What is primary and secondary water treatment?
The principal difference in primary and secondary treatment is the process that breaks down the sewage in wastewater. The initial and primary water treatment process removes large matter from wastewater while the secondary treatment will remove smaller particles already dissolved or suspended.
What is primary treatment of water?
Primary treatment of wastewater involves sedimentation of solid waste within the water. This is done after filtering out larger contaminants within the water. Wastewater is passed through several tanks and filters that separate water from contaminants.
What are primary and secondary ponds?
Facultative stabilization ponds that receive raw wastewater are called primary facultative ponds. If they are receiving wastewater that has already been treated in anaerobic ponds, they are called secondary facultative ponds. Heavy algal growth may block sunlight from penetrating into the pond.
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 is meant by secondary treatment?
Secondary treatment is the second step in most waste treatment systems during which bacteria consume the organic parts of the wastes. This is accomplished by bringing the sewage, bacteria and oxygen together in trickling filters or within an activated sludge process.
What is secondary treatment in water treatment?
Secondary treatment is the removal of biodegradable organic matter (in solution or suspension) from sewage or similar kinds of wastewater. The aim is to achieve a certain degree of effluent quality in a sewage treatment plant suitable for the intended disposal or reuse option.
What do you understand by facultative ponds?
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. In the lower zones of the pond, anaerobic digestion takes place. …
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.
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.
What does secondary water treatment do?
Secondary wastewater treatment processes use microorganisms to biologically remove contaminants from wastewater. Secondary biological processes can be aerobic or anaerobic, each process utilizing a different type of bacterial community.
What is tertiary water treatment?
Tertiary treatment is the third, and final, stage in a standard wastewater management system. Once effluent has been treated in the primary and secondary stages by removing suspended solids, pH balancing and reducing its biochemical oxygen demand (BOD), it is ready to enter the tertiary stage.
Which are the secondary treatments?
What happens to the water in a secondary facultative pond?
The concentration of algae in a healthy facultative pond depends on loading and temperature, but is usually in the range 500-2000 ug chlorophyll per litre. Effluent from the anaerobic pond enter in the secondary facultative pond is converted into carbon dioxide, water and new bacterial and algae cells in the presence of oxygen.
How are facultative lagoons used to treat wastewater?
Facultative lagoons can be used to treat raw, screened, or primary settled municipal wastewater and biodegradable industrial wastewaters. Some advantages and disadvantages of facultative lagoons are listed below: Moderately effective in removing settleable solids, BOD, pathogens, fecal coliform, and ammonia.
How is BOD removal done in a facultative pond?
BOD Removal in Facultative Fends: The activity of further anaerobic oxidation and the aerobic conversion of effluent to carbon dioxide, water and new bacterial and algae cells can result in removal 01 00% of the BOD, of the effluent flowing into the facultative pond (which means an overall removal in the order of 95% over the two ponds).
How big are facultative lagoons in the US?
The technology associated with facultative lagoons has been in widespread use in the United States for at least 90 years, with more than 7,000 facultative lagoons in operation today. These earthen lagoons are usually 1.2 to 2.4 m (4 to 8 feet) in depth and are not mechanically mixed or aerated.