This document provides an overview of sanitation systems and wastewater treatment. It discusses the basics of sanitation including definitions, history of sanitation practices, and the importance of sanitation for public health. It also describes various sanitation technologies like sewers, septic systems, trickling filters used in wastewater treatment plants, and leach fields for dispersing effluent from septic tanks. The document outlines global access to improved sanitation facilities and the development of water supply and sanitation infrastructure over history.
The document discusses various components of sewerage systems and methods of sewage collection and treatment. It describes the key parts of sewerage systems including pipes, pumps, manholes, as well as different systems for collecting domestic and industrial wastewater. It also summarizes common methods for primary and secondary sewage treatment such as screening, sedimentation, and biological processes like trickling filters and activated sludge. Stormwater management techniques are also outlined including ways to store, convey, and infiltrate or detain runoff.
This document discusses different sewage disposal methods and their advantages and disadvantages. It describes on-site sewage disposal systems that use septic tanks and leach drains or French drains to treat sewage in the surrounding soil. It also discusses effluent disposal systems that transport treated sewage from a community to a central lagoon via pipes. Full sewage systems transport all sewage directly to a lagoon, with some options for pretreatment. The septic tank is used to separate solids from liquids before further treatment or disposal.
Introduction to water supply engg. by Prof. D S.Shahdhavalsshah
Introduction to water supply Engineering. Basic definitions in water supply engineering. Importance of water supply engineering.
Financing of water supply schemes. Flow diagram of water supply scheme, layouts of water supply schemes, etc.
This document outlines a fluid mechanics course project on water distribution systems. It defines the aim as delivering water to customers with sufficient quantity and pressure. It describes the main components of distribution systems as pipelines, valves, storage reservoirs, and flow measurement devices. It also covers the different types of distribution systems like grid iron, ring, and radial systems. Common problems addressed are leaks and commercial losses. The conclusion emphasizes the importance of managing distribution systems on a daily basis to ensure a sustainable supply of safe drinking water.
P.P.T on water distribution system by Manish PandeyManish Pandey
The document discusses different types of distribution networks and pipes used in water distribution systems. It describes dead end, radial, grid iron and ring networks. PVC, CPVC, PEX and copper pipes are discussed. Distribution reservoirs help maintain water pressure and quality by absorbing demand fluctuations. Elevated and surface reservoirs are used. Joints like end caps, tees, strainers and reducers connect pipes. The purpose of distribution systems is to deliver water to consumers with appropriate quality, quantity and pressure.
Here you will get all information about sewer design, its type & various tests carried out on it for any leakage or any obstruction present and of improper joints.
The document discusses various components of sewerage systems and methods of sewage collection and treatment. It describes the key parts of sewerage systems including pipes, pumps, manholes, as well as different systems for collecting domestic and industrial wastewater. It also summarizes common methods for primary and secondary sewage treatment such as screening, sedimentation, and biological processes like trickling filters and activated sludge. Stormwater management techniques are also outlined including ways to store, convey, and infiltrate or detain runoff.
This document discusses different sewage disposal methods and their advantages and disadvantages. It describes on-site sewage disposal systems that use septic tanks and leach drains or French drains to treat sewage in the surrounding soil. It also discusses effluent disposal systems that transport treated sewage from a community to a central lagoon via pipes. Full sewage systems transport all sewage directly to a lagoon, with some options for pretreatment. The septic tank is used to separate solids from liquids before further treatment or disposal.
Introduction to water supply engg. by Prof. D S.Shahdhavalsshah
Introduction to water supply Engineering. Basic definitions in water supply engineering. Importance of water supply engineering.
Financing of water supply schemes. Flow diagram of water supply scheme, layouts of water supply schemes, etc.
This document outlines a fluid mechanics course project on water distribution systems. It defines the aim as delivering water to customers with sufficient quantity and pressure. It describes the main components of distribution systems as pipelines, valves, storage reservoirs, and flow measurement devices. It also covers the different types of distribution systems like grid iron, ring, and radial systems. Common problems addressed are leaks and commercial losses. The conclusion emphasizes the importance of managing distribution systems on a daily basis to ensure a sustainable supply of safe drinking water.
P.P.T on water distribution system by Manish PandeyManish Pandey
The document discusses different types of distribution networks and pipes used in water distribution systems. It describes dead end, radial, grid iron and ring networks. PVC, CPVC, PEX and copper pipes are discussed. Distribution reservoirs help maintain water pressure and quality by absorbing demand fluctuations. Elevated and surface reservoirs are used. Joints like end caps, tees, strainers and reducers connect pipes. The purpose of distribution systems is to deliver water to consumers with appropriate quality, quantity and pressure.
Here you will get all information about sewer design, its type & various tests carried out on it for any leakage or any obstruction present and of improper joints.
This document provides an overview of key components and objectives of a water supply system. It discusses the following:
- The objectives of water supply systems are to provide safe, adequate, accessible water to improve public health and economic conditions.
- Components include water sources, intake structures, pumping stations, transmission mains, storage reservoirs, distribution pipes, and public access points.
- Water is treated and purified to remove impurities before storage and distribution to consumers. Proper system design and maintenance help ensure a reliable water supply.
water demand, types of demand, factors affecting per capita demand, design periods, losses in wastes & thefts, varion in demand, coincident draft,effect of variations on components of water supply schemes, factors affecting design periods, population forecasting methods, problems on population forecasting, etc
Collection of sewage & estimation of its dischargeRajdip Bhdaraka
This document provides an overview of wastewater and sewerage systems. It defines wastewater as water used in homes, commercial spaces, and industries that needs treatment and disposal. Effective wastewater collection is important to prevent unhygienic conditions. The document then describes the components of typical sewerage systems and different types of sewer pipes used, including their characteristics and suitable applications. It also discusses factors that affect wastewater flow estimation and formulas used to calculate peak storm discharge in sewer design.
Dry weather flow refers to the waste water flow in sewer systems during dry periods and consists mainly of domestic sewage and industrial wastewater. The key factors that affect dry weather flow are the rate of water supply, population growth, type of area served (residential, industrial, commercial), and infiltration of groundwater. The sewers must be designed to carry a minimum of 150 litres of water per capita per day to account for these factors.
Only 3% of the world's water is fresh water, which is found as surface water, in rivers underground, frozen in glaciers and ice caps, or as groundwater. The water cycle ensures the continuous movement of water on, above, and below the surface of the Earth. Globally, an estimated 69% of fresh water is used for agriculture, 22% for industry, 8% for domestic purposes, and a very small percentage for recreation. Water is treated and stored before being distributed to homes and buildings through a network of pipes and storage systems.
