Stabilization Pond System

Stablisation pond system is an efficient way to treat the wastewater. It utilizes the combination of sedimentation and biological treatment using extensive detention time. These ponds are infact are large shallow excavation, in which sewage from various sewer systems drain into. The sewage in the pond uses biological process to destroy various disease-causing organisms. The effluent is discharged as treated sewage. However the pond requires regular maintenance to avoid foul odors. Operation and maintenance requires following thing:

• Start up the pond
• Manage the pond surface conditions
• Maintain the embankment
• Maintain the pond site
• After few years drain out the pond and remove the sludge.

Waste Stabilization Ponds (WSP), are also known by the name of oxidation ponds or lagoons. They act as holding basins for secondary wastewater treatment, Here organic matter is decomposed naturally, i.e. biologically. In WSP waste is stabilized and pathogens reduced through the action of bacteria and algae. The process aims to convert organic content of the effluent to more stable forms. These ponds are useful in treating variety of wastewater, from domestics wastewater to complex industrial waters. They can function well in wide range of weather conditions and can be used either alone or integrated with other treatment processes.

Due to their efficiency, cost effectiveness and the availability of land this system is very popular in developing countries. The table below will high light the advantages of the system vis a vis other water treatment system.



Categorization Of Stablisation Pond
Stablisation or stabilization pond can be categorized as follows:

Aerobic Ponds
An aerobic pond throughout its entire depth has varying concentration of oxygen.

Anaerobic Pond
Anaerobic pond is devoid of any oxygen except in the top at the air liquid interface. These units are the smallest of the series. These organic load produces strict anaerobic conditions (no dissolved oxygen) throughout the pond. These pond infact functions like open septic tanks and work efficiently in warm climates. Anaerobic pond if designed properly can remove 60% BOD5. The organic matter from the anaerobic pond can be removed in the same fashion as it is removed from any anaerobic reactor.


Facultative Pond
Facultative pond is a combination of both aerobic and anaerobic pond. That is, in its top zone it is aerobic whereas it is anaerobic at its lower zone. Most of the stabilization pond constructed fall into the category of Facultative pond. Facultative ponds are of two types-primary facultative ponds and the secondary Facultative ponds. The primary facultative ponds is one that receives raw wastewater whereas the secondary Facultative pond is one that receives the settled wastewater from the first stage. These ponds reduce BOD that helps in the production of algae that will further generate the oxygen needed to remove soluble BOD5. The population of algae in any optimally performing facultative pond rest on organic load and temperature.

The amount of oxygen present in the pond depends upon the following factors:

• Temperature
• Organic loading
• Sunlight

Maturation ponds
Maturation pond are the ponds that receives effluent from a facultative pond. They are shallow, with less vertical stratification and are well oxygenated. The algae population of the maturation pond is much more diverse than that of facultative ponds. This clearly shows that the diversity of algae increases from pond to pond along the series. It is the Algae that cause the removal of pathogens and faecal coliforms. Though these ponds reduce small amount of BOD5 but they play significant role in phosphorus and nitrogen removal.

Operation and maintenance
After the completion of the construction of the project it should be ensured that all ponds are free of vegetation. This is essential if the stabilization pond is not waterproof. In order to avoid foul odour release, facultative ponds should be filled before anaerobic pond is filled. Biosolids from another anaerobic reactor should be used to seed the anaerobic pond. Moreover, raw wastewater from the maturation pond should be utilized to fill the anaerobic pond.

Freshwater from a river, lake or well should be used for filling facultative and maturation ponds for developing algal and heterotrophic bacterial population. In case of the absence of the fresh water, facultative ponds should be filled with raw wastewater for few weeks in order to allow the microbial populations to develop. A small amount of odour release is inevitable during the implementation of the latter method in the facultative pond.

What Is Advanced Integrated Pond System?
Advanced integrated pond system consists of series of low-cost ponds or earthwork reactors. Normally advanced integrated pond system (AIWPS) of four pond in series

• Facultative pond including fermentations pits.
• Pond with high rate of algal.
• Algal settling ponds.
• Maturation Pond.

These system produce maximum oxygen and reduces the accumulation of sludge. This is achieved through algal photosynthesis. AIWPS is cost effective and require less maintenance and perform well in terms of BOD5 and solids removal.