IPC Mid Sem (RJ) PDF

# CHE-241 (Industrial Pollution & Control) - **Pollutant**: Generally, a compound may or may not be polluted. Both chemistry and concentration are factors used to determine a pollutant. - **Environment**: A combination of various biotic and abiotic factors. - **Ecosystem**: A system where interact...

# CHE-241 (Industrial Pollution & Control) - **Pollutant**: Generally, a compound may or may not be polluted. Both chemistry and concentration are factors used to determine a pollutant. - **Environment**: A combination of various biotic and abiotic factors. - **Ecosystem**: A system where interactions between biotic and abiotic factors take place. - *Biosphere:* All the life beings on Earth - **Aquatic** - **Terrestrial** - Every ecosystem has a unidirectional energy transfer. - **Pyramids**: Number, mass, energy. - **Pollution**: Can infiltrate the food chain. - **Biomagnification**: Increase in contamination (concentration of pollutant) as the ecosystem goes. - Accumulation in top trophic level. - Hg, DDT, Diclofenac. - It is different than bioaccumulation (building up of toxin in an individual organism). ## Terminology - **Environment**: Physical surrounding where a given organism is present at the moment. - **Habitat**: Natural environment where a given organism exists naturally. - **Ecosystem**: Interactions between biotic and abiotic factors. - **Biome**: A geographic area with specific physical environment (abiotic). - **Niche**: A functional space occupied by an organism based on its activity/role. - Unique to a given organism. - Changes from time to time. - **Biomes**: A distinct geographical region with specific climate. - 5 major biomes: Aquatic, forest, grassland, desert, tundra. - A biome can have many ecosystems. # Bacteria - Unicellular organisms - They are prokaryotic (no nucleus). - Based on shape: - **Coccus** (spherical) - **Bacillus** (rod shape) - **Vibrio** (curved) - **Spirilla and spirochetes** (spiral) - Based on staining: - **Gram(+)** - **Gram(-)** - Based on environment: - **Aerobic** (O₂ present) - **Anoxic** (molecular O₂ absent but bound O (NO) present) - **Anaerobic** (both types of O₂ absent) - **Facultative** (both in presence/absence of O₂) - **Gram stain**: - **Gram positive** (thick cell wall) → crystal violet - **Gram negative** (thin cell wall) → stained pink or red ## Bacterial Nomenclature: - *Escherichia coli* - *Genus* - *species* - Not all bacteria of a given genus are pathogenic. ## Respiratory Mechanism: Aerobic - 3-steps: 1. **Glycolysis**: (glucose to pyruvate) 2. **Krebs cycle/ citric acid cycle**: (Pyruvate + O₂ → CO₂ + NADH + FADH₂) 3. **Electron transport chain/ phosphorylation**: (produce H₂O and 36 ATP) - C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP ## Respiratory mechanism: Anaerobic - 2-steps: 1. **Glycolysis**: (glucose to pyruvate) 2. **Fermentation** (production of lactic acid or ethanol/CO₂): - **Animal cells**: Lactic acid fermentation - **Yeast**: Alcoholic fermentation ## Lactic acid - C₃H₆O₃ - Fermentation: C₆H₁₂O₆ → 2C₃H₆O₃ + energy (Lactic acid) - **Anaerobic** - **Aerobic** - Used O₂ - Oxidative phosphorylation - Both make ATP, CO₂, uses glycolysis - Anaerobic (less efficient than aerobic) ## Application of Fermentation waste: - Respiration of anaerobic organism. - Used as survival mechanism (lactic acid fermentation). - For yeast, alcohol and CO₂ are a waste product, but not for humans. - Honey wine around 1700-1100, "fervere" means: - Fermentation from the word "to boil," because of bubbles produced by the mixture of crushed grapes kept in