What is a facultative pond?
A lagoon that forms the second treatment stage in waste stabilisation ponds (WSPs). It is a shallow pond (1 to 2m) consisting of an aerobic zone close to the surface and a deeper, anaerobic zone.
What are types of stabilization ponds?
Waste Stabilization Ponds (WSPs) are large, man-made water bodies. The ponds can be used individually, or linked in a series for improved treatment. There are three types of ponds, (1) anaerobic, (2) facultative and (3) aerobic (maturation), each with different treatment and design characteristics.
Why are most ponds facultative ponds?
The facultative microorganisms have two modes. They can function with or without oxygen. Ponds that have areas with oxygen and areas without oxygen are called facultative ponds. The facultative ponds are the most common.
What are the disadvantages of facultative ponds?
Requires relatively large areas of land. Strong odors occur when the aerobic blanket disappears and during spring and fall lagoon turnovers. Burrowing animals may be a problem. Waste stabilization pond systems are simplistic in appearance, however, the reactions are as complicated as any other treatment process.
How deep are facultative ponds?
1 to 2.5 m
Anaerobic ponds are built to a depth of 2 to 5 m and have a relatively short detention time of 1 to 7 days. Facultative ponds should be constructed to a depth of 1 to 2.5 m and have a detention time between 5 to 30 days. Aerobic ponds are usually between 0.5 to 1.5 m deep with a detention time of 15 to 20 days .
Do facultative lagoons require sludge removal?
First pond The facultative lagoon in the pond sequence functions like the primary clarifier of a conventional sewage treatment system. This facultative lagoon lacks the sludge removal capability of a primary clarifier, so a population of anaerobic organisms will colonize accumulated sludge on the bottom of the lagoon.
How many types of facultative ponds are there?
The ponds can be used individually, or linked in a series for improved treatment. There are three types of ponds, (1) anaerobic, (2) facultative and (3) aerobic (maturation), each with different treatment and design characteristics. WSPs are low-cost for O&M and BOD and pathogenremoval is high.
What are the advantage of stabilization ponds?
The advantages of stabilization ponds include limited technological investment, low cost, cheap/unskilled labour, and minimal maintenance costs (Mara, 2003; Jiménez et al., 2010). However, the main disadvantage is the limitation of land availability in urban areas (Jiménez, 2006). …
What is the percentage removal of beauty by stabilization pond?
Design Considerations
| Pond | BOD Removal | HRT |
|---|---|---|
| Anaerobic Pond | 50 to 85% | 1 to 7 days |
| Facultative Pond | 80 to 95% | 5 to 30 days |
| Maturation Pond | 60 to 80% | 15 to 20 days |
How does a facultative lagoon work?
The facultative lagoon in the pond sequence functions like the primary clarifier of a conventional sewage treatment system. Heavy solids will settle to the bottom of the lagoon, and lighter solids will float.
What happens facultative pond?
In a second pond (facultative pond), algae growing on the surface provide the water with oxygen leading to both anaerobic digestion and aerobic oxidation of the organic pollutants. Due to the algal activity, pH rises leading to inactivation of some pathogens and volatilisation of ammonia.
What is the minimum depth considered while designing an aerated lagoon?
2.5 m
What is the minimum depth considered while designing an aerated lagoon? Explanation: The minimum depth considered for an aerated lagoon is 2.5 m. This is considered as 2.5 m even for an aerated lagoon carried out facultatively. Also for aerated lagoons with solid recycling, this is considered as 2.5 m only.
How does a facultative pond stabilize during the day?
Facultative stabilization ponds stratify with an aerobic surface layer and an anaerobic layer below the surface. The aerobic surface layer limits release of malodorous gas from the anaerobic benthic zone. Algae and cyanobacteria typically grow in the aerobic zone and provide bacteria in the pond with plenty of oxygen during the daytime.
Can a facultative lagoon be replaced with an aerated pond?
The facultative lagoon may be replaced by an aerated lagoon as the first pond of the series. Aerated lagoons have mechanical aerators which minimize anaerobic zones by completely mixing the lagoon to achieve catabolism through a process called extended aeration .
What is the purpose of a waste stabilization pond?
Waste stabilization ponds (WSPs or stabilization ponds or waste stabilization lagoons) are ponds designed and built for wastewater treatment to reduce the organic content and remove pathogens from wastewater.
How are facultative lagoons used in the United States?
United States Environmental Protection Agency. Wastewater Technology Fact Sheet. Facultative Lagoons. DESCRIPTION. Facultative waste stabilization ponds, sometimes referred to as lagoons or ponds, are frequently used to treat municipal and industrial wastewater in the United States.