Oxidation Ponds

What are Oxidation Ponds ?

Oxidation Pond is an open, flow through earthen basin of controlled shape specially design and constructed to treat sewage and bio-degradable industrial waste by natural processes involving bacteria and in many instances algae.

Types Of Oxidation ponds

Aerobic PondsAnaerobic PondsFacultative PondsMaturation or Tertiary Ponds

ApplicationsType of PondsType of Ponds ApplicationsApplications

AerobicAerobic Nutrient removal, treatment of soluble Nutrient removal, treatment of soluble organic waste & effluents from waste water organic waste & effluents from waste water treatment plants.treatment plants.

Anaerobic Anaerobic Treatment of domestic and industrial wastes.Treatment of domestic and industrial wastes.

Facultative Facultative Treatment of untreated screened waste water Treatment of untreated screened waste water and industrial wastes.and industrial wastes.

New Algae

Algae

O2

Bacteria

CO2, NH3, H2O

New Bacteria

Organic Bacteria

Solar Energy

Symbiosis

Aerobic PondsThe aerobic pond is shallow pond in which light penetrates to the bottom there by maintaining active algal photosynthesis through out the entire system.

ALGAE

AEROBIC BACTERIA

Light Energy from Sun

New Algal Biomass

New Bacterial Biomass

Organics from Waste Water

Diurnal Variations in Aerobic Ponds

Diurnal variation in DO concentrationDiurnal variation in pH

Extreme values of these, in either direction may be detrimental to microbial activity.

Design ConsiderationsParameterParameter ValueValue

Depth in mts.Depth in mts. 0.15-.5 0.15-.5

Retention time (day)Retention time (day) 2-62-6

BODBODu u loading( lb/acre-day)loading( lb/acre-day) 100-200100-200

BODBODuu removal(%) removal(%) 80-9080-90

Algae concentration(mg/l)Algae concentration(mg/l) 100-200100-200

Re-circulation ratioRe-circulation ratio 0.2-2.00.2-2.0

Effluent suspended solids Effluent suspended solids concentration(mg/l)concentration(mg/l)

150-350150-350

ProblemsNuisance vegetationInhibitory temperaturesOxygen retentionShock loads

Anaerobic PondsThese ponds requires no D.O. for microbial activity as the organisms use O2 from compounds such as NO3, SO4 as their hydrogen acceptors and give end product such as methane, carbon dioxide etc.

Anaerobic decompositionIt take place in two separate but inter related

steps :-1.Decomposition of dissolved organic waste by

acid producing bacteria to organic acids (such as acetic propionic acid) and,

2.Further decomposition of these acids to the end products of methane, carbon dioxide and water by methane producing bacteria.

Acid producing Bacteria

Methane producing bacteria

H2O, CO2, CH4

Organic Wastes

H2O, CO2

Bacterial Cells

Bacterial Cells

Facultative PondsThese are neither fully aerobic nor fully anaerobic. They are often about 1 to 2 m in depth and favor algal growth along with the growth of aerobic, anaerobic and facultative microorganisms. Such ponds are predominantly aerobic during day light as well as for some hours of the light. In the few remaining hours the pond bottom may turn anaerobic.

Zones of facultative pond

1) Aerobic zone 2) Anaerobic zone 3) Facultative zone

The decomposition of incoming organic waste and products of anaerobic decomposition is done by facultative bacteria.

Wind

CO2

An

aero

bic

Zon

eA

erob

ic

Zon

e

An

aero

bic

Zon

e

Fac

ulta

tive

Z

one

O2

algae

(CO2, NO2, PO4, SO4)

Aerobic Bacteria

Biomass

Biomass

Anaerobic Bacteria

Sludge Blanket

Organic acids & Compounds of C, N, P, S

Impermeable lining

Sunlight

Maturation / Tertiary Ponds

These are similar to aerobic ponds but are very lightly loaded with organic wastes. Generally used for upgrading effluents from conventional secondary treatment processes.

Reasons For Poor Performance of Oxidation Pond

DO level in the pond during night & early morning hours was almost zero.

BOD removal efficiency was only 50-58%BOD loading rate was 91.20 kg/day as compared

to the design BOD of 81kg/day.