a closed vessel. - In 1700 AD, observed yeast by Antoni van Leeuwenhoek. ## Ethanol: - **Beer**: Malted barley, mixture of carbohydrates + yeast. - **Wine**: Grapes + yeast. - **Whiskey, Brandy and other alcoholic liquors**: (upto 20%) - As yeast continues to metabolize sugar, alcohol accumulates, becomes toxic and kills yeast cells. - **Distillation of fermented products** ## Bio-fuel: - **Ethanol** - **Flex-Fuel** (gasoline + ethanol) ## CO₂: - **Bakery**: Grain - hour dough cultured with yeast - **Carbonated beverages**: Sugar + yeast. - **Yogurt and cheese**: Lactose (milk sugar) + bacteria # Fungi: - **Yeast**: Multicellular → Eukaryotic - Examples: molds, mushrooms # Algae: - Need H₂O, CO₂ and minerals to grow. - Unicellular → Eukaryotic - **Algae Bloom** (aka Eutrophication) - Because of algae, DO↑, that contradiction ↑, and BOD↑. (eutrophication) # Symbiotic relation between organisms: - **Lichen**: Symbiotic relation between algae and fungi. - Fungus collects water and minerals from air. - Algae perform photosynthesis. - Grow on fresh exposed rock. - Can't grow in polluted air/ survive in SO₂. - **Rhizobium**: Gram negative bacteria, symbiotic relation with legumes. - Increase in soil fertility by giving N2.. - (Pseudomonas) Denitrification - (Nitrobacter) Nitrification - (Nitrosomonas) - **Mycorrhiza**: Symbiotic relation between fungus and plants. # Bioremediation: - The process of utilizing microorganisms to remove pollution. ## Types of Bioremediation: - **Phytoremedication**: (by plants) - **Bacteriomedication**: (by bacteria). - **Mycoremediation**: (by fungi) - **Phycoremediation**: (by algae) ## Economy-Environment Cyclic relation: - **Economic development** ↑ - **Industrial activities** ↓ - **Depletion of natural resources** - **Disturbance in natural cycle** - **Adverse effects on environment** # Biodiversity: - **Terrestrial vs. Aquatic**: - **Anthropogenic**: Human activities. - **3 types of Biodiversity**: - **Genetic diversity** - **Species diversity** - **Ecosystem diversity** - **Marine** - **Freshwater** - **Brackishwater** - **Tropical forest + Tundra** - **Grassland** - **Desert** - **Freshwater**: Salt conc. < 5 ppt (parts per thousand) - **Ocean/marine**: Salt conc. > 35 ppt - **Brackishwater**: 5 < salt conc. < 35 ppt - **Tundra** - **Temperate**: Grassland/Forest, ex. coniferous - **Tropic** # Aquatic vs. Terrestrial: - **@ ecosystem level:** - Based on phylum or type of species. - Aquatic biota more diverse than terrestrial biota (at phylum level). - Ecosystems: Marine (34 phyla) > Fresh water (17 phyla) > Terrestrial (15 only) - Coral reef ecosystem > Tropical forest > Grassland - **Coral reef:** Coral polyp + Zoanthales (animal phylum) (plant) - **@ genetic level** (species richness): - Based on no of genetically-different species. - Terrestrial >> Aquatic. - Oceans contain less than 2% of species of Earth. - Animals > Plants > Fungi. - More than 80% of all animal species are in the ocean. - **Animals:** - **Vertebrates** - **Invertebrates** - **Arthropods** (highest biodiversity) - **Crustacea** - **Arachnida** - **Insects** - **Myriapoda* ## How temperature is regulated in warm-blooded animals? - Maintaining metabolic rate (ie endothermy) - hence Endothermic (opposite - Ectothermic) - Altering pressure/flow in blood vessels (ie homeostasis) - hence homeothermic (opposite - poikilothermic) # Biodiversity Hotspots - **Criteria**: - Rich biodiversity. - Endemic (indigenous) species must be there. - Existence of significant vulnerability/threats. - **Four of the world's 35 biodiversity hotspots are in India.