Secondary treatment of sewage and other wastewater
Wastewater
Wastewater, also written as waste water, is any water that has been adversely affected in quality by anthropogenic influence. Wastewater can originate from a combination of domestic, industrial, commercial or agricultural activities, surface runoff or stormwater, and from sewer inf…
Full Answer
What is the best water 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.
What is secondary treatment of wastewater in a treatment plant?
· Secondary treatment is a step in wastewater treatment that involves the use of biological processes in order to capture all the dissolved organic materials that were not caught during the initial treatment. Microbes take these organic substances as food, transforming them to water, energy and carbon dioxide.
What is the secondary treatment of wastewater?
· 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.
Do it yourself water treatment?
· This treatment is used to control the acidity, alkalinity, or other water qualities which affect pipes and equipment used to transport water. By controlling these factors, the public water system can reduce the leaching of metals such as copper, iron, and zinc from pipes or fixtures, as well as the color and taste associated with these contaminants.
What is the secondary treatment of wastewater?
With the secondary treatment, the remaining dissolved organics and colloidal existing in wastewater is converted to a more stable form like carbon dioxide and some into beneficial biological mass.
What is secondary treatment?
Secondary treatment is a step in wastewater treatment that involves the use of biological processes in order to capture all the dissolved organic materials that were not caught during the initial treatment.
Can wastewater be treated by a secondary treatment?
The additional removal of this organic matter can be successfully accomplished through secondary treatment. This process is composed of biological treatments that make use of various microorganisms within a strictly controlled environment.
Is wastewater a solid?
Total solids in wastewater can be categorized as inorganic and organic. When it comes to the size, it can be divided into suspended, colloidal and dissolved solids. The main purpose of the initial or primary treatment is to eliminate the suspended solids as much as possible.
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 are the two types of solids in sewage?
SOLIDS IN SEWAGE. The solids present in the sewage are of two types viz., Organic solids, and. Inorganic solids. Organic solids are the substances derived from living things like produces from plant and animal. Examples of organic solids are carbohydrate, protein, and fat.
How is dissolved carbonaceous organic matter removed from wastewater?
The removal of dissolved and suspended carbonaceous BOD and the stabilization of organic matter found in wastewater is accomplished using a v ariety of microorganisms, principally bacteria. Microorganisms are used to oxidize the dissolved and suspended carbonaceous organic matter into simple end products and additional biomass. This is achieved by providing the favourable environment to microorganisms with food, DO, pH, temperature etc. 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. In the biological treatment processes the DO is supplied either through natural means or by mechanical means by agitation.
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 an oxydation ditch?
Oxidation ditch is an extended aeration ASP. It is a large holding tank in a continuous ditch with oval shape similar to that of a race-track. The ditch is built on the surface of the ground and is lined with an impermeable lining. With a detention time of more than 24 hours, the wastewater has plenty of exposure to the open air for the diffusion of oxygen. The liquid depth in the ditches is very shallow, 0.9 to 1.5 in, which helps to prevent anaerobic conditions from occurring at the bottom of the ditch.
How is DO supplied in biological treatment?
In the biological treatment processes the DO is supplied either through natural means or by mechanical means by agitation. Anaerobic organisms can multiply in the absence of DO and do the decomposition, but the end products are undesirable fowl smelling gases like H 2 S, CH, etc.
What is a membrane biological reactor?
Membrane Biological Reactors (MBR) includes a semi-permeable membrane barrier system either submerged or in conjunction with an activated sludge process. This technology guarantees removal of all suspended and some dissolved pollutants. The limitation of MBR systems is directly proportional to nutrient reduction efficiency of the activated sludge process. The cost of building and operating a MBR is usually higher than conventional wastewater treatment.
What are secondary standards?
Secondary standards are set to give public water systems some guidance on removing these chemicals to levels that are below what most people will find to be noticeable.
What are the problems with secondary contaminants?
These problems can be grouped into three categories: Cosmetic effects — effects which do not damage the body but are still undesirable. Technical effects — damage to water equipment or reduced effectiveness of treatment for other contaminants.
What are the problems with water?
These problems can be grouped into three categories: 1 Aesthetic effects — undesirable tastes or odors; 2 Cosmetic effects — effects which do not damage the body but are still undesirable 3 Technical effects — damage to water equipment or reduced effectiveness of treatment for other contaminants
What is the EPA drinking water regulation?
EPA has established National Primary Drinking Water Regulations National Primary Drinking Water Regulations Legally enforceable standards that apply to public water systems. These standards protect drinking water quality by limiting the levels of specific contaminants that can adversely affect public health and which are known or anticipated ...
Where is the state drinking water program located?
Your state drinking water program is usually located in the state capital (or another major city) and is often part of the department of health or environmental regulation.
Do water systems have to monitor for secondary contaminants?
Although state health agencies and public water systems often decide to monitor and treat their supplies for secondary contaminants, federal regulations do not require them to do this. Where secondary contaminants are a problem, the types of removal technologies discussed below are corrective actions which the water supplier can take. They are usually effective depending upon the overall nature of the water supply.
Does the EPA enforce SMCL?
EPA does not enforce these "secondary maximum contaminant levels" ( SMCLs). They are established as guidelines to assist public water systems in managing their drinking water for aesthetic considerations, such as taste, color, and odor. These contaminants are not considered to present a risk to human health at the SMCL.
What is secondary treatment of wastewater?
Secondary treatment of wastewater makes use of oxidation to further purify wastewater. This can be done in one of three ways:
How is wastewater treated?
