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Wastewater treatment

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Wastewater treatment

  1. 1. Water & Wastewaters Treatment 10/9/2014 Waste treatment and cleaner Technologies
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  3. 3. Distribution of water on earth • Ocean and sea - 97% • Snow and ice caps - 2% • Rivers, lakes, Ground water - 1% 10/9/2014 Waste treatment and cleaner Technologies
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  5. 5. Safe drinking water • Free from pathogenic organisms • Clear • Not saline • Free from offensive taste or smell • Free from compounds that may have adverse effect on human health • Free from chemicals that cause corrosion of water supply systems 10/9/2014 Waste treatment and cleaner Technologies
  6. 6. WATER QUALITY PARAMETERS • Physical parameters • Chemical • Bacteriological 10/9/2014 Waste treatment and cleaner Technologies
  7. 7. BUREAU OF INDIAN STANDARDS IS 10500 -1991 Parameters Disirable limit Permissible limit Colour Hazen unit 5 25 Turbidity- NTU 5 10 pH 6.5 - 8.5 6.5 -8.5 Hardness (as CaCO3)mg/l 0.3 1 TDS 500 22000 10/9/2014 Waste treatment and cleaner Technologies
  8. 8. BUREAU OF INDIAN STANDARDS IS 10500 -1991 Parameters Desirable limit Permissible limit Nitrate mg/l 45 45 Chloride mg/l 250 1000 Flouride mg/l 1 1.5 Arsenic mg/l 0.05 0.05 Aluminium mg/l 0.03 0.2 10/9/2014 Waste treatment and cleaner Technologies
  9. 9. Colour • May be due to the Presence of organic matter, metals(iron, manganese) or highly colored industrial waste • Aesthetically displeasing • Desirable that drinking water be colourless • Desirable limit, 5 Hazen unit • Permissible limit 25 Hazen Unit 10/9/2014 Waste treatment and cleaner Technologies
  10. 10. Taste and Odour • Mainly due to organic substances, ,Biological activity, industrial pollution • Taste buds in the oral cavity specially detect inorganic compounds of metals like magnesium, calcium, sodium, copper, iron and zinc • Water should be free from objectionable taste and odour. 10/9/2014 Waste treatment and cleaner Technologies
  11. 11. Turbidity • Caused by suspended matter • High level turbidity shield and protect bacteria from the action of disinfecting agents • Desirable limit-5 NTU should be below 1 NTU when disinfection is practiced Permissible limit-10 NTU 10/9/2014 Waste treatment and cleaner Technologies
  12. 12. pH • It is the measure of hydrogen ion concentration • Neutral water pH-7 • Acidic water has pH below 7 • Basic water has pH above 7 • Desirable limit 6.5-8.5 Beyond this limit the water will affect the mucous membrane and water supply system 10/9/2014 Waste treatment and cleaner Technologies
  13. 13. Substances that change pH of water Acidic Industries Basic industries Sugar 5-6 Paper 8-10 Distillery 3-4 Textile 8.5-11 Electroplating unit 2.5-4 Fertilizer 6.5 - 9 Pickle 2-3 Oil Refineries 6.5- 9 Battery acids <1.0 Milk 6.7 Carbonated Beverages 2 – 4 Rain water 6.5 Lemon juice 2.3 Blood 7.5 Orange juice 4..2 Sea water 8.0 Vinegar 3 Ammonia solution 11.3 Domestic sewage 6.5-8.5 Ground water 7.5-8.5 10/9/2014 Waste treatment and cleaner Technologies
  14. 14. HARDNESS • Capacity of water for reducing and destroying the lather of soap • It is total concentration of calcium and magnesium ions • Temporary hardness – Bicarbonates of Calcium and Magnesium • Permanent hardness – Sulphates, chlorides and nitrates of calcium and magnesium • 0 – 5 0 mg/ l - soft • 50 – 15 0 mg/l - moderately hard • 150 – 3 00 mg/l - hard • 300 above - very hard • Surface water is softer than ground water • Causes encrustations in water supply structures 10/9/2014 Waste treatment and cleaner Technologies
  15. 15. ALKALINITY • Capacity to neutralize acid • Presence of carbonates, bi-carbonates and hydroxide compounds of Ca, Mg, N a and K • Alkalinity = hardness, Ca and Mg salts • Alkalinity > hardness - presence of basic salts, N a, K along with Ca and Mg • Alkalinity < hardness – neutral salts of Ca & Mg present 10/9/2014 Waste treatment and cleaner Technologies
  16. 16. IRON • One of the earth’s most plentiful resource • High iron causes brown or yellow staining of laundry, household fixtures • Metallic taste, offensive odour, poor tasting coffee • Cause iron bacteria • Acceptable limit – 0 .3 mg / l 10/9/2014 Waste treatment and cleaner Technologies
  17. 17. CHLORIDE Causes • Dissolution of salt deposit • Discharge of effluents • Intrusion of sea water • Not harmful to human beings • Regarding irrigation – most troublesome anion • Acceptable limit – 250 mg/l 10/9/2014 Waste treatment and cleaner Technologies
  18. 18. NITRATE Increasing level of nitrate is due to • Agricultural fertilizers, manure, animal dung, nitrogenous material ,sewage pollution (blue baby diseases to infants) • Maximum permissible limit 45 mg / l 10/9/2014 Waste treatment and cleaner Technologies