The document discusses different types of water intake structures. Intakes collect water from sources like lakes, rivers, reservoirs and canals. The main types are lake intakes, river intakes, reservoir intakes and canal intakes. Lake intakes use submersible pipes with bell mouths and screens. River intakes have intake towers with penstocks and screens. Reservoir intakes are towers constructed on dam slopes with intake pipes at different levels. Canal intakes are simple structures with intake pipes in chambers with screens. The document provides details on the design and functioning of each type.
Rain water Harvesting And Roof Top Rain water HarvestingRaj sharma
Rainwater harvesting involves collecting and storing rainwater runoff from roof surfaces before it reaches the aquifer. It has multiple benefits like providing drinking water and irrigation while also recharging groundwater levels. A basic roofwater harvesting system consists of a catchment area, gutters, a filter, a storage tank, and delivery components. Larger buildings can use excess collected water for artificial groundwater recharge through structures like abandoned wells, recharge pits, and trenches. Proper system design is based on factors like annual rainfall, roof area, and household water needs to ensure adequate storage.
Design and Construction of Sewers And Sewer AppurtenancesTulsiram Bhattarai
The document provides information about sewer systems in Nepal. It discusses the historical development of sewage systems in Nepal from the 1920s to present day. It outlines the objectives of understanding sewer types, design criteria, construction, and appurtenances. The document describes various sewer shapes including circular, rectangular, egg-shaped, and others. It covers design criteria such as sewage flow calculations, velocity, gradient, and materials. Common sewer materials like concrete, brick, cast iron are explained. The importance of manholes and other appurtenances for maintenance and inspection is highlighted.
The document discusses and compares four plumbing drainage systems: one pipe system, two pipe system, single stack pipe system, and partially single stack pipe system. It provides details on how each system works, carrying waste or soil water in separate or combined pipes. Advantages include being more economical and easier to install than two pipe systems. Disadvantages include risks of backflow and difficulty in high rise buildings. The partially single stack system uses two single stack pipes with separate ventilation for waste and soil water.
Service reservoirs, also known as distribution reservoirs, store treated water for supplying water to consumers. There are three types: surface reservoirs built at ground level or below ground; elevated reservoirs which are overhead tanks supported on towers; and stand pipes which are tall cylindrical shells resting on the ground. Distribution reservoirs equalize variations in hourly water demand, maintain pressure in the distribution system, and provide time for disinfection. They have components like inlet/outlet pipes, overflow pipes, and devices to control water levels. The total storage includes balancing storage for meeting fluctuating demand, breakdown storage for emergencies, and fire storage.
The document discusses various aspects of sewage conveyance and pumping systems, including:
- Types of sewers like soil pipes, waste pipes, lateral sewers, branch sewers, and main/outfall sewers.
- Materials used for sewer construction like bricks, vitrified clay, concrete, steel, asbestos cement, plastic, and glass fiber reinforced plastic.
- Classification of sewer systems as combined, separate, or partially separate depending on how stormwater and sewage are conveyed. Combined systems convey both through one sewer while separate systems use different sewers.
This document provides an overview of various sewer appurtenances including manholes, lampholes, drop manholes, oil and grease traps, and catch basins. Manholes are constructed on sewer alignments to allow access for inspection, cleaning, and maintenance of sewer lines. They are usually circular or rectangular in shape. Lampholes are similar but smaller openings used in places where there is insufficient space for a full manhole. Drop manholes include vertical drop pipes to connect sewers with significant elevation changes. Oil and grease traps are chambers that separate grease and oil from sewage before it enters sewer lines.
The document discusses the suitability and selection criteria for water supply sources. It explains that surface water quantity varies with rainfall and can contain impurities, while groundwater quality depends on rainfall and geology. Deep wells and tube wells provide more constant supplies than shallow wells and springs. Overall, groundwater quality is better but may require treatment. Key factors in selecting a water source include location, elevation, available quantity and quality, topography between the source and city, and cost. Water supply schemes consider financial aspects, population projections, water quality, consumption rates, potential sources, sanitary conditions, area topography, and future development trends.
The document discusses water demand forecasting and population forecasting methods. It describes calculating total annual water volume, average daily flow rates, and per capita demand. Population forecasting methods covered include arithmetic increase, geometric increase, incremental increase, and graphical methods. Factors affecting per capita demand and reasons for selecting a design period are also outlined.
This document discusses the importance of drinking water treatment plants. It describes several key processes used in water treatment including screening, aeration, flocculation, sedimentation, filtration, disinfection, and softening. Screening is used to remove large solid materials from surface water sources. Aeration removes undesirable gases and organic matter. Flocculation and sedimentation work to combine particles and remove suspended solids. Filtration then removes any remaining fine particles or microorganisms. Softening and disinfection are also important treatment processes.
The document discusses various methods of solid waste and sewage disposal. It describes different types of latrines used for human waste disposal in rural areas, including pit latrines, borehole latrines, and aqua privies. The document also discusses bucket latrines, overhung privies, and flush latrines. It explains sewage disposal systems involving transporting liquid waste via drains, sewers, and sewage treatment plants which screen, remove grit, use sedimentation and aeration to treat sewage before disposal. Improper waste and sewage disposal can spread diseases like typhoid, worms, and hepatitis, so the document emphasizes the importance of sanitation, hygiene and sewage treatment for disease prevention.
Biological and Advanced Water Treatment.pptxYalelet Abera
Micro-organisms play an essential role in the biological treatment of wastewater by converting organic waste into more stable substances. There are three main types of biological wastewater treatment processes - aerobic, anaerobic, and anoxic. Two common biological wastewater treatment methods are trickling filters and activated sludge processes. Trickling filters use microorganisms attached to media to treat wastewater as it trickles down. Activated sludge processes use air and microorganisms in suspension to treat wastewater in aeration tanks, with the treated wastewater then sent to secondary clarifiers. Design considerations for biological wastewater treatment systems include organic loading rates, hydraulic loading rates, and detention
This document provides an overview of key components and objectives of a water supply system. It discusses the following:
- The objectives of water supply systems are to provide safe, adequate, accessible water to improve public health and economic conditions.
- Components include water sources, intake structures, pumping stations, transmission mains, storage reservoirs, distribution pipes, and public access points.
