Overview of Available Control

Strategies for Biofouling Mussels

in an Industrial Setting

Renata Claudi MSc.

RNT Consulting Inc.

Fresh Water Biofouling Mussels

Dreissenid family – Zebra,Quagga,Conrad False Mussel

Mytillid family – Golden mussels

Zebra and Quagga Mussels

Dreissenid family

Zebra mussel

1988

Map: New York Sea Grant

Risks Posed to Industrial Facilities by

Mussel Fouling – Reason for Mitigation

• Decreased flow

• Potential plugging of essential

components/systems

• Increased corrosion

Mechanisms of Fouling

• Settlement of veligers during the breeding season

• Translocation of juvenile and adult mussels

• Migration of adults from surrounding areas on to

available surface

• Transport of shells or clumps of shells from

upstream areas into downstream systems

Additional Risk- Macrofouling by Mussels

Can Enhance Metal Corrosion by;

• Mechanical Damage

• Exposure of fresh surfaces to corrosive

factors

• Production of feces and pseudofeces

which in turn support microorganisms

First step in any mitigation, examine the

environmental parameters at the site you

wish to protect and compare them to the

environmental requirements of the mussel

you wish to control

1. Parameter2. No potential for

adult survival

3. Little potential

for larval

development

4. Moderate potential

for nuisance

infestations

5. High potential for massive

infestations

Chalk Variables

Calcium (mg Ca/L) <1, >100 1-5 5-10, 80-100 10-80

pH <3.0, >10 3.0-5.0 5.0-7.0 7.0-9.0

Alkalinity, total (mgCaCO3/L) <3, >350 3-18 18-35, 280-350 35-280

Hardness, total (mgCaCO3/L) <3, >350 3-18 18-35, 280-350 35-280

Nutrient Variables

Dissolved Oxygen mg/L (% sat) <1 (<10%) 1-3 (10-20%) 3-6 (20-50%) ≥7 (>50%)

Chlorophyll a (μg/L) 0-1, >25 1-2 or 20-25 8-20 2-8

Total phosphorous (μg/L) ? ? ? ?

Total Nitrogen (μg/L) ? ? ? ?

Secchi depth (m) <1, >8 1-2, 6-8 4-6 2.0-4.0

Physical Variables

Temperature, Mean Summer oC <5, >40 5-15 or 32-40 16-26 26-32

Conductivity (μS/cm) <30, > 25,000 9,000-25,000 3,800-9,000 30-3,800

Total Dissolved Solids (mg/L) <0, >17,000 6,000-17,000 2,500-6,000 20-2,500

Salinity mg/L (ppt) <0, >15 5-15 1-5 0-1

Turbidity (NTU) >80 20-80 5-20 <3-65

Total Suspended Solids (mg/L) >96 28-96 8-28 <8

Only after you determine

you will have a problem based

on environmental parameters

of the site do you proceed to

develop a control strategy

Minimizing mussel fouling

• Proactive

Does not allow

growth of

mussels in the

system or on

the surface

protected

• Reactive

Does allow mussels to grow in the system or on the surface. Established populations have to be eliminated periodically

Options for External

Structures*

*Structures That Are in Direct

Contact With the External

Environment; No Isolation Is

Possible

Reactive Options for External

Structures

Mechanical Cleaning

• de-water and use power-wash

• underwater, scrape and vacuum or

power-wash

Proactive Options for External

Structures

Antifouling and Foul Release Coatings

for both steel and concrete

Foul Release Coatings - Non-toxic, soft

silicone barrier coatings

Antifouling - Toxic, copper/zinc based

coatings (ablative and non-ablative) – EPA

approval required

Coatings

• Number of new formulations on the market in response to the ban of tributyl tin coatings in the marine industry

• Given the cost ( $10 - $40/sq.ft) and the extensive surface preparation required, ask for multiyear performance data

• Many coatings fail after 12 to 18 months

• Surface preparation is difficult but essential

Coatings

• Vendors with known successful antifouling

coatings

- CPM Coatings/ Chugoku Paint

Bioclean - Si

- Kansai Paint (Biox Si)

- International Paints (Intersleek)

- GE Coatings (Exsil)

- Fuji Coatings

Coatings

USBR (US Bureau of Reclamation) has

initiated a coating study in 2008 to

examine new generation of coatings.

Results are being posted on their website.