  19. 19. FLOURIDE • Occurs naturally • Long term consumption above permissible level can cause – dental flurosis (molting of teeth) and Skeletal flurosis • Acceptable limit – 1 mg / l • Maximum permissible limit – 1.5 mg / l • Remedy – 1) Deflouridation 2) Mixing Fluoride free water 3) Intake of vitamin C, D, calcium, antioxidants 10/9/2014 Waste treatment and cleaner Technologies
  20. 20. FLOURID E CAUSES Three types of flurosis 1. Dental flurosis 2. Skeletal flurosis 3. Non-skeletal flurosis 10/9/2014 Waste treatment and cleaner Technologies
  21. 21. A R S E N I C • Occur in ground water from arseniferous belt • Industrial waste, agricultural insecticide • High arsenic causes 1) various type of dermatological lesions, muscular weakness, paralysis of lower limbs, can also cause skin and lung cancer • Acceptable limit – 0.05 mg / l 10/9/2014 Waste treatment and cleaner Technologies
  22. 22. Heavy Metals • Present as mineral in soil and rocks of earth • Human activities Battery – Lead & Nickel Textile - Copper Photography – Silver Steel production – Iron 10/9/2014 Waste treatment and cleaner Technologies
  23. 23. Pesticides • Cancer • Birth defects • Blood disorder • Nervous disorder • Genetic damage 10/9/2014 Waste treatment and cleaner Technologies
  24. 24. Common problems Visible effects Reasons Iron taste, change in colour after exposure to atmosphere, change in colour of cloths, utensils Oily appeal- rance on top of water body Iron Soap not lathering hardness Brownish black streaks on teeth Fluoride Growth of Algae Nitrate, phosphate Fish kills Low pH less DO water turns black, smell Waste water Acidic taste Low pH Alkaline taste High pH Boiled Rice hard and yellow High Alkalinity White deposits on boiling Hardness 10/9/2014 Waste treatment and cleaner Technologies
  25. 25. Water Quality DO (ppm) at 20°C Good 8 –9 Slightly polluted 6. 7 – 8 Moderately polluted 4.5 – 6. 7 Heavily polluted 4 – 4.5 Gravely polluted Below 4 10/9/2014 Waste treatment and cleaner Technologies
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  27. 27. • Dilution • Biodegradation of wastes by bacteria takes time • Oxygen sag curve 10/9/2014 Waste treatment and cleaner Technologies
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  34. 34. Major Water Pollutants Have Harmful Effects • Infectious disease organisms: contaminated drinking water • The World Health Organization ( WHO) – 3 Million people die every year, mostly under the age of 5 10/9/2014 Waste treatment and cleaner Technologies
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  37. 37. IMPORTANT WASTEWATER CONTAMINANTS Contaminant Source Environmental significance Suspended solids Domestic use, industrial wastes, erosion by infiltration/inflow Cause sludge deposits and anaerobic conditions in aquatic environment Biodegradable organics Domestic and industrial waste Cause biological degradation, which may use up oxygen in receiving water and result in undesirable conditions Pathogens Domestic waste Transmit communicable diseases Nutrients Domestic and industrial waste May cause eutrophication Refractory organics Industrial waste May cause taste and odor problems, may be toxic or carcinogenic Heavy metals Industrial waste, mining, etc. Are toxic, may interfere with effluent reuse Dissolved inorganic solids Increases above level in water supply by domestic and/or industrial use May interfere with effluent reuse 10/9/2014 Waste treatment and cleaner Technologies
  38. 38. Unit operations, unit processes, and systems for wastewater treatment Contaminant Unit operation, unit process, or treatment system Suspended solids Sedimentation Screening and comminution Filtration variations Flotation Chemical-polymer addition Coagulation sedimentation Land treatment systems Biodegradable organics Activated-sludge variations Fixed-film: trickling filters Fixed-film: rotating biological contactors Lagoon and oxidation pond variations Intermittent sand filtration Land treatment systems Physical-chemical systems Pathogens Chlorination Hypochlorination Ozonation Land treatment systems 10/9/2014 Waste treatment and cleaner Technologies
  39. 39. Nutrients: Nitrogen Suspended-growth nitrification and denitrification variations Fixed-film nitrification and denitrification variations Ammonia stripping Ion exchange Breakpoint chlorination Land treatment systems Phosphorous Metal-salt addition Lime coagulation; sedimentation Biological-chemical phosphorus removal Land treatment systems Refractory Organics Carbon adsorption Tertiary Ozonation Land treatment system Heavy Metals Chemical precipitation Ion exchange Land treatment systems Dissolved inorganic solids Ion exchange Reverse osmosis Electrodialysis 10/9/2014 Waste treatment and cleaner Technologies
