Liquid waste management

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1. Liquid waste management Presenter Abishek Regmi

2. Liquid waste can be defined as such Liquids as wastewater, fats, oils or grease (FOG), used oil, liquids, solids, gases, or sludges and hazardous household liquids. These liquids that are hazardous or potentially harmful to human health or the environment. Liquid waste

3. Sources of liquid waste 1. Domestic sources: sources generated from kitchen , bathroom 2. Industrial sources: industries produce waste water mixed with various chemicals especially where water is used for cooling and washing purposes. 3. City source: washing street, rainy season . 4. Habit of people using more water.

4. Household /Institutional level liquid waste management A) Soakage pit: Suitable for household waste disposal. Pit is about 3 feet in diameter and 4-6 feet deep. Pit is filled with bricks and stone. Liquid waste disposal management

5. B) Soak Well/ Seepage pit: Larger in size than soakage pit. Size: 6-20 feet deep .

6. C) Surface irrigation/kitchen garden irrigation: waste from household irrigates directly to kitchen garden after storage.

7. D) Dispersion trench/ subsoil irritation: This dispersion trench is used where water level is high, and hard to dig the pit . Trench is 1 feet in deep. pipe is covered with gravel and soil.

8. E) Cesspool: A n underground container for the temporary storage of liquid waste and sewage.

9. F) Reed bed: Reed is water and marsh plant. It helps to soaks the liquid waste

10. URBAN AREA/ SEWERED AREA • It consists of water carriage system and sewage treatment plant. • It implies collecting and transporting waste waster and human excreta from residential , industrial and commercial area by under ground pipes. There are two types of water carriage systems 1) Combined sewer system 2) separate sewer system: surface water is not

11. Combined sewer system COMBINE SEWER SYSTEM: Carry both the sewage and surface water. SEPARATE SEWER SYSTEM: Surface water is not admitted . Sewage is waste water from a community containing solid and liquid excreta, derived from houses, street and yard washings, factories and industries . sewage contain 99.9% of water which is dirty and bad smell. Water carriage system consists of: household sanitary fittings( water closet, basin, urinal), house sewer and public sewer.

12. Sewage treatment Aims of sewage treatment: 1. Inadequate sewage treatment should not be discharged into river, sea and other sources of water supply. 2. Bacteria from inadequate treatment water may lead depletion of oxygen and lead to occur death of plant and animals.

13. Treatment of sewage a)Screening b) Removal of grit c) Primary sedimentation. d)Biological sedimentation e)Final sedimentation f)Sludge digestion g)Disposal of effluent Others methods • Sea out fall • River out fall • Land treatment • Oxidation ponds and ditches.

14. Water carriage system 1.Household sanitary fittings: • House hold sanitary fitting are water closet, wash basin and urinal • The closet is connected to a small cistern by a pipe2.5-3.75cm in diameter • Flushing cistern holds 15 liters of water 2. House Sewer: • House drain is 10cm in diameter and laid in the courtyard about 15cm below the ground level on a bed of cement 3. Public Sewer: • Trunk sewers is 22.5 cm in diameter. They are laid 3m below the ground level with cement concrete.

15. 4. Sewer appurtenances: These are opening entrance for man to enter the sewer for inspection, repair and cleaning. Sewage treatment steps( IMP) Primary/mechanical Secondary/biological Tertiary/Chemical

16. Primary Rx 1) Influx and removal of large objects: It is done with mechanical raked screen which removes and screen sticks, sanitary towels, fruits, napkins. This is removed to prevent from damage of sensitive equipment's of treatment plant . 2)Sand and grit removal ( Grit Chamber): Detritor removes sand and grit from channel to prevent damage to pump and other equipment's.

17. 3.) Maceration: Solid are cut into small particles through the use of rotating knife 4)Primary sedimentation : • 50-70% of solids are settle down under the gravity. • Reduction of 30-40% in the number of coliform organization is obtained. Raw sewage Screens Grit chambers Detritus tank Skimming Primary sedimentation tank To secondary treatment plant

18. Secondary Rx • Secondary Rx is designed to degrade the biological content of the sewage derived from food ,waste, soap and detergents. Secondary treatment is classified into two ways : • Fixed or suspended growth. • In fixed system such as rock filters the biomass grows on media and the sewage passes over its surface. • In suspended growth systems: such as activated sludge the biomass is well mixed with the sewage.

19. 1. Trickling filters: Filter beds using plastic media. Is a bed of crushed stone 1 to 2m deep and 2 to 30m in diameter.

20. 2) Activated Sedimentation Mixture of sludge into chamber for 6 to 8hrs. Organic matter of sewage gets oxidized into CO2, nitrates and water with the aerobic bacteria in the activated sludge.

21. 3) Secondary sedimentation Settle down all materials and only contain low levels of organic materials and suspended particles

22. Tertiary RX . • Final stage before discharge water into environment. Also called Effluent polishing. A) Filtration: sand filtration residual suspended matter B) Lagooning: provides settlement and further biological improvement through storage in large man made ponds or lagoons. C) constructed wetland: provides high degree of aerobic biological improvement and can be used instead of secondary treatment for community. Reedbed is used to clean the drainage D) nutrient removal: All nutrient from water is removed which may be toxic to fish and invertebrates. E) Disinfection: in waste water is to reduce the number of living organism in the water. Effectiveness of disinfection is depend upon the water being treated( PH, Turbidity). UV lights is common form of disinfection in UK. Chlorination is most common in North America. Ozone dis-infection.

23. Thankyou