ODOR AND CORROSION CONTROL IN SEWERAGE SYSTEMS PowerPoint Presentation

ODOR AND CORROSION CONTROL IN SEWERAGE SYSTEMS PowerPoint Presentation

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Enrique J. La Motta, Ph.D., P.E.. Professor of Civil and Environmental Engineering. THE . SOUTHEAST SYMPOSIUM ON CONTEMPORARY ENGINEERING TOPICS (SSCET. ). University of New Orleans. September 2014 . ID: 358703

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Slide1

ODOR AND CORROSION CONTROL IN SEWERAGE SYSTEMS

Enrique J. La Motta, Ph.D., P.E.

Professor of Civil and Environmental Engineering

THE

SOUTHEAST SYMPOSIUM ON CONTEMPORARY ENGINEERING TOPICS (SSCET

)

University of New Orleans

September 2014

Slide2

PRESENTATION OUTLINE

Cause

of H

2

S

odor

and

corrosion

Odor and corrosion control technology

o

verview

Problems and solution in NO metropolitan area

Pure oxygen injection

Applications and case studies

Slide3

Bacteria need oxygen to consume org. matter

MAIN CAUSE OF ODOR

Oxygen sources(order of preference):Oxygen (limited)Nitrate (limited)Sulfate (unlimited)

Slide4

Anaerobic slime layer

SO

42-

Anaerobic bacteria

H

2S

Sulfide Generation in Sewers

Condensate: Location of H

2

S oxidizing bacteria

Anaerobic slime layer

H2S is released from solution as gas (rotten egg odor)

Corrosion of moist pipe surface

H2S + O2

Thiobacillus

sulfuricans

H

2SO4

(EPA Manual)

Slide5

EFFECTS OF SEWER CORROSION

(Vitrified Clay Pipe Manual)

Slide6

RATE OF CORROSION

At H2S concentrations of 20ppm in the headspace,concrete will corrode at a rate of 1 inch in 5 years

(

Clidence

and

Shissler

, 2008)

Slide7

MAJOR H2S CORROSION TARGET AREAS

Gravity concrete or cast iron sewersPump stations and force mainsTreatment facilities

Slide8

TREATMENT OBJECTIVES

Maintain DO > 0.5 mg/L.

Keep dissolved sulfides (DS) less than 0.1 (difficult and costly to achieve) to 0.3 mg/L.

Maintain H

2

S in the air at less than 3 to 5 ppm.

Increase pipe crown pH to 4.0 or higher

Slide9

TECHNIQUES AVAILABLE TO CONTROL H2S CORROSION

Oxidations systems:

Pure oxygen

injection

Air injection

Hydrogen peroxide

Chlorine

Potassium permanganate.

Precipitation systems

Iron salts

Zinc salts

pH elevation

Other methods

Slide10

HYDROGEN SULFIDE CONTROL AT ORLEANS PARISH

Significant amount of sulfide generation

occurs

in the sanitary sewer systems of the New Orleans metropolitan area

.

Orleans Parish produces approximately 120 MGD of municipal wastewater

S&WB has tried hydrogen peroxide and Bio-Kat addition

Roughly 24 MGD is

being treated with Bio-

Kat

The annual

cost

of Bio-Kat

0.6 million

dollars

The unit cost is roughly

$25,000 per MGD treated.

Slide11

BEST METHOD: PURE OXYGEN INJECTION

A more cost-effective

H

2

S control system

is wastewater super-

oxygenation.

Oxygen can be generated in situ using modern technology.

Pure oxygen is injected at selected sewage pumping stations.

High oxygen transfer efficiency (>90%)

Slide12

Typical in situ oxygen generation system using the pressure swing adsorption (PSA) technology (Source: OGSI.)

Slide13

Schematic diagram of the ECO

2

oxygen injection system. (

Clidence

and

Shissler

, 2008).

Slide14

Slide15

Typical installation of the ECO

2

pure oxygen injection system at a raw sewage pumping station (Source: ECO

2

web site)

Slide16

ADVANTAGES OF PURE OXYGEN INJECTION

Wastewater remains aerobic through the treatment

plant:

No H

2

S generation

No odors

No corrosion

Wastewater arrives partially treated to the treatment plant

Modern technology makes this system cost effective

Examples of positive results:

Slide17

Untreated H

2

S levels in the Laguna Beach force main

Source:

Clidence

and

Schissler

, WEF/A&WMA, 2008

Slide18

H

2

S

levels in the Laguna Beach force

main after pure oxygen injection. Source

:

Clidence

and

Schissler

, WEF/A&WMA, 2008

Slide19

H2S in the sewer headspace near Gulf Pond force main discharge, Milford, Conn.Source: Bradstreet and Smith, WEFTEC 2012

Slide20

Cost of pure oxygen injection systems

Milford

, Conn

.: Unit

annual cost

=

$

5,400/MGD

Madison,

ME:

Unit annual cost =

$

5,200/MGD

Elk Vale,

SD:

Unit annual cost =

$

5,400/MGD

Trinity River Authority,

Dallas,

TX (primary clarifiers, 150 MGD): Unit

annual cost =

1,700

/MGD

The cost

of super-oxygenation

for H

2

S

and corrosion control

is close to one

-fifth of the cost

of

Bio-

Kat.

Slide21

HYDROGEN SULFIDE CONTROL AT JEFFERSON PARISH

Jefferson Parish tried iron salts addition on West Bank

At Marrero WWTP got black precipitate (Fe

2

S) all over the plant

Got Fe(HO)

3

precipitate at the chlorination chamber

Suspended iron salt addition in 1997.

Severe odor and corrosion problems at the East Bank Wastewater Treatment Plant

UNO has been cooperating with JP by developing a pure oxygen injection program

Slide22

Pure Oxygen Injection At JP East Bank Pumping Station System

Assumptions made to calculate oxygen demand:

Oxygen concentration to meet the oxygen uptake rate = 10 x HRT.

HRT was based on continuous flow at average dry weather flow rate

Oxygen concentration needed to oxidize hydrogen sulfide = 5 x DS at each pumping station.

DS data base was limited.

Calculations were performed, and several changes and adjustments were made.

Final amounts of oxygen to be added are on the next diagram.

Slide23

G6-9 Helios

3340.4

gpm

55.1

ft

0.77 fps

G6-4 Galleria

3795.5

gpm

60.1

ft

7136

gpm

1.27 fps

F6-5 Cleary & W. Napoleon

2966.6

gpm

53.8

ft

10,102.5

gpm

1.79 fps

F6-11 Houma & W. Napoleon

2012.6

gpm

66.4 ft

F6-5 Clearview & W. Napoleon2456.7 gpm46.0 ft

12,115.1 gpm2.15 fps

F6-2 W. Napoleon8065.0 gpm66.64 ft

14,571.8 gpm2.04 fps

E6-7 Transcont. &Vineland8153.3 gpm32.66 ft

3.7 fps

30,790.0 gpm2.89 fps

E5-4 Transcontinental & W. Metairie3384.6 gpm42.6 ft

34,174.6 gpm2.69 fps

EBWWTP

SCHEMATIC DIAGRAM OF THE EAST BANK SEWAGE PUMPING SYSTEM

22,636.8

gpm

2.12 fps

Slide24

SECOND PHASE, JEFFERSON PARISH

Implement the oxygen injection program.

Monitor the successful removal of hydrogen sulfide in the pumping system.

Monitor the remaining odor levels at the EB WWTP.

If odors continue, focus on improving the sludge management system.

Inject pure oxygen into sludge

holding

tank.

Slide25

Questions?

Slide26

Slide27

Slide28

Slide29

Slide30


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