Lagoons System OM.pdf

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Lagoon System

O

ti

d M i t

Operation and Maintenance

Water & Wastewater Utility Operation and

M t f T ib

(2)

Wastewater Lagoon Recap

Pond or basin designed to

i t ith

receive wastes with no prior treatment

• Aerobic Ponds or Aerated Ponds

• Anaerobic Ponds

• Facultative Ponds

(3)

Treatment Process

•• Page 12 schematic Page 12 schematic here

here

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Advantages - Disadvantages

• Does not require

expensive equipment

• May produce odors

• May have algae

p q p

• Relatively simple operation

• May have algae

effluent discharges

• Treats wastes p

• Few short-term sludge

Treats wastes inconsistently

• Dependent upon sludge

handling/disposal problems

Dependent upon weather conditions

• Limited process

• Low O&M costs when properly maintained

ted p ocess control

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Presentation Outline

1. Operation and Maintenance

• Scum Control • Odor Control

• Weed and Insect Control • Levee/Dike Maintenance

H d k d S i

• Headworks and Screening

2. Sampling and Analysis 2. Sampling and Analysis

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Operation and Maintenance

Lagoons and Ponds are probably more

l t d th th t f t t

neglected than any other type of wastewater treatment process

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Scum Control

Facultative and

A t d P d

Aerated Ponds

• Common occurrence

• Usually occurs in spring

Anaerobic ponds

g

• Wind will break up scum

are covered with a

dense scum blanket to keep pond anaerobic

• If not broken up it will dry on top and

7 keep pond anaerobic

and minimize odor

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Wh

y

is scum im

p

ortant?

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Why Is Scum Important?

• Difficult to break up when t d

encrusted

• Blue-green algae can form

• Cuts off sunlight

• Source of botulism

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How Is Scum Removed?

• Scum can be easily broken

if it i dd d l

up if it is addressed early

• Shoreline agitation

• Outboard motors

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Odor Control

Typical Causes

• Overloading

• Short circuitingShort circuiting

• Weather

• Poor Housekeeping • All ponds have odor

issues at some point _• _{Poor Housekeeping}

including:

- Poor circulation

p

• Can lead to more

problems Poor circulation

- Algae overgrowth

Industrial Wastes

problems

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How to Reduce Odors

Operations

• Parallel • Series

Aeration

Recirculation

Elimination

• Septage Dumping • Industrial Waste

Chemical Addition

(13)

O

perations

POND IN SERIES – TO REDUCE SHORT CIRCUITING

POND IN PARALLEL – TO REDUCE OVERLOADING

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A

eration

• Floating Aerators • Diffusers

• Outboard motorOutboard motor

YES

NO

YES

NO

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R

ecirculation

1 to 6 ratio of recycled fl t i fl t fl

flow to influent flows

Recirculation rules:

• Recirculation flow rate m st not ca se rate must not cause overflow

W t h ld b • Water should be

drawn from pond surface

surface

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E

limination

•

Septage Dumping

•

Industrial W

aste

©

www.michigan.gov/images/S

ept

age_

Dumpin

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C

hemical Addition

•

Chlorine

•

Hydrogen Peroxide

•

Potassium permanganatepermanganate

•

(18)

Weed and Insect Control

• Three areas of • Essential part of

O&M concern

1. Emergent Weeds

O&M

• Weeds around the g

2. Suspended Vegetation

edge provide a

sheltered area for

Vegetation

3. Dike Vegetation

mosquitoes and

scum accumulation

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Emergent Weed Control

1. Pond level above three feet

three feet

2. Remove new (first-ear) gro th b hand

year) growth by hand

3. Drown the weeds

4. Cut and Drown

5 Ri

5. Riprap

6. Pond Liner

7. Herbicides

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Emergent Weeds

Tules Bulrush Cattails Pickerelweed

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How do

y

ou control sus

p

ended

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Suspended Vegetation Control

1. Keep the pond exposed to wind exposed to wind

2. Skim with rakes or boards

Duckweed

boards

3. Mechanically harvest

4. Reduce nitrogen of phosphorous sources

p p

5. Ducks

Lagoon with duckweed

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Dike Vegetation Control

Why does it need to be t ll d?

controlled?