** ## Benefits of Biodiversity: - **Food and energy security** - **Medicinal resources and disease control** - **Nutrient recycling for preservation of soil, air and water** - **Mitigating natural disasters and pollution** (Ecotone) - **Ecotone**: Transition zone between two ecosystems. They help in maintaining ecosystems. - **Mangrove forest**: (between terrestrial and marine) - Protects from storms and coastal erosion. - Protects from floods and assist in ground water charging. - **Marshland**: (between dry and wetland) - **Backish water ecosystems** (between freshwater and saltwater) - **Estuary and Lagoon**: Confined mass of ocean water. - Marsh grasses of estuary, act as a filter for pollutants (pesticides, heavy metals) - **Grassland**: (between forest and deserts) - Helps in carbon sequestration. # Conservation Efforts for Biodiversity: - **Advantages** - **Risk factors** - **Conservation efforts** - **Top predator**: Vulture (keystone species) - **Impact of bio mass** - **Foundational species** - **Common species** - **# of bio mass/species** - **Endangered species** - **Vulture regulates the lower trophic levels.** - **Umbrella species**: By taking care of one species, we can take care of the entire species in an ecosystem. - **eg: Tree**: - **Reverse pyramid** - **Detrivore**: That survive on dead species. - **Exotic species "Alien"**: Species of other habitat migrated to different habitat. - Eg: Water Hyacinth (Terai of Bengal) which will overtake the ecosystem or may not survive. - Eucalyptus (consumes a huge amount of water) - **Indicator species**: Species which population decreases if their surviving environment is polluted (indicator of pollution). - Eg: Lichen - Frog, etc. - **Endemic species**: Indigenous species (which are present in specific environment). - Eg: **Red Panda** ## Risk factors to biodiversity: 1. **Habitat destruction due to human activities** (main cause). 2. **Pollution** 3. **Introduction of alien species** 4. **Natural disasters** 5. **Breakdown of ecosystem** ## Conservation Efforts for Biodiversity: - **Natural:** - **Ex-situ:** Taking species from one habitat to other habitat. - Eg: Zoo/Botanical garden, gene bank, aquarium. - **In-situ**: Preserving species in their own habitat. - Eg: Sacred means, protected zones: - **WLS** (Wildlife Sanctuary) - **BSR** (Biospehere Reserve) - **NP** (National Park) - **Highly protected/restricted** - **Biosphere sphere:** - *Buffer zones:* - *Core zone:* (nothing happens) - *Transition zones:* - **Restriction increases as we move towards the core.* - **18 biosphere reserves in India.** # Pollutants - **Based on their origin:** - **Primary pollutants** (eg: NOx, SOx from vehicles, CH₄ (cutter logged region), NH₃, Particulate, CO₂, CO) - **Secondary pollutants** (eg: Smog, PAN, Troposphere O₃, Acid rain) - **Peroxy acetyl nitrate** - **Based on sources:** - **Natural** (NOx, SOx, CH₄) eg: Volcanoes, weathering - **Anthropogenic** (NOx, SOx, CH₄, NH₃) eg: Fertilizers, industry (carried also by Western Disturbances). # Smog: - **Smog**: Smoke + fog. - **Caused by**: Burning of large amounts of coal, vehicular emission and industrial fumes (primary pollutant). - **Contains**: Soot particulates, NOx, SOx and other components. - **Causes**: Reduced visibility, plant damage, eye irritation and respiratory distress. - **Two types**: - **Photochemical smog**: (Los Angeles smog) → due to NOx - NOx + VOC + O₂ + UV → O₃, PAN and other oxidants. - Brownish appearance. - Occurs predominantly in urban areas that have large no. of automobiles. - **Sulfurous smog** (London