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  51. 51. Microorganisms Classification:  Heterotrophic- obtain energy from oxidation of organic matter (organic Carbon)  Autotrophic- obtain energy from oxidation of inorganic matter (CO2, NH4, H+ )  Phototrophic- obtain energy from sunlight 10/9/2014 Waste treatment and cleaner Technologies
  52. 52. Biochemical Pathways  oxidation of organic molecules inside the cell can occur aerobic or anaerobic manner  generalized pathways for aerobic & anaerobic fermentation 10/9/2014 Waste treatment and cleaner Technologies
  53. 53. Biochemical Pathways C6H12O6 + 6O2 +38 ADP + 38 Pi 6 CO2 +38 ATP + 44 H2O  aerobic pathways contains- EMP(Embden–Meyerhof–Parnas) pathways, TCA(tricarboxylic acid cycle) cycle, respiration  anaerobic pathways contains- EMP pathways  released energy stored as ATP molecules  excess food is stored as Glycogen 10/9/2014 Waste treatment and cleaner Technologies
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  60. 60. Embden-Meyerhof-Parnas pathway (EMP pathway), which was first discovered by Gustav Embden, Otto Meyerhof and Jakub Karol Parnas. 10/9/2014 Waste treatment and cleaner Technologies
  61. 61. Tricarboxylic acid cycle (TCA cycle), the Krebs cycle, or the Szent-Gyorgyi–Krebs cycle 10/9/2014 Waste treatment and cleaner Technologies
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  63. 63. Biological growth - exponential growth (batch) - Monod kinetics - Haldane kinetics under toxic conditions 10/9/2014 Waste treatment and cleaner Technologies
  64. 64. Biological growth...  exponential growth dX dt = X Log No. of Cells Time Lag phase Log growth phase Stationary phase Death phase 10/9/2014 Waste treatment and cleaner Technologies
  65. 65. Biological growth...  Monod kinetics Substrate Concentration (S) Specific growth rate ( μ) μ Max. rate m μm/2 ks S m  K S μ μ s  10/9/2014 Waste treatment and cleaner Technologies
  66. 66. Treatment stages - Secondary treatment • Degrade biological content (dissolved organic matter) of the sewage – Ex: human waste, food waste, soaps, detergent • Added bacteria and protozoa into sewage • 3 different approaches – Fixed film system – Suspended film system – Lagoon system 10/9/2014 Waste treatment and cleaner Technologies
  67. 67. Biological Carbonaceous Removal  aerobic - oxidation bacteria CHONS + O2 + Nutrients CO2 + NH3 + C5H7NO2 + other end products (organic matter) (new bacterial cells) - endogenous respiration bacteria C5H7NO2 + 5O2 5CO2 + 2H2O + NH3 + energy (cells) 10/9/2014 Waste treatment and cleaner Technologies
  68. 68. Biological Carbonaceous Removal  anaerobic Hydrolysis Acidogenesis Methenogenesis Complex Organics 100% 20% 5% 60% 15% Intermediates 15% Propionate 35% 17% 10% 13% H2 Acetate 72% 28% Schematic of the Anaerobic Process CH4 10/9/2014 Waste treatment and cleaner Technologies
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  70. 70. Biological treatment – Trickling bed filter – Activated sludge 10/9/2014 Waste treatment and cleaner Technologies
  71. 71. • Fixed Film Systems – grow microorganisms on substrates such as rocks, sand or plastic – wastewater is spread over the substrate – Ex: Trickling filters, rotating biological contactors 10/9/2014 Waste treatment and cleaner Technologies
  72. 72. Trickling filters bed • Spread wastewater over microorganism • made of coke (carbonized coal), limestone chips or specially fabricated plastic media • Optimize their thickness by insect or worm grazing 10/9/2014 Waste treatment and cleaner Technologies
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  75. 75. Advantages • Simple, reliable, biological process. • Suitable in areas where large tracts of land are not available for land intensive treatment systems. • May qualify for equivalent secondary discharge standards. • Effective in treating high concentrations of organics depending on the type of medium used. • Appropriate for small- to medium-sized communities. • Rapidly reduce soluble BOD5 in applied wastewater. • Efficient nitrification units. • Durable process elements. • Low power requirements. • Moderate level of skill and technical expertise needed to manage and operate the system. Disadvantages • Additional treatment may be needed to meet more stringent discharge standards. • Possible accumulation of excess biomass that cannot retain an aerobic condition and can impair TF performance (maximum biomass thickness is controlled by hydraulic dosage rate, type of media, type of organic matter, temperature and nature of the biological growth). • Requires regular operator attention. • Incidence of clogging is relatively high. • Requires low loadings depending on the medium. • Flexibility and control are limited in comparison with activated-sludge processes. • Vector and odor problems. • Snail problems. 10/9/2014 Waste treatment and cleaner Technologies
