PROACTIVE MANAGEMENT OF HAB’s USING IN-LAKE PHOSPHORUS INACTIVATION TECHNOLOGIES

By Dominic Meringolo

Senior Environmental Engineer

Territory Leader

May 13, 2017

Restoring Balance. Enhancing Beauty.

Why Manage Algae?

• Poor water clarity

• Taste & Odor

• Aesthetics

• Recreational impairment

• Diurnal Oxygen Fluctuations

• Cyanobacteria Toxins (HAB’s)

Nuisance Algae Control

Nuisance algae conditions are triggered by excessive nutrients – usually limited by phosphorus

• Control Algae (Treat the symptoms)

– Copper products, alternative algaecides

– Aeration

• Control Nutrients (Treat the source)

– Increase N:P ratio / reduce favorability for cyanos

– Watershed management

– In-Lake Phosphorus Reduction

Why is Watershed Management

Sometimes Not Enough?

• May take many years to make a difference

• Difficult/Expensive to implement

• May not be feasible to lower nutrient concentrations below critical threshold

• Contributions of internal recycling

Methods of In-Lake Phosphorus

Reduction

• Alum Treatment

• Phoslock

• SeClear

• As an alternative to copper treatments until

watershed management efforts come to fruition.

• Address internal recycling when it’s a significant

component of nutrient load.

Alum Treatment - What is

Alum?

• Aluminum Sulfate

• Used extensively in the

drinking water industry.

• Is not a herbicide or

algaecide, but a chemical

precipitant/coagulant that

binds with phosphorus

rendering it biologically

unavailable.

Overview of Alum Technique

• Precipitation vs. Inactivation (Low vs. High Dose)

• Dose Determination (Multiple Methods)

• Dose Verification/Pilot Treatment

• Full-Scale Implementation

• Treatment Monitoring

• Post-Treatment Monitoring

Available Sediment P Reduction (%) vs.

Aluminum Dose (g/m2)

0

10

20

30

40

50

60

70

80

90

100

0 50 100 150 200

Al dose (g/m2)

% R

ed

uc

tio

n i

n a

va

il. P

45 g/m2

74% reduction

Alum Floc

Pictures from underwater camera

Alum Applications

Limitations of alum

• Reaction causes drop in pH

• Must be buffered in soft/low-alkalinity water

• Even with buffering, there are still limitations for

smaller and shallow lakes, so only phosphorus-

Precipitation can occur and not phosphorus-

Inactivation of the sediment

• A patented technology which effectively binds and removes free reactive phosphorus (FRP)

• Consists of two naturally occurring components found in soil - Lanthanum embedded inside modified bentonite clay layers

• No significant change in desired water quality parameters during or after application (pH, D.O., Alkalinity, etc.)

What is Phoslock?

1) Immediate Impact

▪ Rapid P binding

▪ As Phoslock moves through the water column it adsorbs P at different depths in the water body

2) Short- term Impact

▪ Reduction in P

▪ As P becomes the limiting nutrient the N:P ratio increases

▪ Resulting in more balanced water quality conditions

3) Longer- term Impact

▪ Phoslock remains active at the bottom of a water body

▪ Adsorbs P released from sediments

▪ Adsorbs P from new inflow water, as settles to bottom

Water Quality Restoration with

Phoslock

• Phoslock slurry injected or surface applied• Tank mix granule with H2O, constant agitation• Even coverage to maximize performance

Phoslock Applications

SeClear® –

Algaecide &

Water Quality

Enhancer

Example Phosphorous

Management Projects

• Long Pond – Brewster/Harwich, MA (2007)

• Mystic Lake – Barnstable, MA (2010)

• Ticklenaked Pond – Ryegate, VT (2014)

• Cliff Pond – Brewster, MA (2016)

• Crooked Stick Pond (SePRO Demonstration Project)

Long Pond – Brewster/Harwich

• 740-acres

• Largest

waterbody on the

Cape

• State and Town

Funding

• Completed in

2007

• 7 weeks

• 100,000 gallons

combined of alum

and sodium

aluminate

Long Pond – Brewster/Harwich

Mystic Lake - Barnstable

• 149-acres

• Treatment of

~50-acres

• 35-50 g/m2

• Mussel

monitoring

• Significant

mussel die-off

prior to treatment

Mystic Lake - Barnstable

• Significant reduction of sediment phosphorus release (>90%)

• Improved water clarity

• No effects on mussels

Ticklenaked Pond – Ryegate, VT

Consistent Results

Source: Dr. Ken Wagner, WRS – Not yet published

• Phoslock programs successful throughout US

• rapid phosphorus reduction and improved water quality

• Phoslock continued to bind, resulting in low FRP levels

Application 6/23/11

Questions?

solitudelakemanagement.com • 888.480.LAKE

May 13, 2017

By Dominic Meringolo

Senior Environmental Engineer

Territory Leader

DMeringolo@solitudelake.com