• Food source and habitat

©

for wildlife

• Weakens dike

Maintenance

Seed with grass

• Unsightly appearance

T ll t ti • Seed with grass

• Mow regularly • Herbicides

• Tall vegetation can reduce wind action

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Insect Control

Mosquitoes

• Breed in sheltered areas of standing water

• Keep water edge clear of vegetation

• Keep scum broken up

• Drain shallow isolated • Drain shallow isolated

pools left by receding pond levels

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Insect Control

Chironomid midges

• Often produced in wastewater ponds

• Can be a nuisance to nearby activities and create traffic hazards

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Insect Control

Microcrustaceans

• Live on algae

• Large orange or red cloud-Large orange or red cloud-like patterns

• Can be valuable part of

©www.2.bp.blogspot.com

• Can be valuable part of treatment process

• Cause a temporary drop in • Cause a temporary drop in

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Insect Control

CAUTION: Pesticides should only be applied

b li d li t

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Levee and Dikes

• Levee tops should be d

crowned

• Erosion caused by y

wave action or surface runoff can be a serious

i t i

©www.2.bp.blogspot.com maintenance issue

• Can result in a

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Levee and Dikes

Slope Stabilization

• Stone rip rap

• Broken concrete rubble

©www.2.bp.blogspot.com

Broken concrete rubble

• Geotextile

• Low growing spreading grass

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Levee and Dikes

Regular Maintenance

• Mow grass

• Do not allow large grazing i l t t l

animals to control vegetation

• Remove plants with longRemove plants with long roots

• Remove burrowing

Quack!

g animals

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Grit Chamber

PRELIMINARY TREATMENT

Bar screen Grit Chamber To remove debris and grit

a sc ee G t C a be Velocity slows, Coarse grit settles

Grit removal To landfill

Raw sewage

Debris removal

• Grit can be removed by mechanical or © www.apesnature.homestead.com

manual methods

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Operating Strategy

1. Maintain constant water level in ponds

2. Distribute Influent equally to ponds

3. Keep Pond Levees or Dikes in good condition

4. Observe, monitor and test pondsp

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What are three probable p

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Troubleshooting

Possible causes for poor quality effluent 1 E i t f il

1. Equipment failure 2. Organic overload 3. Excessive turbidity 4. Blockage of sunlight 5. Low temperature

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Sampling and Analysis

• Sample per facility

di h it

discharge permit requirements

• Samples must be

representative of the t b i t t d

water being tested

• Two sample typesp yp

- Grab

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Frequency and Location

• Frequency varies

f d t d

from pond to pond

• Test results will

vary by time of day

• Always collected • Always collected

from the same

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Sampling Summary

Frequency and Location of Lab Samples

Test Frequencyq y Location Common Rangeg

pH Weekly Pond 7.5+

Dissolved Oxygen

(DO) Weekly

Pond 4-12 mg/L Effluent 4 12 mg/L

(DO) _Effluent _{4-12 mg/L}

Temperature Weekly Pond

BOD Weekly Influent 100-300 mg/L BOD Weekly

Effluent 20-50 mg/L Coliform-Group

Bacteria Weekly Effluent

MPN>24,000/100 mg/L g (unchlorinated)( )

Chlorine Residual Daily Effluent 0.5-2.0 mg/L

Suspended Solids Weekly Influent 100-350 mg/L Suspended Solids Weekly

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Important Indicators

• Alkalinity test should

b f d

• pH, DO and

t t i di t be performed every day

- Sudden changes

temperature indicators of pond conditions

- Sudden changes

in alkalinity may indicate a problem

i d l i

• BOD, coliform, and solids measure the

efficiency of the pond _{is developing} efficiency of the pond

in treating wastes.

• BOD is used to

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Expected Pond Efficiencies

Expected Ranges of Removal by Ponds

Test Detention Time Expected Removal

BOD 50% to 90%

BOD (fac ltati e BOD (facultative

pond) 50 to 60 days 70% to 80% Coliform bacteria

(facultative pond) 50 to 60 days 90% to 95%

Suspended Solids After 3 days 90%

Dissolved Organic

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Safety

An operator should always be accompanied by a helper when p y p

performing any task that is

dangerous since pond locations are ll i l t d I di t id

usually isolated. Immediate aid might be needed to prevent serious

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Catwalks and Headworks

• Catwalks should

h d il

have guardrails and non skid

surfaces surfaces

• Headworks and enclosed

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Debris Removal

• Never stand in a boat or lean over • Be careful when

removing debris boat or lean over too far to one side

f removing debris

from channels

• Always wear a life

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Electrical

• Always turn off, tag d l k t l t i • Exercise caution

h tti d and lock out electric current when

repairing equipment when cutting weeds

or removing

vegetation near repairing equipment vegetation near

electrical wires

B f l t i l

• Beware of electrical wires in damp areas

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Infections and Disease

• Injuries involving punctures or severe • Two bacteria

Clostridia tetani punctures or severe

tissue damage

immediate medical

- Clostridia tetani

- Clostridia gangrene

attention must be given

• Apply first aid to all cuts and scrapes

• Always wash after maintenance

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Other

• Fences should

d th d

surround the ponds

• Should be placed p not to interfere with mechanical of

l l

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What Have We Learned?

O+M issues with lagoons

• Scum control

• Odor controlOdor control

• Weed and insect control

• Levee/Dike maintenance