LAGOONSLAGOONS Lagoons are deep waste stabilization ponds

-like bodies of water or basins designed to receive, hold, and treat wastewater for a predetermined period of time by artificial means of aeration.

In the lagoon, wastewater is treated through a combination of physical, biological, and chemical processes.

TYPES OF LAGOONSTYPES OF LAGOONSAccording to the microbial activity in the aerated lagoons-

Aerobic aerated lagoons.Facultative aerated lagoons.

AEROBIC AERATED LAGOONSAEROBIC AERATED LAGOONSDissolved oxygen is present throughout much

of the depth of aerobic lagoons. They tend to be much shallower than other

lagoons.They are better suited for warm, sunny

climates, where they are less likely to freeze. HRT = 2 to 10 daysSS concentration between 60 to 300mg/lThe BOD removal is of order of 75 to 85%Oxygenation requirement is of order of .7 to

1.3 kg per kg of BOD removed.

Units of aerobic lagoon

1) The mechanical surface aerators so that solids do not settle to bottom of tank.

2) The other unit is settling tank for removal of suspended solids .

FACULTATIVE AERATED LAGOONSFACULTATIVE AERATED LAGOONSThree types of zones are present

Aerobic Zone.Anaerobic Zone.Facultative Zone.

HRT is higher than aerobic lagoons because time requires for the solids to settle and for many pathogens viruses to either die off or

settle out.

Facultative lagoonsSS concentration is ranging from 30 to 150

mg/l

Detentions time ranges from 3 to 5 days .

BOD removal are of order 75 to 90%

Oxygenation requirement is about .8 kg per kg of BODs

Two, Three, or Four Lagoons Are Better Than OneTwo, Three, or Four Lagoons Are Better Than OneEach lagoon cell has a different function to

perform, and a different kind of lagoon design may be used for each cell.

In SeriesIn SeriesWhen lagoons operate in When lagoons operate in series, more of the solid series, more of the solid material in the wastewater, material in the wastewater, such as algae, has an such as algae, has an opportunity to settle out opportunity to settle out before the effluent is before the effluent is disposed of.disposed of.

In ParallelIn ParallelThis system design is This system design is particularly useful in particularly useful in cold climates or where cold climates or where lagoons are covered lagoons are covered with ice for parts of the with ice for parts of the yearyear

Operation And MaintenanceOperation And MaintenanceFor Aerobic Lagoons

Any earthen structures used as impoundments must be periodically inspected. If left unchecked, rodent damage can cause severe weakening of lagoon embankments.

In submerged diffused aeration, the routine application of HCl gas in the system is used to dissolve accumulated material on the diffuser units

The use of submerged perforated tubing for diffused aeration requires maintenance and cleaning on a routine basis to maintain design aeration rates

Operation And MaintenanceFor Facultative Lagoons

Most facultative lagoons are designed to operate by gravity flow. The system is not maintenance intensive and power costs are minimal because pumps and other electrically operated devices may not be required.

Earthen structures used as impoundments must be inspected for rodent damage.

ApplicabilityApplicabilityType of LagoonType of Lagoon ApplicationApplication

Aerobic LagoonAerobic Lagoon Municipal and industrial wastewaters of Municipal and industrial wastewaters of low to medium strength.low to medium strength.

Facultative LagoonFacultative Lagoon Treated raw, screened, or primary settled Treated raw, screened, or primary settled municipal wastewater and biodegradable municipal wastewater and biodegradable industrial wastewaters.industrial wastewaters.

LimitationsFor Aerated Lagoons

Aerated lagoons may experience ice formation on the water surface during cold weather periods

Reduced rates of biological activity also occur during cold weatherFormation of ice on Floating Aerators.

For facultative LagoonsThe inability of the process to meet a 30 mg/L limit for TSS

due to the presence of algae in the effluent.

Odors may be a problem in the spring and fall during periods of excessive algal blooms and unfavorable weather conditions

References:-1.

www.oilgae.com/ref/glos/oxidation_ponds.html

2. www.microbiologyprocedure.com3. www.eco-web.com/cat/2.5.html4. www.eco-web.com/cat/2.5.html5.www.mazzei.net/applications/wastewater/

odor.htm6.www.brighthub.com/engineering/civil/

articles/50611.aspx