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Fundamentals of Environmental Engineering II

Introduction to protecting air, water, and food quality, with focus on water supply, waste management, pollution control, and water requirements. Learn about the history, sources of water, pollution, system models, and design principles.

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Fundamentals of Environmental Engineering II

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  1. ENVIRONMENTAL ENGINEERING II Mr. Shree Kamble DEPARTMENT OF CIVIL ENGINEERING Dr. D Y PATIL INSTITUTE OF ENGINEERING MANAGEMENT & RESEARCH

  2. UNIT 1: Introduction • Air , water & food essential for human existence • If polluted creates problems: air- respiratory deceases, water - water borne deceases & food- food poisoning • Therefore essential to protect them • Productivity of nation dependents on these factors

  3. Objectives of EE • To supply water safe in quality & adequate in quantity • To collect treat and dispose WW generated in community • Domestic waste contributes 60 % of total water pollution • To put in place, the methods on pollution prevention in industries • I.e. Solid waste, liquid waste and air pollutants • To control air pollution • To control solid waste ( Community & industry)

  4. Quantity & Quality • History: • Civilization development on banks of river • Importance of quantity was realized very earlier but not the quality • Storage of water in copper vessels: Bactericidal property to water (Indian literature) • First recorded incident: 1854- Central London, Dr. John Snow • Handled Broad Street hand pump: Colara decease • Removed handle of hand pump and got punished

  5. Attributes of Drinking Water: • Aesthetics : Free from colour, taste, odour & pleasing (physical perception) Hence, subjective test. • Safety : • Bacteriological ( Free from pathogens disease causing micro-organisms) Analytical test. • Chemical: Free from toxicants like heavy metals. • Anthropogenic activities (Mercury- Biomagnification) • Natural (Arsenic – geological formations) • Economics

  6. Quantity of Water: • ¾ surface is covered with water • 0.62% of the total water is available as fresh water for supplies • Sources of water: • Groundwater (Fe & Mn – causes stains) • Shallow <30m ( Bactriological contamination) • Deep >300m ( Inorganic contaminants ) • Surfacewater ( Pathogens, organic inorganic pollutants) • Lakewater ( Algal growth, taste & odour) • Seawater ( Salinity, TDS) • Treated Effluents ( Pathogens, nutrients) – ZLD Concept

  7. Basic concepts: • Pollution : Foreign organic or inorganic material • Sources of pollution: Point / Nonpoint • Contamination : Micro-organisms, pathogens • Pollution caused by Anthropogenic activities : • Suspended load • Colloidal/ Coarse • Chemical • Organic – Biodegradable / Non-biodegradable • Inorganic - Pesticides • Microbiological - Pathogens

  8. System Model • Water Quality Graph

  9. Design Period • Collection system i.e. Sewer Network : 30 yrs • Pumping station (Civil Work) : 30 yrs • Pumping machinery : 15 yrs • Sewage Treatment Plant (STP) : 30 yrs • Effluent disposal & utilization : 30 yrs

  10. Collection of Sewage • Separate system: Municipal wastewater • Combined system : Municipal wastewater + Storm water

  11. Flow Quantity Estimation • Design period • Population forecasting • Per capita sewage flow • For dry weather : 40 % • For well developed areas : 90 % due to industrial wastewater • Generally, 80 % of water supply is expected to reach sewers • Minimum of 100 lpcd is considered for design of sewers • Variations • Peak factors are adopted for hydraulic design of sewers • Peak factor : (2-3) based on contributory population

  12. Water Requirements • Per capita water demand – 135 lpcd and a minimum of 70 to 100 lpcd • Bathing – 55 • Washing of cloths – 20 • Flushing of WC – 30 • Washing of house – 10 • Washing of utensils – 10 • Cooking – 5 • Drinking – 5 Total – 135

  13. Water Requirements • Institutional use • Hospital • Bed < 100 ---- 450 per bed • Bed > 100 ---- 340 per bed • Hotels - 180 • Hostels, Boarding schools colleges - 135 • Restaurants, Airports / Sea ports - 70 • Day schools, colleges & offices – 45 • Cinema, concert halls - 15

  14. Design of circular sanitary Sewer • The sewage in sewer should flow under gravity with 0.5 to 0.8 full at designed discharge • The sewers should be laid at least 2 to 3 m deep to carry sewage from basement. • Calculation of design peak flow from given data • Minimum daily flow = 1/3 to 2/3 of Avg daily flow • While designing the sewers the flow velocity at full depth is generally kept at about 0.8m/sec • It is necessary to check the sewer for minimum velocity of about 0.45 m/sec at the time of minimum flow (1/3 of average flow) and the velocity of about 0.9 to 1.2 m/sec should be developed at a time of average flow.

