Dr. caite.infoa Rathnam. Associate Professor in Civil Engineering. National Institute of Technology Warangal. Design of Sewage Treatment Plants. This book exists in two different forms: print and electronic (pdf file). Wastewater treatment is a fast-developing field in India. A sewage treatment plant (“STP”) has to handle the designed quantity of sewage and deliver. This is to certify that the thesis entitled “Characterization of sewage and design of sewage treatment plant” submitted by Falguni Krishna Prasad. Mishra, Roll No.
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PDF | 11+ hours read | An overview of a detailed design for a Membrane Bioreactor and an Oil-Water Separator. Design Project 2. planning and designing of publicly owned municipal wastewater facilities in Japan. .. minimum requirement for publicly owned wastewater treatment plants. WASTEWATER TREATMENT PLANT DESIGN HANDBOOK. J. Peña Ventura. WASTEWATER TREATMENT PLANT DESIGN HANDBOOK Water.
In the primary sedimentation stage, sewage flows through large tanks, commonly called "pre-settling basins", "primary sedimentation tanks" or "primary clarifiers ". Sand filters, lagooning and reed beds can all be used to reduce nitrogen, but the activated sludge process if designed well can do the job the most easily. Wilner, P. The greasy materials are collected from the top of the tank and the collected are skimmed of specially designed mechanical equipments. New activated sludge is produced continuously and W.
Clarifiers and mechanized secondary treatment are more efficient under uniform flow conditions. Equalization basins may be used for temporary storage of diurnal or wet-weather flow peaks.
Basins provide a place to temporarily hold incoming sewage during plant maintenance and a means of diluting and distributing batch discharges of toxic or high-strength waste which might otherwise inhibit biological secondary treatment including portable toilet waste, vehicle holding tanks, and septic tank pumpers.
Flow equalization basins require variable discharge control, typically include provisions for bypass and cleaning, and may also include aerators. Cleaning may be easier if the basin is downstream of screening and grit removal. In some larger plants, fat and grease are removed by passing the sewage through a small tank where skimmers collect the fat floating on the surface. Air blowers in the base of the tank may also be used to help recover the fat as a froth.
Many plants, however, use primary clarifiers with mechanical surface skimmers for fat and grease removal. In the primary sedimentation stage, sewage flows through large tanks, commonly called "pre-settling basins", "primary sedimentation tanks" or "primary clarifiers ". Primary settling tanks are usually equipped with mechanically driven scrapers that continually drive the collected sludge towards a hopper in the base of the tank where it is pumped to sludge treatment facilities.
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 treat the settled sewage liquor using aerobic biological processes. To be effective, the biota require both oxygen and food to live. The bacteria and protozoa consume biodegradable soluble organic contaminants e. Some secondary treatment methods include a secondary clarifier to settle out and separate biological floc or filter material grown in the secondary treatment bioreactor.
The purpose of tertiary treatment is to provide a final treatment stage to further improve the effluent quality before it is discharged to the receiving environment sea, river, lake, wet lands, ground, etc.
More than one tertiary treatment process may be used at any treatment plant. If disinfection is practised, it is always the final process. It is also called "effluent polishing.
Sand filtration removes much of the residual suspended matter. Lagoons or ponds provide settlement and further biological improvement through storage in large man-made ponds or lagoons. These lagoons are highly aerobic and colonization by native macrophytes , especially reeds, is often encouraged.
Small filter-feeding invertebrates such as Daphnia and species of Rotifera greatly assist in treatment by removing fine particulates. Biological nutrient removal BNR is regarded by some as a type of secondary treatment process,  and by others as a tertiary or "advanced" treatment process. Wastewater may contain high levels of the nutrients nitrogen and phosphorus. Excessive release to the environment can lead to a buildup of nutrients, called eutrophication , which can in turn encourage the overgrowth of weeds, algae , and cyanobacteria blue-green algae.
This may cause an algal bloom , a rapid growth in the population of algae. The algae numbers are unsustainable and eventually most of them die. The decomposition of the algae by bacteria uses up so much of the oxygen in the water that most or all of the animals die, which creates more organic matter for the bacteria to decompose.
In addition to causing deoxygenation, some algal species produce toxins that contaminate drinking water supplies. Different treatment processes are required to remove nitrogen and phosphorus.
Nitrogen is removed through the biological oxidation of nitrogen from ammonia to nitrate nitrification , followed by denitrification , the reduction of nitrate to nitrogen gas. Nitrogen gas is released to the atmosphere and thus removed from the water. Nitrification itself is a two-step aerobic process, each step facilitated by a different type of bacteria. Denitrification requires anoxic conditions to encourage the appropriate biological communities to form.
