Oxidation Ponds & Lagoons

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A Presentation on Oxidation Ponds & Lagoons

Oxidation PondsWhat are Oxidation Ponds ?Oxidation Ponds are large earthen basins in which waste water is treated by natural processes involving bacteria and in many instances algae.

Types Of Oxidation pondsAerobic Ponds Anaerobic Ponds Facultative Ponds Maturation or Tertiary Ponds

SymbiosisAlgaeNew Algae O2 Solar Energy CO2, NH3, PO4, H2O

Organic Bacteria Bacteria

New Bacteria

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.

Light Energy from Sun

ALGAE

New Algal Biomass

Organics from Waste Water

AEROBIC BACTERIA

New Bacterial Biomass

Diurnal Variations in Aerobic Ponds

Diurnal variation in DO concentration Diurnal variation in pH Extreme values of these, in either direction may be detrimental to microbial activity.

Design ConsiderationsParameterDepth in mts. Retention time (day)

Value0.15-.5 2-6

BODu loading( lb/acre-day)BODu removal(%) Algae concentration(mg/l) Re-circulation ratio

100-20080-90 100-200 0.2-2.0

Effluent suspended solids concentration(mg/l)

150-350

ProblemsNuisance vegetation Inhibitory temperatures Oxygen retention Shock 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.

H2O, CO2

Organic Wastes

Acid producing Bacteria

Bacterial Cells

H2O, CO2, CH4

Methane producing bacteria

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.

WindSunligh t alga e O2 Aerobic Bacteria Organic acids & Compounds of C, N, P, S Biomass Biomass Aerobic Anaerobi c Zone Anaerobi c Zone(CO2, NO2, PO4, SO4)

CO2

Facultative Zone

Anaerobic Bacteria Sludge Blanket Impermeable lining

Maturation / Tertiary PondsThese are similar to aerobic ponds but are very lightly loaded with organic wastes. Generally used for upgrading effluents from conventional secondary treatment processes. The principal purpose is to achieve reduction in fecal colliform count.

ApplicationsType of PondsAerobic

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

Anaerobic

Treatment of domestic and industrial wastes.

Facultative

Treatment of untreated screened waste water and industrial wastes.

Hamirpur REC Campus

Outlet of pond Oxidation pond

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. Black effluent was found exerting very high BOD values of 80-110mg/l.

LAGOONS

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 LAGOONSAccording to the microbial activity in the aerated lagoonsAerobic aerated lagoons. Facultative aerated lagoons.

AEROBIC AERATED LAGOONS

Dissolved 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 3 days.

FACULTATIVE AERATED LAGOONS

Three 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.

Two, Three, or Four Lagoons Are Better Than One

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

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

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

Factors to consider for transfer of the oxygen

Alpha factor. Beta factor. Theta factor. Atmospheric pressure.

Misleading Parameters

The first myth is that effluent BOD5 measures the biodegradable carbonaceous material in the effluent The second myth is that the effluent BOD5, or CBOD5, is the residual of the BOD5 in the influent to the lagoon.

Operation And MaintenanceFor Aerobic LagoonsAny 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 LagoonsMost 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.

ApplicabilityType of LagoonAerobic Lagoon

ApplicationMunicipal and industrial wastewaters of low to medium strength.

Facultative Lagoon

Treated raw, screened, or primary settled municipal wastewater and biodegradable 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 weather Formation of ice on Floating Aerators. For facultative Lagoons The 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

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