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. The resulting “sludge” is then fed into a digester, in which further processing takes place. This primary batch of sludge contains nearly 50% of suspended solids within wastewater.
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.
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Project Background Process control is key to maximizing wastewater treatment efficiency while minimizing operating costs. Implementing the right process control system in conjunction with the right equipment can save money on electrical costs and equipment maintenance.
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WWTP for small populations. The low-load activated sludge treatment plant (extended aeration) with high-efficiency fixed culture CVC-OXIDEP-TC is usually used to treat the water of small towns and is certified according to EN 12566-3 Standard.
What is secondary treatment?
Secondary treatment is designed to substantially degrade the biological content of the sewage which are derived from human waste, food waste, soaps and detergent. The majority of municipal plants use aerobic biological processes as a secondary treatment step. To be effective, the biota require both oxygen and food to live.
What is primary treatment of sewage?
Primary treatment of sewage by quiescent settling allows separation of floating material and heavy solids from liquid waste. The remaining liquid usually contains less than half of the original solids content and approximately two-thirds of the BOD in the form of colloids and dissolved organic compounds.
How much BOD is in secondary treated sewage?
Secondary treated sewage is expected to produce effluent with a monthly average of less than 30 mg/l BOD and less than 30 mg/l suspended solids. Weekly averages may be up to 50 percent higher.
Why does BOD drop in secondary bioreactors?
A similar problem occurs as BOD concentrations drop when low flow increases waste residence time within the secondary treatment bioreactor. Secondary treatment ecosystems of college communities acclimated to waste loading fluctuations from student work/sleep cycles may have difficulty surviving school vacations. Secondary treatment systems accustomed to routine production cycles of industrial facilities may have difficulty surviving industrial plant shutdown. Populations of species feeding on incoming waste initially decline as concentration of those food sources decrease. Population decline continues as ecosystem predator populations compete for a declining population of lower trophic level organisms.
How is primary clarifier effluent discharged?
Primary clarifier effluent was discharged directly to eutrophic natural wetlands for decades before environmental regulations discouraged the practice. Where adequate land is available, stabilization ponds with constructed wetland ecosystems can be built to perform secondary treatment separated from the natural wetlands receiving secondary treated sewage. Constructed wetlands resemble fixed-film systems more than suspended growth systems, because natural mixing is minimal. Constructed wetland design uses plug flow assumptions to compute the residence time required for treatment. Patterns of vegetation growth and solids deposition in wetland ecosystems, however, can create preferential flow pathways which may reduce average residence time. Measurement of wetland treatment efficiency is complicated because most traditional water quality measurements cannot differentiate between sewage pollutants and biological productivity of the wetland. Demonstration of treatment efficiency may require more expensive analyses.
What is a secondary clarifier?
This small secondary clarifier at a rural sewage treatment plant is a typical phase separation mechanism to remove biological solids formed in a suspended growth or fixed-film bioreactor.
How can waste flow be reduced?
Wastewater flow variations may be reduced by limiting stormwater collection by the sewer system, and by requiring industrial facilities to discharge batch process wastes to the sewer over a time interval rather than immediately after creation. Discharge of appropriate organic industrial wastes may be timed to sustain the secondary treatment ecosystem through periods of low residential waste flow. Sewage treatment systems experiencing holiday waste load fluctuations may provide alternative food to sustain secondary treatment ecosystems through periods of reduced use. Small facilities may prepare a solution of soluble sugars. Others may find compatible agricultural wastes, or offer disposal incentives to septic tank pumpers during low use periods.
What is secondary treatment of wastewater?
Secondary treatment of wastewater further purifies the wastewater through additional processes. The first is biofiltration that uses filters with sand, contact filters or trickling filters that remove sediment from the sewage.
How is primary treatment different from secondary treatment?
Another difference between these processes is how much time they take to complete. The primary treatment takes a shorter period to finish, but the secondary takes much longer as organic microbes consume the waste.
How is wastewater treated?
The primary treatment of wastewater occurs through sedimentation with filtering out large contaminant particles within the liquid. The contaminants separate as they are passed through several tanks and other filters. Leftover sludge filters through a digester to suspend solids from the wastewater.
What is primary wastewater treatment?
The primary wastewater process utilizes equipment to break up larger particles and then uses sedimentation or a floating process for extraction. Many treatments that use the primary method then proceed to the secondary treatment process.
What is the process of removing impurities from water?
The removal in the secondary wastewater treatment process generally occurs through a biological process with consumption of impurities in water by microbes, converting the matter into energy, carbon dioxide gases, and water. AOS can help with municipal wastewater treatment services in both primary and secondary processes.
What is the process of removing large particles from 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. Sedimentation and filtration are the processes involved in the primary treatment method while biological breakdown occurs through aerobic or anaerobic units in secondary processes.
What is primary treatment?
Through the primary treatment, it is possible to remove materials that float and settle on top of water. Through primary treatment, it is possible to implement screening water treatment, reduce particles to fragments, remove grit and initiate sedimentation. The primary treatment pushes sewage through screens into the comminutor for grip disposal ...
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 ...
How much BOD is removed from wastewater?
Conventional sedimentation the major process in primary wastewater treatment, normally removes 60 to 70 % of suspended solids matter containing 30% to 40% of the BOD present in municipal wastewater, leaving 150 to 200 mg/ l of BOD's and about 100mg/l SS in the primary effluent.
What is the assimilative capacity of bod in water?
Tip: Assimilative capacity of BOD in water is not more than or should be less then 4mg/l.
Is dissolved oxygen required in wastewater?
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. Practical aerobic biological treatment ...