Copper/Beryllium after 2 years

•

Bioclean Silicone after 4 years

Options for Internal Piping

Systems

Reactive Options for Internal

Piping Systems

• Thermal Wash - 32oC for 48 hours (90o F)

40oC for 1 hour (104o F)

• Mechanical Cleaning

- scrape large diameter pipes

- water jetting/hydrolazing

- remote vehicle tools on difficult areas

• Flushing with weak acids

• Oxygen Deprivation

Reactive Options for Internal Piping

Systems – treatment once/year, every 6

month or every 3 monthNon-oxidizing chemical treatment - proprietary

chemicals, most of which have to be de-toxified on discharge (Betz, Nalco,Buckmann, Bayer, Mexel)

(12 -36 hour treatment)

Potassium salts, copper sulphate, copper ion generator, Bio-bullets, bacterial product

Oxidizing chemical treatment- chlorine, bromine, chlorine dioxide, chloramines, ozone, potassium permanganate,

Ferrate

(10+ days treatment at approx.1ppm)

Proprietary Non-oxidizing

chemicals

• Many based on quaternary amines

• Some based on isothiazolones

• Some based on other organic compounds

• Most require detoxification with bentonite

clay resulting in large volume of material

being deposited in the discharge

• Relatively high cost for the chemicals

Potassium salts

• Potassium compounds are toxic to most

bivalves

• Potassium chloride

20mg/L killed adult zm in 52 days

600mg/L killed adult zm in 48 hours

Used for eradication in small bodies of

water

Copper sulphate

• 14 – 81 µgCu/L caused virtually complete

mortality in zebra mussel veliger in 24

hours

• Applicable where already in use for algae

control

• Used for eradication of zebra mussels

from Offut Base Lake in Nebraska

(massive fish kill)

Copper ion generator

• Copper ion generators used for at least 40 years

to protect ship cooling systems from

macrofouling in salt water

• Tested in fresh water in the 90’s

• Commercialized under the name of Macrotech

• Used by one fossil generating plant on Lake

Michigan since 2003

• 10ppb of copper ion continuously during

breeding season

Zequanox (Bacterial Product) -

Reactive Treatment Chemical substance produced by Pseudomonas

fluorescence bacteria. This species is commonly present in soil

Specific strain developed by Dr.Dan Molloy in the U.S.

This strain when present in high enough concentration causes mortality in the Dreissenid mussels.

No mortality observed in any native mussels or clams of North America

Currently being commercialized by Marrone Organic Innovations from California

Potential for this to be a preventative treatment

BioBullets

• Patented process to coat chemicals for control of filter feeders in edible coating and create particles of appropriate size

• Potentially noxious chemical within the particle is not detected, filter feeder will keep ingesting the particles and not close down in self–defence

• Advantage of lower chemical loading to the environment and quicker kill

Reactive Treatment Using

Oxidizing Chemicals

• chlorine, bromine, chlorine dioxide,

chloramines, ozone, potassium

permanganate

• Most used at 1 – 3 mg/L concentration for

10+ days to eliminate adults

• Length of treament is temperature

dependent

Bruce A/B Treatment

Mussel mortality results

0

10

20

30

40

50

60

70

80

90

100

1 2 3 4 5 6 7 8 91

01

11

21

31

41

51

61

71

81

92

02

12

22

32

42

52

62

72

82

93

03

13

23

33

43

53

63

73

83

94

04

14

24

34

44

54

64

74

84

95

05

15

25

35

45

55

65

75

85

96

0

Treatment Day

Pe

rce

nt

Mo

rtal

ity

Unit 0 (A) Unit 3 Unit 4 Unit 0 (B)Unit 5 Unit 6 Unit 7 Unit 8

Ferrate

• Ferrate is the anion FeO42- in which iron

is in a +6 formal oxidation state. Ferrate

can be formed by oxidizing iron with strong

oxidizing agents under alkaline conditions.

• Cheaper than ozone, more powerful than

chlorine, no by-products of concern.

• On-site generation, most likely to be used

as a once/week treatment

Proactive Options for Internal

Piping Systems

• Sand/media filtration - has to remove all

particles greater than ready to settle

veligers

• Mechanical filtration - has to remove all

particles greater than ready to settle

veligers. Actual mesh size is dependent on

the application and industry using the filter.