- Water is treated and purified to remove impurities before storage and distribution to consumers. Proper system design and maintenance help ensure a reliable water supply.
water demand, types of demand, factors affecting per capita demand, design periods, losses in wastes & thefts, varion in demand, coincident draft,effect of variations on components of water supply schemes, factors affecting design periods, population forecasting methods, problems on population forecasting, etc
Collection of sewage & estimation of its dischargeRajdip Bhdaraka
This document provides an overview of wastewater and sewerage systems. It defines wastewater as water used in homes, commercial spaces, and industries that needs treatment and disposal. Effective wastewater collection is important to prevent unhygienic conditions. The document then describes the components of typical sewerage systems and different types of sewer pipes used, including their characteristics and suitable applications. It also discusses factors that affect wastewater flow estimation and formulas used to calculate peak storm discharge in sewer design.
Dry weather flow refers to the waste water flow in sewer systems during dry periods and consists mainly of domestic sewage and industrial wastewater. The key factors that affect dry weather flow are the rate of water supply, population growth, type of area served (residential, industrial, commercial), and infiltration of groundwater. The sewers must be designed to carry a minimum of 150 litres of water per capita per day to account for these factors.
Only 3% of the world's water is fresh water, which is found as surface water, in rivers underground, frozen in glaciers and ice caps, or as groundwater. The water cycle ensures the continuous movement of water on, above, and below the surface of the Earth. Globally, an estimated 69% of fresh water is used for agriculture, 22% for industry, 8% for domestic purposes, and a very small percentage for recreation. Water is treated and stored before being distributed to homes and buildings through a network of pipes and storage systems.
The document discusses different types of water intake structures. Intakes collect water from sources like lakes, rivers, reservoirs and canals. The main types are lake intakes, river intakes, reservoir intakes and canal intakes. Lake intakes use submersible pipes with bell mouths and screens. River intakes have intake towers with penstocks and screens. Reservoir intakes are towers constructed on dam slopes with intake pipes at different levels. Canal intakes are simple structures with intake pipes in chambers with screens. The document provides details on the design and functioning of each type.
Rain water Harvesting And Roof Top Rain water HarvestingRaj sharma
Rainwater harvesting involves collecting and storing rainwater runoff from roof surfaces before it reaches the aquifer. It has multiple benefits like providing drinking water and irrigation while also recharging groundwater levels. A basic roofwater harvesting system consists of a catchment area, gutters, a filter, a storage tank, and delivery components. Larger buildings can use excess collected water for artificial groundwater recharge through structures like abandoned wells, recharge pits, and trenches. Proper system design is based on factors like annual rainfall, roof area, and household water needs to ensure adequate storage.
Design and Construction of Sewers And Sewer AppurtenancesTulsiram Bhattarai
The document provides information about sewer systems in Nepal. It discusses the historical development of sewage systems in Nepal from the 1920s to present day. It outlines the objectives of understanding sewer types, design criteria, construction, and appurtenances. The document describes various sewer shapes including circular, rectangular, egg-shaped, and others. It covers design criteria such as sewage flow calculations, velocity, gradient, and materials. Common sewer materials like concrete, brick, cast iron are explained. The importance of manholes and other appurtenances for maintenance and inspection is highlighted.
The document discusses and compares four plumbing drainage systems: one pipe system, two pipe system, single stack pipe system, and partially single stack pipe system. It provides details on how each system works, carrying waste or soil water in separate or combined pipes. Advantages include being more economical and easier to install than two pipe systems. Disadvantages include risks of backflow and difficulty in high rise buildings. The partially single stack system uses two single stack pipes with separate ventilation for waste and soil water.
Service reservoirs, also known as distribution reservoirs, store treated water for supplying water to consumers. There are three types: surface reservoirs built at ground level or below ground; elevated reservoirs which are overhead tanks supported on towers; and stand pipes which are tall cylindrical shells resting on the ground. Distribution reservoirs equalize variations in hourly water demand, maintain pressure in the distribution system, and provide time for disinfection. They have components like inlet/outlet pipes, overflow pipes, and devices to control water levels. The total storage includes balancing storage for meeting fluctuating demand, breakdown storage for emergencies, and fire storage.
The document discusses various aspects of sewage conveyance and pumping systems, including:
- Types of sewers like soil pipes, waste pipes, lateral sewers, branch sewers, and main/outfall sewers.
- Materials used for sewer construction like bricks, vitrified clay, concrete, steel, asbestos cement, plastic, and glass fiber reinforced plastic.
- Classification of sewer systems as combined, separate, or partially separate depending on how stormwater and sewage are conveyed. Combined systems convey both through one sewer while separate systems use different sewers.
This document provides an overview of various sewer appurtenances including manholes, lampholes, drop manholes, oil and grease traps, and catch basins. Manholes are constructed on sewer alignments to allow access for inspection, cleaning, and maintenance of sewer lines. They are usually circular or rectangular in shape. Lampholes are similar but smaller openings used in places where there is insufficient space for a full manhole. Drop manholes include vertical drop pipes to connect sewers with significant elevation changes. Oil and grease traps are chambers that separate grease and oil from sewage before it enters sewer lines.
The document discusses the suitability and selection criteria for water supply sources. It explains that surface water quantity varies with rainfall and can contain impurities, while groundwater quality depends on rainfall and geology. Deep wells and tube wells provide more constant supplies than shallow wells and springs. Overall, groundwater quality is better but may require treatment. Key factors in selecting a water source include location, elevation, available quantity and quality, topography between the source and city, and cost. Water supply schemes consider financial aspects, population projections, water quality, consumption rates, potential sources, sanitary conditions, area topography, and future development trends.
The document discusses water demand forecasting and population forecasting methods. It describes calculating total annual water volume, average daily flow rates, and per capita demand. Population forecasting methods covered include arithmetic increase, geometric increase, incremental increase, and graphical methods. Factors affecting per capita demand and reasons for selecting a design period are also outlined.
This document discusses the importance of drinking water treatment plants. It describes several key processes used in water treatment including screening, aeration, flocculation, sedimentation, filtration, disinfection, and softening. Screening is used to remove large solid materials from surface water sources. Aeration removes undesirable gases and organic matter. Flocculation and sedimentation work to combine particles and remove suspended solids. Filtration then removes any remaining fine particles or microorganisms. Softening and disinfection are also important treatment processes.
The document discusses various methods of solid waste and sewage disposal. It describes different types of latrines used for human waste disposal in rural areas, including pit latrines, borehole latrines, and aqua privies. The document also discusses bucket latrines, overhung privies, and flush latrines. It explains sewage disposal systems involving transporting liquid waste via drains, sewers, and sewage treatment plants which screen, remove grit, use sedimentation and aeration to treat sewage before disposal. Improper waste and sewage disposal can spread diseases like typhoid, worms, and hepatitis, so the document emphasizes the importance of sanitation, hygiene and sewage treatment for disease prevention.