smog) → due to SOx - SOx + H₂O + PM → Grey-S-smog - Acid rain. - **Based on the presence:** - **Quantitative**: (when cure of pollutants increase in the environment already presents) - **Qualitative**: (Added by human to environment), not found naturally, even a single trace can be a pollutant. - **Based on degradability**: - **Biodegradable** - **Non-biodegradable** (plastics). ## Types of plastic: 1. **PET** (Polyethylene terephthalate) → waterproof heat resistant, indestructible 2. **HDPE** (High-density polyethylene) → semi-flexible, solid, waterproof 3. **PVC** (Polyvinyl chloride) → transparent, transparent, unbranched 4. **LDPE** (Low-density polyethylene) → tough, flexible, branched 5. **PP** (Polypropylene) → glass-like surface. 6. **PS** (Polystyrene) ## PMMA: - **Polymethyl methacrylate** → transparent, Acrylic sheet, Acrylic Laminar sheet (flexed glass), (glossy). - **Polycarbonate** - **ABS** (Acrylonitrile Butadiene Styrene) - Monomers combined: Acrylonitrile, 1-3 butadiene , styrene. - **Teflon** (PTFE) - Relatively high melting points. - **PBT** (Polybutylene Terephthalate). - **PVB** (Polyvinyl butyral). # Petrochemical Industry: - **Building blocks of Petrochemicals:** - **Syngas** (or synthesis gas) [(CO + H₂) + trace of CO₂/CH₄] - CH₄ + H₂O → CO + 3H₂ (steam reforming) - C + H₂O → CO + H₂ (coal gasification) - **Olefins**: (Ethylene, Propylene, Butylene) - Formed by steam cracking of alkanes and naphtha. - **Benzene, Toluene, Xylene (BTX).** - **Feedstock**: - **Methane (C₁)**, **Carbon**, **Alkane (C₂-C₄)**, **Naphtha** (C₅-C₉) - **Natural source**: Natural gas, coal, crude oil ## Pollutants from Fuel and Petrochemicals Products: - **Fossil fuels**: Coal, natural gas, crude oil. # Thermal Power Plants: - Almost two-thirds of electricity requirements of the world is fulfilled by thermal power plants. - Much of the coal being burned today in India is low-grade coal and results in significant air pollution. - **Coal types**: - **Peat**: Low carbon, high concentration of salt. - **Lignite**: Sub-bituminous - **Anthracite**: High carbon content. - **Bituminous**: Semi-anthracite - **Coal thermal power plants (TPPs)** are responsible for a higher share of emissions in the industrial sector. - 60% of PM (particulate matters) - 45% of SO₂ - 30% of NO₂ and 80% of Hg. ## Common particulate matter (PM) sizes: - Smaller the PM sizes - more dangerous to humans. - **PM₁₀**: (aerodynamic diameter < 10 µm) - **PM₂.₅**: (dia < 2.5 µm) → linked to health impacts. - **PM₁**: (dia < 1 µm) → new research linked to health impacts. - **UFP**: (dia < 100 nm)→ emerging research linked to health impacts. - **Fly ash**: Fly ash is the fine powder from the mineral matter present in coal, consisting of non-combustible matter. - **Hazardous** for humans and agri-crops, used in cement making. - **Major components**: SiO₂, Al₂O₃, Fe₂O₃, lime, MgO, SO₂. ## SOx Emission: - **TPPs** are the major contributors in the SOx emission. - **Automobile sector** is the next one. - To regulate SOx emission, in the automobile sector, the **Bharat Stage (BS) emission standards** are laid down since 2000. - To regulate output of air pollutants from engines - Regulated by CPCB under MoEFCC. - **BS-VI norm**, states sulphur amount to be less than 10 ppm. ## Bio-mass Co-Firing: - Process of using biomass in coal thermal plants as a partial replacement. - **Less sulphur** than coal fuel replacements, co-firing reduces emissions of CO₂, CO. - An effective way to curb emissions from open burning of crop residue, can help cut emissions from open combustion of fossil fuels. # Steel