It is facilitated by a wide diversity of bacteria. Sand filters, lagooning and reed beds can all be used to reduce nitrogen, but the activated sludge process if designed well can do the job the most easily.
This can be, depending on the waste water, organic matter from feces , sulfide , or an added donor like methanol. The sludge in the anoxic tanks denitrification tanks must be mixed well mixture of recirculated mixed liquor, return activated sludge [RAS], and raw influent e. Over time, different treatment configurations have evolved as denitrification has become more sophisticated.
An initial scheme, the Ludzack—Ettinger Process, placed an anoxic treatment zone before the aeration tank and clarifier, using the return activated sludge RAS from the clarifier as a nitrate source. Influent wastewater either raw or as effluent from primary clarification serves as the electron source for the facultative bacteria to metabolize carbon, using the inorganic nitrate as a source of oxygen instead of dissolved molecular oxygen. This denitrification scheme was naturally limited to the amount of soluble nitrate present in the RAS.
Nitrate reduction was limited because RAS rate is limited by the performance of the clarifier. The "Modified Ludzak—Ettinger Process" MLE is an improvement on the original concept, for it recycles mixed liquor from the discharge end of the aeration tank to the head of the anoxic tank to provide a consistent source of soluble nitrate for the facultative bacteria.
In this instance, raw wastewater continues to provide the electron source, and sub-surface mixing maintains the bacteria in contact with both electron source and soluble nitrate in the absence of dissolved oxygen.
Many sewage treatment plants use centrifugal pumps to transfer the nitrified mixed liquor from the aeration zone to the anoxic zone for denitrification. At times, the raw or primary effluent wastewater must be carbon-supplemented by the addition of methanol, acetate, or simple food waste molasses, whey, plant starch to improve the treatment efficiency.
These carbon additions should be accounted for in the design of a treatment facility's organic loading. Bardenpho and Biodenipho processes include additional anoxic and oxidative processes to further polish the conversion of nitrate ion to molecular nitrogen gas. Use of an anaerobic tank following the initial anoxic process allows for luxury uptake of phosphorus by bacteria, thereby biologically reducing orthophosphate ion in the treated wastewater.
Even newer improvements, such as Anammox Process, interrupt the formation of nitrate at the nitrite stage of nitrification, shunting nitrite-rich mixed liquor activated sludge to treatment where nitrite is then converted to molecular nitrogen gas, saving energy, alkalinity, and secondary carbon sourcing.
Every adult human excretes between and 1, grams 7. Phosphorus removal is important as it is a limiting nutrient for algae growth in many fresh water systems. For a description of the negative effects of algae, see Nutrient removal. It is also particularly important for water reuse systems where high phosphorus concentrations may lead to fouling of downstream equipment such as reverse osmosis.
Phosphorus can be removed biologically in a process called enhanced biological phosphorus removal. In this process, specific bacteria, called polyphosphate-accumulating organisms PAOs , are selectively enriched and accumulate large quantities of phosphorus within their cells up to 20 percent of their mass.
When the biomass enriched in these bacteria is separated from the treated water, these biosolids have a high fertilizer value. Phosphorus removal can also be achieved by chemical precipitation , usually with salts of iron e. Chemical phosphorus removal requires significantly smaller equipment footprint than biological removal, is easier to operate and is often more reliable than biological phosphorus removal.
Some systems use both biological phosphorus removal and chemical phosphorus removal. The chemical phosphorus removal in those systems may be used as a backup system, for use when the biological phosphorus removal is nor removing enough phosphorus, or may be used continuously. In either case, using both biological and chemical phosphorus removal has the advantage of not increasing sludge production as much as chemical phosphorus removal on its own, with the disadvantage of the increased initial cost associated with installing two different systems.
Once removed, phosphorus, in the form of a phosphate-rich sewage sludge , may be dumped in a landfill or used as fertilizer. In the latter case, the treated sewage sludge is also sometimes referred to as biosolids. The purpose of disinfection in the treatment of waste water is to substantially reduce the number of microorganisms in the water to be discharged back into the environment for the later use of drinking, bathing, irrigation, etc.
The effectiveness of disinfection depends on the quality of the water being treated e. Cloudy water will be treated less successfully, since solid matter can shield organisms, especially from ultraviolet light or if contact times are low. Generally, short contact times, low doses and high flows all militate against effective disinfection. Common methods of disinfection include ozone , chlorine , ultraviolet light , or sodium hypochlorite. After multiple steps of disinfection, the treated water is ready to be released back into the water cycle by means of the nearest body of water or agriculture.
