The secondary stage of treatment removes about 85 percent of the organic matter in sewage by making use of the bacteria in it. The principal secondary treatment techniques used in secondary treatment are the trickling filter and the activated sludge process.
Full Answer
What is secondary treatment of wastewater?
Oct 16, 2009 · 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 are the available options in the biological treatment processes of sewage?
Secondary Wastewater treatment is divided into two different treatment processes:-1. Aerobic Treatment: Aerobic wastewater treatment is a biological treatment that uses oxygen to break down organic matter and remove other pollutants like nitrogen and phosphorus. Aerobic treatment technologies are:
What materials are removed from wastewater treatment plants?
Mar 23, 2017 · There are five types of aerobic biological treatment processes used to treat municipal sewage. Tricking filters; Rotating biological contactors (filter) Activated sludge. Oxidization ponds. Aerated lagoons (used for pre treat ion industrial effluent) Trickling Filter Introduction to trickling filter system: It is the most common attached growth process.
How is wastewater treated at the Metro wastewater treatment plant?
There are two bar screens located inside the Raw Wastewater Pump Building. The trash is collected and disposed of at the landfill. The screened wastewater is then pumped to the Hydrocyclone Grit Separator where it is spun, thereby separating the inorganic solids (grit) from the lighter weight organic solids. The grit is transported to the City landfill for environmentally …
Which process is a secondary wastewater treatment process?
The secondary stage of treatment removes about 85 percent of the organic matter in sewage by making use of the bacteria in it. The principal secondary treatment techniques used in secondary treatment are the trickling filter and the activated sludge process.
What is secondary treatment of wastewater in a treatment plant?
Which of the following are examples of secondary wastewater treatment processes?
- Activated sludge.
- Trickling filter.
- Non-electric secondary filtration (FilterPod)
- Oxidation ponds.
What type of process is secondary treatment?
What steps are taken during secondary treatment of waste water Why secondary treatment is called biological treatment?
What is primary and secondary wastewater treatment?
What is secondary waste?
What is secondary wastewater treatment?
Secondary Wastewater treatment is the second stage of wastewater treatment. In primary treatment, suspended solids, colloidal particles, oil, and grease are removed. In secondary treatment, biological treatment is done on the wastewater to remove the organic matter present. This treatment is performed by indigenous and aquatic micro-organisms like ...
What is secondary treatment?
In secondary treatment, biological treatment is done on the wastewater to remove the organic matter present. This treatment is performed by indigenous and aquatic micro-organisms like bacteria and protozoa which consume biodegradable soluble contaminants like sugar, fat, detergent, and food waste. These processes are sensitive to temperature ...
Can anaerobic bacteria use oxygen?
However, anaerobic bacteria can and will use oxygen that is found in the oxides introduced into the system or they can obtain it from organic material within the wastewater. Anaerobic treatment technology is Up-flow Anaerobic Sludge Blanket Reactor (UASB)
What is MBBR in biofilm?
A Moving Bed Biofilm Reactor (MBBR) consists of an aeration tank which is similar to an activated sludge tank with special plastic carriers that provide a higher surface area where a biofilm can grow.
What is a membrane bioreactor?
Membrane Bioreactor – MBR is the combination of ultrafiltration (UF) and activated sludge process. MBR produces effluent of high quality which can be discharged to surface water for reuse. It can be retrofitted in existing installations.
What is the process of dissimilation?
The dissimilation process of breaking down the nitrate molecule to make it chemically-bound oxygen requires both an electron donor and an electron acceptor. Nitrate gains (accepts) electrons and is reduced to nitrogen gas and a carbon source loses (donates) electrons and is oxidized to carbon dioxide.
What is oxygen used for?
It is used to reduce the organic matter (BOD and COD), oxygen is bubbled with a mixture of wastewater and activated sludge. After this treatment, the treated water can be discharged on surface water.
What is the main objective of secondary treatment?
The main objective of secondary treatment: To remove most of the fine suspended and dissolved degradable organic matter that remains after primary treatment, so that the effluent may be rendered suitable for discharge. Conventional secondary treatment can reduce the BOD's to below 20mg/l and Suspended Solids to below 30mg/l which is acceptable in ...
What is nitrification in biology?
Nitrification: Means the oxidation of ammonia to nitrate. Nitrification is possible with aerobic biological processes. If they are operated at low organic load rates-hence the units must be large than those which would be required for oxidation of carbonaceous matter alone.
What is aerobic biological process?
Aerobic Biological Processes. Are those where sufficed amount of dissolved oxygen is required into the wastewater to sustain aerobic action, as one of the major polluting effects of wastewater on streams results form the depletion of dissolved oxygen by the action of aerobic organisms in degrading the organic content of the waste.