Industry: - After fossil fuel based sources, **steel and cement industries** are major CO₂ emitters. - **Steel**: Alloy of iron + carbon. - **Due to emissions** from blast furnace. - **Based on carbon content**: - **Pig iron**: (Less C) - **Wrought iron**: (upto 2-4%) - **Lutein**: (upto 2%) - Fe₂O₃ + 3C → ¹¹²³K 2Fe + 3CO - Fe₂O₃ + 3CO → ¹¹²³K 2Fe + 3CO₂ - **More C content in cast iron > steel > wrought iron** ## Green house gases (GHGs) - A part of the Earth is the main source of IR radiation. - **Greenhouse effect:** Solar radiation passes through the clear atmosphere, most radiation is absorbed by Earth's surface and warms it. Some solar radiation is reflected by Earth and the atmosphere, some of infrared radiation passes through the atmosphere and some is absorbed and re-emitted in all molecules. The effect of this is to warm the Earth's surface and the lower temperature. Infrared radiation is emitted from the Earth's surface (terrestrial radiation). - **Albedo Radiation:** Solar radiation, which gets reflected back by Earth’s surface. - **Any gas which absorbs IR, then it is called GHG (greenhouse gases)**. - **Temperature decreases as we move away from the Earth’s surface.** - **Lapse rate:** Rate of change of temperature with respect to change in height is called as lapse rate (dT/dz). - **Adiabatic**: PdV = -VdP (pvr = constant) - **1st law of thermodynamics**: MdT - VdP = 0. - **Dry adiabatic lapse rate:** -dT = g = 9.8 °C/Km, - **Wet adiabatic LR ~ 6 °C/Km < DALR**. - **A “Stable” Atmosphere**: - Gradual temperature decreases with height (ie humid environment.) - Minimal vertical convection of air parcels. - Calm and predictable weather. - Often associated with layered clouds with little vertical development . - Prone to temperature inversion. - **Temperature inversion occurs generally in foggy weather.** * - **Stagnant zone, no air convection.** ## GHGS - Absorb infrared radiation. - To absorb IR, molecules must have dipoles/transient dipoles/dipole vibrates. - **Relative global warming potentials of main GHGs**: CO₂ < CH₄ < N₂O < HFCs < NF₃ < SF₆. # Water Quality Parameters: ## Physical: - TDS - TSS - Turbidity - Color - Particle size and shape. ## Chemical: - Hardness - Chlorine - DO (dissolved oxygen) - BOD (Biochemical oxygen demand) - COD (Chemical oxygen demand) - TIC (Total inorganic carbon) - TOC (Total organic carbon) - TC (Total carbon) - Phosphorus, sulphur, chloride, and other trace elements. ## Biological: - Microbes such as bacteria, viruses, parasites, O₂ required for nitrification and microbial population. ## Size classification of solids: - **Suspended** (above 1µm) - **Colloidal** (between 1µm to 1µm) → may exhibit the characteristics of dissolved solids. - **Dissolved** (below 1µm) ## Solution: - Solute is atomically dispersed. - **Resolution Limit (RL) = λ/2NA** - Human eyes can’t see below 1µm. # Colloidal solution: - A dispersed phase (discontinuous phase, small amount) - A dispersed medium (continuous phase, large amount). - Particles have diameter of between approximately 1µm - 100 nm - **Solid in solid**: Solid-sol (alloys) - **Solid in liquid**: Sol (ink, blood) - **Solid in gas**: Aerosol (smoke) - **Liquid in solid**: Gel (jelly) - **Liquid in liquid**: Emulsion (milk) - **Liquid in gas**: Liquid aerosol (cloud, fog) - **Gas in solid**: Solid foam (aerogel) - **Gas in liquid**: foam (shaving cream) - **Gas in gas**: None. # TSS (Total Suspended Solid) - **mg/L** - Desirable limit for TSS is **zero** - **Thermogravimetric method**: Filter size ≤ 1µm - Pass the water through a filter. # TDS (Total