Afterwards, the water can be transferred to reserves for everyday human uses. Chlorination remains the most common form of waste water disinfection in North America due to its low cost and long-term history of effectiveness. One disadvantage is that chlorination of residual organic material can generate chlorinated-organic compounds that may be carcinogenic or harmful to the environment.
Residual chlorine or chloramines may also be capable of chlorinating organic material in the natural aquatic environment. Further, because residual chlorine is toxic to aquatic species, the treated effluent must also be chemically dechlorinated, adding to the complexity and cost of treatment. Ultraviolet UV light can be used instead of chlorine, iodine, or other chemicals.
Because no chemicals are used, the treated water has no adverse effect on organisms that later consume it, as may be the case with other methods.
UV radiation causes damage to the genetic structure of bacteria, viruses , and other pathogens , making them incapable of reproduction. The key disadvantages of UV disinfection are the need for frequent lamp maintenance and replacement and the need for a highly treated effluent to ensure that the target microorganisms are not shielded from the UV radiation i. In the United Kingdom, UV light is becoming the most common means of disinfection because of the concerns about the impacts of chlorine in chlorinating residual organics in the wastewater and in chlorinating organics in the receiving water.
Some sewage treatment systems in Canada and the US also use UV light for their effluent water disinfection. Ozone O 3 is generated by passing oxygen O 2 through a high voltage potential resulting in a third oxygen atom becoming attached and forming O 3.
Ozone is very unstable and reactive and oxidizes most organic material it comes in contact with, thereby destroying many pathogenic microorganisms. Ozone is considered to be safer than chlorine because, unlike chlorine which has to be stored on site highly poisonous in the event of an accidental release , ozone is generated on-site as needed from the oxygen in the ambient air. Ozonation also produces fewer disinfection by-products than chlorination. A disadvantage of ozone disinfection is the high cost of the ozone generation equipment and the requirements for special operators.
Micropollutants such as pharmaceuticals, ingredients of household chemicals, chemicals used in small businesses or industries, environmental persistent pharmaceutical pollutant EPPP or pesticides may not be eliminated in the conventional treatment process primary, secondary and tertiary treatment and therefore lead to water pollution. For pharmaceuticals , the following substances have been identified as "toxicologically relevant": Techniques for elimination of micropollutants via a fourth treatment stage during sewage treatment are implemented in Germany, Switzerland, Sweden [ citation needed ] and the Netherlands and tests are ongoing in several other countries.
Such process steps mainly consist of activated carbon filters that adsorb the micropollutants. The combination of advanced oxidation with ozone followed by GAC, Granulated Activated Carbon, has been suggested as a cost-effective treatment combination for pharmaceutical residues.
For a full reduction of microplasts the combination of ultra filtration followed by GAC has beed suggested. Also the use of enzymes such as the enzyme laccase is under investigation.
To reduce pharmaceuticals in water bodies, also "source control" measures are under investigation, such as innovations in drug development or more responsible handling of drugs. Odors emitted by sewage treatment are typically an indication of an anaerobic or "septic" condition.
Large process plants in urban areas will often treat the odors with carbon reactors, a contact media with bio-slimes, small doses of chlorine , or circulating fluids to biologically capture and metabolize the noxious gases.
High-density solids pumps are suitable for reducing odors by conveying sludge through hermetic closed pipework. For conventional sewage treatment plants, around 30 percent of the annual operating costs is usually required for energy.
For example, constructed wetlands have a lower energy requirement than activated sludge plants, as less energy is required for the aeration step. In conventional secondary treatment processes, most of the electricity is used for aeration, pumping systems and equipment for the dewatering and drying of sewage sludge.
Advanced wastewater treatment plants, e. The sludges accumulated in a wastewater treatment process must be treated and disposed of in a safe and effective manner. The purpose of digestion is to reduce the amount of organic matter and the number of disease-causing microorganisms present in the solids.
The most common treatment options include anaerobic digestion , aerobic digestion , and composting. Incineration is also used, albeit to a much lesser degree. Sludge treatment depends on the amount of solids generated and other site-specific conditions. Composting is most often applied to small-scale plants with aerobic digestion for mid-sized operations, and anaerobic digestion for the larger-scale operations. The sludge is sometimes passed through a so-called pre-thickener which de-waters the sludge.
Types of pre-thickeners include centrifugal sludge thickeners  rotary drum sludge thickeners and belt filter presses. Many processes in a wastewater treatment plant are designed to mimic the natural treatment processes that occur in the environment, whether that environment is a natural water body or the ground.
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ManoharPanchal Good morning sir, great presentation Show More. No Downloads. Views Total views. Actions Shares. Embeds 0 No embeds. No notes for slide. Sewage Treatment Plant Design Project 1. The steady incremental in the city population results in the increase of domestic sewage generation.