What is a trickling filter?
It is the most common attached growth process. The trickling filter is like a circular well having depth up to 2 meter filled with granular media like stone, plastic sheets and redwood, slag, slate. The first tricking filter was placed in operation in England in 1893. the concept of a tricking filter was grew form the of contact frets which were water tight basins filled with broken stones. The limitation the contact filters included a relatively.
What is biosolid fertilizer?
The stabilized sludge ( biosolids) are dewatered and applied by manure spreader onto both City-owned and private farmland. The biosolids are utilized in an environmentally acceptable manner as a beneficial and valuable fertilizer and soil conditioner.
How is methane gas produced?
Methane gas is produced by this anaerobic digestion and is used as fuel. Gas produced from anaerobic digestion is used as fuel in a boiler and then heats water used to heat some of the treatment plant buildings and to provide heating to improve the sludge digestion process and produce more gas. Step 3.
What is a secondary wastewater treatment system?
This act required that wastewater treatment plants operate with a secondary treatment system. The systems are designed to remove pollutants that generally would be released into a natural body of water, such as, lakes, rivers, and bays.
What is secondary effluent?
The secondary effluent that settles will either enter a digester or re-enter the trickling system. Secondary effluent that re-enters the trickling filter serves several purposes, the following are examples; 1. further treatment, 2. preventing the microorganism from drying out, and 3. diluting or supplementing primary effluent.
Why is secondary treatment important?
Secondary treatment of sewage and other wastewater is the stage of wastewater treatment designed to substantially degrade the biological content of the sewage.
What is anaerobic treatment?
Anaerobic treatment is sometimes used, in the form of septic tanks and in biogas digesters. in the case of septic tanks the primary and secondary phases are combined in one unit. If biogas digesters are used for secondary treatment, the primary treatment phase is reduced or emitted (aiming to remove matter such as gravel ...
When did the Clean Water Act start?
In response to the escalating pollution of natural bodies of water, the Federal Government passed the Clean Water Act [1] in 1972 . This act required that wastewater treatment plants operate with a secondary treatment system.
How does activated sludge work?
Process: During the activated sludge process primary effluent flows into an aeration tank, where it is mixed with microorganisms. The aeration tank injects a steady supply of oxygen or air into the wastewater, ensuring that the organisms have an adequate supply of oxygen needed to breakdown the organic matter that remains in the effluent. The effluent then flows into secondary settling tanks. At this point the sludge goes in one of two directions; 1. back to the aeration tank, this is because the return sludge contains a large amount of microorganisms that will rapidly breakdown organic matter, or 2. to the sludge digester [4]. The treated water will enter the tertiary treatment stage; here it will go through the final treatment stage before it is released into a natural water system. Figure 1 is an example an active sludge system.
What is the purpose of an aeration tank?
The aeration tank injects a steady supply of oxygen or air into the wastewater, ensuring that the organisms have an adequate supply of oxygen needed to breakdown the organic matter that remains in the effluent. The effluent then flows into secondary settling tanks.
What is the most effective method of secondary treatment of wastewater?
This method of secondary treatment of wastewater employs sand filters, contact filters, or trickling filters to ensure that additional sediment is removed from wastewater. Of the three filters, trickling filters are typically the most effective for small-batch wastewater treatment.
What is primary treatment of wastewater?
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 is the third step in wastewater management?
This third and last step in the basic wastewater management system is mostly comprised of removing phosphates and nitrates from the water supply. Substances like activates carbon and sand are among the most commonly used materials that assist in this process.
How long does it take for a wastewater solution to be aerated?
The resulting mixture is then aerated for up to 30 hours at a time to ensure results.
What happens when wastewater enters the secondary clarifier?
When the wastewater enters the two Secondary Clarifiers, it still contains lots of microorganisms from the Aeration Basins and looks brown and murky. The Secondary Clarifiers are identical to the Primary Clarifiers; materials in the wastewater sink and float and rotating arms remove this material from the water.
What is secondary clarifier?
The Secondary Clarifiers are identical to the Primary Clarifiers; materials in the wastewater sink and float and rotating arms remove this material from the water. After treatment in the Secondary Clarifiers, the wastewater is now ready to be released to the Napa River, or further treated to produce recycled water.
What is the process of aeration of wastewater?
From the Primary Clarifiers, the wastewater flows into large, rectangular tanks called Aeration Basins, where a biological treatment called the “activated sludge process” occurs. The wastewater flows slowing through a series of chambers as large volumes of air are bubbled up through the water. There is so much air added that it looks as if the water is boiling. 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.”