13

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

15

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

16

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.

17

$20 retail, wholesale ??? replacement after 700 L

18

$75 retail, $30 “insider” wholesale replacement after 18,000 L

19

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.

20

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

21

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

22

0

2

4

6

8

10

12

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

josh@aqsolutions.org | (+1) 720 989 3959 | Skype: joshkearns

23

Biochar workshop tomorrow

ECHO Farm A-T Center!