  76. 76. • Suspended Film Systems – stir and suspend microorganisms in wastewater – settled out as a sludge – pumped back into the incoming wastewater – Ex: Activated sludge, extended aeration 10/9/2014 Waste treatment and cleaner Technologies
  77. 77. Activated sludge • mixed community of microorganisms • Both aerobic and anaerobic bacteria may exist • Biological floc is formed 10/9/2014 Waste treatment and cleaner Technologies
  78. 78. physical components of activated sludge process • Aeration tank – oxygen is introduced into the system • Aeration source – ensure that adequate oxygen is fed into the tank – provided pure oxygen or compressed air • Secondary clarifiers – activated-sludge solids separate from the surrounding wastewater • Activated sludge outflow line – Pump activated sludge back to the aeration tank • Effluent outflow line – discharged effluent into bay or tertiary treatment plant 10/9/2014 Waste treatment and cleaner Technologies
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  80. 80. • Lagoon Systems – hold the waste-water for several months – natural degradation of sewage 10/9/2014 Waste treatment and cleaner Technologies
  81. 81. Treatment stages – Tertiary treatment • remove disease-causing organisms from wastewater • 3 different disinfection process – Chlorination – UV light radiation – Ozonation 10/9/2014 Waste treatment and cleaner Technologies
  82. 82. What can effluent use for? • discharged into a stream, river, bay, lagoon or wetland • used for the irrigation of a golf course, green way or park • If it’s sufficiently clean, it can be used for groundwater recharge 10/9/2014 Waste treatment and cleaner Technologies
  83. 83. Advanced Treatment • Nitrogen removal -)→ nitrate (NO3 – Ammonia (NH3) → nitrite (NO2 -) • Phosphorous removal – Precipitation with iron or aluminums salt • Lead to eutrophication • May cause algae bloom 10/9/2014 Waste treatment and cleaner Technologies
  84. 84. Sludge treatment • Primary sludge usually have strong odors • Secondary sludge have high concentration of microorganism • Goals of treatments are: – Reduce odors – Remove water reduce volume – Decompose organic matter 10/9/2014 Waste treatment and cleaner Technologies
  85. 85. 3 different sludge treatments • Aerobic digestion • Anaerobic digestion • composting 10/9/2014 Waste treatment and cleaner Technologies
  86. 86. Aerobic digestion • Bacterial process • Need oxygen • Consume organic matter • Convert into carbon dioxide (CO2) Anaerobic digestion • Bacterial process • Do not require oxygen • Consume organic matter • Produce biogas, which can be used in generators for electricity 10/9/2014 Waste treatment and cleaner Technologies
  87. 87. Composting • aerobic process • requires the correct mix of carbon, nitrogen, oxygen and water with sludge • Generate large amount of heat 10/9/2014 Waste treatment and cleaner Technologies
  88. 88. Sludge disposal • Superheat sludge and convert into small granules that are rich in nitrogen – Sell it to local farmer as fertilizer • Spread sludge cake on the field • Save landfill space 10/9/2014 Waste treatment and cleaner Technologies
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  104. 104. Water Quality Parameters and Definitions Temperature it affects the amount of dissolved oxygen Temperature also affects the rate of photosynthesis of plants, the metabolic rate of aquatic animals, rates of development, timing and success of reproduction, mobility, migration patterns and the sensitivity of organisms to toxins, parasites and disease. Life cycles of aquatic organisms are often related to changes in temperature. Salinity Salinity is a measure of the dissolved salts in the water pH pH is a measure of the acidity or alkalinity of water. Turbidity a measure of the water’s murkiness. Turbidity is measured in Nephelometric Turbidity Units (NTU’s). Dissolved oxygen (do) The amount of oxygen in water Conductivity Conductivity indicates the presence of ions within the water Colour (Hazen) Colour is vital as most water users, be it domestic or industrial, usually prefer colourless water Total Suspended Solids, TSS Total Dissolved Solids, TDS The total dissolved solids (TDS) in water consist of inorganic salts and dissolved materials. Biochemical Oxygen Demand, BOD BOD is a measure of organic pollution to both waste and surface water Chemical Oxygen Demand, COD Ammoniacal Nitrogen Potassium Microbiological Total Coliform Count Faecal Coliform Count Pesticides Chlorinated, Glyphosphate, Paraquat ,Methamidaphos 10/9/2014 Waste treatment and cleaner Technologies

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