What Is Aerated Lagoon?

What Is Aerated Lagoon?

What Is Aerated Lagoon?

An aerated lagoon is a waste water treatment process that uses a large basin with mechanical aerators to maintain aerobic conditions and prevent settling of biomass.

Wastewater flows through the lagoon, retaining for a set period of time, and exits through an outlet.

The initial microbe population is lower than in an activated sludge process, resulting in a longer retention time for equivalent effluent quality, but this time can be advantageous for treating complex chemicals.

Aerated lagoons are more resilient to process disruptions due to their large size and extended retention time, but lack the settling tanks and sludge recirculation of ASPs.

The effluent may receive further treatment in a maturation pond.

How Many Types Of Aerated Lagoons Are There?

Aerated lagoons come in two types, based on how the solid microbial mass is managed: Suspended Growth and Facultative.

  • Suspended Growth Aerated Lagoon: These are shallow basins (2 to 5m) with mechanical aerators on floats or fixed platforms.

The aerators provide oxygen for biological treatment and keep the biological solids in suspension, resulting in a fully aerobic system with high solids concentration in the effluent.

The design is based on SRT, which is typically 3 to 6 days for domestic wastewater treatment.

  • Facultative Aerated Lagoon: In this type, some solids settle in the lagoon while some leave with the effluent stream. The bottom may be anaerobic and the top aerobic, hence the name “facultative”.

They are simpler to operate, require less land and machinery, and can remove 70-80% BOD from domestic sewage.

  • Mixing: Mixing is beneficial as it prevents therm stratification and growth of algae, and exhausts carbon dioxide.

What Are The Benefits Of Aerated Lagoons?

The benefits of aerated lagoons are:

  • They are straightforward to operate, with the only dynamic component being the aerator.
  • Their power efficiency for waste removal is comparable to other aerobic treatment methods.
  • Construction mainly involves excavation and land usage is minimal, needing only 5-10% of the space needed for stabilization ponds.
  • Aerated lagoons are often used for treating industrial waste.

What Are The Limitations Of Aerated Lagoons?

Aerated lagoons may have ice formation and reduced biological activity during cold weather, but if designed properly, they can still function and produce acceptable waste output.

Using floating aerators in cold climates may require the use of submerged diffused aeration. This type of aeration requires regular maintenance and cleaning to maintain aeration rates.

There are different types of submerged aeration equipment that can be used in warm or cold weather and should be considered in design.

HCl gas is used to dissolve accumulated material on the diffuser units in submerged diffused aeration.

Earth-based impoundments must also be periodically checked to avoid rodent damage which can weaken the lagoon embankments.

Related Posts

error: Content is protected !!