How to Waste Stabilization Ponds Work?
Blackwater, greywater, or feces are treated naturally in Waste Stabilization Ponds (WSPs), which are sizable man-made bodies of water. These processes depend on the sun's rays, the wind's movement, microbes, and algae. Users can use the ponds separately or connect them in a series for better treatment.
Three different types of waste stabilization ponds exist:
(2) Facultative, and
(3) Aerobic (maturation), each with distinct design and treatment features.
For O&G and BOD, WSPs are inexpensive, and pathogen elimination is effective. Along with this, let’s understand about the components of waste stabilization ponds, and their working principle.
Anaerobic Treatment Ponds (APs)
Anaerobic ponds' primary purpose is to remove BOD, which can be done by reducing it by 40 to 85%. The anaerobic pond performs the following functions as a whole:
• Consolidate non-biodegradable solids and undigested material as bottom sludge.
• Break down biodegradable organic material.
· Break down dissolved organic matter.
The same principles that regulate BOD elimination in other anaerobic reactors also apply to anaerobic ponds, which either lack algae entirely or only occasionally.
Treatment in anaerobic ponds
Anaerobic digestion takes place in the resultant sludge layer, after the sedimentation of settable solids, just like in septic tanks. Biogas is created during anaerobic digestion, and might be captured by enclosing the anaerobic pond with a floating plastic membrane. If enough biogas can be gathered, the recovered biogas can be used for energy production, cooking, and heating.
Facultative Treatment Ponds (FPs)
Facultative Ponds are the most basic WSPs, consisting of a deep aerobic zone and a deeper, anaerobic zone. At temperatures above 20°C, they can treat water with a BOD range of 100 to 400 kg/ha/day, or 10 to 40 g/m2/day. They are intended for the removal of BOD.
Treatment in facultative ponds
In aerobic ponds, algal oxygen production takes place up to the depth where light can reach (i.e. typically up to 500 mm). The vertical mixing of the water allows for the introduction of more oxygen via the wind.If the pond is too deep, the colour is too dark to allow light to fully penetrate.
Also, if the BOD and COD in the lower layer are higher than the supply, oxygen cannot be maintained in the bottom layers. There is a diurnal change in the concentration of dissolved oxygen, because of the photosynthetic activities of the pond algae.
Due to algal activity, the pond will be primarily aerobic during the height of solar radiation, whereas at sunrise, it will be mostly anaerobic.
The facultative pond serves:
- Sedimentation and aerobic organic material oxidation, which can be used to further treat wastewater.
- Decrease odour.
- If pH rises, reduce some disease-causing bacteria.
- Keep leftovers as bottom sludge.
Maturation Ponds (MPs)
Anaerobic and facultative ponds are made to remove BOD, whereas maturation or polishing ponds are primarily made to remove pathogens, and hold onto suspended stabilized solids. Maturation pond is efficient at eliminating the bulk of nitrogen and phosphorus from the effluent, when combined with algae, or fish harvesting.
Working principle of waste stabilization ponds
Solids and organic materials that can settle to the bottom create sludge in the first pond, which is anaerobically digested by microorganisms.
In a second pond (facultative pond), algae on the surface oxygenate the water, causing the organic contaminants to be digested anaerobically, and then burned aerobically. The pH increases because of the algal activity, rendering some diseases inactive, and causing ammonia to volatilize.
The final ponds are used for the storage of stabilized solids, and the inactivation of pathogenic microorganisms, through solar disinfections and heating pH levels.
The effluent from the anaerobic pond is transported to the facultative pond in a series of WSPs, where further BOD is eliminated. Natural diffusion, wind mixing, and algae-driven photosynthesis, all contribute to the top layer of the pond's oxygen supply. The lowest layer loses oxygen and develops anoxia or anaerobic conditions. Solids settle out, collect, and digest on the pond's bottom. Together, the aerobic and anaerobic organisms can reduce BOD by up to 75%.
Choose the best wastewater treatment manufacturer for your industry
Netsol Water is a well-known wastewater treatment plant producer in India, offering a wide range of services, including WTP manufacturing, WWTP manufacturing, STP manufacturing, ETP manufacturing, and much more. In the best suitable treatment, we provide waste stabilization ponds, which consist of facultative, maturation, or anaerobic ponds, at affordable prices.