EVALUATING WATER QUALITY AT COMBINED SEWER OVERFLOWS BY A NOVEL APPROACH

Ting Lu Ph.D.

Metropolitan Sewer District of Greater Cincinnati (MSDGC)

OWEA Annual Conference

Sandusky OH

Challenge

WWIP

Asset Management

Water qualityWater quantity

Level of service

Sustainability AFFORDABILITY

Impact of Water Quality

CSO

SSO Private systems

Stormwater runoff

Urban runoff Agriculture

Take home message

Importance of integrating science and technology to solve environmental problems.

A multisource, multiagency and regional strategy is needed in order to lead to full water quality standards compliance.

Outline

Introduction CSO Removal Approach CSO Monitoring Approach Pilot Project Conclusion

210 combined sewer overflow (CSO) that discharge to 19 receiving waters.

MSD collects and treats approximately 192 MGD of wastewater by operating seven major treatment plants.

How Great is MSD’s Environmental Challenge?

MSD’s Wet Weather Strategy

Hydraulic Grade Line inside sewer

Problem Identification: Lick Run Watershed

Typical Year flow

(modeled)

1.7 Billion Gallons

Current number

customers

5,700 accounts

Land Area 2,720 acres

Tunnel Solution

$244 Million

Sustainable Solution

Estimated to reduce 1

billion gallons

Lick Run: Source Control Opportunities

In order to utilize source control,

Monitoring strategy

Source identificat

ion

E. coli

Where is it applied?

Indication of in - stream water qualityCriteria in NPDES permitPrediction of water recreation status Prioritization on capital improvement projects to remove CSOs and SSOsDecision- making to evaluate projects effectiveness to improve water quality

Escherichia coli (E. coli)

Where is it from?• human waste• animal waste

Why is it used?• indication of the disease-causing

bacteria, viruses and protozoans• grown easily• model organism

How is it used?

Culture based method to identify and enumerate microorganisms:

The assumption in the method is that each viable microorganism can produce offspring that form countable colonies in the assay.

Serially dilution

Spread onto Petri

plates

Incubation

Count colony forming

units

Culture based method: as a ‘gold standard’ in microbiological monitoring for more than a century

Water Quality vs. Bacterial activity

Dead Viable but not culturable

(VBNC)

Culturable 0

0.1

0.2

0.3

0.4

0.5

0.6

Perc

en

tag

e

Culture based method

How to quantify

this portion?

Neglecting the VBNC portion could lead to inaccurate information for human health risk

Are E. coli and Fecal coliform the right indicator for water quality and human health risk?

Is there alternative water quality indicators?

Outline

Introduction CSO Removal Approach CSO Monitoring Approach Pilot project Conclusion

Pilot project: develop novel biomarker approach to monitor stream health

Little Miami River (“National and State

Scenic River”)

An Interdisciplinary Approach to Monitor Water Quality

WHERE: Duck Creek stream WHEN: using rain gauge data to identify the time to

monitor the stream by real time monitoring the rain event

HOW: (Standard-NPDES permit analysis coupled with novel molecular approach) o Water Quantity

• System Wide Model o Water Quality

Chemical analysis Biological analysis Molecular Tools: using microbial diversity and

signature bacteria as an indicator

Sampling locations

Membrane filtration

Molecular Approach

How many species are there? ------Bacterial screening: 16S

rRNA based method What are the signature bacteria?

------Bacteroides

Identity: who is present and how many? ------16S rRNA gene

E. coli GCUUGAGUCU CGUAGAGGGG GGUAGAAUUCA. calc GCUAGAGUAU GGGAGAGGAU GGUAGAAUUC

Identification of bacteria because: • Highly conserved primer binding sites• Hypervariable regions

Why Bacteroides are the signature bacteria?

1/3 of fecal flora Anaerobe Host-specific Found to correlate more often than E.coli

to pathogens

Why do we care about this?

1. Measure the project effectiveness

2. Identify Pollution Source: Point Source or Non Point Source Pollution?

Isolate signature bacteria under each monitor site

Bacteria associated with

Cause: Point Source Cause: Non-Point Source

Human feces

Animal feces

Mitigation: e.g. Household Sewage Treatment System (HSTS) elimination, CSO removal

Mitigation: Collaboration with other agenciesto remove the source

Source Identification

3. Water Quality vs. Human Health

Human Health Risk

human feces

animals feces

Active E. coli cells

Live but not

active E. coli cells

Dead E. coli cells

Goal: minimize the human health risks as well as being affordable

Integrated watershed management:

CSO removalvs.

Sustainability

Level of service

vs. Affordability

Water quality

vs. Water

quantity

Acknowledgement

Ms. Beverly Head, MSDGC Mr. Biju Gegore, MSDGC Mr. Donald Linn, MSDGC Dr. David Wendell, University of

Cincinnati Mr. Chris Yoder, Midwest Biodiversity

Institute Dr. Francis de los Reyes III, North

Carolina University Dr. Jorge Santo Domingo, USEPA

Thank you!

Questions or Comments?

For more information contact:

Ting Lu Metropolitan Sewer District of Greater

Cincinnati1600 Gest Street

Cincinnati, OH 45204Ting.Lu@cincinnati-oh.gov