Introduction: Sewage: •Also known as waste water •The liquid waste obtained from a community. •Includes discharges from latrines, urinals, & stables •Discharges from industry & rainfall are also included Types of Sewage: a. Sanitary Sewage b. Industrial Sewage c. Combined Sewagea. Sanitary Sewage: b. Industrial Sewage: c. Combined Sewage:• Also known as Domestics Sewage • The foul discharges from • Combination of Sanitary• The foul discharges from industries sewage & Storm water residential & commercial area • It includes discharges • Storm water is rain & snow• It mainly includes discharges produced during the melt that runs off surfaces such from latrines, urinals, laundry etc manufacturing of goods as rooftops, paved streets, highways & parking lots.
Sewerage System:Sewerage:• Sewage is produced everyday in towns & cities.• Accumulation of sewage increases if not conveyed regularly• Sewage has to be removed as early as possible.• If not removed, it will cause insanitary condition• The network of collecting & conveying sewage by water carriagesystem through under ground pipes sewers is known as Sewerage.• Components of sewerage system are :a) Drain b) Manhole c) Pumping station d) Sewer Drain: Man hole: Pumping Station:Is a plumbing fixture that The opening or hole through Includes pumps &equipmentsprovides an exit-point for which a man can enter the sewer for pumping fluids.waste water or water that line or other closed structure for Supplies water to removeis to be re-circulated inspection and cleaning sewage from processing site
Sewer:• Are the underground conduits or drains• Used for carrying the sewage•The most common types of sewer are:I. Sanitary Sewer :• Is a underground carriage system.• Used for transporting sewage from houses and commercial buildings• Sanitary sewers serving industrial areas also carry Industrial sewage.• Sanitary sewage is collected with the help of sanitary sewer line• The sanitary sewer is attached to a main sewer.• The main sewer runs directly to the sewage treatment plant.II. Storm Sewer:• A storm sewer collects storm water with the help of gutter & catch basin• Gutter allow the storm water to drain from the street directly into the storm sewer.
Sewer:III. Combined Sewer:• Type of sewer system• Collects sanitary sewage & storm water run off in a single pipe system.• Can cause serious water pollution problems due to combined sewer overflows• Caused by large variations in flow between dry and wet weather.• This type of sewer design is no longer used in building new communities.
Principles Of Sanitation: Following are the principles for better living condition: Waste materials like sewage should be removed as early as possible Sewage after collection should be treated within four hours. Effluent should be disposed of immediately Building should be damp proof Water supply should be regular & sufficient so that the lavatories may be done properly
Features Of Sewerage System: Main features of sewerage system are : A. Collection B. Conveyance C. Treatment D. DisposalA. Collection & Conveyance :• Sewage is collected & conveyed through the system of pipe lines or sewers• The system of sewers is called sewerage or sewerage system• Where sewerage system is not provided, sewage is collected in septic or imhoff tankC. Sewage Treatment:• Is a process of removing contaminants from sewage• Objective is to produce an environmentally safe treated effluent and sludge suitable for disposal or reuse• Discharge to the environment must be accomplished without transmitting diseases or endangering aquatic organisms,
Sewage Treatment :There are 2 types of treatment system:I. Septic & Imhoff Treatment System II. Waste Water Treatment Plant (WWTP) I. A) Septic System: • Consists of two major parts, the septic tank & drain field • The septic tank separates the sewage into three components : Sludge(solid waste), Scum (floatables) & Effluent (grey - water) • Working Of Septic Tank: 1. Sewage enters via the inlet pipe 2. Gravity pulls the solids to the base. 3. Scum layer is formed on the surface due to anaerobic biological action. 4. Grey water leaves through the outlet pipe. 5. The effluent flows into a distribution box which then distributes the effluent equally among the trenches in the drain field.
Sewage Treatment : Working Of Drain field: 1. The final treatment takes place in drain field. 2. Effluent trickles out of the pipes, through the gravel layer and passes into the soil 3. The soil filters the wastewater as it passes through the pore spaces 4. The soil microbes deactivates the disease germs that remain in the effluent 5. Eventually treated water enters the groundwater 6. These processes work best where the soil is dry, permeable, and contains plenty of oxygen below the drain field.
Sewage Treatment : I. B) Imhoff Treatment System: • Is a 2 storied sludge digestion tank • Invented by German scientist Mr. Karl Imhoff • Working Of Imhoff Tank: 1. Sewage enters via the inlet pipe 2. Settling of solids occurs in the upper compartment. 3. Effluent leaves through the outlet pipe. 4. Sludge falls through the slot to the digestion tank. 5. Anaerobic bacteria decomposes the organic matter. 6. Digestion process generates biogas 7. Biogas escapes through gas vent 8. Digested sludge is removed by the sludge removal pipe
Sewage Treatment :II. Waste Water Treatment Plant:• It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants.• Sewage treatment is a multistep process• Sewage treatment involves four stages:1) Preliminary treatment2) Primary treatment3) Secondary treatment4) Tertiary treatment
Sewage Treatment Process:1) Preliminary Treatment: A• Removes large objects and non-degradable materials.• Protects pumps and equipment from damage• Consists of following:a. Bar Screen catches large objects that have gotten into sewer system such as bricks, bottles, pieces of wood, etc B Cb. Grit Chamber removes rocks, gravel, broken glass, etcc. Mesh Screen removes diapers, combs, towels, plastic bags, syringes, etc
Sewage Treatment Process:2) Primary Treatment:• It is a physical process.• Also known as sedimentation stage• Sewage flow is slowed down• Suspended solids settles to the bottom by gravity• The material that settles is called sludge or bio solids• Sludge is pumped to the sludge digestion tank.• Effluent is pumped to the trickling filter or aeration tank for secondary treatment.
Sewage Treatment Process:3) Secondary Treatment:• The primary effluent is put into an aerated basin which is mixed with air.• Organic matter is eaten by aerobic bacteria.• The mixture of uneaten particles and microbes is transferred to secondary clarifier.• Microbes & organic matter settles down due to gravity in secondary clarifier.• Part of them are sent back to eat more sewage while the rest is sent to sludge digestion tank.• The solid free effluent from the clarifier is further sent for Tertiary treatment.
Sewage Treatment Process:4) Tertiary Effluent Treatment:• It is a chemical process.• Nitrogen, phosphorus, fine suspended particles and microbes are removed• Disinfectants are added to destroy micro-organisms.• Common disinfectants used are ozone , chlorine & ultra violent rays.• Thus effluent is then discharged to the water body.4) Tertiary Sludge Treatment:• Sludge obtained is transported to digestion tank• Organic matter is broken down by bacteria an-aerobically• Sludge effluent obtained after digestion is further kept for drying• Some portion of the sludge effluent is disposed off• Rest is converted to methane gas to power the treatment processes.
Sewage Treatment Process:
Features Of Sewerage System:D. Sewage Disposal :• Is an action or a process of throwing away or getting rid of sewage.• Purpose of Sewage disposal: To conserve water resources. To prevent contamination of drinking supplies. To help promote health & comfortable living To prevent the contamination of surface water use for bathing and other resourceful uses.• Various way of disposing sewage are:1) Dumping of treated effluent into underground2) Incineration : Dumping of effluent into seas.3) Agriculture: Using treated sludge as manure4) Reuse of reclaimed water
Reuse Of Effluent Reuse of treated effluent or grey water can be done in following ways : Fire Fighting System Irrigation Flushing Car wash Industries Road wash