Efficacy of Jerry Can Cleaning Techniques: Methods Development

for a Large-scale Study

Gabrielle String, Hanaa Badr, Marta Domini, and Daniele Lantagne

Department of Civil and Environmental Engineering, Tufts University, Medford, MA, USA

Overview

• Introduction

– Jerry cans for water storage

– Biofilms

– Results from previous cleaning studies

• Large-scale study objectives

• Methods development and results

– Growing biofilms on coupons, enumerating

• Outcomes

• Preliminary results from large-scale study

2

Introduction: Jerry cans

Jerry cans are commonly used for household water storage and often distributed

in emergency contexts.

3

Introduction: Biofilms

• Biofilms are microbial communities comprised of pathogenic and non-pathogenic organisms

• Persist and grow on surfaces in contact with a liquid

• Able to shed cells promoting the growth of microorganisms

• Resistance to environmental changes and disinfection

4Zeng, Bay Area Lyme Foundation

Introduction: Cleaning jerry cans

• Biofilm growth inside water storage containers acts as microbial reservoir

• Previous studies compared cleaning methods with NaOCl or abrasives in-situ

– E. coli concentration reduced after cleaning

– No reduction in E. coli recontamination

• Studies did not address impact of cleaning on surface roughness of jerry cans

5

Steele et. al, J Water Health, 2008 Jagals et. al, J Water Health, 2003Burkowska et. al, J Water Health, 2015 Momba et. al, Water Res, 2002

Large-scale laboratory objectives

Do cleaning methods impact the surface roughness of jerry cans?

●

Does surface roughness influence the growth of biofilms?

●

How effective are different cleaning methods at removing E. coli biofilms from jerry cans?

6

Preparing coupons

• 1 cm2 coupons cut from jerry cans

• Coupons mounted on a polishing table for 1 min at 200 N force– Coarse: 120 grit – Medium: 240 grit– Fine: 400 grit

7

Thomas, et al, Carbon, 2014

Method: Growing biofilms

8

Place in Falcon tubes

Immersion

SpikeIncubation

Refresh25mL LB broth or PBS

E. coli at 104, 105, or 106 CFU/100mL

Repeat cycle every 48 hours

35ºC on a shake plate at 70 rpm

Continue for 10 and 21 days

Method: Enumerating E. coli

9

Enumeration Technique

Culture Imaging

Potential for recontamination Structure and size of matrix

Results: Culturable E. coli

10

Biofilm(CFU/cm2)

PBS Environment(CFU/100mL)

10 days 21 days10 days 21 days

Virgin 7.6 x 104 7.2 x 105 2.7 x 108 3.2×109

Coarse 5.2 x 104 8.0 x 105 2.2 x 109 2.5×109

Medium 4.8 x 104 2.3 x 106 2.1 x 109 2.1×109

Fine 8.0 x 104 2.4 x 106 2.1 x 109 2.5×109

Results: Imaging E. coli

11

Cross-sectional image of biofilm through z-direction

Results: Varied surface roughness

12

E. coli growth along coarse scratches

E. coli growth on virgin jerry can surface

Outcomes

13

• Successfully grew E. coli biofilms on coupons of varying surface roughness

• Applied a repeatable method for enumerating E. coli in biofilm

• Utilized a staining and imaging method to visualize biofilms on HDPE coupons

Large-scale laboratory study

14

Total: 72 containers, maintained for 90 days

Preliminary Results

15

Single E. coli

Preliminary Results

16

Next Steps

17

• Analyze collected data– Free chlorine residual and E. coli (after cleaning) and imaging (monthly)

• Trial most promising cleaning method on field collected containers

• Make recommendations on jerry can cleaning

Acknowledgements

Alenka Lovy Imaging Core Manager, Tufts

Trang Vu, Marlene Wolfe Lantagne Group

Melissa Opryszko USAID-OFDA

Students

Molly Lie, Magnifique Mukundwa, Katherine Sweetser, Katie Painter, Miranda Johnston, Tharina Messeroux, Himamshu

Ghimire, Derrick Sosa, Kelly Donohue, Faith Patrick