dissolved solid) - Source: Salts dissolved in water. - Desirable limit: - Below 300 mg/L or ppm (WHO) - Below 500 mg/L or ppm (BIS) - Total solid = Boil off the water and measure weight of residue (TS). - **Thermogravimetric method** - TS - TSS = TDS ## Electrochemical method: - TDS (mg/L) = K x EC (µS/cm) - Electrical conductivity - The relationship between conductivity and TDS is not linear. - The value of K will increase along with the increase of ions in water. - Depends on the type of water (ie nature of ions) # Turbidity: - Measure of cloudiness, i.e TSS, which leads to turbidity. - Upper limit of turbidity → Measured in **NTU** (Neflon Turbidity units). - **Drinking water:** < 1 NTU (or desired) - **Safe:** < 5 NTU. - Measured by **Neflanter**. - **If particle size < λ**: Forward scattering (Low TSS) . - **If particle size > λ**: Backward scattering (High TSS). - Neflanter captures the scattered light at a specific angle and calibrates reading. # Color: - **Measures** absorbance of the sample in UV-visible range. - **UV-Vis spectrophotometer** (measures the color). - **Absorbance**, A, of the solution is related to transmittance and incident intensities as following: - T = I_t/I_₀ - A = log I_₀/ I_t - { A + R + T = 1} - reflection= small, assumed negligible. - A = 1 - T = 1 - (1 - σMT) - very small - A = -σMT ## Beer-Lambert Law: - **Beer’s law**: Absorbance of a solution (fractional decrease in intensity of beam) I is directly proportional to conc. of absorbing species (A α C) - **Lambert’s Law**: A α path length (l) by light in sample. - On combining A α cl → A = εcl. - **ε**: Molar absorption coefficient (m^-1cm^-1) - **c**: Molar concentration (M) - **l**: Optical path length (cm) ## Derivation of Beer-Lambert Law: - Total area A, absorbing species of cross-section area σ. - σ = capture area of one molecule. - N = molecules / cm³ - Total opaque/capture area on the slab due to absorbers = σ*N*A*dz - Decrease in the intensity (capture area/area): (Fraction lost?)= {[[[*σ*N*A*dz]/A} - -dI_z = {[[*σ*N*A*dz]/A} - dI_z = ∫_₀^b -[σ*N*A*dz] - ∫_{I_₀}^I_z dI_z = ∫_₀^b -[σ*N*A*dz] - -ln(I_z/I_₀) = σ*Ν*b/A ## Limitations of Beer Lambert Law: - The linearity of the Beer-Lambert law is limited by: - Deviations in the absorptivity coefficients of high concentrations (>0.01 M) due to electrostatic interactions between molecules in close proximity. - Fluorescence or phosphorescence of the sample. - Changes in refractive index at high analyte concentration. - Scattering of light due to particulates in the sample. # Size (particle size measurement): - **Dynamic light scattering**: It measures Brownian motion and relates this to the size of the particles. - Smaller particles move faster, larger particles move slower. - **Illuminating the particles with a laser and analyzing the intensity fluctuations in the scattered light**. - **Light scattered by moving particles carries information about the size distribution.** - The velocity of a particle measured by an electric field is referred too as it's **electrophoretic mobility**, measured by **Doppler effect** due to change in frequency. ## DLS for particle size measurement: - **Stokes-Einstein equation**: D_h = k_BT/ 3πηD_t{D_t: Diffusion coefficient = v x l x 3}. - Where D_n is the hydrodynamic diameter (goal: Particle size) - D_t is the translational diffusion coefficient (find by dynamic light scattering) - k_B: Boltzmann constant - T: Thermodynamic temperature (controlling it) - η: Dynamic viscosity (known) # Shape: ## Resolution of a microscope - d (resolution limit) = λ/[2n sin(β)] = λ/2(NA). - d_min = λ/2 in air. - Resolution limit α 1/ resolution power. ## SEM (Scanning Electron Microscopy): - < 10nm, Nowadays, field emission (FESEM) is used. - SEM is a microscope that uses electrons rather than light to form an image. - Clean environment is required - Electron gun (sheet electron beam) - Electromagnetic Lenses (anode lens, magnetic lens) - Only analyze limited number of particles. - **Applications**: - Structural analysis - Chemical information. - **Secondary electrons**: will tell topography, - **Backscattered electrons**: will tell mass. - **X-rays**: will tell about atomic number of the element (chemistry). - **Heavy elements (high AN)** backscatter electrons more strongly. ## EDX (energy-dispersive X-ray): - Analytical technique used for the elemental analysis of a surface. - Used for **chemical characterization of a sample by analyzing X-rays** emitted by the matter. - **Applications**: - Traces of heavy metals. - Characterize different isotopes. - **Limitations**: 1. It does not work with elements with low atomic number (H, He). 2. If the conc. of an element in the sample is too low, the amount of energy given off by X-rays after hitting the samples will be insufficient to measure the proportion. 3. Li, Be have low atomic no., that energy of X-ray given off is insufficient for measurement. 4. X-rays can only effective at measuring at surface layers (no much penetration). # Carbon compounds in water: - **TC**: Total C - **TOC**: Non-organic C. - **Not oxidizable**: COD - **Not biologically degradable**: BOD - **COD**: mg of O₂ required to oxidize organic C present in IL of water. - **BOD**: mg of O₂ required to degrade or to oxidize biological organic C in IL of water ## Determination of COD by Titrimetric method: - **Reaction** - C_x H_y O_z + Cr₂O₇^-2 (excess) →^Ag₂SO₄ CO₂ + H₂O + Cr⁺³ - **K₂Cr₂O₇ (acidic)** - (Potassium permanaganate) - Cr₂O₇^-2 (residue) + 6Fe⁺² + 14H⁺ → 6Fe⁺³ + 2Cr⁺³ + 7H₂O - (FAS) - Organic compound in water sample oxidizing by excess of K₂Cr₂O₇ under acid and hot condition. Excess of K₂Cr₂O₇ titrated by standard FAS (ferrous ammonium sulfate) solution to ferroin as indicator remaining. - **End point**: Greenish hue to brownish red. - **COD**: - (a - b) X N x 8000/ mL sample - **a**: mL FAS for blank titration. - **b**: mL FAS sample titration waste water. - **N**: Normality of FAS. - **(a - b) x V**: mg-eq. of organic C present in sample. - **mg of O₂ equivalent** in 1L of water to oxidize C. ## Dissolved oxygen (D.O) - mg O₂ dissolved in 1L of water. - Solubility of Oxygen in water is 8-9 mg/L (T = 20°C). - **Solubility of oxygen in water is influenced by**: - Temperature - Pressure - Water turbulence - Level of contamination. - **High level of DO**: Quality of water is good. - **Low DO level**: Indicates water contaminant . ## Determination of D.O by Winkler method: - **Reaction:** 1. MnSO₄ + 2KOH → Mn(OH)₂ + K₂SO₄ (alkaline) 2. Mn(OH)₂ + 1/2O₂ → MnO₂ + H₂O 3. MnO₂ + 2I⁻ + 4H⁺ → Mn⁺² + I₂ + 2H₂O 4. I₂ + 2S₂O₃^-2 → S₄O₆⁻² + 2I⁻ - Oxygen in sample oxidizing Mn⁺² which additionally under base condition, until precipitate formation of MnO₂. By addition of H₂SO₄ and KI, then will be released I₂ eqed to dissolved O₂. Released of I₂, then titrated by standard Na₂S₂O₃ solution. - **DO (mg/L) = 1000 x a x [Na₂S₂O₃] x 8/V_sample.** # BOD - BOD is measured over 5 days. - BOD₅ of wastewater = DO consumed by diluted sample x Vol. of diluted sample/Vol. of undiluted sewage used. (ΔDO) - ΔDO = DO after 5 days - Initial DO. - Vol. of diluted sample = Total water taken. - Waste water volume in taken volume.