Biological and Advanced Water Treatment.pptxYalelet Abera
Micro-organisms play an essential role in the biological treatment of wastewater by converting organic waste into more stable substances. There are three main types of biological wastewater treatment processes - aerobic, anaerobic, and anoxic. Two common biological wastewater treatment methods are trickling filters and activated sludge processes. Trickling filters use microorganisms attached to media to treat wastewater as it trickles down. Activated sludge processes use air and microorganisms in suspension to treat wastewater in aeration tanks, with the treated wastewater then sent to secondary clarifiers. Design considerations for biological wastewater treatment systems include organic loading rates, hydraulic loading rates, and detention
The sewage is a wastewater generated from domestic activities including kitchen, bathroom, toilet & floor washing. Due to several reasons, the sewage may not be properly collected & treated in some urban centers.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Sewage treatment involves physical, chemical, and biological processes to remove contaminants from wastewater and produce an effluent suitable for discharge. It includes three main stages - primary treatment to separate solids, secondary treatment using microorganisms to break down biological matter, and tertiary treatment using additional processes like filtration, nutrient removal, and disinfection to further polish the water before environmental discharge or reuse. The goal is to remove physical, chemical and biological contaminants from sewage originating from residences and commercial/industrial sources in order to protect water quality in receiving environments.
Sewage treatment involves physical, chemical, and biological processes to remove contaminants from wastewater and produce an effluent that is safe to discharge back into the environment. It generally involves three stages - primary treatment to separate solids, secondary treatment using microorganisms to break down organic matter, and tertiary treatment using additional processes like filtration, nutrient removal, and disinfection to further polish the water before discharge. The goal is to protect water quality by removing harmful pathogens, excess nutrients, and other pollutants from residential, commercial, and industrial wastewater before returning the treated water to nature.
The document discusses wastewater treatment processes. It describes that wastewater contains a variety of pollutants from physical to biological contaminants. The size of treatment systems depends on sewage volume and anticipated flows. Common treatment methods include primary, secondary, and tertiary levels. Primary treatment involves screens, comminution, grit removal and sedimentation to remove solids. Secondary treatment uses biological processes like trickling filters, activated sludge, and oxidation ponds to further reduce organic matter. Tertiary treatment can achieve very high removal rates of 99% for drinking water quality effluent.
The document discusses estimating the quantity of sewage that will flow through sewer pipes. It is theoretically equal to the water supply but there are additions and subtractions in practice. Additions include unaccounted private water sources and infiltration of groundwater into sewer pipes. Subtractions include water used for purposes other than sewage like watering gardens. The design sewage quantity is estimated by considering factors like population growth rates and per capita water consumption rates. Peak sewage flows also need to be estimated to size sewer pipes appropriately.
Human excreta and improper excreta disposal pose major public health risks like soil, water, and food contamination which can spread diseases. There are various methods for excreta disposal, including latrines, septic tanks, and sewerage systems, with the goal being proper segregation and treatment of excreta to prevent transmission of diseases. Community sanitation aims to break the disease cycle at key points like excreta disposal, water protection, and fly control.
Env activity set for city collegea new (recovered)this oneDr Robert Craig PhD
This 15-day unit plan explores New York City's wastewater treatment system. Students will learn about the history and development of the system, visit relevant sites, and model the wastewater treatment process. Over the course of the unit, students will gain an understanding of wastewater treatment, from the collection of sewage to its treatment and disposal. They will draw diagrams, define key terms, and do a final presentation to share what they have learned. The goal is for students to explore facets of city planning and disaster preparedness through studying the city's wastewater infrastructure.
Overview for the Safe Drinking Water.pptxRashmiSanghi1
The document discusses ensuring access to safe drinking water. It notes that water is essential for life and health. The World Health Organization and UN have emphasized providing universal access to safe drinking water. Standards and guidelines for drinking water quality have been developed to assess water sources and ensure treatment and supply by authorities is effective. Regular testing of drinking water supplies is important to understand health risks and implement proper controls.
This document discusses different types of on-site sewage treatment systems. It describes 10 common system types including septic tank systems, aerobic treatment units, mound systems, drip distribution systems, conventional systems, chamber systems, recirculating sand filter systems, evapotranspiration systems, constructed wetland systems, and cluster/community systems. It provides details on how each system type works and the components involved in the wastewater treatment process. Primary components discussed include septic tanks, aerobic tanks, pump tanks, sand filters, and drainage fields.
1) Sewage treatment plants are necessary to purify wastewater before discharge into rivers or oceans. They employ natural biological processes to break down pollutants.
2) The typical sewage treatment process has four stages: primary treatment to remove solids; secondary biological treatment using microorganisms to oxidize compounds; secondary settling; and tertiary treatment if needed before discharge.
3) Common secondary treatment methods are biological filtration using media to support microbe growth, activated sludge using aeration to sustain microbes, and Pasveer Ditches which circulate and aerate sewage.
The document discusses wastewater treatment processes and septic systems. It provides details on various treatment stages like primary, secondary and tertiary treatment. It also describes different treatment units like trickling filters, activated sludge process and aerated lagoons. Regarding septic systems, it explains how wastewater flows from the house to the septic tank where solids settle and are partially decomposed. The treated water then flows to a drain field where further treatment occurs as it percolates through the soil. Proper maintenance of septic systems is important to prevent contamination of groundwater sources.
This document provides information on various methods for water conservation and wastewater treatment in green buildings, including rainwater harvesting, reuse of recycled water, and physical, chemical, and biological wastewater treatment techniques. It discusses components of roof top rainwater harvesting systems, such as catchments, transportation, first flush devices, and filters. Methods of rainwater harvesting include storage and direct use or recharging groundwater. The document outlines dos and don'ts for rainwater harvesting and different wastewater treatment methods like sedimentation, screening, aeration, filtration, chlorination, ozonation, and neutralization.
Sewage refers to wastewater produced by communities and contains liquid waste from toilets, sinks, and other sources, as well as solid waste. Sewage is transported through sewer systems to treatment plants where it undergoes processes to remove contaminants before being released into water bodies. Proper sewage management is important for public health, environmental protection, water quality preservation, and economic reasons. Sewage comes from residential, commercial, industrial, and other sources and is treated through preliminary, primary, secondary, tertiary, disinfection, sludge treatment, and effluent release or reuse processes. Common sewage disposal methods include municipal treatment plants, septic systems, composting toilets, lago
Sanitation is the hygienic means of preventing human contact with the multiple hazards associated with waste in order to promote health.
