Secondary treatment is a treatment process for wastewater (or sewage) to achieve a certain degree of effluent quality by using a sewage treatment plant with physical phase separation to remove settleable solids and a biological process to remove dissolved and suspended organic compounds.
Full Answer
What are the main steps in sewage treatment?
What is the first step in sewage treatment?
- Step 1: Screening and Pumping. The incoming wastewater passes through screening equipment where objects such as rags, wood fragments, plastics, and grease are removed.
- Step 2: Grit Removal.
- Step 3: Primary Settling.
- Step 4: Aeration / Activated Sludge.
- Step 5: Secondary Settling.
- Step 8: Oxygen Uptake.
- Sludge Treatment.
What are the primary stages of sewage treatment?
There are four major processes under the tertiary treatment:
- Solids removal
- Biological nitrogen removal
- Biological phosphorus removal
- Disinfection.
How expensive is sewage treatment?
Dolgeville’s wastewater treatment plant’s digester needs an emergency cleaning, and the project will be an expensive one. Village officials estimate the total cost could run to $200,000 or more. “It must be done. We have no other choice but to bond for it,” said Dolgeville Mayor Mary Puznowski.
What are the three stages of wastewater treatment?
What are the main treatment steps in a water treatment plant to treat river water?
- Coagulation.
- Coagulation-Flocculation.
- Flocculation.
Why is secondary wastewater treatment important?
Secondary treatment removes the soluble organic matter that escapes primary treatment. It also removes more of the suspended solids. Removal is usually accomplished by biological processes in which microbes consume the organic impurities as food, converting them into carbon dioxide, water, and energy…
What is the primary purpose of secondary treatment?
The purpose of secondary treatment is to remove the suspended solids that did not settle out in the primary tanks and the dissolved BOD that is unaffected by physical treatment. It is called biological treatment because it involves the use of microbes.
What is the purpose of secondary treatment and why it is called biological treatment?
Secondary treatment removes the dissolved organic matter by the use of biological agents and hence, known as biological treatment. This is achieved by microbes which can consume and degrade the organic matter converting it to carbon dioxide, water, and energy for their own growth and reproduction.
What does secondary wastewater treatment target?
Secondary Treatment In these basins, the wastewater is mixed with the “activated sludge;” hundreds of millions of actively growing single-celled microorganisms (mostly bacteria and protozoa) referred to as “bugs.”
How does secondary treatment of sewage reduce BOD?
During secondary treatment of primary effluents, vigorous growth of useful aerobic microbes into flocs occur when it is agitated mechanically and air is pumped into it in a large aeration tank. These microbes while growing consume major part of the organic matter in the effluent. This significantly reduces BOD.
What is the difference between primary and secondary sewage treatment?
Primary sewage treatment is a physical process that removes large impurities while secondary sewage treatment is a biological process that removes organic matter of sewage through the action of microbes.
Why is secondary treatment of water in sewage plant called biological treatment?
Secondary treatment of wastewater works on a deeper level than primary level. It is called as biological treatment because it is designed to substantially degrade the biological content of the waste through aerobic biological processes. This step removes the dissolved organic matter by the use of biological agents.
What is true about secondary treatment in STP?
Secondary sewage treatment is mainly a biological process. In secondary treatment primary effluent is passed into large aeration tanks, where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of useful aerobic microbes into floes.
What steps are taken during secondary treatment of waste water?
Secondary Wastewater Treatment TREATMENTActivated Sludge Process (ASP) / Extended Aeration System (EAS)Sequential Batch Reactor (SBR)Moving Bed Bio Film Reactor (MBBR)Membrane Bioreactor (MBR)
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 waste?
Secondary waste is waste generated from different sources and of different nature, i.e. waste generated in a process that is known as a waste treatment operation; it includes residual materials originating from recovery and disposal operations, such as incineration and composting residues.
What is the purpose of sewage treatment?
The purpose of the sewage treatment is to remove the solids present in the sewage. ROLE OF MICROORGANISMS. Microorganisms are unicellular microscopic living things. They multiply by binary division of cells within 10 to 20 minutes. They require oxygen for their respiration.
What is secondary treatment?
The secondary treatment is designed to remove soluble organics from the wastewater. Secondary treatment consists of a biological process and secondary settling is designed to substantially degrade the biological content of the sewage such as are derived from human waste, food waste, soaps and detergent.
What is activated sludge?
The activated sludge process (ASP) is an aerobic biological wastewater treatment process that uses microorganisms, including bacteria, fungi, and protozoa, to speed up decomposition of organic matter requiring oxygen for treatment.
What is the only thing to be provided for the respiration of aerobic organisms?
The organic solids present in the wastewater serve as food for the aerobic microorganisms. The only thing to be provided is the DO , which is essential for the respiration of the aerobic organisms.
What are the end products of anaerobic and aerobic processes?
Under aerobic conditions, if completely oxidized, organic matter is transformed into non-hazardous products. But an anaerobic process can produce methane (CH 4 ), which is explosive, and ammonia (NH 3) and hydrogen sulfide (H 2 S), which are toxic.
What are the two types of biological processes?
TYPES OF BIOLOGICAL PROCESSES. There are two types of biological treatment process; aerobic and anaerobic. Aerobic process means that oxygen is present for the microbes for respiration. Anaerobic process means that the process proceeds in the absence of DO.
What do aerobic bacteria use for respiration?
Aerobic bacteria use dissolved oxygen (DO) from the water bodies for their respiration. They oxidize organic matter under aerobic conditions. The end products of the decomposition are water, CO 2 and Cell tissues. Anaerobic bacteria use oxygen derived from chemical substances for their respiration.