Piping Materials Used in Water Distribution Affect Biofilm Growth and Drinking Water Quality

D. Clark, Chemical Engineering; V. Sumner, Chemical Engineering; S. Palmer, Chemical Engineering

GRA: H. Jing, AC: Dr. G. Sorial, Dr. M. Kupferle, Environmental Engineering, University of Cincinnati

Introduction

Materials and Methods

Results

Conclusions

• Biofilm grows on moist wet surfaces, including water pipelines.• The water distribution system consists of a few types of piping

materials which could effect the growth of biofilm on their surfaces.

Materials• Pipe materials: copper, stainless steel, polyvinyl chloride, and

polyethylene• Biofilm bacteria: Pseudomonas fluorescens (gram-negative)

Methods• Scanning Electron Microscope used to see the surface structure

of different materials • Laser Scanning Microscope and Live/Dead BacLight staining

solution used to quantify biofilm growth• Zeta-Potential Analyzer used to determine overall surface

charge on different materials

Acknowledgements• Funding provided by the National Science Foundation• Grant numbers: DUE-0756921 and EEC-1004623• Equipment provided by U.S. Environmental Protection Agency

Scanning Electron Microscopy showed differences in surface structure of pipe materials.

Laser Scanning Microscopy showed variation of biofilm growth on different materials with time.

Stainless Steel

Polyethylene

Copper

Polyvinyl Chloride

Zeta–Potential Analysis showed that the overall surface charge varied with material type and pH.

Stainless Steel

Polyethylene

Copper

Polyvinyl Chloride

Coupon Material

What is expected?

Why? Zeta -Potential in mV

Biofilm Growth Patterns

Surface Structure

Copper Medium-high biofilm growth

Rough surface structure

-13.04 High biofilm growth, then dropped

Large crevasses

Stainless Steel

Low biofilm growth

Relatively smooth surface

-28.54 Very little biofilm growth

Relatively smooth

Polyvinyl Chloride (PVC)

Low biofilm growth

Smooth surface 13.18 Medium growth A little rough

Polyethylene (PE)

High growth Release nutrients for biofilm (carbon)

-38.21 Little growth at first, then high growth

Smooth

LSM Week 5 (Green = Live Cells; Red = Dead Cells)Laser Scanning Microscope

Scanning Electron Microscope

Zeta–Potential Analyzer

http://organicsoiltechnology.com/pseudomonas-fluorescens-phosphate-solubilization.html

Pseudomonas fluorescens

http://www.premierwatermn.com/water-quality/water-contaminants/bacteria-virus-and-microorganisms-in-water/

SEM images provided by Christina Bennett-Stamper (U.S. EPA)

• Scanning Electron Microscope: copper has large crevasses on its surface, which could be why it had high biofilm growth.

• Laser Scanning Microscope: stainless steel had lowest growth, copper had the highest, while PVC and PE had variances over the weeks.

• Zeta Potential: PVC was the only material with a positive reading, which could explain the unexpected growth of biofilm.

http://water.epa.gov/lawsregs/rulesregs/sdwa/tcr/distributionsystems.cfm

1 2 3 4 5

-1.6E+05

4.0E+04

2.4E+05

4.4E+05

6.4E+05

8.4E+05

Biofilm Growth on Different Piping MaterialsCopper Stainless Steel Polyvinyl Chloride Polyethylene

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