Some of the hazards include physical, microbiological, biological and chemical.
The most common hazards that pose health problems originate from human and animal faeces, solid waste, domestic wastewater, and industrial and agricultural waste.
To prevent the health threat posed by these wastes, engineering solutions such as sewerage and wastewater treatment and simple technologies like latrines, septic tanks or even hand washing with soap rank high.
This technical seminar report summarizes a 5 MLD sewage treatment plant in Ursugutta. The report provides details on the primary treatment processes including a raw sewage sump, screens, and grit removal. It then describes the secondary treatment which uses a C-Tech sequencing batch reactor process. This involves cycles of fill, aeration, settling, and decanting to achieve BOD removal, nitrification, denitrification, and phosphorus removal. The report provides details on the treatment methodology and components of the C-Tech system.
FIELD VISIT REPORT ON MOONPLAINS SANITARY LAND FILL IN NUWARAELIYA Sivanesan Somanathar
The Moon Plains sanitary landfill in Nuwara Eliya, Sri Lanka was visited by MSc environmental science students. The landfill was engineered by JICA and uses semi-aerobic methods. It has leachate collection pipes, a treatment facility using coconut fibers and wetlands, and gas vents. However, problems include a lack of monitoring of leachate and gas emissions. The landfill's classification is also problematic as bedrock is discontinuous and could allow leachate contamination of nearby reservoirs without proper sealing.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
Best Digital Marketing Strategy Build Your Online Presence 2024.pptxpavankumarpayexelsol
This presentation provides a comprehensive guide to the best digital marketing strategies for 2024, focusing on enhancing your online presence. Key topics include understanding and targeting your audience, building a user-friendly and mobile-responsive website, leveraging the power of social media platforms, optimizing content for search engines, and using email marketing to foster direct engagement. By adopting these strategies, you can increase brand visibility, drive traffic, generate leads, and ultimately boost sales, ensuring your business thrives in the competitive digital landscape.
2. 2
Sanitation:
Sanitation is the hygienic means of promoting health through prevention of human
contact with the hazards of wastes as well as the treatment and proper disposal of
sewage wastewater. Hazards can be either physical, microbiological, biological or
chemical agents of disease. Wastes that can cause health problems include human and
animal feces, solid wastes, domestic wastewater.
The word 'sanitation' also refers to the maintenance of hygienic conditions, through
services such as garbage collection and wastewater disposal.
The term "sanitation" is applied to a wide range of subjects such as:
Improved sanitation - refers to the management of human faeces at the
household level. This terminology is the indicator used to describe the target of
the Millennium Development Goal on sanitation, by the WHO/UNICEF Joint
Monitoring Programme for Water Supply and Sanitation.
On-site sanitation - the collection and treatment of waste is done where it is
deposited. Examples are the use of pit latrines, septic tanks, and Imhoff tanks.
Food sanitation - refers to the hygienic measures for ensuring food safety.
Environmental sanitation - the control of environmental factors that form links in
disease transmission. Subsets of this category are solid waste management,
water and wastewater treatment, industrial waste treatment and noise and
pollution control.
Ecological sanitation - an approach that tries to emulate nature through the
recycling of nutrients and water from human and animal wastes in a hygienically
safe manner.
HISTORY:
a) The earliest evidence of urban sanitation was seen in Harappa, Mohenjo-daro.
This urban plan included the world's first urban sanitation systems.
b) Roman cities and Roman villas had elements of sanitation systems, delivering
water in the streets of towns such as Pompeii, and building stone and wooden
drains to collect and remove wastewater from populated areas .
Wastewater collection: The standard sanitation technology in urban areas is
the collection of wastewater in sewers, its treatment in wastewater treatment plants
for reuse or disposal in rivers, lakes or the sea. Sewers are either combined with
storm drains or separated from them as sanitary sewers. In developed countries
treatment of municipal wastewater is now widespread.
3. 3
Health Impacts of Sanitation:
For any social and economic development, adequate sanitation in conjunction with good
hygiene and safe water are essential to good health. Lack of proper sanitation cause
diseases. The lack of clean water and poor sanitation has caused many diseases and
the spread of diseases. Sanitation is a serious issue that is affecting most parts of the
world especially the developing countries.
On-site treatment:
In many suburban and rural areas households are not connected to sewers. They
discharge their wastewater into septic tanks or other types of on-site sanitation. On-site
systems include drain fields, which require significant area of land.
Reuse of wastewater
The reuse of untreated wastewater in irrigated agriculture is common in developing
countries. The reuse of treated wastewater in landscaping, especially on golf courses,
irrigated agriculture and for industrial use is becoming increasingly widespread.
Ecological sanitation: Ecological sanitation is sometimes presented as a radical
alternative to conventional sanitation systems. Ecological sanitation is based on
composting or vermicomposting toilets and recycling is done. It thus eliminates the
creation of blackwater . If ecological sanitation is practiced municipal wastewater
consists only of greywater, which can be recycled for gardening.
Sanitation and public health
The importance of the isolation of waste lies in an effort to prevent diseases which can
be transmitted through human waste, which afflict both developed countries as well as
developing countries to differing degrees. It is estimated that up to 5 million people die
each year from preventable water-borne diseases,as a result of inadequate sanitation
and hygiene practices.
Global access to improved sanitation
The Joint Monitoring Programme for Water Supply and Sanitation of WHO and UNICEF
has defined improved sanitation as follows:
Flush toilet
Connection to a piped sewer system
Connection to a septic system
4. 4
Flush / pour-flush to a pit latrine
Ventilated improved pit (VIP) latrine
Pit latrine with slab
Composting toilet
Disposal of solid waste is most commonly conducted in landfills, but incineration,
recycling, composting and conversion to biofuels are also avenues. For incineration
options, the release of air pollutants, including certain toxic components is an attendant
adverse outcome. Recycling and biofuel conversion are the sustainable options that
generally have superior life cycle costs, particularly when total ecological consequences
are considered.
History of water supply and sanitation:
Ancient Age: Throughout history people have devised systems to make getting and
using water more convenient. The Indus Valley Civilization has early evidence of public
water supply and sanitation. The Roman Empire had indoor plumbing, meaning a
system of aqueducts and pipes that terminated in homes and at public wells and
fountains for people to use. Rome and other nations used lead pipes, often unknowing
about lead poisoning. Persian Qanats have been used
for water supply and cooling in the Middle East.
5. 5
London water supply infrastructure developed over many centuries from early
mediaeval conduits.