But still now there is no treatment plant. So it is required to construct a Sewage Treatment Plant with sufficient capacity to treat the increased sewage.
The project deals with the design of the Sewage Treatment plant and its major components such screening chamber, grit chamber, skimming tank, sedimentation tank, secondary clarifier, active sludge tank and sludge drying beds. The project covers the With regard to Vellore, almost the entire town and environment are plain and the general slope is from West to East.
The soil of the area is being gravel, rocky and a large proportion of sand and gravel.
By the execution of the project the entire sewage of the city can be treated effectively and efficiently. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants. Its objective is to produce a treated effluent and a solid waste or sludge suitable for discharge or reuse back into the environment. This material is often inadvertently contaminated with many toxic organic and inorganic compounds.
Sewage implies the collecting of wastewaters from occupied areas and conveying them to some point of disposal. The liquid wastes will require treatment before they are discharged into the water body or otherwise disposed of without endangering the public health or causing offensive conditions. As the cities have grown, the more primitive method of excreta disposal have gain place to the water-carried sewerage system.
Even in the small cities the greater safety of sewerage, its convenience, and freedom from nuisance have caused it to be adopted wherever finances permit. Sewage is liquid, consists of any one or a mixture of liquid waste origins from urinals, latrines, bath rooms, kitchens of a dwelling, commercial building or institutional buildings.
Storm sewage is a liquid flowing in sewer during or following a period of rainfall and resulting there from. A Partially Separate Sewer System is the sewerage system in which the domestic sewage is carried with the storm water in the rain season. Activated sludge is the active biological floc produced in activated sludge plants, largely composed of saprotrophic bacteria, protozoan flora amoebae and a range of other filter feeding species.
Return activated sludge R. S is the activated sludge extracted from the system and mixed with raw water to form the mixed liquor. Waste activated sludge W.
Sludge Age is the average residence time of biological solids in the system. It can be defined as the average lifespan of bacteria in the system. This parameter is the design factor in designing the settling tanks. The treatment of sewage consists of many complex functions.
The degree of treatment depends upon the characteristics of the raw inlet sewage as well as the required effluent characteristics. Treatment processes are often classified as: Preliminary treatment consists solely in separating the floating materials like tree branches, papers, pieces of rags, wood etc. The processes under this are: Primary treatment consists in removing large suspended organic solids.
It is usually accomplished by sedimentation in settling basins. Here the effluent from primary treatment is treated through biological decomposition of organic matter carried out either aerobic or anaerobic conditions.
Aerobic Biological Units: Anaerobic Biological Units: The purpose of tertiary treatment is to provide a final treatment stage to raise the effluent quality before it is discharged to the receiving environment sea, river, lake, ground, etc.
More than one tertiary treatment process may be used at any treatment plant. If disinfection is practiced, it is always the final process. It is also known as "effluent polishing". A sewerage scheme involves the laying of underground sewer pipes and construction of costly treatment units, which cannot be replaced or increased in their capacities easily or conveniently at a later date. In order to avoid such 6 7. The future period for which the provision is made in designing the capacities of various components of the sewerage is known as design period.
This sewage treatment plant is designed for 30 years. Forecasting method: Incremental increase method. Year Population Incremental Incremental increase 7 8. Ultimate design period as , 8 9. This sewage is disposed of by dilution or on land after its collection and conveyance.
Dailey, P. Harold, P. Hines R. Horres D. Morgan C. Pomeroy, Ph. Pope A. Sandy K. Schnaars A. Shaw, P. Swift A. Umble, Ph. Typical polymer dosages for thickening and dewatering. It facilitates access to those design guides by providing concise information from them and enabling the reader to quickly locate addi- tional information by following direct references. This reference is written for students and design professionals familiar with wastewater treatment concepts, the design process, plant operations, and the regulatory basis of water pollution control.
It is not intended to be a primer for either the inexperienced or the generalist but still a tool for them as well, allow- ing them to quickly identify where they can find more information for unfamil- iar subjects. As such, the authors of this handbook are industry professionals who have used their experience as both students and design professionals to identify the most critical information to present in tables and figures.
It is highly recommended that the reader does not rely solely on information, such as de- sign criteria, identified by this handbook as it is not inclusive. A thorough un- derstanding of the principles behind these summary chapters is necessary for the correct application and use of all information contained in this handbook.
This publication was produced under the direction of Hannah T. The principal authors of this publication are as follows: Chapter 1 Hannah T. Chapter 2 Hannah T. Chapter 3 Hannah T. Chapter 4 Hannah T.