Lagoons System OM.pdf

  

Lagoon System

O ti d M i t Operation and Maintenance

Water & Wastewater Utility Operation and

Wastewater Lagoon Recap

  Pond or basin designed to receive wastes with no i t ith prior treatment _{© www.lagoonsonline.com} Pond Types

  Aerobic Ponds or • Aerated Ponds Anaerobic Ponds • Facultative Ponds Facultative Ponds •

  Treatment Process

  Page 12 schematic Page 12 schematic •• here here

Advantages - Disadvantages

• Does not require May produce odors

  expensive equipment p q p

• May have algae • May have algae

  effluent discharges

• Relatively simple

  operation p Treats wastes Treats wastes • inconsistently

• Few short-term

  sludge Dependent upon • sludge Dependent upon handling/disposal weather conditions problems

• Limited process ted p ocess

  control Low O&M costs when • properly maintained

  Slow to recover •

Presentation Outline

  1. Operation and Maintenance

• Scum Control • Odor Control • Weed and Insect Control • Levee/Dike Maintenance • Headworks and Screening H d k d S i

  2. Sampling and Analysis

  2. Sampling and Analysis

  3. Safety

  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

Scum Control

  Facultative and Aerated Ponds A t d P d

  Common occurrence • Usually occurs in • _{© http:// web.deu.tr} spring g Wind will break up •

  Anaerobic ponds scum are covered with a

  If not broken up it will • dense scum blanket to dry on top and dry on top and keep pond anaerobic keep pond anaerobic

  ortant? p is scum im

Why Is Scum Important?

• Difficult to break up when

  t d encrusted

• Blue-green algae can form
>Cuts off sunlight
• Source of botulism • Source of botulism

  © www.pollutionsolutions-online.com

  

How Is Scum Removed?

• Scum can be easily broken

  if it i dd d l up if it is addressed early

• Shoreline agitation
>Jets of water
• Outboard motors • Outboard motors

  © www.gadgetgrid.com

Odor Control

  Typical Causes

  Overloading • Short circuiting Short circuiting •

• All ponds have odor Weather • issues at some point p
• Poor Housekeeping • Poor Housekeeping includ
• Can lead to more

  Poor circulation Poor circulation - problems problems

  Algae overgrowth - Industrial Wastes - Industrial Wastes

How to Reduce Odors O perations

• Parallel • Series

  A eration R ecirculation E limination

• Septage Dumping • Industrial Waste

  C hemical Addition

  O perations POND IN SERIES – TO REDUCE SHORT CIRCUITING

POND IN PARALLEL TO REDUCE OVERLOADING POND IN PARALLEL – TO REDUCE OVERLOADING

A eration

• Floating Aerators • Diffusers • Outboard motor Outboard motor _{© http://isma.pagesperso-orange.fr/en_pure-solutions.html}

R ecirculation

  1 to 6 ratio of recycled flow to influent flows fl t i fl t fl Recirculation rules:

• Recirculation flow rate m st not ca se rate must not cause overflow
• Water should be W t h ld b drawn from pond _{© http://www.waikatodistrict.govt.nz}

  surface surface

  aste Septage Dumping Industrial W

• • •

  limination _g E _Dumpin age_

• Chlorine
• Hydrogen Peroxide
• Potassium permanganatepermanganate
• Sodium nitrate

C hemical Addition

Weed and Insect Control

  Essential part of • Three areas of •

  O&M O&M concern

• 1. Emergent Weeds g

  Weeds around the edge provide a

  2. Suspended

  sheltered area for

  Vegetation Vegetation

  mosquitoes and scum accumulation

  3. Dike Vegetation

  Weeds hinder • circulation

Emergent Weed Control

  1. Pond level above three feet three feet

  2. Remove new (first- _{© www.michigan.gov/images/Septage_Dumpin g} year) growth by hand ear) gro th b hand

  3. Drown the weeds

  4. Cut and Drown

  5 Ri

  5. Riprap

  6. Pond Liner

  Emergent Weeds Tules Bulrush Cattails Pickerelweed

  ended p vegetation? ou control sus yp y

Suspended Vegetation Control

  1. Keep the pond exposed to wind exposed to wind

  2. Skim with rakes or boards

  Duckweed ^{© www.michigan.gov/images/Septage_Dumpin g}

  boards

  3. Mechanically harvest

  4. Reduce nitrogen of phosphorous sources p p

  5. Ducks

Dike Vegetation Control

  Why does it need to be t ll d? controlled?