Middle and early modern age :
Pail closets, outhouses, and cesspits were used to collect human waste. The use of
human waste as fertilizer was especially important in China and Japan, where cattle
manure was less available.Industrial age :
The first screw-down water tap was patented in 1845. The germ theory of disease
emphasized the need of clean water supply, separated from sewerage.Water towers
appeared around the late 19th century, as building height rose, and steam, electric and
diesel-powered water pumps became available. As skyscrapers appeared, they needed
rooftop water towers.
The technique of purification of drinking water by use of compressed
liquefied chlorine gas was developed in 1910. During the beginning of the 21st Century,
especially in areas of urban and suburban population centres, traditional centralized
infrastructure have not been able to supply sufficient quantities of water to keep up with
growing demand.
6. 6
Trickling filter
A trickling filter consists of a fixed bed of rocks, lava, coke, gravel, slag, polyurethane
foam, sphagnum peat moss, ceramic, or plastic media over which sewage or other
wastewater flows downward and causes a layer of microbial slime (biofilm) to grow,
covering the bed of media. Aerobic conditions are maintained by splashing, diffusion,
and either by forced air flowing through the bed or natural convection of air if the filter
medium is porous.
A schematic cross section of contact face of bed media in a trickling filter
The removal of pollutants from the wastewater stream involves both absorption and
adsorption of organic compounds by the layer of microbial biofilm. Typical materials are
often porous and have considerable internal surface area in addition to the external
surface of the medium. Passage of the wastewater over the media furnishes dissolved
air, the oxygen which the slime layer requires for the biochemical oxidation of the
organic compounds and releases carbon dioxide gas, water and other oxidized end
products. Typically, a trickling filter is followed by a clarifier or sedimentation tank for the
separation and removal of the sloughing.
Types
The three basic types of trickle filters are used for:
the treatment of small individual residential or rural sewage
large centralized systems for treatment of municipal sewage
systems applied to the treatment of industrial wastewater.
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Septic system leach field
This is the simplest form of waste liquid disposal system, typically using pipes buried in
loose sand or gravel to dissipate the liquid outflow from a septic tank. Liquid purification
is performed by a biofilm which naturally forms as a coating on the sand and gravel in
the absorption field and feeds on the dissolved nutrients in the waste stream.
Leach field dosing
Generally it is better if the biofilm is permitted a period of time to rest between liquid
influxes and for the liquids to be evenly distributed through the leaching bed to promote
biofilm growth throughout the pipe network. Typically flows from septic systems are
either small surges (handwashing) or very large surges (clothes washer emptying),
resulting in highly erratic liquid outflow into the field and uneven biofilm growth
concentrating primarily around the field inlet and dropping off in the outer reaches of the
piping system.
For this reason it is common for engineered mound systems to include an electrically
powered dosing system which consists of a large capacity underground storage tank
and lift pump after the septic tank. When the tank fills to a predetermined level, it is
emptied into the leaching field.
The storage tank collects small outflows such as from hand washing and saves them for
dosing when the tank fills from other sources. When full, the discharge dose fills out the
entire field completely to the same degree of flow, every time, promoting an even biofilm
growth throughout the system.
Sewage treatment trickle filters
Onsite sewage facilities (OSSF) are recognized as viable, low-cost, long-term,
decentralized approaches to sewage treatment if they are planned, designed, installed,
operated and maintained properly (USEPA, 1997).
Sewage trickling filters are used in areas not serviced by municipal wastewater
treatment plants (WWTP). They are typically installed in areas where the traditional
septic tank system are failing, cannot be installed due to site limitations.
Sites with a high water table, high bedrock, heavy clay, small land area, or which
require minimal site destruction (for example, tree removal) are ideally suited for
trickling filters.
8. 8
Configurations and components
All sewage trickling filter systems share the same fundamental components:
a septic tank for fermentation and primary settling of solids
a filter medium upon which beneficial microbes (biomass, biofilm) are promoted
and developed
a container which houses the filter medium
a distribution system for applying wastewater to be treated to the filter medium
a distribution system for disposal of the treated effluent or percolation ponds.
By treating septic tank effluent before it is distributed into the ground, higher treatment
levels are obtained and smaller disposal means such as leach field, shallow pressure
trench or area beds are required.
Industrial wastewater treatment trickle filters
Wastewaters from a variety of industrial processes have been treated in trickling filters.
Such industrial wastewater trickling filters consist of two types:
Large tanks or concrete enclosures filled with plastic packing or other media.
Vertical towers filled with plastic packing or other media.
The treated water effluent from industrial wastewater trickling filters is very often
subsequently processed in a clarifier-settler to remove the sludge that sloughs off the
microbial slime layer attached to the trickling filter media
A typical complete trickling filter system
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Wastewater
Wastewater is any water that has been adversely affected in quality by anthropogenic
influence. Municipal wastewater is usually conveyed in a combined sewer or sanitary
sewer, and treated at a wastewater treatment plant or septic tank. Treated wastewater
is discharged into a receiving water via an effluent sewer.
Sewage is the subset of wastewater that is contaminated with feces or urine, but is
often used to mean any wastewater. Sewage includes domestic, municipal, or industrial
liquid waste products disposed of, usually via a pipe or sewer (sanitary or combined),
sometimes in a cesspool emptier.
Sewerage is the physical infrastructure, including pipes, pumps, screens, channels etc.
used to convey sewage from its origin to the point of eventual treatment or disposal. It is
found in all types of sewage treatment, with the exception of septic systems, which treat
sewage on-site.
Etymology: The words "sewage" and "sewer" came from Old French essouier = "to
drain", which came from Latin
Origin
Wastewater or sewage can come from the following:
Human waste also known as blackwater, usually from lavatories;
Cesspit leakage;
Septic tank discharge;
Sewage treatment plant discharge;
Washing water (personal, clothes, floors, dishes, etc.), also known as greywater
or sullage;
Rainfall collected on roofs, yards,etc.
Groundwater infiltrated into sewage;
Surplus manufactured liquids from domestic sources (drinks, cooking oil,
pesticides, lubricating oil, paint, cleaning liquids, etc.);
Urban rainfall runoff from roads, carparks, roofs, sidewalks, or pavements
Seawater ingress (high volumes of salt and microbes
Direct ingress of river water (high volumes of micro-biota);
Direct ingress of manmade liquids (illegal disposal of pesticides, used oils, etc.);
Highway drainage (oil, de-icing agents, rubber residues);
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Storm drains (almost anything, including cars, shopping trolleys, trees, cattle,
etc.);
Industrial waste
Wastewater constituents
The composition of wastewater varies widely. It may consists of the following
Water which is often added during flushing to carry waste down a drain;
Pathogens such as bacteria, viruses, prions and parasitic worms; & Non-
pathogenic bacteria;
Organic particles & Inorganic particles such as sand, grit, metal particles,
ceramics, etc.;
Soluble organic material such as urea, fruit sugars, soluble proteins, drugs, etc.