  15. Design of circular sanitary Sewer • Hydraulic Formulae for Determining Flow Velocities • Manning’s Formula V = 1/n r^2/3 s^1/2 n = 0.011 to 0.015 • Chezy’s Formula V = C r^0.5 s^0.5 • Hazen Williams Formula V = 0.849 C r^0.63 s^ 0.54 C = 120 • Minimum velocity : Self cleansing velocity • Vs = (8K/f’ * (Ss-1)g.d’)^1/2 • K = 0.04 for inorganic solids and 0.06 for organic solids • F = 0.03 Darcy Weisbatch friction factor • Ss = Specific gravity of sediments • d’ = Diameter of grain , m

  16. Pumping of Sewage • Necessity & Location • Pumping of sewage from localized low lying pockets • To prevent excavation to lay down sewers • Pumping of sewage from basements of structures • Transfer of sewage across high ridge (i.e. instead of tunnel ) • Effect of change of lifestyle on sewage quality

  17. Effluent Discharge Standards

  18. Stream Sanitation • Self purification of natural streams • Rive classification as per MoEF & CC

  19. Self purification of natural streams • Physical Forces • Dilution & Dispersion : CsQs + CRQR = C (Qs+QR) • Sedimentation • Sunlight : stabilizing bacteria & photosynthesis) • Bio-Chemical Forces • Oxidation • Reduction : Hydrolysis of settled OM ---- ultimate oxidation

  20. Self purification of natural streams • Factors affecting : • Temperature : High rate of reaction & low solubility of DO • Turbulence : Maintenance of aerobic conditions • Hydrography ( flow parameters ) • Available DO • Amount and type of OM • Rate of Re-aeration

  21. Self purification of natural streams • Zones of pollution in river stream • Zone of degradation / Zone of pollution • Water is charatceried with colour and turbidity • DO reduced to 40% of its saturation value (7.6 mg/l at 30 degree c. ) • Sludge deposits • High CO2 concentrations • De-oxygenation is more than Re-oxygenation

  22. Self purification of natural streams • Zones of pollution in river stream • Zone of Recovery • River tries to regain its normal position • Cleaner water with algae formations • BOD falls down, DO conc. Rises above 40%

  23. Stream Sanitation • Oxygen Sag Curve • Streeter Phelps Equation

  24. Wastewater • Two types : Domestic & Industrial • Constituents / Components: • Solids • Suspended & Dissolved • Organic ( C,H,O, sometimes N,P,S) • Inorganic (Other than C,H,O like Ca, Mg, Heavy metals) • Nutrients (N & P) • Micro-organisms

  25. Characteristics of Sewage • Physical : (Colour, Turbidity, Solids, Conductivity) • Chemical : (pH, Acidity, Alkalinity, Chlorides etc.) • Biological: (Organic matter) • OM: • BOD5 at 20 deg. C– Biochemical Oxygen Demand (UBOD) • COD – Chemical Oxygen Demand • Th. OD = COD + NOD • TOC – Total Organic Carbon

  26. Characteristics of Sewage • Physical Characteristics • Solids • Turbidity • Colour • pH • Conductivity

  27. Characteristics of Sewage • Solids • Classified depending upon size • Very very small (Nanometer) – Dissolved Solids • 0.01 µm to 1 µm – Colloidal solids (Stable so cant settle, in Brownian movement) • Suspended solids can be removed by Settling • Settlable solids - 60 % of Total OM – Imhoff cone (ml/l) • Total Solids (TS) – Evaporate all water at 105 C (mg/l) • Total Suspended solids (TSS) - Glassfiber filter (2µm) filtration • Volatile Suspended Solids (VSS) – Muffel Furnace at 500 +- 50 C • TSS – FSS ( Left over) = VSS • Volatile Dissolved Solids (VDS) & Fixed Dissolved Solids (FDS) • Silica crucible – TDS – FDS = VDS • TVS = VSS + VDS • TFS = FSS + FDS • TS = TVS + TFS

  28. Characteristics of Sewage • Colour • Apparent colour - Due to TSS • True colour – Due to TDS • Measured with the help of colorimeter • Colour of wastewater • Grey – Non-septic • Black – Septic sewage • Grey Water – Other than toilet • Black water – From toilet

  29. Characteristics of Sewage • Physical Characteristics • pH • Conductivity • Indirect measure of measuring TDS • Conductivity = 2.5 x 10^-5 (TDS) – Applicable in case of water due to IOM solids • Wastewater mainly consists OM

  30. Characteristics of Sewage • Chemical Characteristics • Biochemical Oxygen Demand - BOD • Chemical Oxygen Demand – COD • Total Organic Carbon - TOC • Theoretical Oxygen Demand - ThOD • Nutrients • Toxic Compounds • Alkalinity • Hardness