• Food source and habitat
• Weakens dike _{© www.hbrc.govt.nz}

  © for wildlife

• Unsightly appearance T ll t ti
• Seed with grass
• Mow regularly

  Maintenance

  Seed with grass

• Tall vegetation can reduce wind action

Insect Control

  © http://inc.mcbryde.com

  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 p

Insect Control

  © www.flickr.com

  Chironomid midges

• Often produced in wastewater ponds
>Can be a nuisance to nearby activities and create traffic hazards
• Only control is through insecticides

Insect Control

  Microcrustaceans

• Live on algae
• Large orange or red cloud- Large orange or red cloud- like patterns
• Can be valuable part of • Can be valuable part of _{© www.2.bp.blogspot.com}

  treatment process

• Cause a temporary drop in • Cause a temporary drop in DO and pH

  Insect Control

  CAUTION: Pesticides should only be applied by a licensed applicator. b li d li t

Levee and Dikes

  Levee tops should be • crowned d Erosion caused by y • wave action or surface _{© www.2.bp.blogspot.com} runoff can be a serious maintenance issue i t i

  Can result in a • narrowing of the levee crown and limit access

Levee and Dikes

  Slope Stabilization

• Stone rip rap
• Broken concrete rubble Broken concrete rubble _{© www.2.bp.blogspot.com}
• Geotextile • Low growing spreading grass

Levee and Dikes

  Regular Maintenance

• Mow grass
• Do not allow large grazing i l t t l animals to control vegetation
• Remove plants with long Remove plants with long roots
• Remove burrowing

  Quack! g animals

• If seepage or leakage

Grit Chamber PRELIMINARY TREATMENT

  Bar screen a sc ee G t C a be Grit Chamber To remove debris and grit Velocity slows, Coarse grit settles

  Raw sewage Grit removal Debris removal _{© www.apesnature.homestead.com} To landfill

  Grit can be removed by mechanical or • manual methods All Disposal methods for screenings and All Disposal methods for screenings and •

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 ponds p

  5. Use baffles to increase pond efficiency

  6. Troubleshooting g

  What are three probable p causes of poor quality effluent in a wastewater lagoon?

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

  6. Toxic material in influent

  7. Loss of pond volume

Sampling and Analysis

• Sample per facility

  discharge permit di h it requirements Samples must be • _{© www bae ncsu edu © www.bae.ncsu.edu} representative of the water being tested t b i t t d Two sample types p yp •

• Grab - Composite p

Frequency and Location

  Frequency varies • from pond to pond f d t d Test results will • vary by time of day Always collected • Always collected • from the same location _{© www.irf info.com © www irf-info com}

Sampling Summary

  

Frequency and Location of Lab Samples

Test Frequency q y Location Common Range g

_{pH Weekly Pond 7.5+}

_{Dissolved Oxygen (DO) (DO) Weekly Effluent Effluent 4-12 mg/L 4 12 mg/L} Pond 4-12 mg/L

  Temperature Weekly Pond _{BOD BOD Weekly Weekly Influent 100-300 mg/L Coliform-Group}

_{Weekly Effluent}

Effluent 20-50 mg/L _{MPN>24,000/100 Chlorine Residual Daily Effluent 0.5-2.0 mg/L Bacteria mg/L g} ( (unchlorinated) ) _{Suspended Solids Suspended Solids Weekly Weekly} Influent 100-350 mg/L

Important Indicators

• pH, DO and Alkalinity test should

  t temperature indicators t i di t b be performed every f d of pond conditions day

• Sudden changes - Sudden changes
• BOD, coliform, and

  in alkalinity may solids measure the indicate a problem efficiency of the pond efficiency of the pond i d is developing l i in treating wastes.

  BOD is used to • BOD is used to • calculate loading on the pond p

  Expected Pond Efficiencies Expected Ranges of Removal by Ponds _BOD Test Detention Time Expected Removal _{50% to 90% Coliform bacteria} BOD (facultative BOD (fac ltati e _{pond) 50 to 60 days 70% to 80% (facultative pond)} 50 to 60 days 90% to 95% _{Dissolved Organic} Suspended Solids After 3 days 90% _Solids After 10 days 80%

  Safety

  An operator should always be accompanied by a helper when p y p performing any task that is dangerous since pond locations are usually isolated. Immediate aid ll i l t d I di t id might be needed to prevent serious injury of loss of life. injury of loss of life

Catwalks and Headworks

  Catwalks should • have guardrails h d il and non skid surfaces surfaces Headworks and • enclosed equipment should be well ventilated be well ventilated

Debris Removal

• Never stand in a
• Be careful when

  boat or lean over

  removing debris boat or lean over too far to one side f removing debris from channels

• Always wear a life
• Do not lift too

  jacket when in a boat

  much boat

• Make sure of

  secure footing

Electrical

• Exercise caution •

  Always turn off, tag when cutting weeds h tti d and lock out electric d l k t l t i or removing current when vegetation near vegetation near repairing equipment repairing equipment electrical wires

• B Beware of electrical f l t i l

  wires in damp areas Be careful when • spraying weeds

Infections and Disease

• Two bacteria
• Injuries involving

  punctures or severe

• Clostridia tetani
• Clostridia gangrene

  Clostridia tetani

  punctures or severe tissue damage immediate medical

• Apply first aid to all

  attention must be given

  cuts and scrapes

• Always wash after

  maintenance practices

Other

  Fences should • surround the ponds d th d Should be placed p • not to interfere with mechanical of manual slope l l maintenance

What Have We Learned?

  O+M issues with lagoons