Soluble inorganic material such as ammonia, road-salt, sea-salt, cyanide,
hydrogen sulfide, thiocyanates, thiosulfates, etc.;
Animals such as protozoa, insects, arthropods, small fish, etc.;
Macro-solids such as napkins, nappie, children's toys, dead animals or plants,
etc.;
Gases such as hydrogen sulfide, carbon dioxide, methane, etc.;
Emulsions such as paints, adhesives, mayonnaise, hair colorants, emulsified oils,
etc.;
Toxins such as pesticides, poisons, herbicides, etc.
Pharmaceuticals and hormones.
Since all natural waterways contain bacteria and nutrients, almost any waste
compounds introduced into such waterways will initiate biochemical reactions (such as
shown above). Those biochemical reactions create what is measured in the laboratory
as the Biochemical oxygen demand (BOD).
Such chemicals are also liable to be broken down using strong oxidizing agents and
these chemical reactions create what is measured in the laboratory as the Chemical
oxygen demand (COD). Both the BOD and COD tests are a measure of the relative
oxygen-depletion effect of a waste contaminant. Both have been widely adopted as a
measure of pollution effect. The BOD test measures the oxygen demand of
biodegradable pollutants whereas the COD test measures the oxygen demand of
oxidizable pollutants.
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Sewage disposal
In some urban areas, sewage is carried separately in sanitary sewers and runoff from
streets is carried in storm drains. Access to either of these is typically through a
manhole. During high precipitation periods a sanitary sewer overflow can occur, forcing
untreated sewage to flow back into the environment. This can pose a serious threat to
public health and the surrounding environment.
Treatment
There are numerous processes that can be used to clean up wastewaters depending on
the type and extent of contamination. There are two basic approaches:
1) to use the waste in the water as a resource (such as constructed wetlands)
2) strictly as a pollution (such as the majority of today's treatment plants).
Most wastewater is treated in industrial-scale energy intensive wastewater
treatment plants (WWTPs) which include physical, chemical and biological
treatment processes. However, the use of septic tanks and other On-Site
Sewage Facilities (OSSF) is widespread in rural areas.
The most important aerobic treatment system is the activated sludge process,
based on the maintenance and recirculation of a complex biomass. Some wastewater
may be highly treated and reused as reclaimed water.
Tertiary treatment is being increasingly applied and most common technologies
are micro filtration or synthetic membranes. After membrane filtration, the treated
wastewater is indistinguishable from waters of natural origin of drinking quality (without
its minerals).
Disposal of Reuse
Treated wastewater can be reused as drinking water, in industry (cooling towers), in
artificial recharge of aquifers, in agriculture and in the rehabilitation of natural
ecosystems .Wastewaters from an industrial plant is a difficult and costly problem.
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Sewage treatment:
Sewage treatment is the process of removing contaminants from wastewater and
household sewage, both runoff (effluents), domestic, commercial and institutional. It
includes physical, chemical, and biological processes to remove physical, chemical and
biological contaminants. Its objective is to produce an environmentally safe fluid waste
stream (or treated effluent) and a solid waste (or treated sludge) suitable for disposal or
reuse (usually as farm fertilizer). Eg: Singapore is the only country to implement such
technology on a production scale.
Origins of sewage
Sewage is generated by residential, institutional, commercial and industrial
establishments. It includes household waste liquid from toilets, baths, showers,
kitchens, sinks and so forth that is disposed of via sewers. In many areas, sewage also
includes liquid waste from industry and commerce. The separation and draining of
household waste into greywater and blackwater is becoming more common in the
developed world, with greywater being permitted to be used for watering plants or
recycled for flushing toilets.
Sewage may include stormwater runoff. Sewerage systems capable of handling storm
water are known as combined sewer systems. Sanitary sewers are typically much
smaller than combined sewers, and they are not designed to transport stormwater.
Process overview : Sewage treatment generally involves three stages, called primary,
secondary and tertiary treatment.
Primary treatment consists of temporarily holding the sewage in a quiescent
basin where heavy solids can settle to the bottom while oil, grease and lighter
solids float to the surface. The settled and floating materials are removed and the
remaining liquid may be discharged or subjected to secondary treatment.
Secondary treatment removes dissolved and suspended biological matter.
Secondary treatment may require a separation process to remove the micro-
organisms from the treated water prior to discharge or tertiary treatment.
Tertiary treatment -Treated water is sometimes disinfected chemically or
physically (for example, by lagoons and microfiltration) prior to discharge into a
stream, river, bay, lagoon or wetland, or it can be used for the irrigation of a golf
course, green way or park. If it is sufficiently clean, it can also be used for
groundwater recharge or agricultural purposes.
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1) Pretreatment: Pretreatment removes materials that can be easily collected from
the raw sewage before they damage or clog the pumps and sewage lines of
primary treatment clarifiers (trash, tree limbs, leaves, branches etc.)
2) Screening: The influent sewage water passes through a bar screen to remove all
large objects like cans, rags, sticks, plastic packets etc. carried in the sewage
stream. This is most commonly done with an automated mechanically raked bar
screen.
3) Grit removal: Pretreatment may include a sand or grit channel or chamber, where
the velocity of the incoming sewage is adjusted to allow the settlement of sand,
grit, stones, and broken glass.
4) 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.
5) Fat & Grease 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.
Activated sludge
In general, activated sludge plants encompass a variety of mechanisms and processes
that use dissolved oxygen to promote the growth of biological floc that substantially
removes organic material.
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Surface-aerated basins (lagoons)
In an aerated basin system, the aerators provide two functions: they transfer air into the
basins required by the biological oxidation reactions, and they provide the mixing
required for dispersing the air and for contacting the reactants (that is, oxygen,
wastewater and microbes).
Filter beds (oxidizing beds)
In older plants and those receiving variable loadings, trickling filter beds are used where
the settled sewage liquor is spread onto the surface of a bed made up of carbonized
coal, limestone chips or specially fabricated plastic media. The liquor is typically
distributed through perforated spray arms. The distributed liquor trickles through the bed
and is collected in drains at the base. These drains also provide a source of air which
percolates up through the bed, keeping it aerobic.