  31. Characteristics of Sewage • Chemical Characteristics • Biochemical Oxygen Demand (BOD) – Gives pollution status of water • Oxygen demand by microbs during degradation of organic matter to CO2 & H2O under aerobic conditions at a particular temperature & incubation period • Three things are important – Micro-organisms, nutrients and DO • For valid test, DO consumption should be minimum 2 mg/l and final DO of >1 mg/l • MO seed - 10^6 to 10^7 MO per ml of domestic wastewater

  32. UBOD • Oxidation CHONS + O2 + Bacteria CO2 + H2O + NH3 + Other end products + Energy • Synthesis CHONS + O2 + Bacteria + Energy C5H7NO2 (New cell ) • Endogenous Respiration C5H7NO2 + 5O2 5CO2 + 2H2O + NH3 UBOD = O2 required for ( Oxidation + Synthesis + Endogenous Respiration )

  33. Characteristics of Sewage • Biochemical Oxygen Demand - BOD • Microbes consumes OM as a function of time (Not instantaneous consumption of OD) • BOD exertion – OM consumption : First order reaction • dL/dtα L • Where, L= OM present at any time • dL/dt = -K L • Where, K = BOD rate constant , Doubles for rvery 10 degree rise in temp • Property of OM present in wastewater • Integrating we get, L = L0 e^-Kt

  34. Characteristics of Sewage • BOD

  35. Characteristics of Sewage • BOD

  36. Characteristics of Sewage • Chemical Oxygen Demand - COD • To reduce time required for BOD (to assess pollution strength) • Microbes and DO in BOD are replaced by strong oxidizing chemicals • Potassium dichromate (Cr+6) : At high temp & low pH (Initially added – Remaining = Consumed for oxidation of OM) • Titrated with the help of FAS & Ferroin indicator • BOD/COD > 0.5 Go for biological treatment. For, Sewage it is > 0.7

  37. Characteristics of Sewage • Total Organic Carbon – TOC OM+ UV + High Temp ------------- CO2 ( detected IR analyser ) • ThOD • Used when exact composition of OM is known. ( By stoichiometric calculations) • E.g. Glucose solution C6H12O6 + 6O2 6CO2 + 6H2O One mole of glucose (180gm) = 6 Moles of O2 (192gm) ThOD = 192/180 = 1.06 gm of O2 / gm of glucose

  38. Characteristics of Sewage • Nutrients • Causes Eutrophication • Nitrates & Phosphates • Nitrates • Organic Nitrogen • Ammonical Nitrogen Org. N & NH3 NO2- (Nitrites) NO3– (Nitrates) NitrosomonasNitrobacter

  39. Characteristics of Sewage • Toxic chemicals (Difficult to degrade) • Phenols – From cleaning • Detergents & surfactants • Pesticides (DDT, BHC) • Volatile Organic Compounds - VOC - From Industries • Heavy metals – Accumulative chemicals • Copper, Cadmium, Nickel, Zinc, Mercury • Enters food chain and get Biomagnified – (Max Permissible Body Burden, MPBB)

  40. Characteristics of Sewage • Biological Characteristics • Virus • Bactria • Fungus • Yeast • Protozoa

  41. Unit Processes & Unit Operation • Unit operations are the physical operations to remove the impurities present in the water and waste water • Whereas the unit processes are the chemical and biological conversion on the status of the impurities that they will be converted to a form that can be easily separated.

  42. UNIT 2: Unit Processes & Unit Operation • Unit Operations • Screening • Skimming • Settling • Filtration • Unit Processes • Biological processes • Aerobic. An-aerobic, Anoxic etc • Chemical Processes

  43. Unit Processes & Unit Operation

  44. Introduction to Sewage Treatment • Preliminary • Screening, O&G Chamber, Grit Chamber / Detritus tank • Primary • Settling Basins • 15 to 30% BOD removal • Secondary • Filters, Aeration tanks, Oxidation ponds, Aerated Lagoon, Anaerobic Digesters etc. • Along with Secondary Settling Basins • Tertiary • Disinfection (Chlorination) • Filtration – If reuse of treated water is desired

  45. Introduction to Sewage Treatment

  46. Classification of Sewage Treatment Processes • Based On Bacterial Growth • Suspended Growth • Attached Growth • Based on mode of operation • Continuous • Batch • Based on Ecnomics • Standard (High Cost) • Low cost Treatments

  47. Sewage Treatment • Chemical • Biological • Aerobic – In presence of Oxygen • ASP, Aerated Lagoon, Oxidation Ditch, SBR, Extended Aeration, Aerated Wetland etc. • Anaerobic – In absence of Oxygen • UASB, Anaerobic Lagoon, Trickling Filters, Septic Tank etc. • Anoxic – In presence as well as absence of Oxygen • Nitrification etc.

  48. Design of Process Flow Sheets • Activated Sludge Process (ASP)

  49. Design of Process Flow Sheets • Oxidation Ditch

  50. Design of Process Flow Sheets • Aerated Lagoon & Waste Stabilization Pond

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