Environmental Criteria affecting the

performance of the filter

• Total suspended solids (TSS) load in the in-

coming water

• Seasonal variation in TSS

• What is the particle size distribution of the TSS

• Continuous operation required to prevent fouling

of the filter

Example of small pore self cleaning filters

37

Fine Filter

Chamber

Filter Silt

Discharge

Strainer

Drain

Filtered Water

Discharge

Main Access

Hatch

Influent

Raw Water

Strainer and

Filter Vent

Strainer

Discharge

Access Hatches

Course Strainer

Chamber

Drive Unit with

1/2 HP Motor

Pad Eye Pad Eye

Direction

of Flow

Fine Filter

Drain

Mesh RequirementsSquare Weave Mesh is

EssentialRobust Support of the Mesh is Critical

Mechanical filtration test

• Installed at Nanticoke TGS, Lake Erie in

spring of 2000

• 760 l/s (12000 usgpm)

• 40 micron mesh

• Automatic

• backwash

Test Performed at Parker Dam

February 2009

• Self cleaning filter sized to accommodate

flow of 450 USGPM installed to protect

domestic water line

• Interchangeable screens - 40 micron (57

micron absolute) and 80 micron (120

micron absolute) size

40 Mic ron F ilter T es ts

0

50

100

150

200

250

300

350

400

< 100 100-200 200-400 > 400

Velig er S iz e (µm)

Nu

me

r o

f V

eli

ge

rs

B efore

After

80 Mic ron F ilter T es ts

0

100

200

300

400

500

600

< 100 100-200 200-400 > 400

Velig er S iz e (µm)

Nu

mb

er

of

Ve

lig

ers

B efore

After

Proactive Options for

Internal Piping Systems –

UV

Environmental Criteria affecting the

performance of UV

• How well does your raw water transmit UV

(various factors such as colour, hardness,

presence of iron and total suspended solids)

• Seasonal variation in above factors

4

6

Open channel UV Installation

UV Host Site: Bruce 5-8 CSW

900 l/s (15,000 usgpm)

20 hi-intensity,

medium pressure lamps0.07 to 0.1 Watt-seconds/cm2Sample

Point

Sample

Point

UV Lights

4

7

UV Light Bank for open channel

48

In pipe UV Installation

Access to Lamps

(Both ends of chamber) Electrical Junction Box

(wiring from cabinets) Upstream Isolation Valve

(Not visible)

Downstream

Isolation Valve

UV Monitor Access HatchAir Release

Wiper Motor Housing

Direction of Flow

Proactive Options for Internal

Piping Systems –

Sparker

What is a Sparker - high voltage spark passes

between two electrodes submerged in water

Plasma

discharge

P

ElectrodeUV

The spark arcs between the electrodes at predetermined time

intervals (seconds or minutes)

Electrical discharge vaporizes water quickly producing a

plasma bubble (with hot gas/water vapour):

pressure pulse

light pulse

The vapor-filled “bubble” expands and contracts,

producing additional pulses

The electric discharge creates a vacuum and UV light which

break water-molecule bonds in the vicinity of the discharge.

This produces hydroxyl radicals (OH)

Test site

Power

and

Controls

Traveling

Screen

Sparker

115 m

~5m

0.76 m

Zebra bags

Flow

Float and Line

Mussel

Bag

Weighted Disc

0%

10%

20%

30%

40%

50%

60%

0.001 0.01 0.1 1 10

Pulse Energy (J m-2

per pulse)

Prop

orti

on

of

dea

d m

uss

les

Proactive Use of Oxidizing Chemicals

for Protection of Internal Piping

Systems

• Low levels of the chemical are added

continuously or semi-continuously

throughout the mussel breeding season

to prevent settling by creating a hostile

environment.

Proactive Use of Ozone at

Ontario Power Generation

• Continuous ozone addition system

installed at Lennox TGS, Lake Erie

• 0.3mg/L added continuously during

breeding season

Start-up: September 2000

Proactive Use of Ozone at

Ontario Power Generation

• Intermittent ozone addition system installed in Bruce 1-4 CWS

• 600 l/s (9500 usgpm)

• 2 kg/day ozone

• 1 kg injected for 5 minutes, 2 times/day

• manufacturer - Mitsubishi

Start-up: October 2000

Proactive Use of Chlorine at

Ontario Power Generation

• Continuously at 0.3 - 0.5ppm TRC (at the

end of the treated system)

• Semi-continuously at 0.3 - 0.5ppm TRC

(at the end of the treated system). Most

often used regime, 15 minute on 30 to 90

minutes off.

Proactive Use of Chlorine at

Ontario Power Generation

• Regulatory limit is 10ppb TRC in the

combined discharge.

• Regulatory objective is 2ppb .

How to Select a Strategy

• Based on clear objective

• Site specific

• Affordable

• Acceptable to the regulator