Constructed wetlands
Constructed wetlands (can either be surface flow - horizontal or vertical flow), include
engineered reedbeds and belong to the family of phytorestoration and ecotechnologies;
they provide a high degree of biological improvement and depending on design, act as
a primary, secondary and sometimes tertiary treatment.
Soil bio-technology
A new process called soil bio-technology (SBT) developed at IIT Bombay has shown
tremendous improvements in process efficiency enabling total water reuse. Typically
SBT systems can achieve chemical oxygen demand (COD) levels less than 10 mg/L
from sewage input of COD 400 mg/L. SBT plants exhibit high reductions in COD values
and bacterial counts as a result of the very high microbial densities available in the
media. Unlike conventional treatment plants, SBT plants produce insignificant amounts
of sludge.
Biological aerated filters
Biological Aerated (or Anoxic) Filter (BAF) or Biofilters combine filtration with biological
carbon reduction, nitrification or denitrification. BAF usually includes a reactor filled with
a filter media. The media is either in suspension or supported by a gravel layer at the
foot of the filter.
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Rotating biological contactors
Rotating biological contactors (RBCs) are mechanical secondary treatment systems,
which are robust and capable of withstanding surges in organic load. The rotating disks
support the growth of bacteria and micro-organisms present in the sewage, which break
down and stabilize organic pollutants.
Membrane bioreactors
Membrane bioreactors (MBR) combine activated sludge treatment with a membrane
liquid-solid separation process. The membrane component uses low pressure
microfiltration or ultrafiltration membranes and eliminates the need for clarification and
tertiary filtration. The membranes are typically immersed in the aeration tank; however,
some applications utilize a separate membrane tank.
Secondary sedimentation
The final step in the secondary treatment stage is to settle out the biological floc or filter
material through a secondary clarifier and to produce sewage water containing low
levels of organic material and suspended matter.
Tertiary treatment
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,
ground, etc.).
Filtration
Sand filtration removes much of the residual suspended matter.Filtration over activated
carbon, also called carbon adsorption, removes residual toxins.
Lagooning
Lagooning provides settlement and further biological improvement through storage in
large man-made ponds or lagoons.
Nutrient removal
Wastewater may contain high levels of the nutrients nitrogen and phosphorus.
Excessive release to the environment can lead to a build up of nutrients, called
eutrophication, which can in turn encourage the overgrowth of weeds, algae, and
16. 16
cyanobacteria (blue-green algae). Different treatment processes are required to remove
nitrogen and phosphorus.
Disinfection
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.g., cloudiness, pH, etc.), the type of
disinfection being used, the disinfectant dosage (concentration and time), and other
environmental variables.
Odor control
Odors emitted by sewage treatment are typically an indication of an anaerobic or
"septic" condition.Early stages of processing will tend to produce foul smelling gases,
with hydrogen sulfide being most common in generating complaints. 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.
Sludge treatment and disposal
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.
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Activated sludge
Activated sludge is a process for treating sewage and industrial wastewaters using air
and a biological floc composed of bacteria and protozoa.
Purpose
In a sewage (or industrial wastewater) treatment plant, the activated sludge process is a
biological process that can be used for one or several of the following purposes:
oxidizing carbonaceous biological matter.
oxidizing nitrogeneous matter: mainly ammonium and nitrogen in biological
matter.
removing phosphates.
driving off entrained gases such as carbon dioxide, ammonia, nitrogen, etc.
generating a biological floc that is easy to settle.
generating a liquor that is low in dissolved or suspended material.
The process
The process involves air or oxygen being introduced into a mixture of screened, and
primary treated sewage or industrial wastewater (wastewater) combined with organisms
to develop a biological floc which reduces the organic content of the sewage.
The combination of wastewater and biological mass is commonly known as mixed
liquor. In all activated sludge plants, once the wastewater has received sufficient
treatment, excess mixed liquor is discharged into settling tanks and the treated
supernatant is run off to undergo further treatment before discharge. Part of the settled
material, the sludge, is returned to the head of the aeration system to re-seed the new
wastewater entering the tank. This fraction of the floc is called return activated sludge
(R.A.S.). Excess sludge is called surplus activated sludge (S.A.S.) or waste activated
sludge (W.A.S).
The general arrangement of an activated sludge process for removing carbonaceous
pollution includes the following items:
Aeration tank where air (or oxygen) is injected in the mixed liquor.
Settling tank (usually referred to as "final clarifier" or "secondary settling tank") to
allow the biological flocs (the sludge blanket) to settle, thus separating the
biological sludge from the clear treated water.
18. 18
A generalized, schematic diagram of an activated sludge process.
Types of plants
There are a variety of types of activated sludge plants.These include:
a) Package plants :There are a wide range of other types of plants, often serving
small communities or industrial plants that may use hybrid treatment processes
often involving the use of aerobic sludge to treat the incoming sewage. In such
plants the primary settlement stage of treatment may be omitted. In these plants,
a biotic floc is created which provides the required substrate.Package plants are
commonly variants of extended aeration.
b) Oxidation ditch :In some areas, where more land is available, sewage is treated
in large round or oval ditches with one or more horizontal aerators typically called
brush or disc aerators which drive the mixed liquor around the ditch and provide
aeration. Oxidation ditches are installed commonly as 'fit & forget' technology,
with typical design parameters of a hydraulic retention time of 24 - 48 hours, and
a sludge age of 12 - 20 days.
Deep Shaft
Where land is in short supply sewage may be treated by injection of oxygen into a
pressured return sludge stream which is injected into the base of a deep columnar tank
buried in the ground. Such shafts may be up to 100 metres deep and are filled with
sewage liquor. The rising oxygen and injected return sludge provide the physical
mechanism for mixing of the sewage and sludge. Mixed sludge and sewage is decanted
at the surface and separated into supernatant and sludge components. The efficiency of
deep shaft treatment can be high.However, the costs of construction are high.
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Surface-aerated Basins/Lagoons
Most biological oxidation processes for treating industrial wastewaters have in common
the use of oxygen (or air) and microbial action. The basins may range in depth from 1.5
to 5.0 metres and utilize motor-driven aerators floating on the surface of the wastewater.
In an aerated basin system, the aerators provide two functions: they transfer air into
the basins required by the biological oxidation reactions, and they provide the mixing
required for dispersing the air and for contacting the reactants (that is, oxygen,
wastewater and microbes). Biological oxidation processes are sensitive to temperature
and, between 0 °C and 40 °C, the rate of biological reactions increase with temperature.